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Sample records for giant magnetostrictive materials

  1. Tailoring volume magnetostriction of giant magnetostrictive materials by engineering magnetic domain morphology

    NASA Astrophysics Data System (ADS)

    Zhang, Changsheng; Ma, Tianyu; Sun, Guangai

    2017-02-01

    Volume conservation is usually considered for the classic magnetostrictive materials during technical magnetization process. The present work reports the forced volume magnetostriction prior to saturation magnetization in the rare-earth giant magnetostrictive materials by engineering the initial magnetic domain morphology. It is found that the volume magnetostriction can be manipulated with the changeable sign and magnitude from about -200 × 10-6 at the thermal-demagnetized state to 450 × 10-6 at the domain-aligned state. Such behavior arises from the different domain pathways. On the light of these observations, the exploration of materials design and applications based on the volume magnetostriction effect might be facilitated.

  2. Application of Giant Magnetostrictive Materials for Sonar Transducers

    NASA Astrophysics Data System (ADS)

    Long, Nguyen Thang; van Hien, Nguyen; Thuy, Nguyen Phu; Hien, Vu The

    2001-04-01

    Giant magnetostrictive material (Terfenol-D) has been extensively used in many applications such as actuators and sonar projectors. However, its major disadvantage is the relative high price due to the complication of manufacturing process. A high strain at moderate field can only be obtained with the single crystal or grain oriented polycrystal. In addition, the use of Terfenol-D is limited at high frequencies because its electrical conductivity is as high as metals. Overcoming this problem by using laminated or rolled sheets of Terfenol-D requires expensive techniques due to their brittleness. In this paper, we present studies on the behavior of Terfenol-D rod under dynamic condition in a Tonpilz type transducer. In addition, a Zinc-bonded sample is prepared and measured to compare with that of the bulk material.

  3. On the use of giant magnetostrictive materials in sonic transducers for liquid atomizers

    NASA Astrophysics Data System (ADS)

    Sheykholeslami, M.; Ghodsi, M.; Hojjat, Y.; Sadeghian, H.; Cinquemani, S.

    2016-04-01

    Liquid atomization has many applications such as car fuel injector, heat dissipation, coating, medical use, etc. The most common way in atomization is to exploit high frequency and high vibration amplitudes of piezoelectric devices. This paper investigates the effectiveness of a giant magnetostrictive transducer for atomizing liquids. Effect of vibration amplitudes on output parameters such as atomization size and output Dubai have been investigated so as the frequency response of the transducer when plunged into the water. Droplet size particles have been measured through high speed camera. Results show that using giant magnetostrictive transducer leads to uniformity that is considered a key factor in many applications. Results demonstrates that sonic transducers based on giant magnetostrictive material can be profitably used as liquid atomizers.

  4. Static and dynamic property experiments of giant magnetostrictive material-fiber Bragg grating magnetic field sensors

    NASA Astrophysics Data System (ADS)

    Ding, Guoping; Liu, Jiayi; Gao, Bin; Zhang, Biyun

    2015-02-01

    Nowadays, there are many kinds of magnetic field sensors such as Hall sensor, Gauss meter and so on. But few of them can be used in the small air gaps which size is about millimeter. A thin-slice Giant Magnetostrictive Material-fiber Bragg grating (GMM-FBG) magnetic field sensor was proposed with the size of 14mm×7mm×1.5mm. The FBG was bonded along the GMM slice length orientation, perpendicular to the major magnetostriction orientation, to measure the GMM's strain caused by external magnetic field. Experiment systems were established to test the GMM-FBG sensor's static and dynamic properties. The results show that the sensor's static property is consistent with the theoretical prediction, and the dynamic response is feasible in low frequencies from 1Hz to 20Hz.

  5. An analytical and explicit multi-field coupled nonlinear constitutive model for Terfenol-D giant magnetostrictive material

    NASA Astrophysics Data System (ADS)

    Zhou, Hao-Miao; Li, Meng-Han; Li, Xiao-Hong; Zhang, Da-Guang

    2016-08-01

    For a giant magnetostrictive rod under the action of multiple physical loads, such as an external magnetic field, temperature and axial pre-stress, this paper proposes a general one-dimensional nonlinear magneto-thermo-mechanical coupled constitutive model. This model is based on the Taylor expansion of the elastic Gibbs free energy of giant magnetostrictive material and thermodynamic relations from the perspective of macro continuum mechanics. Predictions made using this model are in good agreement with experimental data for magnetization and the magnetostrictive strain curve under the collective effect of pre-stress and temperature. Additionally, the model overcomes the drawback of the existing magneto-thermo-mechanical constitutive model that cannot accurately predict the magnetization and magnetostrictive strain curve for different temperatures and pre-stresses. Furthermore, the constitutive model does not contain an implicit function and is compact, and can thus be applied in both situations of tensile and compressive stress and to both positive and negative magnetostrictive materials, and it is thus appropriate for engineering applications. Comprehensive analysis shows that the model fully describes the nonlinear coupling properties of a magnetic field, magnetostrictive strain and elasticity of a magnetostrictive material subjected to stress, a magnetic field and heat.

  6. Study on the dynamic characteristics of a high frequency brake based on giant magnetostrictive material

    NASA Astrophysics Data System (ADS)

    Xu, Ai Qun

    2016-06-01

    In order to meet the requirements of rapid and smooth braking, high-frequency braking using a giant magnetostrictive actuator is proposed, which can solve the problems in hydraulic braking, such as, it leaks easily, catches fire easily, is difficult to find failures, high cost on maintenance and repairing, etc. The main factors affecting the force of a high-frequency braking actuator are emphatically analyzed, the brakes dynamic model is established and a performance testing device for high frequency braking is constructed based on LabVIEW. The output force of the actuator increases with the excitation current of the driving coil increasing, and the increased multiple of the output force is greater than that of the excitation current; the range of the actuator force amplitude is 121.63 N ∼ 158.14 N, which changes little, while excitation frequency changes between 200 Hz ∼ 1000 Hz. In a minor range of pre-stress, the output force decreases with an increase in the axial pre-stress of the giant magnetostrictive rod, but is not obvious. It is known by finite element simulation analysis that high-frequency braking shortens the braking displacement and time effectively, which proves the feasibility and effectiveness of high frequency braking. Theoretical analysis and experimental results indicate that the output force of the actuator changes at the same frequency with excitation current; it is controllable and its mechanical properties meet the requirements of high frequency braking.

  7. Design and experimental study of a novel giant magnetostrictive actuator

    NASA Astrophysics Data System (ADS)

    Xue, Guangming; Zhang, Peilin; He, Zhongbo; Li, Dongwei; Huang, Yingjie; Xie, Wenqiang

    2016-12-01

    Giant magnetostrictive actuator has been widely used in precise driving occasions for its excellent performance. However, in driving a switching valve, especially the ball-valve in an electronic controlled injector, the actuator can't exhibit its good performance for limits in output displacement and responding speed. A novel giant magnetostrictive actuator, which can reach its maximum displacement for being exerted with no bias magnetic field, is designed in this paper. Simultaneously, elongating of the giant magetostrictive material is converted to shortening of the actuator's axial dimension with the help of an output rod in "T" type. Furthermore, to save responding time, the driving voltage with high opening voltage while low holding voltage is designed. Responding time and output displacement are studied experimentally with the help of a measuring system. From measured results, designed driving voltage can improve the responding speed of actuator displacement quite effectively. And, giant magnetostrictive actuator can output various steady-state displacements to reach more driving effects.

  8. Magnetization and magnetostriction in highly magnetostrictive materials

    SciTech Connect

    Thoelke, Jennifer Beth

    1993-05-26

    The majority of this research has been in developing a model to describe the magnetostrictive properties of Terfenol-D, Tbsub>1-xDyxFey (x = 0.7-0.75 and y = 1.8--2.0), a rare earth-iron alloy which displays much promise for use in device applications. In the first chapter an introduction is given to the phenomena of magnetization and magnetostriction. The magnetic processes responsible for the observed magnetic properties of materials are explained. An overview is presented of the magnetic properties of rare earths, and more specifically the magnetic properties of Terfenol-D. In the second chapter, experimental results are presented on three composition of Tb< with x = 0.7, y= 1.9, 1.95, and x= 0.73, y= 1.95. The data were taken for various levels of prestress to show the effects of composition and microstructure on the magnetic and magnetostrictive properties of Terfenol-D. In the third chapter, a theoretical model is developed based on the rotation of magnetic domains. The model is used to explain the magnetic and magnetostrictive properties of Terfenol-D, including the observed negative strictions and large change in strain. The fourth chapter goes on to examine the magnetic properties of Terfenol-D along different crystallographic orientations. In the fifth chapter initial data are presented on the time dependence of magnetization in nickel.

  9. Method of making active magnetic refrigerant, colossal magnetostriction and giant magnetoresistive materials based on Gd-Si-Ge alloys

    DOEpatents

    Gschneidner, Jr., Karl A.; Pecharsky, Alexandra O.; Pecharsky, Vitalij K.

    2003-07-08

    Method of making an active magnetic refrigerant represented by Gd.sub.5 (Si.sub.x Ge.sub.1-x).sub.4 alloy for 0.ltoreq.x.ltoreq.1.0 comprising placing amounts of the commercially pure Gd, Si, and Ge charge components in a crucible, heating the charge contents under subambient pressure to a melting temperature of the alloy for a time sufficient to homogenize the alloy and oxidize carbon with oxygen present in the Gd charge component to reduce carbon, rapidly solidifying the alloy in the crucible, and heat treating the solidified alloy at a temperature below the melting temperature for a time effective to homogenize a microstructure of the solidified material, and then cooling sufficiently fast to prevent the eutectoid decomposition and improve magnetocaloric and/or the magnetostrictive and/or the magnetoresistive properties thereof.

  10. Analytical model of a giant magnetostrictive resonance transducer

    NASA Astrophysics Data System (ADS)

    Sheykholeslami, M.; Hojjat, Y.; Ansari, S.; Cinquemani, S.; Ghodsi, M.

    2016-04-01

    Resonance transducers have been widely developed and studied, as they can be profitably used in many application such as liquid atomizing and sonar technology. The active element of these devices can be a giant magnetostrictive material (GMM) that is known to have significant energy density and good performance at high frequencies. The paper introduces an analytical model of GMM transducers to describe their dynamics in different working conditions and to predict any change in their performance. The knowledge of the transducer behavior, especially in operating conditions different from the ideal ones, is helpful in the design and fabrication of highly efficient devices. This transducer is design to properly work in its second mode of vibration and its working frequency is around 8000 Hz. Most interesting parameters of the device, such as quality factor, bandwidth and output strain are obtained from theoretical analysis.

  11. Design, analysis, and modeling of giant magnetostrictive transducers

    NASA Astrophysics Data System (ADS)

    Calkins, Frederick Theodore

    The increased use of giant magnetostrictive, Terfenol-D transducers in a wide variety of applications has led to a need for greater understanding of the materials performance. This dissertation attempts to add to the Terfenol-D transducer body of knowledge by providing an in-depth analysis and modeling of an experimental transducer. A description of the magnetostriction process related to Terfenol-D includes a discussion of material properties, production methods, and the effect of mechanical stress, magnetization, and temperature on the material performance. The understanding of the Terfenol-D material performance provides the basis for an analysis of the performance of a Terfenol-D transducer. Issues related to the design and utilization of the Terfenol-D material in the transducers are considered, including the magnetic circuit, application of mechanical prestress, and tuning of the mechanical resonance. Experimental results from two broadband, Tonpilz design transducers show the effects of operating conditions (prestress, magnetic bias, AC magnetization amplitude, and frequency) on performance. In an effort to understand and utlilize the rich performance space described by the experimental results a variety of models are considered. An overview of models applicable to Terfenol-D and Terfenol-D transducers is provided, including a discussion of modeling criteria. The Jiles-Atherton model of ferromagnetic hysteresis is employed to describe the quasi-static transducer performance. This model requires the estimation of only six physically-based parameters to accurately simulate performance. The model is shown to be robust with respect to model parameters over a range of mechanical prestress, magnetic biases, and AC magnetic field amplitudes, allowing predictive capability within these ranges. An additional model, based on electroacoustics theory, explains trends in the frequency domain and facilitates an analysis of efficiency based on impedance and admittance

  12. Giant self-biased magnetoelectric response with obvious hysteresis in layered homogeneous composites of negative magnetostrictive material Samfenol and piezoelectric ceramics

    NASA Astrophysics Data System (ADS)

    Zhang, Jitao; Li, Ping; Wen, Yumei; He, Wei; Yang, Aichao; Lu, Caijiang

    2013-11-01

    Giant self-biased magnetoelectric (ME) response and obvious hysteresis are observed in trilayer homogenous ME laminate composite consisting of negative magnetostrictive Samfenol (SmFe2) plates and piezoelectric ceramic PZT (Pb(Zr,Ti)O3) plates. The large anisotropic field of SmFe2 oriented the direction [111] of easy magnetization results in an enhanced internal bias due to its huge intrinsic anisotropic constant. The experimental results demonstrate that this composite exhibits ˜30 times higher ME voltage coefficient than that of composite FeNi/PZT/FeNi with weak ME coupling at zero bias. These results provide the possibility of this homogeneous ME composite for ultra-sensitive magnetic field sensing without bias.

  13. Electromechanical coupling measurement of a new giant magnetostrictive structure for double-nut ball screw pre-tightening

    NASA Astrophysics Data System (ADS)

    Wang, Qingdong; Lin, Mingxing

    2016-12-01

    Under the action of an external magnetic field, giant magnetostrictive material (GMM) is magnetized and generates magnetostriction, so its dimension will change accordingly. In this work, two giant magnetostrictive structures are proposed for ball screw pre-tightening, but a finite element calculation shows that solid cylindrical GMM is better than a hollow one because it has a more uniform magnetization intensity. So a solid cylindrical GMM is used to build a ball screw pre-tightening structure. Experiments show that when the working current changes from  -3 A to 3 A, the magnetostrictive structure made of ϕ 10  ×  120 mm GMM will output magnetostrictive deformation in the form of pre-tightening force, which is up to 1892.87 N. The axial rigidity performance of ball screw is improved by pre-tightening force adjustment. This research not only lays the theoretical and experimental foundations for applying a giant magnetostrictive structure to double-nut ball screw pre-tightening, but also provides a new method for the timely adjustment of a double-nut ball screws pre-tightening force.

  14. Structure design and driving voltage optimization of a novel giant magnetostrictive actuator

    NASA Astrophysics Data System (ADS)

    Xue, Guangming; Zhang, Peilin; He, Zhongbo; Li, Dongwei; Cai, Canwei

    2017-01-01

    Typical giant magnetostrictive actuator (GMA) cannot meet the requirement of driving a high-speed on-off valve for limitation in bias magnetic field exerted on giant magnetostrictive material. To solve this problem, a novel GMA is designed with zero bias magnetic field. Furthermore, to satisfy the requirement of the displacement direction, a “T” type transfer rod is joined to convert material’s elongating into actuator’s shortening. Simultaneously, long responding time of the actuator, especially the rising time of coil current, is also considered in this paper. The transient-state current is modeled based on the equivalent circuit considering parallel resistance of the coil, and from computed result, high opening voltage can be taken to promote responding speed of the actuator, and then an optimized driving voltage wave is presented. At last, with the help of an experimental system, the current model is verified and the driving effect of optimized voltage wave is tested and analyzed.

  15. A critical analysis of the feasibility of pure strain-actuated giant magnetostrictive nanoscale memories

    NASA Astrophysics Data System (ADS)

    Gowtham, P. G.; Rowlands, G. E.; Buhrman, R. A.

    2015-11-01

    Concepts for memories based on the manipulation of giant magnetostrictive nanomagnets by stress pulses have garnered recent attention due to their potential for ultra-low energy operation in the high storage density limit. Here, we discuss the feasibility of making such memories in light of the fact that the Gilbert damping of such materials is typically quite high. We report the results of numerical simulations for several classes of toggle precessional and non-toggle dissipative magnetoelastic switching modes. Material candidates for each of the several classes are analyzed and forms for the anisotropy energy density and ranges of material parameters appropriate for each material class are employed. Our study indicates that the Gilbert damping as well as the anisotropy and demagnetization energies are all crucial for determining the feasibility of magnetoelastic toggle-mode precessional switching schemes. The roles of thermal stability and thermal fluctuations for stress-pulse switching of giant magnetostrictive nanomagnets are also discussed in detail and are shown to be important in the viability, design, and footprint of magnetostrictive switching schemes.

  16. Modeling of magnetostrictive materials and structures

    SciTech Connect

    Gopalakrishnan, S.

    2008-07-29

    The constitutive model for a magnetostrictive material and its effect on the structural response is presented in this article. The example of magnetostrictive material considered is the TERFENOL-D. As like the piezoelectric material, this material has two constitutive laws, one of which is the sensing law and the other is the actuation law, both of which are highly coupled and non-linear. For the purpose of analysis, the constitutive laws can be characterized as coupled or uncoupled and linear or non linear. Coupled model is studied without assuming any explicit direct relationship with magnetic field. In the linear coupled model, which is assumed to preserve the magnetic flux line continuity, the elastic modulus, the permeability and magnetoelastic constant are assumed as constant. In the nonlinear-coupled model, the nonlinearity is decoupled and solved separately for the magnetic domain and the mechanical domain using two nonlinear curves, namely the stress vs. strain curve and the magnetic flux density vs. magnetic field curve. This is performed by two different methods. In the first, the magnetic flux density is computed iteratively, while in the second, the artificial neural network is used, where in the trained network will give the necessary strain and magnetic flux density for a given magnetic field and stress level. The effect of nonlinearity is demonstrated on a simple magnetostrictive rod.

  17. Giant Magnetostriction in Annealed Co1-xFex Thin-Films

    DTIC Science & Technology

    2011-11-01

    REPORT Giant magnetostriction in annealed Co1?xFex thin-films 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: Chemical and structural heterogeneity and the...structural heterogeneity in textured Co1?xFex thin films, effective magnetostriction ?eff as large as 260 p.p.m. can be achieved at low-saturation field of...Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS Giant magnetostriction in annealed Co1?xFex thin-films

  18. Strain of optic-fiber/giant magnetostrictive film structure in magnetic field by finite element analysis

    NASA Astrophysics Data System (ADS)

    Hu, Jiafei; Pan, Mengchun; Xin, Jianguang; Chen, Dixiang

    2008-12-01

    The magnetostrictive transducer is the most important part of the optic-fiber magnetic field sensor, and the optic-fiber/giant magnetostrictive(GMS) film coupled structure is a novel coupling form of the magnetostrictive transducer. Always we analyze the coupled structure based on the entire coupled structure being sputtered GMS material without tail-fibers. In practical application, the coupled structure has tail-fibers without films at two ends. When the entire coupled structure is immersed in the detected magnetic field, the detected magnetic field causes the GMS film strain then causing optic-fiber strain. This strain transmission process is different from it in the coupled structure entirely with GMS films without tail-fibers. The strain transmission relationship can be calculated theoretically in the coupled structure without tail-fibers, but it's complicated to theoretically calculate the strain transmission relationship in the coupled structure with tail-fibers. After large numbers of calculations and analyses by ANSYS software, we figure out some relationships of the two strain transmission processes in the respective structures and the stress distribution in the tail-fibers. These results are helpful to the practical application of the optic-fiber/ GMS film coupled structure.

  19. Research on giant magnetostrictive actuator online nonlinear modeling based on data driven principle with grating sensing technique

    NASA Astrophysics Data System (ADS)

    Han, Ping

    2017-01-01

    A novel Giant Magnetostrictive Actuator (GMA) experimental system with Fiber Bragg Grating (FBG) sensing technique and its modeling method based on data driven principle are proposed. The FBG sensors are adopted to gather the multi-physics fields' status data of GMA considering the strong nonlinearity of the Giant Magnetostrictive Material and GMA micro-actuated structure. The feedback features are obtained from the raw dynamic status data, which are preprocessed by data fill and abnormal value detection algorithms. Correspondingly the Least Squares Support Vector Machine method is utilized to realize GMA online nonlinear modeling with data driven principle. The model performance and its relative algorithms are experimentally evaluated. The model can regularly run in the frequency range from 10 to 1000 Hz and temperature range from 20 to 100 °C with the minimum prediction error stable in the range from -1.2% to 1.1%.

  20. Hysteresis Modeling in Magnetostrictive Materials Via Preisach Operators

    NASA Technical Reports Server (NTRS)

    Smith, R. C.

    1997-01-01

    A phenomenological characterization of hysteresis in magnetostrictive materials is presented. Such hysteresis is due to both the driving magnetic fields and stress relations within the material and is significant throughout, most of the drive range of magnetostrictive transducers. An accurate characterization of the hysteresis and material nonlinearities is necessary, to fully utilize the actuator/sensor capabilities of the magnetostrictive materials. Such a characterization is made here in the context of generalized Preisach operators. This yields a framework amenable to proving the well-posedness of structural models that incorporate the magnetostrictive transducers. It also provides a natural setting in which to develop practical approximation techniques. An example illustrating this framework in the context of a Timoshenko beam model is presented.

  1. Vibration energy harvesting by magnetostrictive material

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Yuan, F. G.

    2008-08-01

    A new class of vibration energy harvester based on magnetostrictive material (MsM), Metglas 2605SC, is designed, developed and tested. It contains two submodules: an MsM harvesting device and an energy harvesting circuit. Compared to piezoelectric materials, the Metglas 2605SC offers advantages including higher energy conversion efficiency, longer life cycles, lack of depolarization and higher flexibility to survive in strong ambient vibrations. To enhance the energy conversion efficiency and alleviate the need of a bias magnetic field, Metglas ribbons are transversely annealed by a strong magnetic field along their width direction. To analyze the MsM harvesting device a generalized electromechanical circuit model is derived from Hamilton's principle in conjunction with the normal mode superposition method based on Euler-Bernoulli beam theory. The MsM harvesting device is equivalent to an electromechanical gyrator in series with an inductor. In addition, the proposed model can be readily extended to a more practical case of a cantilever beam element with a tip mass. The energy harvesting circuit, which interfaces with a wireless sensor and accumulates the harvested energy into an ultracapacitor, is designed on a printed circuit board (PCB) with plane dimension 25 mm × 35 mm. It mainly consists of a voltage quadrupler, a 3 F ultracapacitor and a smart regulator. The output DC voltage from the PCB can be adjusted within 2.0-5.5 V. In experiments, the maximum output power and power density on the resistor can reach 200 µW and 900 µW cm-3, respectively, at a low frequency of 58 Hz. For a working prototype under a vibration with resonance frequency of 1.1 kHz and peak acceleration of 8.06 m s-2 (0.82 g), the average power and power density during charging the ultracapacitor can achieve 576 µW and 606 µW cm-3, respectively, which compete favorably with piezoelectric vibration energy harvesters.

  2. Giant magnetostriction in Tb-doped Fe{sub 83}Ga{sub 17} melt-spun ribbons

    SciTech Connect

    Wu, Wei; Liu, Jinghua; Jiang, Chengbao; Xu, Huibin

    2013-12-23

    Giant magnetostriction is achieved in lightly Tb-doped Fe{sub 83}Ga{sub 17} melt-spun ribbons. The average perpendicular magnetostriction λ{sub ⊥} is −886 ppm along the melt-spun ribbon direction in the Fe{sub 82.89}Ga{sub 16.88}Tb{sub 0.23} alloy and the calculated parallel magnetostriction λ{sub ‖‖} is 1772 ppm. These values are more than four times as large as those found in binary Fe{sub 83}Ga{sub 17}. The enhanced magnetostriction is attributed to a small amount of Tb entering solution in the A2 matrix phase during rapid solidification. The strong localized magnetocrystalline anisotropy of terbium is thought to cause the giant magnetostriction.

  3. Giant volume magnetostriction in the Y{sub 2}Fe{sub 17} single crystal at room temperature

    SciTech Connect

    Nikitin, S. A. Pankratov, N. Yu.; Smarzhevskaya, A. I.; Politova, G. A.; Pastushenkov, Yu. G. Skokov, K. P.; Moral, A. del

    2015-05-21

    An investigation of the Y{sub 2}Fe{sub 17} compound belonging to the class of intermetallic alloys of rare-earth and 3d-transition metals is presented. The magnetization, magnetostriction, and thermal expansion of the Y{sub 2}Fe{sub 17} single crystal were studied. The forced magnetostriction and magnetostriction constants were investigated in the temperature range of the magnetic ordering close to the room temperature. The giant field induced volume magnetostriction was discovered in the room temperature region in the magnetic field up to 1.2 T. The contributions of both anisotropic single-ion and isotropic pair exchange interactions to the volume magnetostriction and magnetostriction constants were determined. The experimental results were interpreted within the framework of the Standard Theory of Magnetostriction and the Landau thermodynamic theory. It was found out that the giant values of the volume magnetostriction were caused by the strong dependence of the 3d-electron Coulomb charge repulsion on the deformations and width of the 3d-electron energy band.

  4. The principle and physical models of novel jetting dispenser with giant magnetostrictive and a magnifier

    PubMed Central

    Zhou, C.; Li, J.H.; Duan, J.A.; Deng, G.L.

    2015-01-01

    In order to develop jetting technologies of glue in LED and microelectronics packaging, giant-magnetostrictive-material (GMM) is firstly applied to increase jetting response, and a new magnifying device including a lever and a flexible hinge is designed to improve jetting characteristics. Physical models of the jetting system are derived from the magnifying structure and working principle, which involves circuit model, electro-magneto-displacement model, dynamic model and fluid-solid coupling model. The system model is established by combining mathematical models with Matlab-Simulink. The effectiveness of the GMM-based dispenser is confirmed by simulation and experiments. The jetting frequency significantly increases to 250 Hz, and dynamic behaviors jetting needle are evaluated that the velocity and displacement of the jetting needle reaches to 320 mm•s-1 and 0.11 mm respectively. With the increasing of the filling pressure or the amplitude of the current, the dot size will become larger. The dot size and working frequency can be easily adjusted. PMID:26670008

  5. The principle and physical models of novel jetting dispenser with giant magnetostrictive and a magnifier

    NASA Astrophysics Data System (ADS)

    Zhou, C.; Li, J. H.; Duan, J. A.; Deng, G. L.

    2015-12-01

    In order to develop jetting technologies of glue in LED and microelectronics packaging, giant-magnetostrictive-material (GMM) is firstly applied to increase jetting response, and a new magnifying device including a lever and a flexible hinge is designed to improve jetting characteristics. Physical models of the jetting system are derived from the magnifying structure and working principle, which involves circuit model, electro-magneto-displacement model, dynamic model and fluid-solid coupling model. The system model is established by combining mathematical models with Matlab-Simulink. The effectiveness of the GMM-based dispenser is confirmed by simulation and experiments. The jetting frequency significantly increases to 250 Hz, and dynamic behaviors jetting needle are evaluated that the velocity and displacement of the jetting needle reaches to 320 mm•s-1 and 0.11 mm respectively. With the increasing of the filling pressure or the amplitude of the current, the dot size will become larger. The dot size and working frequency can be easily adjusted.

  6. The principle and physical models of novel jetting dispenser with giant magnetostrictive and a magnifier.

    PubMed

    Zhou, C; Li, J H; Duan, J A; Deng, G L

    2015-12-16

    In order to develop jetting technologies of glue in LED and microelectronics packaging, giant-magnetostrictive-material (GMM) is firstly applied to increase jetting response, and a new magnifying device including a lever and a flexible hinge is designed to improve jetting characteristics. Physical models of the jetting system are derived from the magnifying structure and working principle, which involves circuit model, electro-magneto-displacement model, dynamic model and fluid-solid coupling model. The system model is established by combining mathematical models with Matlab-Simulink. The effectiveness of the GMM-based dispenser is confirmed by simulation and experiments. The jetting frequency significantly increases to 250 Hz, and dynamic behaviors jetting needle are evaluated that the velocity and displacement of the jetting needle reaches to 320 mm•s-1 and 0.11 mm respectively. With the increasing of the filling pressure or the amplitude of the current, the dot size will become larger. The dot size and working frequency can be easily adjusted.

  7. Integration of a nonlinear energy sink and a giant magnetostrictive energy harvester

    NASA Astrophysics Data System (ADS)

    Fang, Zhi-Wei; Zhang, Ye-Wei; Li, Xiang; Ding, Hu; Chen, Li-Qun

    2017-03-01

    This paper explores a promising novel approach by integrating nonlinear energy sink (NES) and giant magnetostrictive material (GMM) to realize vibration control and energy harvesting. The vibration-based apparatus consisting of a NES, a Terfenol-D rod, and a linear oscillator (the primary system) is proposed. The mathematical model of the prototype under displacement driven has been established and simulated by utilizing the Runge-Kutta algorithm. The exhibited responses and the obtained electric energy are computed. Furthermore, the Fast Fourier Transform (FFT) of the resonant responses is performed. The distribution of the input energy is calculated to evaluate the designed structure. The instantaneous transaction of the energy is then examined by considering the energy transaction measure (ETM). Lastly, a parametric study is conducted for further optimization. The numerical simulations demonstrate that the nonlinear pumping phenomena occur, that is, the target energy transfer (TET) that leads to a very efficient vibration suppression. In addition, the results also illustrate that the localized vibration energy can be converted into magnetic field energy due to the Villari effect and then transformed into electric energy.

  8. Research on hysteresis loop considering the prestress effect and electrical input dynamics for a giant magnetostrictive actuator

    NASA Astrophysics Data System (ADS)

    Zhu, Yuchuan; Yang, Xulei; Wereley, Norman M.

    2016-08-01

    In this paper, focusing on the application-oriented giant magnetostrictive material (GMM)-based electro-hydrostatic actuator, which features an applied magnetic field at high frequency and high amplitude, and concentrating on the static and dynamic characteristics of a giant magnetostrictive actuator (GMA) considering the prestress effect on the GMM rod and the electrical input dynamics involving the power amplifier and the inductive coil, a methodology for studying the static and dynamic characteristics of a GMA using the hysteresis loop as a tool is developed. A GMA that can display the preforce on the GMM rod in real-time is designed, and a magnetostrictive model dependent on the prestress on a GMM rod instead of the existing quadratic domain rotation model is proposed. Additionally, an electrical input dynamics model to excite GMA is developed according to the simplified circuit diagram, and the corresponding parameters are identified by the experimental data. A dynamic magnetization model with the eddy current effect is deduced according to the Jiles-Atherton model and the Maxwell equations. Next, all of the parameters, including the electrical input characteristics, the dynamic magnetization and the mechanical structure of GMA, are identified by the experimental data from the current response, magnetization response and displacement response, respectively. Finally, a comprehensive comparison between the model results and experimental data is performed, and the results show that the test data agree well with the presented model results. An analysis on the relation between the GMA displacement response and the parameters from the electrical input dynamics, magnetization dynamics and mechanical structural dynamics is performed.

  9. Deformation of rectangular thin glass plate coated with magnetostrictive material

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoli; Yao, Youwei; Liu, Tianchen; Liu, Chian; Ulmer, M. P.; Cao, Jian

    2016-08-01

    As magnetic smart materials (MSMs), magnetostrictive materials have great potential to be selected as coating materials for lightweight x-ray telescope mirrors due to their capability to tune the mirror profile to the desired shape under a magnetic field. To realize this potential, it is necessary to study the deformation of the mirror substrate with the MSM coating subjected to a localized magnetic field. In this paper, an analytical model is developed to calculate the deformation of rectangular coated samples locally affected by magnetostrictive strains driven by an external magnetic field. As a specific case to validate the model, a square glass sample coated with MSMs is prepared, and its deformation is measured in a designed experimental setup by applying a magnetic field. The measured deformation of the sample is compared with the results calculated from the analytical model. The comparison results demonstrate that the analytical model is effective in calculating the deformation of a coated sample with the localized mismatch strains between the film and the substrate. In the experiments, different shape patterns of surface profile changes are achieved by varying the direction of the magnetic field. The analytical model and the experimental method proposed in this paper can be utilized to further guide the application of magnetostrictive coating to deformable lightweight x-ray mirrors in the future.

  10. Giant magnetostriction in annealed Co(1-x)Fe(x) thin-films.

    PubMed

    Hunter, Dwight; Osborn, Will; Wang, Ke; Kazantseva, Nataliya; Hattrick-Simpers, Jason; Suchoski, Richard; Takahashi, Ryota; Young, Marcus L; Mehta, Apurva; Bendersky, Leonid A; Lofland, Sam E; Wuttig, Manfred; Takeuchi, Ichiro

    2011-11-01

    Chemical and structural heterogeneity and the resulting interaction of coexisting phases can lead to extraordinary behaviours in oxides, as observed in piezoelectric materials at morphotropic phase boundaries and relaxor ferroelectrics. However, such phenomena are rare in metallic alloys. Here we show that, by tuning the presence of structural heterogeneity in textured Co(1-x)Fe(x) thin films, effective magnetostriction λ(eff) as large as 260 p.p.m. can be achieved at low-saturation field of ~10 mT. Assuming λ(100) is the dominant component, this number translates to an upper limit of magnetostriction of λ(100)≈5λ(eff) >1,000 p.p.m. Microstructural analyses of Co(1-x)Fe(x) films indicate that maximal magnetostriction occurs at compositions near the (fcc+bcc)/bcc phase boundary and originates from precipitation of an equilibrium Co-rich fcc phase embedded in a Fe-rich bcc matrix. The results indicate that the recently proposed heterogeneous magnetostriction mechanism can be used to guide exploration of compounds with unusual magnetoelastic properties.

  11. Magnetostriction measurement of a giant magnetoresistance film on a practical substrate covered by a shield layer

    NASA Astrophysics Data System (ADS)

    Okita, Kazuhiko; Ishiyama, Kazushi; Miura, Hideo

    2012-04-01

    Magnetostriction constant of a magnetic thin film is conventionally measured by detecting the deformation of a coupon sample that consists of the magnetic film deposited on a thin glass substrate (e.g., cover glass of size 10 mm × 25 mm) under an applied field using a laser beam [A. C. Tam and H. Schroeder, J. Appl. Phys. 64, 5422 (1988)]. This method, however, cannot be applied to films deposited on actual large-size substrates (wafers) with diameter from 3 to 6 in. or more. In a previous paper [Okita et al., J. Phys.: Conf. Ser. 200, 112008 (2010)], the authors presented a method for measuring magnetostriction of a magnetic thin film deposited on an actual substrate by detecting the change of magnetic anisotropy field, Hk, under mechanical bending of the substrate. It was validated that the method is very effective for measuring the magnetostriction constant of a free layer on the actual substrate. However, since a Ni-Fe shield layer usually covers a magnetic head used for a hard disk drive, this shield layer disturbs the effective measurement of R-H curve under minor loop. Therefore, a high magnetic field that can saturate the magnetic material in the shield layer should be applied to the head in order to measure the magnetostriction constant of a pinned layer under the shield layer. In this paper, this method was applied to the measurement of the magnetostriction constant of a pinned layer under the shield layer by using a high magnetic field up to 320 kA/m (4 kOe).

  12. Investigation of magnetostrictive/piezoelectric multilayer composite with a giant zero-biased magnetoelectric effect

    NASA Astrophysics Data System (ADS)

    Lu, Caijiang; Li, Ping; Wen, Yumei; Yang, Aichao; He, Wei; Zhang, Jitao; Yang, Jin; Wen, Jing; Zhu, Yong; Yu, Miao

    2013-11-01

    In this paper, we investigate the resonance magnetoelectric (ME) effect in the middle supported multilayer composites consisting of high-permeability Fe-based nanocrystalline soft magnetic alloy Fe73.5Cu1Nb3Si13.5B9 (FeCuNbSiB), Nickel (Ni), and piezoelectric Pb(Zr1- x Ti x )O3 (PZT). The coupling effect between positive magnetostrictive FeCuNbSiB and negative magnetostrictive Ni results in the build-in magnetic bias due to their different magnetic permeability and coercivity. As a result, a giant resonance ME voltage coefficient ( α ME, r ) at zero DC magnetic bias field ( H dc) and multi-peaks of α ME, r for FeCuNbSiB/Ni/PZT/Ni/FeCuNbSiB composite are observed. The experimental results show that the giant zero-biased α ME, r strongly depends on the thickness of FeCuNbSiB ribbon. The maximum zero-biased α ME, r is up to 86 V/cm Oe for FeCuNbSiB/Ni/PZT/Ni/FeCuNbSiB with four-layer FeCuNbSiB ribbons, which is ˜500 times higher than that of the previously reported NKNLS-NZF/Ni/NKNLS-NZF trilayer composite. Compared with the peak α ME, r and the optimum H dc of Ni/PZT/Ni composite, the largest peak α ME, r of FeCuNbSiB/Ni/PZT/Ni/FeCuNbSiB composite with four-layer FeCuNbSiB ribbons increases ˜185 %, and the optimum H dc decreases ˜300 Oe, respectively. Based on the nonlinear magnetostrictive constitutive relation and the magnetoelectric equivalent circuit, a theoretical model of α ME, r versus H dc is built under free boundary conditions. Calculated zero-biased α ME, r and α ME, r versus H dc are in good agreement with the experimental data. This laminate composite shows promising applications for high-sensitivity power-free magnetic field sensors, zero-biased ME transducers and small-size energy harvesters.

  13. Rare earth-iron magnetostrictive materials and devices using these materials

    DOEpatents

    Savage, Howard T.; Clark, Arthur E.; McMasters, O. Dale

    1981-12-29

    Grain-oriented polycrystalline or single crystal magnetostrictive materials n the general formula Tb.sub.x Dy.sub.1-x Fe.sub.2-w, Tb.sub.x Ho.sub.1-x Fe.sub.2-w, Sm.sub.x Dy.sub.1-x Fe.sub.x-w, Sm.sub.x Ho.sub.1-x Fe.sub.2-w, Tb.sub.x Ho.sub.y Dy.sub.z Fe.sub.2-w, or Sm.sub.x Ho.sub.y Dy.sub.z Fe.sub.2-w, wherein O.ltoreq.w.ltoreq.0.20, and x+y+z=1. X, y, and z are selected to maximize the magnetostrictive effect and the magnetomechanical coupling coefficient K.sub.33. These material may be used in magnetostrictive transducers, delay lines, variable frequency resonators, and filters.

  14. Non-Joulian magnetostriction.

    PubMed

    Chopra, Harsh Deep; Wuttig, Manfred

    2015-05-21

    All magnets elongate and contract anisotropically when placed in a magnetic field, an effect referred to as Joule magnetostriction. The hallmark of Joulian magnetostriction is volume conservation, which is a broader definition applicable to self-accommodation of ferromagnetic, ferroelectric or ferroelastic domains in all functional materials. Here we report the discovery of 'giant' non-volume-conserving or non-Joulian magnetostriction (NJM). Whereas Joulian strain is caused by magnetization rotation, NJM is caused by facile (low-field) reorientation of magnetoelastically and magnetostatically autarkic (self-sufficient) rigid micro-'cells', which define the adaptive structure, the origin of which is proposed to be elastic gradients ultimately caused by charge/spin density waves. The equilibrium adaptive cellular structure is responsible for long-sought non-dissipative (hysteresis-free), linearly reversible and isotropic magnetization curves along all directions within a single crystal. Recently discovered Fe-based high magnetostriction alloys with special thermal history are identified as the first members of this newly discovered magnetic class. The NJM paradigm provides consistent interpretations of seemingly confounding properties of Fe-based alloys, offers recipes to develop new highly magnetostrictive materials, and permits simultaneously large actuation in longitudinal and transverse directions without the need for stacked composites.

  15. Magnetostrictive Pressure Regulating System

    NASA Technical Reports Server (NTRS)

    Richard, James A. (Inventor); Pickens, Herman L. (Inventor)

    2013-01-01

    A magnetostrictive pressure regulating system includes a magnetostrictive valve that incorporates a magnetostrictive actuator with at least one current-carrying coil disposed thereabout. A pressure force sensor, in fluid communication with the fluid exiting the valve, includes (i) a magnetostrictive material, (ii) a magnetic field generator in proximity to the magnetostrictive material for inducing a magnetic field in and surrounding the magnetostrictive material wherein lines of magnetic flux passing through the magnetostrictive material are defined, and (iii) a sensor positioned adjacent to the magnetostrictive material and in the magnetic field for measuring changes in at least one of flux angle and flux density when the magnetostrictive material experiences an applied force that is aligned with the lines of magnetic flux. The pressure of the fluid exiting the valve causes the applied force. A controller coupled to the sensor and to the current-carrying coil adjusts a current supplied to the current-carrying coil based on the changes so-measured.

  16. Material for magnetostrictive sensors and other applications based on ferrite materials

    DOEpatents

    McCallum, R. William; Snyder, John E.; Dennis, Kevin W.; Schwichtenberg, Carl R.; Jiles, David C.

    2000-07-25

    The present invention provides magnetostrictive compositions that include an oxide ferrite which provides mechanical properties that make the magnetostrictive compositions effective for use as sensors and actuators.

  17. Magnetostrictive materials and method for improving AC characteristics in same

    DOEpatents

    Pulvirenti, Patricia P.; Jiles, David C.

    2001-08-14

    The present invention provides Terfenol-D alloys ("doped" Terfenol) having optimized performances under the condition of time-dependent magnetic fields. In one embodiment, performance is optimized by lowering the conductivity of Terfenol, thereby improving the frequency response. This can be achieved through addition of Group III or IV elements, such as Si and Al. Addition of these types of elements provides scattering sites for conduction electrons, thereby increasing resistivity by 125% which leads to an average increase in penetration depth of 80% at 1 kHz and an increase in energy conversion efficiency of 55%. The permeability of doped Terfenol remains constant over a wider frequency range as compared with undoped Terfenol. These results demonstrate that adding impurities, such as Si and Al, are effective in improving the ac characteristics of Terfenol. A magnetoelastic Gruneisen parameter, .gamma..sub.me, has also been derived from the thermodynamic equations of state, and provides another means by which to characterize the coupling efficiency in magnetostrictive materials on a more fundamental basis.

  18. Magnetostrictive Alternator

    NASA Technical Reports Server (NTRS)

    Dyson, Rodger; Bruder, Geoffrey

    2013-01-01

    This innovation replaces the linear alternator presently used in Stirling engines with a continuous-gradient, impedance-matched, oscillating magnetostrictive transducer that eliminates all moving parts via compression, maintains high efficiency, costs less to manufacture, reduces mass, and eliminates the need for a bearing system. The key components of this new technology are the use of stacked magnetostrictive materials, such as Terfenol-D, under a biased magnetic and stress-induced compression, continuous-gradient impedance-matching material, coils, force-focusing metallic structure, and supports. The acoustic energy from the engine travels through an impedancematching layer that is physically connected to the magnetostrictive mass. Compression bolts keep the structure under compressive strain, allowing for the micron-scale compression of the magnetostrictive material and eliminating the need for bearings. The relatively large millimeter displacement of the pressure side of the impedance-matching material is reduced to micron motion, and undergoes stress amplification at the magnetostrictive interface. The alternating compression and expansion of the magnetostrictive material creates an alternating magnetic field that then induces an electric current in a coil that is wound around the stack. This produces electrical power from the acoustic pressure wave and, if the resonant frequency is tuned to match the engine, can replace the linear alternator that is commonly used.

  19. Cobalt ferrite based magnetostrictive materials for magnetic stress sensor and actuator applications

    NASA Technical Reports Server (NTRS)

    Jiles, David C. (Inventor); Paulsen, Jason A. (Inventor); Snyder, John E. (Inventor); Lo, Chester C. H. (Inventor); Ring, Andrew P. (Inventor); Bormann, Keith A. (Inventor)

    2008-01-01

    Magnetostrictive material based on cobalt ferrite is described. The cobalt ferrite is substituted with transition metals (such manganese (Mn), chromium (Cr), zinc (Zn) and copper (Cu) or mixtures thereof) by substituting the transition metals for iron or cobalt to form substituted cobalt ferrite that provides mechanical properties that make the substituted cobalt ferrite material effective for use as sensors and actuators. The substitution of transition metals lowers the Curie temperature of the material (as compared to cobalt ferrite) while maintaining a suitable magnetostriction for stress sensing applications.

  20. Frequency spectra of magnetostrictive and Lorentz forces generated in ferromagnetic materials by a CW excited EMAT

    NASA Astrophysics Data System (ADS)

    Rouge, C.; Lhémery, A.; Aristégui, C.

    2014-04-01

    Magnetostriction arises in ferromagnetic materials subjected to magnetization, e.g., when an EMAT (Electro-Magnetic Acoustic Transducer) is used to generate ultrasonic waves. In such a case, the magnetostriction force must be taken into account as a transduction process that adds up to the Lorentz force. When the static magnetic field is high compared to the dynamic field, both forces are driven by the excitation frequency. For lower static relative values of the magnetic fields, the Lorentz force comprises both the excitation frequency and its first harmonic. In this work, a model is derived to predict the frequency content of the magnetostrictive force that comprises several harmonics. The discrete frequency spectrum strongly depends on both the static field and the relative amplitude of the dynamic field. The only material input data needed to predict it is the curve of macroscopic magnetostrictive strain that can be measured in the direction of an imposed magnetic field. Then, the various frequency-dependent distributions of Lorentz and magnetostriction body forces can be transformed into equivalent surface stresses. Examples of computation are given for different static and dynamic magnetic fields to study their influence on the frequency content of waves generated in ferromagnetic materials.

  1. A general one-dimension nonlinear magneto-elastic coupled constitutive model for magnetostrictive materials

    SciTech Connect

    Zhang, Da-Guang; Li, Meng-Han; Zhou, Hao-Miao

    2015-10-15

    For magnetostrictive rods under combined axial pre-stress and magnetic field, a general one-dimension nonlinear magneto-elastic coupled constitutive model was built in this paper. First, the elastic Gibbs free energy was expanded into polynomial, and the relationship between stress and strain and the relationship between magnetization and magnetic field with the polynomial form were obtained with the help of thermodynamic relations. Then according to microscopic magneto-elastic coupling mechanism and some physical facts of magnetostrictive materials, a nonlinear magneto-elastic constitutive with concise form was obtained when the relations of nonlinear strain and magnetization in the polynomial constitutive were instead with transcendental functions. The comparisons between the prediction and the experimental data of different magnetostrictive materials, such as Terfenol-D, Metglas and Ni showed that the predicted magnetostrictive strain and magnetization curves were consistent with experimental results under different pre-stresses whether in the region of low and moderate field or high field. Moreover, the model can fully reflect the nonlinear magneto-mechanical coupling characteristics between magnetic, magnetostriction and elasticity, and it can effectively predict the changes of material parameters with pre-stress and bias field, which is useful in practical applications.

  2. Optical fiber magnetic field sensors with TbDyFe magnetostrictive thin films as sensing materials.

    PubMed

    Yang, Minghong; Dai, Jixiang; Zhou, Ciming; Jiang, Desheng

    2009-11-09

    Different from usually-used bulk magnetostrictive materials, magnetostrictive TbDyFe thin films were firstly proposed as sensing materials for fiber-optic magnetic field sensing characterization. By magnetron sputtering process, TbDyFe thin films were deposited on etched side circle of a fiber Bragg Grating (FBG) as sensing element. There exists more than 45pm change of FBG wavelength when magnet field increase up to 50 mT. The response to magnetic field is reversible, and could be applicable for magnetic and current sensing.

  3. Material for magnetostrictive sensors and other applications based on ferrite materials

    DOEpatents

    McCallum, R. William; Snyder, John E.; Dennis, Kevin W.; Schwichtenberg, Carl R.; Jiles, David C.

    2002-03-05

    The present invention provides magnetostrictive composites that include an oxide ferrite and metallic binders which provides mechanical properties that make the magnetostrictive compositions effective for use as sensors and actuators.

  4. Giant volume magnetostriction and colossal magnetoresistance at room temperature in La(0.7)Ba(0.3)MnO(3).

    PubMed

    Demin, R V; Koroleva, L I; Mukovskii, Ya M

    2005-01-12

    Giant volume magnetostriction at room temperature is found for the first time in a La(0.7)Ba(0.3)MnO(3) single crystal, achieving 2.54 × 10(-4) in a magnetic field of 8.2 kOe. An even greater value of the volume magnetostriction, equal to 4 × 10(-4) in the same magnetic field, is observed at the Curie point T(C) = 310 K.Volume magnetostriction and magnetoresistance exhibit similar dependences on temperature and magnetic field in the T(C)-region, that is explained by the presence in this compound of a magnetic two-phase ferromagnetic-antiferromagnetic state due to strong s-d exchange.

  5. Magnetostrictive resonance excitation

    DOEpatents

    Schwarz, Ricardo B.; Kuokkala, Veli-Tapani

    1992-01-01

    The resonance frequency spectrum of a magnetostrictive sample is remotely determined by exciting the magnetostrictive property with an oscillating magnetic field. The permeability of a magnetostrictive material and concomitant coupling with a detection coil varies with the strain in the material whereby resonance responses of the sample can be readily detected. A suitable sample may be a magnetostrictive material or some other material having at least one side coated with a magnetostrictive material. When the sample is a suitable shape, i.e., a cube, rectangular parallelepiped, solid sphere or spherical shell, the elastic moduli or the material can be analytically determined from the measured resonance frequency spectrum. No mechanical transducers are required and the sample excitation is obtained without contact with the sample, leading to highly reproducible results and a measurement capability over a wide temperature range, e.g. from liquid nitrogen temperature to the Curie temperature of the magnetostrictive material.

  6. Non-linear dynamic characteristics and optimal control of giant magnetostrictive film subjected to in-plane stochastic excitation

    SciTech Connect

    Zhu, Z. W.; Zhang, W. D. Xu, J.

    2014-03-15

    The non-linear dynamic characteristics and optimal control of a giant magnetostrictive film (GMF) subjected to in-plane stochastic excitation were studied. Non-linear differential items were introduced to interpret the hysteretic phenomena of the GMF, and the non-linear dynamic model of the GMF subjected to in-plane stochastic excitation was developed. The stochastic stability was analysed, and the probability density function was obtained. The condition of stochastic Hopf bifurcation and noise-induced chaotic response were determined, and the fractal boundary of the system's safe basin was provided. The reliability function was solved from the backward Kolmogorov equation, and an optimal control strategy was proposed in the stochastic dynamic programming method. Numerical simulation shows that the system stability varies with the parameters, and stochastic Hopf bifurcation and chaos appear in the process; the area of the safe basin decreases when the noise intensifies, and the boundary of the safe basin becomes fractal; the system reliability improved through stochastic optimal control. Finally, the theoretical and numerical results were proved by experiments. The results are helpful in the engineering applications of GMF.

  7. Non-linear dynamic characteristics and optimal control of giant magnetostrictive film subjected to in-plane stochastic excitation

    NASA Astrophysics Data System (ADS)

    Zhu, Z. W.; Zhang, W. D.; Xu, J.

    2014-03-01

    The non-linear dynamic characteristics and optimal control of a giant magnetostrictive film (GMF) subjected to in-plane stochastic excitation were studied. Non-linear differential items were introduced to interpret the hysteretic phenomena of the GMF, and the non-linear dynamic model of the GMF subjected to in-plane stochastic excitation was developed. The stochastic stability was analysed, and the probability density function was obtained. The condition of stochastic Hopf bifurcation and noise-induced chaotic response were determined, and the fractal boundary of the system's safe basin was provided. The reliability function was solved from the backward Kolmogorov equation, and an optimal control strategy was proposed in the stochastic dynamic programming method. Numerical simulation shows that the system stability varies with the parameters, and stochastic Hopf bifurcation and chaos appear in the process; the area of the safe basin decreases when the noise intensifies, and the boundary of the safe basin becomes fractal; the system reliability improved through stochastic optimal control. Finally, the theoretical and numerical results were proved by experiments. The results are helpful in the engineering applications of GMF.

  8. Efficient and robust nonlinear model for smart materials with application to composite magnetostrictive plates

    NASA Astrophysics Data System (ADS)

    Tari, Hafez; Santapuri, Sushma S.; Dapino, Marcelo J.

    2017-04-01

    This paper presents a computationally efficient and robust nonlinear modeling framework for smart materials. The framework describes a smart material system through a new 3D inversion scheme for coupled nonlinear constitutive equations which can be integrated with the variational form of governing equations. Building on the Newton technique, the inversion scheme can be applied to any nonlinear smart material with a differentiable direct constitutive model. To further improve computational efficiency, the inversion scheme is integrated with a reduced dimensional (2D) model for smart composite structures. The resulting coupled 2D framework is applied to an aluminum-Galfenol composite plate that operates in actuation mode, and is solved using multiphysics finite element software. Major and minor magnetostriction curves are obtained for the actuator displacements at the tip of the Galfenol element by applying unbiased and biased magnetic fields. A significant advantage in numerical convergence and computational time, an almost six-time speedup for a dynamic simulation case, is demonstrated via comparison with an existing approach for magnetostrictive material modeling. The framework is suitable for fast design and optimization of nonlinear smart material structures.

  9. Vibration energy harvesting using the nonlinear oscillations of a magnetostrictive material

    NASA Astrophysics Data System (ADS)

    Tsutsumi, Erika; del Rosario, Zachary; Lee, Christopher

    2012-04-01

    A novel magnetostrictive-material-based device concept to convert ambient mechanical vibration into electricity has been designed, fabricated, and tested. In order to harvest energy over a greater frequency range as compared to state-of- the-art devices, an L-shaped beam which is tuned so that the first two (bending) natural frequencies have a (near) two-to-one ratio is used as a mechanical transducer to generate nonlinear oscillations. Under harmonic excitation, an internal resonance or autoparametric, dynamic response can occur in which one vibration mode parametrically excites a second vibration mode resulting in significant displacement of both modes over an extended frequency range. A magnetostrictive material, Metglas 2605SA1, is used to convert vibration into electricity. Vibration-induced strain in the Metglas changes its magnetization which in turn generates current in a coil of wire. Metglas is highly flexible so it can undergo large displacement and does not fatigue under extended excitation. Demonstration devices are used to study how this nonlinear response can be exploited to generate electricity under single-frequency, harmonic and random base excitation.

  10. Magnetostrictive and Kinematic Model Considering the Dynamic Hysteresis and Energy Loss for GMA

    NASA Astrophysics Data System (ADS)

    LIU, Huifang; SUN, Xingwei; GAO, Yifei; WANG, Hanyu; GAO, Zijin

    2017-03-01

    Due to the influence of magnetic hysteresis and energy loss inherent in giant magnetostrictive materials (GMM), output displacement accuracy of giant magnetostrictive actuator (GMA) can not meet the precision and ultra precision machining. Using a GMM rod as the core driving element, a GMA which may be used in the field of precision and ultra precision drive engineering is designed through modular design method. Based on the Armstrong theory and elastic Gibbs free energy theory, a nonlinear magnetostriction model which considers magnetic hysteresis and energy loss characteristics is established. Moreover, the mechanical system differential equation model for GMA is established by utilizing D'Alembert's principle. Experimental results show that the model can preferably predict magnetization property, magnetic potential orientation, energy loss for GMM. It is also able to describe magnetostrictive elongation and output displacement of GMA. Research results will provide a theoretical basis for solving the dynamic magnetic hysteresis, energy loss and working precision for GMA fundamentally.

  11. Giant enhancement in the magnetostrictive effect of FeGa alloys doped with low levels of terbium

    NASA Astrophysics Data System (ADS)

    Jiang, Liping; Yang, Jiandong; Hao, Hongbo; Zhang, Guangrui; Wu, Shuangxia; Chen, Yajie; Obi, Ogheneyunume; Fitchorov, Trifon; Harris, Vincent G.

    2013-06-01

    We present the effects of terbium additives upon the microstructure and magnetic properties of Fe83Ga17Tbx alloys (x = 0, 0.2, 0.4, 0.6, and 0.8), prepared by vacuum electric arc-melting and directional solidification techniques. Experiments indicate that small amounts of terbium more than double the saturation magnetostriction of a [110] textured Fe83Ga17 alloy with λ = 72 × 10-6 and lower the magnetostriction saturation field. The pronounced increase in magnetostriction stems from the appearance of [100] texture in polycrystalline alloys. It is verified that [110] and [100] textures are enhanced by the introduction of terbium atoms preferentially residing in a Tb-rich intergranular phase.

  12. The design, construction and testing of a scour monitoring system using magnetostrictive materials

    NASA Astrophysics Data System (ADS)

    Day, Steven Richard

    A system for the continuous monitoring of scour has been designed, constructed and implemented. The system detects the level of scour by attaching flow to a buried post at known depths, and detecting when individual sensors become unearthed. Two bio-inspired flow sensors were designed and constructed for use on the post. The first, resembling a seal whisker, utilized the magnetostrictive materials Alfenol and Galfenol and was optimized for >0.15m/s flow. The second, resembling seaweed, used a conventional permanent magnet and was optimized for <0.15m/s flow. A small, low powered data acquisition system was designed and constructed to monitor and record the data from the sensors. A total of four scour posts were installed at two different sites; two vertically to monitor conventional scour and two horizontally to monitor lateral riverbed migration. Data from the posts was analyzed and presented and lessons learned were documented.

  13. Evaluation of magnetostrictive composite coated fabric as a fragment barrier material

    NASA Astrophysics Data System (ADS)

    Son, Kwon Joong; Fahrenthold, Eric P.

    2012-10-01

    Over the last decade a surge in fragment barrier research has led to investigation of numerous materials and material augmentations in the attempt to improve the ballistic performance of systems designed to protect personnel, vehicles or infrastructure from impact and blast loads. One widely studied material augmentation approach is the use of coatings, often polymers, to enhance the performance of protection systems constructed from metal, concrete, composite and fabric materials. In recent research the authors have conducted the first experimental study of the ballistic performance of fabrics coated with a magnetically responsive polymer. Zero field impact experiments on coated fabric targets showed a 61% increase in impact energy dissipation, although the coated targets were not competitive with neat fabrics on a protection per unit mass basis. Under an applied field of 110 kA m-1, the ballistic performance of the coated fabric was reduced. The reduction in performance may be attributed to a reduction in material damping and an increase in material modulus for the magnetostrictive component of the coating. Analysis of the coated fabric response to magnetic preloads suggests that coating tensile stresses and coating-fabric interface stresses induced by the applied field may also adversely affect ballistic performance.

  14. Characterization of the Dynamic Material Properties of Magnetostrictive Terfenol-D

    NASA Technical Reports Server (NTRS)

    Calkins, Frederick T.; Flatau, Alison B.; Hall, David L.

    1996-01-01

    A major limitation in use of electromagnetic and/or magnetomechanical models for design of Terfenol-D actuators is the lack of reliable material property data for Terfenol-D. In particular data on the performance of Terfenol-D as employed in a transducer, operating under real world dynamic conditions is needed. To provide this information, Terfenol-D rod properties need to be measured under as run prestressed and magnetically biased states. Using a Terfenol-D actuator, the following properties can be measured and/or calculated: mechanical quality factor, speed of sound in the material, the resonant frequency, the anti-resonant frequency, two magnetic permeabilities (one at constant stress and one at constant strain), two Young's moduli (one at constant amplitude applied magnetic field and one at constant amplitude magnetic flux density in the material), the magnetomechanical coupling, and the axial strain coefficient. The development of the material properties measurements and calculations is based on the model of low signal, linear, magnetostriction from Clark, the linear transduction equations for a transducer from Hunt, and a one degree of freedom mechanical model of the transducer. The electrical impedance and admittance mobility loops are used to determine the resonant, anti-resonant, and half power point frequencies. The rest of the material properties indicated above can then be calculated using these frequencies, acceleration from an accelerometer mounted on the actuator arm, and readily measurable transducer and Terfenol-D rod parameters.

  15. Effect of magnetostrictive material layer on the stress and deformation behaviour of laminated structure

    NASA Astrophysics Data System (ADS)

    Suman, S. D.; Hirwani, C. K.; Chaturvedi, A.; Panda, S. K.

    2017-02-01

    In the present investigation, static bending and strength behaviour of the laminated composite plate embedded with magnetostrictive (MS) material has been computed numerically using commercial finite element tool. For the analysis purpose, a simulation model of the laminated plate embedded with and without MS material is derived using the batch input technique popularly termed as ANSYS parametric design language (APDL). The MS bonded composite model is discretised with the help of available suitable element from ANSYS element library. The elements are chosen suitably by considering the compatibility between the mechanical and the magnetic fluxes indices. For the calculation of the necessary responses, APDL code has been prepared in ANSYS environment. Further, the stability of the model has been checked by computing the responses for various mesh sizes. Subsequently, the accuracy of the model has also been checked by conducting the comparison test. For the comparison, central deflection of the clamped Graphite/Epoxy laminated plate embedded with Terfenol-D has been evaluated and compare them with those of the available earlier published literature. The comparison study clearly indicates that, the present responses are in-line and showing good agreement with that of the reference. Further, the versatility and the applicability of the simulation model has been proven by solving the different illustrations. In the illustration, the influence of the different geometrical parameter such as thickness ratio and aspect ratio on the bending behaviour has been investigated and discussed in detail.

  16. An optimal design of magnetostrictive material (MsM) based energy harvester

    NASA Astrophysics Data System (ADS)

    Hu, Jingzhen; Yuan, Fuh-Gwo; Xu, Fujun; Huang, Alex Q.

    2010-04-01

    In this study, an optimal vibration-based energy harvesting system using magnetostrictive material (MsM) has been designed to power the Wireless Intelligent Sensor Platform (WISP), developed at North Carolina State University. A linear MsM energy harvesting device has been modeled and optimized to maximize the power output. The effects of number of MsM layers and glue layers, and load matching on the output power of the MsM energy harvester have been analyzed. From the measurement, the open circuit voltage can reach 1.5 V when the MsM cantilever beam operates at the 2nd natural frequency 324 Hz. The AC output power is 0.97 mW, giving power density 279 μW/cm3. Since the MsM device has low open circuit output voltage characteristics, a full-wave quadrupler has been designed to boost the rectified output voltage. To deliver the maximum output power to the load, a complex conjugate impedance matching between the load and the MsM device has been implemented using a discontinuous conduction mode (DCM) buck-boost converter. The maximum output power after the voltage quadrupler is now 705 μW and power density reduces to 202.4 μW/cm3, which is comparable to the piezoelectric energy harvesters given in the literature. The output power delivered to a lithium rechargeable battery is around 630 μW, independent of the load resistance.

  17. Self-contained hybrid electro-hydraulic actuators using magnetostrictive and electrostrictive materials

    NASA Astrophysics Data System (ADS)

    Chaudhuri, Anirban

    Hybrid electro-hydraulic actuators using smart materials along with flow rectification have been widely reported in recent years. The basic operation of these actuators involves high frequency bidirectional operation of an active material that is converted into unidirectional fluid motion by a set of valves. While theoretically attractive, practical constraints limit the efficacy of the solid-fluid hybrid actuation approach. In particular, inertial loads, fluid viscosity and compressibility combine with loss mechanisms inherent in the active material to limit the effective bandwidth of the driving actuator and the total output power. A hybrid actuator was developed by using magnetostrictive TerFeNOL-D as the active driving element and hydraulic oil as the working fluid. Tests, both with and without an external load, were carried out to measure the unidirectional performance of the actuator at different pumping frequencies and operating conditions. The maximum no-load output velocity was 84 mm/s with a 51 mm long rod and 88 mm/s with a 102 mm long rod, both noted around 325 Hz pumping frequency, while the blocked force was close to 89 N. Dynamic tests were performed to analyze the axial vibration characteristics of the Terfenol-D rods and frequency responses of the magnetic circuits. A second prototype actuator employing the same actuation principle was then designed by using the electrostrictive material PMN-32%PT as the driving element. Tests were conducted to measure the actuator performance for varying electrical input conditions and fluid bias pressures. The peak output velocity obtained was 330 mm/s while the blocked force was 63 N. The maximum volume flow rate obtained with the PMN-based actuator was more than double that obtained from the Terfenol-D--based actuator. Theoretical modeling of the dynamics of the coupled structural-hydraulic system is extremely complex and several models have been proposed earlier. At high pumping frequencies, the fluid inertia

  18. Giant low-field magnetostriction of epoxy/TbxDy1-x(Fe0.8Co0.2)2 composites (0.20 ≤ x ≤ 0.40)

    NASA Astrophysics Data System (ADS)

    Liu, J. J.; Pan, Z. B.; Si, P. Z.; Du, J.

    2013-07-01

    Spin configuration, magnetocrystalline anisotropy compensation, and magnetostriction of TbxDy1-x(Fe0.8Co0.2)2 (0.20 ≤ x ≤ 0.40) compounds have been investigated. Experimental evidence for the anisotropy compensation has been observed directly by performing x-ray diffraction on magnetic-field aligned powders and by evaluating the Mössbauer spectra. The easy magnetization direction (EMD) at room temperature rotates from the ⟨100⟩ (x ≤ 0.27) to the ⟨111⟩ axis (x ≥ 0.32), subjected to the anisotropy compensation between Tb3+ and Dy3+ ions. The strong grain-⟨111⟩-oriented pseudo-1-3 epoxy/composite has been fabricated by curing under a moderate magnetic field. A giant low-field magnetostriction, longitudinal λ|| and linear anisotropic λa (=λ|| - λ⊥) up to 550 and 760 ppm at 3 kOe, respectively, is obtained for Tb0.32Dy0.68(Fe0.8Co0.2)2 composite, which can be attributed to anisotropy compensation, a large magnetostriction coefficients λ111, EMD lying along ⟨111⟩ direction, the strong ⟨111⟩-textured orientation, and the chain structure. The good magnetoelastic properties, besides only containing 27 vol. % alloy particles in the insulating epoxy, make it a promising candidate for magnetostriction applications.

  19. Optimal design of a vibration-based energy harvester using magnetostrictive material (MsM)

    NASA Astrophysics Data System (ADS)

    Hu, J.; Xu, F.; Huang, A. Q.; Yuan, F. G.

    2011-01-01

    In this study, an optimal vibration-based energy harvesting system using magnetostrictive material (MsM) was designed and tested to enable the powering of a wireless sensor. In particular, the conversion efficiency, converting from magnetic to electric energy, is approximately modeled from the magnetic field induced by the beam vibration. A number of factors that affect the output power such as the number of MsM layers, coil design and load matching are analyzed and explored in the design optimization. From the measurements, the open-circuit voltage can reach 1.5 V when the MsM cantilever beam operates at the second natural frequency 324 Hz. The AC output power is 970 µW, giving a power density of 279 µW cm - 3. The attempt to use electrical reactive components (either inductors or capacitors) to resonate the system at any frequency has also been analyzed and tested experimentally. The results showed that this approach is not feasible to optimize the power. Since the MsM device has low output voltage characteristics, a full-wave quadrupler has been designed to boost the rectified output voltage. To deliver the maximum output power to the load, a complex conjugate impedance matching between the load and the MsM device is implemented using a discontinuous conduction mode (DCM) buck-boost converter. The DC output power after the voltage quadrupler reaches 705 µW and the corresponding power density is 202 µW cm - 3. The output power delivered to a lithium rechargeable battery is around 630 µW, independent of the load resistance.

  20. Measurement of the Length of Installed Rock Bolt Based on Stress Wave Reflection by Using a Giant Magnetostrictive (GMS) Actuator and a PZT Sensor.

    PubMed

    Luo, Mingzhang; Li, Weijie; Wang, Bo; Fu, Qingqing; Song, Gangbing

    2017-02-23

    Rock bolts, as a type of reinforcing element, are widely adopted in underground excavations and civil engineering structures. Given the importance of rock bolts, the research outlined in this paper attempts to develop a portable non-destructive evaluation method for assessing the length of installed rock bolts for inspection purposes. Traditionally, piezoelectric elements or hammer impacts were used to perform non-destructive evaluation of rock bolts. However, such methods suffered from many major issues, such as the weak energy generated and the requirement for permanent installation for piezoelectric elements, and the inconsistency of wave generation for hammer impact. In this paper, we proposed a portable device for the non-destructive evaluation of rock bolt conditions based on a giant magnetostrictive (GMS) actuator. The GMS actuator generates enough energy to ensure multiple reflections of the stress waves along the rock bolt and a lead zirconate titantate (PZT) sensor is used to detect the reflected waves. A new integrated procedure that involves correlation analysis, wavelet denoising, and Hilbert transform was proposed to process the multiple reflection signals to determine the length of an installed rock bolt. The experimental results from a lab test and field tests showed that, by analyzing the instant phase of the periodic reflections of the stress wave generated by the GMS transducer, the length of an embedded rock bolt can be accurately determined.

  1. Stochastic bifurcation and fractal and chaos control of a giant magnetostrictive film-shape memory alloy composite cantilever plate subjected to in-plane harmonic and stochastic excitation

    NASA Astrophysics Data System (ADS)

    Zhu, Zhiwen; Zhang, Qingxin; Xu, Jia

    2014-05-01

    Stochastic bifurcation and fractal and chaos control of a giant magnetostrictive film-shape memory alloy (GMF-SMA) composite cantilever plate subjected to in-plane harmonic and stochastic excitation were studied. Van der Pol items were improved to interpret the hysteretic phenomena of both GMF and SMA, and the nonlinear dynamic model of a GMF-SMA composite cantilever plate subjected to in-plane harmonic and stochastic excitation was developed. The probability density function of the dynamic response of the system was obtained, and the conditions of stochastic Hopf bifurcation were analyzed. The conditions of noise-induced chaotic response were obtained in the stochastic Melnikov integral method, and the fractal boundary of the safe basin of the system was provided. Finally, the chaos control strategy was proposed in the stochastic dynamic programming method. Numerical simulation shows that stochastic Hopf bifurcation and chaos appear in the parameter variation process. The boundary of the safe basin of the system has fractal characteristics, and its area decreases when the noise intensifies. The system reliability was improved through stochastic optimal control, and the safe basin area of the system increased.

  2. Measurement of the Length of Installed Rock Bolt Based on Stress Wave Reflection by Using a Giant Magnetostrictive (GMS) Actuator and a PZT Sensor

    PubMed Central

    Luo, Mingzhang; Li, Weijie; Wang, Bo; Fu, Qingqing; Song, Gangbing

    2017-01-01

    Rock bolts, as a type of reinforcing element, are widely adopted in underground excavations and civil engineering structures. Given the importance of rock bolts, the research outlined in this paper attempts to develop a portable non-destructive evaluation method for assessing the length of installed rock bolts for inspection purposes. Traditionally, piezoelectric elements or hammer impacts were used to perform non-destructive evaluation of rock bolts. However, such methods suffered from many major issues, such as the weak energy generated and the requirement for permanent installation for piezoelectric elements, and the inconsistency of wave generation for hammer impact. In this paper, we proposed a portable device for the non-destructive evaluation of rock bolt conditions based on a giant magnetostrictive (GMS) actuator. The GMS actuator generates enough energy to ensure multiple reflections of the stress waves along the rock bolt and a lead zirconate titantate (PZT) sensor is used to detect the reflected waves. A new integrated procedure that involves correlation analysis, wavelet denoising, and Hilbert transform was proposed to process the multiple reflection signals to determine the length of an installed rock bolt. The experimental results from a lab test and field tests showed that, by analyzing the instant phase of the periodic reflections of the stress wave generated by the GMS transducer, the length of an embedded rock bolt can be accurately determined. PMID:28241503

  3. Stochastic bifurcation and fractal and chaos control of a giant magnetostrictive film-shape memory alloy composite cantilever plate subjected to in-plane harmonic and stochastic excitation

    SciTech Connect

    Zhu, Zhiwen; Zhang, Qingxin Xu, Jia

    2014-05-07

    Stochastic bifurcation and fractal and chaos control of a giant magnetostrictive film–shape memory alloy (GMF–SMA) composite cantilever plate subjected to in-plane harmonic and stochastic excitation were studied. Van der Pol items were improved to interpret the hysteretic phenomena of both GMF and SMA, and the nonlinear dynamic model of a GMF–SMA composite cantilever plate subjected to in-plane harmonic and stochastic excitation was developed. The probability density function of the dynamic response of the system was obtained, and the conditions of stochastic Hopf bifurcation were analyzed. The conditions of noise-induced chaotic response were obtained in the stochastic Melnikov integral method, and the fractal boundary of the safe basin of the system was provided. Finally, the chaos control strategy was proposed in the stochastic dynamic programming method. Numerical simulation shows that stochastic Hopf bifurcation and chaos appear in the parameter variation process. The boundary of the safe basin of the system has fractal characteristics, and its area decreases when the noise intensifies. The system reliability was improved through stochastic optimal control, and the safe basin area of the system increased.

  4. Magnetostrictive direct drive motors

    NASA Technical Reports Server (NTRS)

    Naik, Dipak; Dehoff, P. H.

    1990-01-01

    Developing magnetostrictive direct drive research motors to power robot joints is discussed. These type motors are expected to produce extraordinary torque density, to be able to perform microradian incremental steps and to be self-braking and safe with the power off. Several types of motor designs have been attempted using magnetostrictive materials. One of the candidate approaches (the magnetostrictive roller drive) is described. The method in which the design will function is described as is the reason why this approach is inherently superior to the other approaches. Following this, the design will be modelled and its expected performance predicted. This particular candidate design is currently undergoing detailed engineering with prototype construction and testing scheduled for mid 1991.

  5. Remote control of magnetostriction-based nanocontacts at room temperature.

    PubMed

    Jammalamadaka, S Narayana; Kuntz, Sebastian; Berg, Oliver; Kittler, Wolfram; Kannan, U Mohanan; Chelvane, J Arout; Sürgers, Christoph

    2015-09-01

    The remote control of the electrical conductance through nanosized junctions at room temperature will play an important role in future nano-electromechanical systems and electronic devices. This can be achieved by exploiting the magnetostriction effects of ferromagnetic materials. Here we report on the electrical conductance of magnetic nanocontacts obtained from wires of the giant magnetostrictive compound Tb0.3Dy0.7Fe1.95 as an active element in a mechanically controlled break-junction device. The nanocontacts are reproducibly switched at room temperature between "open" (zero conductance) and "closed" (nonzero conductance) states by variation of a magnetic field applied perpendicularly to the long wire axis. Conductance measurements in a magnetic field oriented parallel to the long wire axis exhibit a different behaviour where the conductance switches between both states only in a limited field range close to the coercive field. Investigating the conductance in the regime of electron tunneling by mechanical or magnetostrictive control of the electrode separation enables an estimation of the magnetostriction. The present results pave the way to utilize the material in devices based on nano-electromechanical systems operating at room temperature.

  6. Remote control of magnetostriction-based nanocontacts at room temperature

    PubMed Central

    Jammalamadaka, S. Narayana; Kuntz, Sebastian; Berg, Oliver; Kittler, Wolfram; Kannan, U. Mohanan; Chelvane, J. Arout; Sürgers, Christoph

    2015-01-01

    The remote control of the electrical conductance through nanosized junctions at room temperature will play an important role in future nano-electromechanical systems and electronic devices. This can be achieved by exploiting the magnetostriction effects of ferromagnetic materials. Here we report on the electrical conductance of magnetic nanocontacts obtained from wires of the giant magnetostrictive compound Tb0.3Dy0.7Fe1.95 as an active element in a mechanically controlled break-junction device. The nanocontacts are reproducibly switched at room temperature between “open” (zero conductance) and “closed” (nonzero conductance) states by variation of a magnetic field applied perpendicularly to the long wire axis. Conductance measurements in a magnetic field oriented parallel to the long wire axis exhibit a different behaviour where the conductance switches between both states only in a limited field range close to the coercive field. Investigating the conductance in the regime of electron tunneling by mechanical or magnetostrictive control of the electrode separation enables an estimation of the magnetostriction. The present results pave the way to utilize the material in devices based on nano-electromechanical systems operating at room temperature. PMID:26323326

  7. Influence of Joule heating on magnetostriction and giant magnetoimpedance effect in a glass covered CoFeSiB microwire

    NASA Astrophysics Data System (ADS)

    Kraus, L.; Knobel, M.; Kane, S. N.; Chiriac, H.

    1999-04-01

    The influence of annealing parameters (time ta, current Ia, and applied stress σa) on magnetic properties of Joule heated amorphous Co68.15Fe4.35Si12.5B15 glass covered microwire (13 μm) was investigated. Annealing under applied stress induces additional anisotropy which is proportional to σa and can be removed by subsequent heating without stress. The magnetoimpedance, measured on the sample with the lowest anisotropy field (HK≈120 Am-1), shows sharp maxima at H=±HK. For driving currents higher than 0.2 mA nonlinear behavior is observed, and the magnitude of giant magnetoimpedance significantly decreases. The maximum relative change of impedance (60%), observed for the highest frequency, 900 kHz, compares well with the values reported on conventional wires.

  8. Magnetostrictive Brake

    NASA Technical Reports Server (NTRS)

    Diftler, Myron A.; Hulse, Aaron

    2010-01-01

    A magnetostrictive brake has been designed as a more energy-efficient alternative to a magnetic fail-safe brake in a robot. (In the specific application, failsafe signifies that the brake is normally engaged; that is, power must be supplied to allow free rotation.) The magnetic failsafe brake must be supplied with about 8 W of electric power to initiate and maintain disengagement. In contrast, the magnetostrictive brake, which would have about the same dimensions and the same torque rating as those of the magnetic fail-safe brake, would demand only about 2 W of power for disengagement. The brake (see figure) would include a stationary base plate and a hub mounted on the base plate. Two solenoid assemblies would be mounted in diametrically opposed recesses in the hub. The cores of the solenoids would be made of the magnetostrictive alloy Terfenol-D or equivalent. The rotating part of the brake would be a ring-and spring- disk subassembly. By means of leaf springs not shown in the figure, this subassembly would be coupled with the shaft that the brake is meant to restrain. With no power supplied to the solenoids, a permanent magnet would pull axially on a stepped disk and on a shelf in the hub, causing the ring to be squeezed axially between the stepped disk and the hub. The friction associated with this axial squeeze would effect the braking action. Supplying electric power to the solenoids would cause the magnetostrictive cylinders to push radially inward against a set of wedges that would be in axial contact with the stepped disk. The wedges would convert the radial magnetostrictive strain to a multiplied axial displacement of the stepped disk. This axial displacement would be just large enough to lift the stepped disk, against the permanent magnetic force, out of contact with the ring. The ring would then be free to turn because it would no longer be squeezed axially between the stepped disk and the hub.

  9. A continuum three-dimensional, fully coupled, dynamic, non-linear finite element formulation for magnetostrictive materials

    NASA Astrophysics Data System (ADS)

    Pérez-Aparicio, José L.; Sosa, Horacio

    2004-06-01

    Magnetostriction is a phenomenon observed in all ferromagnetic materials. It couples elastic, electric, magnetic and in some situations also thermal fields and is of great industrial interest for use in sensors, actuators, adaptive or functional structures, robotics, transducers and MEMS. In this work, the governing equations of the three-field problem (i.e., the interactions of elastic, electric and magnetic effects) are formulated in three dimensions, accounting for non-linear (through magnetic body forces represented by the Maxwell tensor) and dynamic effects, and with constitutive equations resembling those of piezoelectricity. Through manipulation of Maxwell equations it is possible to find suitable expressions for developing the numerical weak, Galerkin and matrix forms in a natural way, including seven residuals (one for each nodal degree of freedom) and non-symmetric tangent, 'capacity' and mass consistent matrices. Simple backward Euler and central difference schemes can be used for the time domain integration. The only assumption made in this work for simplification is that the time variation of electric induction is negligible. This is justified by the relatively low frequencies ({\\ll }1 GHz) under which magnetostrictive materials usually work. The principal feature of the equations is the use of a magnetic potential (without much physical meaning) that allows a complete 'displacement' finite element formulation: all elastic, electric and magnetic nodal unknowns are zero derivatives. This allows the algorithm to be treated in a standard way, and important effects such as eddy currents can be obtained naturally. The formulation is implemented in the research finite element code FEAP. Although seven degrees of freedom per node is computer expensive to solve (especially for 3D problems), the current trend in the performance of computers, even personal ones, makes it worthwhile to build complete finite elements following the well-established (in mechanics

  10. Two phase modeling of the influence of plastic strain on the magnetic and magnetostrictive behaviors of ferromagnetic materials

    NASA Astrophysics Data System (ADS)

    Hubert, Olivier; Lazreg, Said

    2017-02-01

    A growing interest of automotive industry in the use of high performance steels is observed. These materials are obtained thanks to complex manufacturing processes whose parameters fluctuations lead to strong variations of microstructure and mechanical properties. The on-line magnetic non-destructive monitoring is a relevant response to this problem but it requires fast models sensitive to different parameters of the forming process. The plastic deformation is one of these important parameters. Indeed, ferromagnetic materials are known to be sensitive to stress application and especially to plastic strains. In this paper, a macroscopic approach using the kinematic hardening is proposed to model this behavior, considering a plastic strained material as a two phase system. Relationship between kinematic hardening and residual stress is defined in this framework. Since stress fields are multiaxial, an uniaxial equivalent stress is calculated and introduced inside the so-called magneto-mechanical multidomain modeling to represent the effect of plastic strain. The modeling approach is complemented by many experiments involving magnetic and magnetostrictive measurements. They are carried out with or without applied stress, using a dual-phase steel deformed at different levels. The main interest of this material is that the mechanically hard phase, soft phase and the kinematic hardening can be clearly identified thanks to simple experiments. It is shown how this model can be extended to single phase materials.

  11. Characteristics of magnetic force control device with magnetostrictive and piezoelectric laminate composite

    NASA Astrophysics Data System (ADS)

    Ueno, Toshiyuki; Qiu, Jinhao; Tani, Junji

    2003-08-01

    A magnetic force control device with laminate composite of giant magnetostrictive material (GMM) and piezo-electric material (PZT) is proposed. This magnetic force control is based on inverse magnetostrictive effect of a magnetic material, whereby the variation of stress applied on the material is converted to that of magnetic force via magnetic circuits. For the purpose of realizing the method in practical applications, disks of GMM and PZT are laminated to control the stress of GMM by electric field on PZT. Due to the capacitive properties of PZT, the device requires little electric energy hence generates no heat to maintain constant force. Furthermore compared with conventional electromagnetics, the device can be fabricated easily and in small size to be suitable for microactuators. This paper presents the principle of the magnetic force control by the lamination of GMM and PZT and investigates the static and dynamic characteristics of several devices to demonstrate their capabilities of the magnetic force control.

  12. Dirac State in Giant Magnetoresistive Materials

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Jo, N. H.; Ochi, M.; Huang, L.; Mou, D.; Kong, T.; Mun, E.; Wang, L.; Lee, Y.; Bud'Ko, S. L.; Canfield, P. C.; Trivedi, N.; Arito, R.; Kaminski, A.

    We use ultrahigh resolution, tunable, vacuum ultraviolet laser-based angle-resolved photoemission spectroscopy (ARPES) to study the electronic properties of materials that recently were discovered to display titanic magnetoresistance. We find that that several of these materials have Dirac-like features in their band structure. In some materials those features are ``ordinary'' Dirac cones, while in others the linear Dirac dispersion of two crossing bands forms a linear object in 3D momentum space. Our observation poses an important question about the role of Dirac dispersion in the unusually high, non-saturating magnetoresistance of these materials. Research was supported by the US DOE, Office of Basic Energy Sciences under Contract No. DE-AC02-07CH11358; Gordon and Betty Moore Foundation EPiQS Initiative (Grant No. GBMF4411); CEM, a NSF MRSEC, under Grant No. DMR-1420451.

  13. Giant magnetoresistance materials for magnetic recording technology

    SciTech Connect

    Heffner, R.H.; Adams, C.D.; Brosha, E.L.

    1997-12-01

    This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). This work focused on a class of transition-metal-oxide (TMO) materials (LaMnO{sub 3} doped with Ca, Ba, or Sr) that exhibits an insulator-to-metal transition near a ferromagnetic phase transition temperature. This yields a very large magnetoresistance; thus these materials may have important uses as magnetic sensors in a variety of applications, ranging from automobiles to read heads for magnetic storage. In addition, the transport current in the ferromagnetic state is likely to be very highly polarized, which means that additional device applications using the phenomena of spin-polarized tunneling can be envisioned. Use of these materials as magnetic sensors depends upon learning to control the synthesis parameters (principally temperature, pressure and composition) to achieve a specific carrier concentration and/or mobility. A second challenge is the high magnetic fields ({ge}1 Tesla) currently required to achieve a large change in resistance. The authors began an investigation of two novel approaches to this field-sensitivity problem, involving the development of multilayer structures of the TMO materials. Finally, they began to explore the use of epitaxial strain as a means of changing the transport properties in thin-film multilayers.

  14. Investigation of a Magnetostrictive Fiber Optic Interferometric Sensor

    DTIC Science & Technology

    1989-12-01

    interference property is responsible for the high sensitivity of the sensor since changes in the length of the sensor arm (on the order of the wavelength...technology. The magnetostrictive materials used included: cobalt, iron, and nickel. These materials all exhibit magnetostrictive properties , and they...and fabricating new sensor arms using Terfenol, a rare earth magnetic alloy (Tb0.3DyI.7 Fe2.9), as the magnetostrictive material. The use of lock-in

  15. Giant spin Seebeck effect in a non-magnetic material.

    PubMed

    Jaworski, C M; Myers, R C; Johnston-Halperin, E; Heremans, J P

    2012-07-11

    The spin Seebeck effect is observed when a thermal gradient applied to a spin-polarized material leads to a spatially varying transverse spin current in an adjacent non-spin-polarized material, where it gets converted into a measurable voltage. It has been previously observed with a magnitude of microvolts per kelvin in magnetically ordered materials, ferromagnetic metals, semiconductors and insulators. Here we describe a signal in a non-magnetic semiconductor (InSb) that has the hallmarks of being produced by the spin Seebeck effect, but is three orders of magnitude larger (millivolts per kelvin). We refer to the phenomenon that produces it as the giant spin Seebeck effect. Quantizing magnetic fields spin-polarize conduction electrons in semiconductors by means of Zeeman splitting, which spin-orbit coupling amplifies by a factor of ∼25 in InSb. We propose that the giant spin Seebeck effect is mediated by phonon-electron drag, which changes the electrons' momentum and directly modifies the spin-splitting energy through spin-orbit interactions. Owing to the simultaneously strong phonon-electron drag and spin-orbit coupling in InSb, the magnitude of the giant spin Seebeck voltage is comparable to the largest known classical thermopower values.

  16. Large Scale Magnetostrictive Valve Actuator

    NASA Technical Reports Server (NTRS)

    Richard, James A.; Holleman, Elizabeth; Eddleman, David

    2008-01-01

    Marshall Space Flight Center's Valves, Actuators and Ducts Design and Development Branch developed a large scale magnetostrictive valve actuator. The potential advantages of this technology are faster, more efficient valve actuators that consume less power and provide precise position control and deliver higher flow rates than conventional solenoid valves. Magnetostrictive materials change dimensions when a magnetic field is applied; this property is referred to as magnetostriction. Magnetostriction is caused by the alignment of the magnetic domains in the material s crystalline structure and the applied magnetic field lines. Typically, the material changes shape by elongating in the axial direction and constricting in the radial direction, resulting in no net change in volume. All hardware and testing is complete. This paper will discuss: the potential applications of the technology; overview of the as built actuator design; discuss problems that were uncovered during the development testing; review test data and evaluate weaknesses of the design; and discuss areas for improvement for future work. This actuator holds promises of a low power, high load, proportionally controlled actuator for valves requiring 440 to 1500 newtons load.

  17. Giant magnetoresistive nanostructured materials by electrodeposition

    NASA Astrophysics Data System (ADS)

    Myung, No Sang

    NiFe/Cu and CoFe/Cu multilayers and NiFe compositional modulated alloys (CMA) electrodeposited by newly developed flow-through electrochemical reactor. Sub-micron (Ni)Cu and nano-size (CoFe)Cu granular alloys have been electrodeposited by magneto-electrodeposition method. These two methods eliminate the problems confronted by conventional methods and provide a new direction in fabrication of nanostructured materials by electrodeposition. Prior to fabrication of GMR materials, electrodeposition kinetics of individual metals (Co, NiFe, Cu) were studied. In Co electrodeposition and dissolution from sulfate bath, substrates have a great impact on the initial growth mode of film. On polycrystalline platinum metal, cobalt film grew in hemispherical shape (nodule) where it grew in right conical shape on amorphous glass carbon. In NiFe alloys electrodeposition, the effects of applied current density, solution composition, substrate and solution hydrodynamics on current efficiency, film composition, crystal structure, corrosion resistant, and magnetic properties of NiFe alloys from all-chloride and citrate-sulfate-chloride bath have been studied. Citrate ions enhance the anomalous codeposition phenomena in NiFe electrodeposition. In crystal structure studies on electrodeposited. NiFe, the narrow mixed phase solid region was noted around 50% Fe. In addition, the smallest grain size were also observed in that region. In corrosion studies, the maximum corrosion resistance was observed at 50% Fe in naturally aerated 0.5 M NaCl. In Ni/Cu and Co/Cu multilayers by single bath technique, the optimum deposition potential ranges of pure copper and nickel (cobalt) were determined to minimize copper codeposition during nickel (cobalt) deposition and to minimize cobalt dissolution during copper deposition. Well defined laminated NiFe/Cu and CoFe/Cu multilayers and NiFe compositional modulated alloys (CMA) were successfully electrodeposited by utilizing flow-through electrochemical

  18. Magnetostrictive direct drive motor

    NASA Technical Reports Server (NTRS)

    Naik, Dipak; Dehoff, P. H.

    1991-01-01

    Highly magnetostrictive materials such as Tb.3Dy.7Fe2, commercially known as TERFENOL-D, have been used to date in a variety of devices such as high power actuators and linear motors. The larger magnetostriction available in twinned single crystal TERFENOL-D, approx. 2000 ppm at moderate magnetic field strengths, makes possible a new generation of magnetomechanical devices. NASA researchers are studying the potential of this material as the basis for a direct microstepping rotary motor with torque densities on the order of industrial hydraulics and five times greater than that of the most efficient, high power electric motors. Such a motor would be a micro-radian stepper, capable of precision movements and self-braking in the power-off state. Innovative mechanical engineering techniques are juxtaposed on proper magnetic circuit design to reduce losses in structural flexures, inertias, thermal expansions, eddy currents, and magneto-mechanical coupling, thus optimizing motor performance and efficiency. Mathematical models are presented, including magnetic, structural, and both linear and nonlinear dynamic calculations and simulations. In addition, test results on prototypes are presented.

  19. Theory of giant-caloric effects in multiferroic materials

    NASA Astrophysics Data System (ADS)

    Vopson, Melvin M.

    2013-08-01

    A generalized thermodynamic theory of giant-caloric effects in coupled multiferroic solids is introduced. The generalized theory allows analytical derivation of any caloric effect in solids displaying any type of cross coupling. In the particular cases of the non-coupled ferroic materials, the theory reproduces the well-known formulae describing magnetocaloric, electrocaloric or elastocaloric effects. This work facilitates adequate modeling tools and analytical relations capable of predicting caloric effects in complex coupled multiferroic materials, which is very beneficial to future developments in solid-state cooling technologies.

  20. Finite element analysis for acoustic characteristics of a magnetostrictive transducer

    NASA Astrophysics Data System (ADS)

    Kim, Jaehwan; Jung, Eunmi

    2005-12-01

    This paper presents a finite element analysis for a magnetostrictive transducer by taking into account the nonlinear behavior of the magnetostrictive material and fluid interaction. A finite element formulation is derived for the coupling of magnetostrictive and elastic materials based upon a separated magnetic and displacement field calculation and a curve fitting technique of material properties. The fluid and structure coupled problem is taken into account based upon pressure and velocity potential fields formulation. Infinite wave envelope elements are introduced at an artificial boundary to deal with the infinite fluid domain. A finite element code for the analysis of a magnetostrictive transducer is developed. A magnetostrictive tonpilz transducer is taken as an example and verification for the developed program is made by comparing with a commercial code. The acoustic characteristics of the magnetostrictive tonpilz transducer are calculated in terms of radiation pattern and transmitted current response.

  1. Relation between giant volume magnetostriction, colossal magnetoresistance, and crystal lattice softening in manganites La{sub 1-x}A{sub y}MnO{sub 3} (A = Ca, Ag, Ba, Sr)

    SciTech Connect

    Koroleva, L. I. Demin, R. V.; Kozlov, A. V.; Zashchirinskii, D. M.; Mukovskii, Ya. M.

    2007-02-15

    Giant volume magnetostriction (GVM) is detected near the Curie temperature T{sub C} in La{sub 1-x}A{sub x}MnO{sub 3} single crystals (A = Ca, Sr, Ba, 0.1 {<=} x {<=} 0.3) and above T{sub C} in La{sub 1-x}Ag{sub y}MnO{sub 3} (x = y = 0.15, 0.2 and x = 0.2, y = 0.1) ceramics (in the latter system, giant volume magnetostriction attains a value of 6.5 x 10{sup -4} in a magnetic field of 8.2 kOe). The behavior of GVM and colossal magnetoresistance (CMR) is found to be the same: both quantities have negative values, the temperature dependences of their absolute values pass through a peak, and the isotherms do not exhibit saturation up to the maximal measuring fields of 130 kOe. In compounds with compositions La{sub 0.7}Ba{sub 0.3}MnO{sub 3} and La{sub 0.85}Ag{sub 0.15}MnO{sub 3}, GVM and CMR were observed at room temperatures (in a magnetic field of 8.2 kOe, GVM attains values of 2.54 x 10{sup -4} and 2 x 10{sup -4} and CMR is equal to 11.6 and 11.2%, respectively). Both phenomena are attributed to the presence of a magnetic (ferromagnetic-antiferromagnetic) two-phase state in these systems, which is associated with a strong s-d exchange. It is found that the maximum value of the GVM in single crystals of La{sub 1-x}A{sub x}MnO{sub 3} (A = Ba, Sr, Ca, Ag) depends on the radius R{sub A} of cation A (it is the higher, the larger the difference |R{sub A}-R{sub LA{sup 3}{sup +}}|). The only exception is the compound with A = Ag, in which the pattern is complicated by additional defectiveness. Local disorder in the La{sub 1-x}A{sub x} sublattice, which is associated with the presence of cations with different radii, leads to a displacement of oxygen ions and to crystal lattice softening. The exchange s-d interactions in La{sub 1-x}A{sub x}MnO{sub 3} (A = Ca, Sr, Ba, Ag) are found to be comparable with electrostatic interactions ensuring the existence of the crystal; this facilitates manifestation of the GVM.

  2. Development of a polymer based fiberoptic magnetostrictive metal detector system.

    PubMed

    Hua, Wei Shu; Hooks, Joshua Rosenberg; Wu, Wen Jong; Wang, Wei Chih

    2010-10-01

    This paper presents a new metal detector using a fiberoptic magnetostriction sensor. The metal sensor uses a fiber-optic Mach-Zehnder interferometer with a newly developed ferromagnetic polymer as the magnetostrictive sensing material. This polymeric magnetostrictive fiberoptic metal sensor is simple to fabricate, small in size, and resistant to RF interference (which is common in typical electromagnetic type metal detectors). Metal detection is based on disruption of the magnetic flux density across the magnetostriction sensor. In this paper, characteristics of the material being sensed and magnetic properties of the ferromagnetic polymers will be discussed.

  3. Development of a polymer based fiberoptic magnetostrictive metal detector system

    PubMed Central

    Hua, Wei Shu; Hooks, Joshua Rosenberg; Wu, Wen Jong; Wang, Wei Chih

    2011-01-01

    This paper presents a new metal detector using a fiberoptic magnetostriction sensor. The metal sensor uses a fiber-optic Mach-Zehnder interferometer with a newly developed ferromagnetic polymer as the magnetostrictive sensing material. This polymeric magnetostrictive fiberoptic metal sensor is simple to fabricate, small in size, and resistant to RF interference (which is common in typical electromagnetic type metal detectors). Metal detection is based on disruption of the magnetic flux density across the magnetostriction sensor. In this paper, characteristics of the material being sensed and magnetic properties of the ferromagnetic polymers will be discussed. PMID:26425735

  4. Large magnetostriction and negative thermal expansion in the frustrated antiferromagnet ZnCr2Se4.

    PubMed

    Hemberger, J; von Nidda, H-A Krug; Tsurkan, V; Loidl, A

    2007-04-06

    A detailed investigation of ZnCr2Se4 is presented which is dominated by strong ferromagnetic exchange but orders antiferromagnetically at TN=21 K. Specific heat and thermal expansion exhibit sharp first-order anomalies at the antiferromagnetic transition. TN is shifted to lower temperatures by external magnetic fields and finally is fully suppressed by a field of 65 kOe. The relative length change DeltaL/L(T) is unusually large and exhibits negative thermal expansion alpha below 75 K down to TN indicating strong frustration of the lattice. Magnetostriction DeltaL/L(H) reveals large values comparable to giant magnetostrictive materials. These results point to a spin-driven origin of the structural instability at TN explained in terms of competing ferromagnetic and antiferromagnetic exchange interactions.

  5. Magnetostriction of field-structured magnetoelastomers.

    PubMed

    Martin, James E; Anderson, Robert A; Read, Douglas; Gulley, Gerald

    2006-11-01

    We investigate the magnetostriction of field-structured magnetoelastomers, which are an important class of materials that have great potential as both sensors and actuators. Field-structured magnetoelastomers are synthesized by suspending magnetic particles in a polymeric resin and subjecting these to magnetic structuring fields during polymerization. These structuring fields can consist of as many as three orthogonal ac components, allowing a wide variety of particles structures--chains, sheets, or networks--to be formed. A principal issue is how particle structure and loading affects the magnetostriction of these materials. To investigate magnetostriction in these field-structured composites we have constructed a constant stress, optical cantilever apparatus capable of 1 ppm strain resolution. Magnetoelastomers having a wide range of particle loadings and structures are investigated, and it is shown that the observed deformation depends strongly on composite structure. The best magnetoelastomers exhibit a contractive strain of 10,000 ppm, the worst materials exhibit a negative, tensile response, which we show is due to the dominance of demagnetizing field effects over magnetostriction. Finally, some discussion is given to the surprising finding that magnetostriction is proportional to the sample prestrain. Simulations of a chain of particles in an elastomer show that particle clumping transitions can occur, but this does not account for the dependence of magnetostriction on prestrain.

  6. Magnetostriction and Magnetic Heterogeneities in Iron-Gallium

    DTIC Science & Technology

    2010-07-08

    REPORT Magnetostriction and Magnetic Heterogeneities in Iron-Gallium 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: Iron-gallium alloys Fe1-xGax exhibit...an exceptional increase in magnetostriction with gallium content. We present small-angle neutron scattering investigations on a Fe0.81Ga0.19 single...magnetic heterogeneities in the mechanism for magnetostriction in this material. 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 13. SUPPLEMENTARY NOTES

  7. Magnetostrictive direct drive motors

    NASA Technical Reports Server (NTRS)

    Naik, Dipak; Dehoff, P. H.

    1992-01-01

    A new rare earth alloy, Terfenol-D, combines low frequency operation and extremely high energy density with high magnetostriction. Its material properties make it suitable as a drive element for actuators requiring high output torque. The high strains, the high forces and the high controllability of Terfenol alloys provide a powerful and challenging basis for new ways to generate motion in actuators. Two prototypes of motors using Terfenol-D rods were developed at NASA Goddard. The basic principles of operation are provided of the motor along with other relevant details. A conceptual design of a torque limiting safety clutch/brake under development is illustrated. Also, preliminary design drawings of a linear actuator using Terfenol-D is shown.

  8. Materials with Giant Mechanocaloric Effects: Cooling by Strength.

    PubMed

    Mañosa, Lluís; Planes, Antoni

    2016-12-27

    The search for materials with large caloric effects has become a major challenge in material science due to their potential in developing near room-temperature solid-state cooling devices, which are both efficient and clean, and that can successfully replace present refrigeration technologies. There are three main families of caloric materials: magnetocaloric, electrocaloric, and mechanocaloric. While magnetocaloric and electrocaloric materials have been studied intensively in the last few decades, mechanocaloric materials are only very recently receiving a great deal of attention. The mechanocaloric effect refers to the reversible thermal response of a solid when subjected to an external mechanical field, and encompasses both the elastocaloric effect, corresponding to a uniaxial force, and the barocaloric effect, which corresponds to the response to hydrostatic pressure. Here, the state of the art in giant mechanocaloric effects is reviewed and a critical analysis of the thermodynamic quantities that characterize the major families of barocaloric and elastocaloric materials is provided. Finally perspectives for further development in this area are given.

  9. Determination of the magnetostrictive response of nanoparticles via magnetoelectric measurements.

    PubMed

    Martins, P; Silva, M; Lanceros-Mendez, S

    2015-06-07

    It is successfully demonstrated that nanoparticle's magnetostriction can be accurately determined based on the magnetoelectric effect measured on polymeric composite materials. This represents a novel, simple and versatile method for the determination of particle's magnetostriction at the nano scale and in their dispersed state, which has been, up to now, a difficult and imprecise task.

  10. Preparation and applications of magnetostrictive thin films

    NASA Astrophysics Data System (ADS)

    Quandt, E.; Geriach, B.; Seemann, K.

    1994-11-01

    Amorphous magnetostrictive films of the binary compound Sm(x)Fe(1-x) as well as of the ternary compound (Tb(y)Dy(1-y)(x)Fe(1-x) were prepared by rf or dc magnetron sputtering using either a multitarget arrangement with pure element targets or cash composite-type targets. The magnetostrictive properties of (Tb0.3Dy0.7)(0.4)Fe0.6 and Sm0.Fe0.6 films were investigated in relation to their preparation conditions. Depending upon these conditions (especially upon the deposition rate, the bias voltage, and the Ar sputtering pressure) amorphous films with a giant magnetostriction of about 250 ppm (-220 ppm) at 0.1 T and 400 ppm (-300 ppm) at 0.5 T for the TbDyFe (SmFe) and an in-plane magnetic easy axis could be prepared. In view of applications in microsystem technologies (e.g., pumps, valves, positioning elements) these films have been tested in a simple cantilever arrangement and the predicted deflection of a magnetostrictive actuated membrane has been calculated.

  11. FEM implementation of a magnetostrictive transducer

    NASA Astrophysics Data System (ADS)

    Benatar, J. G.; Flatau, A. B.

    2005-05-01

    Magnetostrictive transducers are used in a broad variety of applications that include linear pump drives mechanisms, active noise and vibration control systems and sonar systems. Optimization of their performance relies on accurate modeling of the static and dynamic behavior of the magnetostrictive material. The nonlinearity of some magnetostrictive material properties along with eddy current power losses occurring in both the magnetostrictive material and in the magnetic circuit of the system makes this task particularly difficult. This paper introduces a static and a dynamic three-dimensional multi-physics boundary value problem that includes magneto-mechanical coupling for modeling magnetostriction and electromagnetic coupling for modeling eddy-current power loss (dynamic case only). It also includes the effect of the magnetic stress tensor, also known as Maxwell stress tensor, introduced by Kannan. The dynamic formulation is inspired by the finite element formulation in the Galerkin form introduced by Perez-Aparicio and Sosa, but focuses on a weak form formulation of the problem suitable for implementation in the finite element commercial software FEMLAB 3.1. Finally, an example is presented and compared to experimental results to validate the static model.

  12. Giant Mechanocaloric Effects in Fluorite-Structured Superionic Materials

    NASA Astrophysics Data System (ADS)

    Cazorla, Claudio; Errandonea, Daniel

    2016-05-01

    Mechanocaloric materials experience a change in temperature when a mechanical stress is adiabatically applied on them. Thus far, only ferroelectrics and superelastic metallic alloys have been considered as potential mechanocaloric compounds to be exploited in solid-state cooling applications. Here we show that giant mechanocaloric effects occur in hitherto overlooked fast ion conductors (FIC), a class of multicomponent materials in which above a critical temperature, Ts, a constituent ionic species undergoes a sudden increase in mobility. Using first-principles and molecular dynamics simulations, we found that the superionic transition in fluorite-structured FIC, which is characterised by a large entropy increase of the order of 100 J/K*Kg, can be externally tuned with hydrostatic, biaxial or uniaxial stresses. In particular, Ts can be reduced several hundreds of degrees through the application of moderate tensile stresses due to the concomitant drop in the formation energy of Frenkel pair defects. We predict that the adiabatic temperature change in CaF2 and PbF2, two archetypal fluorite-structured FIC, close to their critical points are of the order of 100 and 10 K, respectively. This work advocates that FIC constitute a new family of mechanocaloric materials showing great promise for prospective solid-state refrigeration applications.

  13. Giant Mechanocaloric Effects in Fluorite-Structured Superionic Materials.

    PubMed

    Cazorla, Claudio; Errandonea, Daniel

    2016-05-11

    Mechanocaloric materials experience a change in temperature when a mechanical stress is applied on them adiabatically. Thus, far, only ferroelectrics and superelastic metallic alloys have been considered as potential mechanocaloric compounds to be exploited in solid-state cooling applications. Here we show that giant mechanocaloric effects occur in hitherto overlooked fast ion conductors (FIC), a class of multicomponent materials in which above a critical temperature, Ts, a constituent ionic species undergoes a sudden increase in mobility. Using first-principles and molecular dynamics simulations, we found that the superionic transition in fluorite-structured FIC, which is characterized by a large entropy increase of the order of 10(2) JK(-1) kg(-1), can be externally tuned with hydrostatic, biaxial, or uniaxial stresses. In particular, Ts can be reduced several hundreds of degrees through the application of moderate tensile stresses due to the concomitant drop in the formation energy of Frenkel pair defects. We predict that the adiabatic temperature change in CaF2 and PbF2, two archetypal fluorite-structured FIC, close to their critical points are of the order of 10(2) and 10(1) K, respectively. This work advocates that FIC constitute a new family of mechanocaloric materials showing great promise for prospective solid-state refrigeration applications.

  14. Magnetostrictive valve assembly

    NASA Technical Reports Server (NTRS)

    Richard, James A. (Inventor)

    2008-01-01

    A magnetostrictive valve assembly includes a housing that defines a passage with a seat being formed therein. A magnetically-biased and axially-compressed magnetostrictive assembly slidingly fitted in the passage is configured as a hollow and open-ended conduit adapted to support a flow of a fluid therethrough. Current-carrying coil(s) disposed about the passage in the region of the magnetostrictive assembly generate a magnetic field in the passage when current flows through the coil(s). A hollow valve body with side ports is coupled on one end thereof to an axial end of the magnetostrictive assembly. The other end of the valve body is designed to seal with the seat formed in the housing's passage when brought into contact therewith.

  15. Giant Hall Photoconductivity in Narrow-Gapped Dirac Materials.

    PubMed

    Song, Justin C W; Kats, Mikhail A

    2016-12-14

    Carrier dynamics acquire a new character in the presence of Bloch-band Berry curvature, which naturally arises in gapped Dirac materials (GDMs). Here, we argue that photoresponse in GDMs with small band gaps is dramatically enhanced by Berry curvature. This manifests in a giant and saturable Hall photoconductivity when illuminated by circularly polarized light. Unlike Hall motion arising from a Lorentz force in a magnetic field, which impedes longitudinal carrier motion, Hall photoconductivity arising from Berry curvature can boost longitudinal carrier transport. In GDMs, this results in a helicity-dependent photoresponse in the Hall regime, where photoconductivity is dominated by its Hall component. We find that the induced Hall conductivity per incident irradiance is enhanced by up to 6 orders of magnitude when moving from the visible regime (with corresponding band gaps) to the far infrared. These results suggest that narrow-gap GDMs are an ideal test-bed for the unique physics that arise in the presence of Berry curvature and open a new avenue for infrared and terahertz optoelectronics.

  16. Effect of the elastic modulus of the matrix on magnetostrictive strain in composites

    SciTech Connect

    Chen, Y.; Snyder, J.E.; Schwichtenberg, C.R.; Dennis, K.W.; Falzgraf, D.K.; McCallum, R.W.; Jiles, D.C.

    1999-02-01

    The effect of the matrix material on the magnetostriction of composites containing highly magnetostrictive particles has been studied. Experimental results showed that the elastic modulus of the matrix is an important factor determining the bulk magnetostriction of the composite. For a series of composites with the same volume fraction of magnetostrictive particles but different matrix materials, the bulk magnetostriction was found to increase systematically with decreasing elastic modulus of the matrix. A model theory for the magnetostriction of such composites has been developed, based on two limiting assumptions: uniform strain or uniform stress inside the composite. The theory was then used to predict the magnetostriction of the entire material from the volume fractions of the components, their elastic moduli and magnetostrictions. These predictions were in agreement with the experimental results. It is concluded that to obtain a high magnetostriction and adequate mechanical properties of a composite, the elastic moduli of the magnetostrictive phase and the matrix should be as close as possible in value. {copyright} {ital 1999 American Institute of Physics.}

  17. Giant and universal magnetoelectric coupling in soft materials and concomitant ramifications for materials science and biology

    NASA Astrophysics Data System (ADS)

    Liu, Liping; Sharma, Pradeep

    2013-10-01

    Magnetoelectric coupling—the ability of a material to magnetize upon application of an electric field and, conversely, to polarize under the action of a magnetic field—is rare and restricted to a rather small set of exotic hard crystalline materials. Intense research activity has recently ensued on materials development, fundamental scientific issues, and applications related to this phenomenon. This tantalizing property, if present in adequate strength at room temperature, can be used to pave the way for next-generation memory devices such as miniature magnetic random access memories and multiple state memory bits, sensors, energy harvesting, spintronics, among others. In this Rapid Communication, we prove the existence of an overlooked strain mediated nonlinear mechanism that can be used to universally induce the giant magnetoelectric effect in all (sufficiently) soft dielectric materials. For soft polymer foams—which, for instance, may be used in stretchable electronics—we predict room-temperature magnetoelectric coefficients that are comparable to the best known (hard) composite materials created. We also argue, based on a simple quantitative model, that magnetoreception in some biological contexts (e.g., birds) most likely utilizes this very mechanism.

  18. Magnetostrictive thin films for microwave spintronics.

    PubMed

    Parkes, D E; Shelford, L R; Wadley, P; Holý, V; Wang, M; Hindmarch, A T; van der Laan, G; Campion, R P; Edmonds, K W; Cavill, S A; Rushforth, A W

    2013-01-01

    Multiferroic composite materials, consisting of coupled ferromagnetic and piezoelectric phases, are of great importance in the drive towards creating faster, smaller and more energy efficient devices for information and communications technologies. Such devices require thin ferromagnetic films with large magnetostriction and narrow microwave resonance linewidths. Both properties are often degraded, compared to bulk materials, due to structural imperfections and interface effects in the thin films. We report the development of epitaxial thin films of Galfenol (Fe81Ga19) with magnetostriction as large as the best reported values for bulk material. This allows the magnetic anisotropy and microwave resonant frequency to be tuned by voltage-induced strain, with a larger magnetoelectric response and a narrower linewidth than any previously reported Galfenol thin films. The combination of these properties make epitaxial thin films excellent candidates for developing tunable devices for magnetic information storage, processing and microwave communications.

  19. Magnetostrictive thin films for microwave spintronics

    PubMed Central

    Parkes, D. E.; Shelford, L. R.; Wadley, P.; Holý, V.; Wang, M.; Hindmarch, A. T.; van der Laan, G.; Campion, R. P.; Edmonds, K. W.; Cavill, S. A.; Rushforth, A. W.

    2013-01-01

    Multiferroic composite materials, consisting of coupled ferromagnetic and piezoelectric phases, are of great importance in the drive towards creating faster, smaller and more energy efficient devices for information and communications technologies. Such devices require thin ferromagnetic films with large magnetostriction and narrow microwave resonance linewidths. Both properties are often degraded, compared to bulk materials, due to structural imperfections and interface effects in the thin films. We report the development of epitaxial thin films of Galfenol (Fe81Ga19) with magnetostriction as large as the best reported values for bulk material. This allows the magnetic anisotropy and microwave resonant frequency to be tuned by voltage-induced strain, with a larger magnetoelectric response and a narrower linewidth than any previously reported Galfenol thin films. The combination of these properties make epitaxial thin films excellent candidates for developing tunable devices for magnetic information storage, processing and microwave communications. PMID:23860685

  20. Nebular and Interstellar Materials in a Giant Cluster IDP of Probable Cometary Origin

    NASA Astrophysics Data System (ADS)

    Messenger, S.; Brownlee, D. E.; Joswiak, D. J.; Nguyen, A. N.

    2015-07-01

    We are conducting coordinated mineralogical, and isotopic studies of a giant cluster CP-IDP to determine proportions of inner solar system and interstellar materials. We have identified an 16O-rich enstatite grain that likely formed near the Sun.

  1. Stress magnetization model for magnetostriction in multiferroic composite

    NASA Astrophysics Data System (ADS)

    Gualdi, A. J.; Zabotto, F. L.; Garcia, D.; de Oliveira, A. J. A.

    2013-08-01

    An alternative to obtain multiferroic materials is the production of composite materials that combine ferroelectric and magnetic materials. In particular, the use of magnetostrictive materials as ferromagnetic phase in composites is very important because the mechanical stress applied in ferroelectric phase induces the appearance of magnetoelectric effect. In this work, we have proposed a generalized model for the magnetostriction dependence with the magnetization of the 0-3 type composite magnetoelectric materials. Including both piezomagnetic and stress dependence in the magnetostriction, a relevant improvement was reached as compared to the ordinary square magnetization model. Based on the Gibbs free energy expansion, the magnetostriction behavior of the composite (1-x)Pb(Mg1/3Nb2/3)-xPbTiO3/CoFe2O4 at 300 K and 5 K is described. Furthermore, using the piezomagnetic correction, the magnetostriction data for the pure CoFe2O4 is fitted showing that this ferrite presents a relevant piezomagnetic effect.

  2. Improved magnetostrictive transducer drive elements achieved by reduction of crystalline defects and improved crystalline orientation. Final report

    SciTech Connect

    McMasters, D.

    1993-10-29

    The discovery of the giant magnetostrictive rare earth-iron alloys in the 1970's was a direct result of the efforts initiated at DOD's Naval Surface Warfare Center (NSWC), Silver Spring, MD in conjunction with DOE's Ames Laboratory (AL), Ames, IA. This research into these new materials was specifically targeted for the development of low frequency, high power transducers for underwater sonar systems. The most technologically advanced of these materials in TERFENOL-D, Tb(3)Dy(7)Fe(1.9-1.95) an intermetallic compound consisting of iron (Fe) and the rare earth metals terbium (Tb) and dysprosium (Dy). Because of the advantages over existing transducer materials, the use of TERFENOL-D as a transducer drive element is expanding into a broad range of commercial applications and advanced defense systems. One of the disadvantages is the cost of these drivers, primarily the terbium and dysprosium raw materials.

  3. Magnetostrictive-piezoelectric composite structures for energy harvesting

    NASA Astrophysics Data System (ADS)

    Lafont, Thomas; Gimeno, L.; Delamare, J.; Lebedev, G. A.; Zakharov, D. I.; Viala, B.; Cugat, O.; Galopin, N.; Garbuio, L.; Geoffroy, O.

    2012-09-01

    In this paper, harvesters coupling magnetostrictive and piezoelectric materials are investigated. The energy conversion of quasi-static magnetic field variations into electricity is detailed. Experimental results are exposed for two macroscopic demonstrators based on the rotation of a permanent magnet. These composite/hybrid devices use both piezoelectric and magnetostrictive (amorphous FeSiB ribbon or bulk Terfenol-D) materials. A quasi-static (or ultra-low frequency) harvester is constructed with exploitable output voltage, even in quasi-static mode. Integrated micro-harvesters using sub-micron multilayers of active materials on Si have been built and are currently being characterized.

  4. Rhombohedral magnetostriction in dilute iron (Co) alloys

    SciTech Connect

    Jones, Nicholas J. Wun-Fogle, Marilyn; Restorff, J. B.; Petculescu, Gabriela; Clark, Arthur E.; Hathaway, Kristl B.; Schlagel, Deborah; Lograsso, Thomas A.

    2015-05-07

    Iron is a well-utilized material in structural and magnetic applications. This does not mean, however, that it is well understood, especially in the field of magnetostriction. In particular, the rhombohedral magnetostriction of iron, λ{sub 111}, is anomalous in two respects: it is negative in sign, in disagreement with the prediction of first principles theory, and its magnitude decreases with increasing temperature much too rapidly to be explained by a power law dependence on magnetization. These behaviors could arise from the location of the Fermi level, which leaves a small region of the majority 3d t{sub 2g} states unfilled, possibly favoring small internal displacements that split these states. If this view is correct, adding small amounts of Co to Fe fills some of these states, and the value of λ{sub 111} should increase toward a positive value, as predicted for perfect bcc Fe. We have measured the magnetostriction coefficients (λ{sub 111} and λ{sub 100}) of pure Fe, Fe{sub 97}Co{sub 3}, and Fe{sub 94}Co{sub 6} single crystals from 77 K to 450 K. Resonant ultrasound spectroscopy has been used to check for anomalies in the associated elastic constants, c{sub 44} and c′. The additional electrons provided by the cobalt atoms indeed produced positive contributions to both magnetostriction constants, λ{sub 111} and λ{sub 100}, exhibiting an increase of 2.8 × 10{sup −6} per at. % Co for λ{sub 111} and 3.8 × 10{sup −6} per at. % Co for λ{sub 100}.

  5. Anisotropic magnetostrictive metal-polymer composites for functional devices

    NASA Astrophysics Data System (ADS)

    Kiseleva, T. Yu.; Zholudev, S. I.; Il'inykh, I. A.; Novakova, A. A.

    2013-12-01

    New metal-polymer composites based on mechanochemically synthesized magnetostrictive Fe-Ga phase particles with dimensions of up to 2 μm dispersed and spatially oriented in a polymer matrix have been studied. The polymer matrix for spatial anisotropic stabilization of particles was represented by modified polyurethane (PU). An increase in the magnetostrictive effect was achieved by directed orientation of particles in a magnetic field applied during polymerization of the PU matrix. The spatial anisotropy of the composite has been studied by the methods of conversion Mössbauer spectroscopy with resonant X-ray detection and scanning electron microscopy. It is shown that the mechanochemical synthesis is an effective method of obtaining particles with microstress-enhanced magnetostriction. The use of these particles for the formation of a functional elastomer composite provides a material with significant magnetostrictive effect, which can be several-fold increased due to orientation of particles in an applied magnetic field. The obtained anisotropic magnetostrictive composite is a promising material for the creation of smart functional components of positioning systems, attenuators, and sensors.

  6. Magnetism, elasticity, and magnetostriction of FeCoGa alloys

    NASA Astrophysics Data System (ADS)

    Dai, Liyang; Cullen, James; Wuttig, Manfred; Lograsso, T.; Quandt, Eckhard

    2003-05-01

    It is known that the substitution of Co for Fe gives rise to increases in magnetization and Curie temperature, not only in the bcc metals, but also in intermetallic compounds and alloys as well. With the expectation that this is the case in Co-substituted FeGa, we measured magnetization, Curie temperature, magnetostriction and elastic constants of a series of polycrystalline FeCoGa ternary alloys with up to 17% Ga and up to 10% Co. The magnetostriction at saturation for Fe0.93-xCo.07Gax increases to 90 ppm for x=0.17. For larger percentages of Co, the rise in magnetostriction is not as sharp as it is in the 7% case. The shear elastic modulus decreases with Ga, again in keeping with the results for FeGa. The magnetostriction and the elastic constants are sensitive to sample preparation for the high-Ga material. We conclude that the substitution of small (<0.10) percentages of Co for Fe in bcc FeCoGa alloys enhances the magnetic and magnetostrictive properties of the parent FeGa material.

  7. Development of magnetostrictive active members for control of space structures

    NASA Technical Reports Server (NTRS)

    Johnson, Bruce G.; Avakian, Kevin M.; Fenn, Ralph C.; Gaffney, Monique S.; Gerver, Michael J.; Hawkey, Timothy J.; Boudreau, Donald J.

    1992-01-01

    The goal of this Phase 2 Small Business Innovative Research (SBIR) project was to determine the technical feasibility of developing magnetostrictive active members for use as truss elements in space structures. Active members control elastic vibrations of truss-based space structures and integrate the functions of truss structure element, actively controlled actuator, and sensor. The active members must control structural motion to the sub-micron level and, for many proposed space applications, work at cryogenic temperatures. Under this program both room temperature and cryogenic temperature magnetostrictive active members were designed, fabricated, and tested. The results of these performance tests indicated that room temperature magnetostrictive actuators feature higher strain, stiffness, and force capability with lower amplifier requirements than similarly sized piezoelectric or electrostrictive active members, at the cost of higher mass. Two different cryogenic temperature magnetostrictive materials were tested at liquid nitrogen temperatures, both with larger strain capability than the room temperature magnetostrictive materials. The cryogenic active member development included the design and fabrication of a cryostat that allows operation of the cryogenic active member in a space structure testbed.

  8. Magnetization and magnetostriction of Terfenol-D near spin reorientation boundary

    NASA Astrophysics Data System (ADS)

    Wang, Ben L.; Jin, Yongmei M.

    2012-05-01

    Magnetization and magnetostriction behaviors of quasi-binary TbxDy1-xFe2 alloys (Terfenol-D) near spin reorientation boundary (SRB) between <111> and <100> easy axes are studied by computer simulation of magnetic domain rotations under increasing magnetic field and compressive stress along [112] growth direction. The simulation results reveal coexistence of <111> and <100> domains near SRB and show that the switching field first decreases then increases when crossing the SRB from the <100> region into the <111> region of the quasi-binary phase diagram, while the magnetostriction first increases then saturates, thus providing an optimal combination of large magnetostriction and low switching field near the SRB as desired for actuator application. This finding has general implications for other magnetostrictive quasi-binary alloys that also exhibit spin reorientation phenomenon, allowing material design for improved magnetostrictive property near SRB, in analogy to morphotropic phase boundary ferroelectrics.

  9. Magnetostrictive microelectromechanical loudspeaker.

    PubMed

    Albach, Thorsten S; Lerch, Reinhard

    2013-12-01

    A microelectromechnical-loudspeaker based on the magnetostrictive effect is presented. The membrane consists of a comb structure of monomorph bending cantilevers with an area of about 16 mm(2). Prototypes generate a sound pressure level (SPL) of up to 102 dB at 450 Hz with a total harmonic distortion of 2% inside a 2 cm(3) measurement volume. The fabrication process of the device as well as a coupled simulation model to calculate its sound pressure is introduced. The model reproduces the measurements and is employed to further optimize the loudspeaker membrane. As a result, a computed maximum SPL of 106 dB has been achieved with a -6 dB frequency range extending from 100 Hz to 2.6 kHz.

  10. Vibration Control via Stiffness Switching of Magnetostrictive Transducers

    NASA Technical Reports Server (NTRS)

    Scheidler, Justin J.; Asnani, Vivake M.; Dapino, Marcelo J.

    2016-01-01

    This paper presents a computational study of structural vibration control that is realized by switching a magnetostrictive transducer between high and low stiffness states. Switching is accomplished by either changing the applied magnetic field with a voltage excitation or changing the shunt impedance on the transducer's coil (i.e., the magnetostrictive material's magnetic boundary condition). Switched-stiffness vibration control is simulated using a lumped mass supported by a damper and the magnetostrictive transducer (mount), which is represented by a nonlinear, electromechanical model. Free vibration of the mass is calculated while varying the mount's stiffness according to a reference switched-stiffness vibration control law. The results reveal that switching the magnetic field produces the desired change in stiffness, but also an undesired actuation force that can significantly degrade the vibration control. Hence, a modified switched-stiffness control law that accounts for the actuation force is proposed and implemented for voltage-controlled stiffness switching. The influence of the magnetomechanical bias condition is also discussed. Voltage-controlled stiffness switching is found to introduce damping equivalent to a viscous damping factor up to about 0.25; this is shown to primarily result from active vibration reduction caused by the actuation force. The merit of magnetostrictive switched-stiffness vibration control is then quantified by comparing the results of voltage- and shunt-controlled stiffness switching to the performance of optimal magnetostrictive shunt damping.

  11. Vibration analysis of magnetostrictive thin-film composite cantilever actuator

    NASA Astrophysics Data System (ADS)

    Xu, Yan; Shang, Xinchun

    2016-09-01

    The transverse vibration of a composed cantilever beam with magnetostrictive layer is analyzed, which is employed to simulate dynamic response of an actuator. The high-order shear deformation theory of beam and the coupling magnetoelastic constitutive relationship are introduced to construct the governing equations, all interface conditions between magnetostrictive film and elastic substrate as well as the free stress condition on the top and bottom surfaces of the beam can be satisfied. In order to demonstrate validity of the presented mathematical modeling, the verification examples are also given. Furthermore, the effect of geometry and material parameters on dynamic characteristics of magnetostrictive cantilever beam, such as the nature frequency and amplitude, is discussed. Moreover, through computing the magneto-mechanical coupling factor of the beam structure, the variation tendency curves of the factor along with different parameters and frequencies of magnetostrictive cantilever beam actuator have been presented. These numerical results should be useful for the design of beam-type with magnetostrictive thin-film actuators.

  12. Interpretation of the magnetization mechanism in Terfenol-D using Barkhausen pulse-height analysis and irreversible magnetostriction

    SciTech Connect

    Jiles, D.C. ); Hariharan, S. )

    1990-05-01

    The ternary alloy Dy{sub 0.7}Tb{sub 0.3}Fe{sub 1.9}, known as Terfenol-D, is a highly magnetostrictive alloy with magnetostriction coefficients along the principal crystallographic directions of {lambda}{sub 111}=1640{times}10{sup {minus}6} and {lambda}{sub 100}{le}100({plus minus}30){times}10{sup {minus}6}. The bulk magnetostriction {lambda} is dependent on the state of magnetization {ital M}, on the original domain configuration, and on the texture of the material. This paper reports on Barkhausen measurements and magnetostriction. The pulse-height distribution of Barkhausen emissions revealed events occurring at a specific amplitude which were stress dependent. The magnetostriction results gave a saturation magnetostriction in excess of 2000 {mu} strain.

  13. Wheatstone bridge technique for magnetostriction measurements.

    PubMed

    Sullivan, M

    1980-03-01

    A basic Wheatstone bridge, with additional electronic instrumentation, has been used in the measurement of magnetostriction. This method allows a resolution of approximately 10% on measurements of magnetostrictions less than 0.75 parts per million.

  14. An Energy-Based Hysteresis Model for Magnetostrictive Transducers

    NASA Technical Reports Server (NTRS)

    Calkins, F. T.; Smith, R. C.; Flatau, A. B.

    1997-01-01

    This paper addresses the modeling of hysteresis in magnetostrictive transducers. This is considered in the context of control applications which require an accurate characterization of the relation between input currents and strains output by the transducer. This relation typically exhibits significant nonlinearities and hysteresis due to inherent properties of magnetostrictive materials. The characterization considered here is based upon the Jiles-Atherton mean field model for ferromagnetic hysteresis in combination with a quadratic moment rotation model for magnetostriction. As demonstrated through comparison with experimental data, the magnetization model very adequately quantifies both major and minor loops under various operating conditions. The combined model can then be used to accurately characterize output strains at moderate drive levels. The advantages to this model lie in the small number (six) of required parameters and the flexibility it exhibits in a variety of operating conditions.

  15. Magnetostriction and magnetic heterogeneities in iron-gallium.

    PubMed

    Laver, M; Mudivarthi, C; Cullen, J R; Flatau, A B; Chen, W-C; Watson, S M; Wuttig, M

    2010-07-09

    Iron-gallium alloys Fe(1-x)Ga(x) exhibit an exceptional increase in magnetostriction with gallium content. We present small-angle neutron scattering investigations on a Fe(0.81)Ga(0.19) single crystal. We uncover heterogeneities with an average spacing of 15 nm and with magnetizations distinct from the matrix. The moments in and around the heterogeneities are observed to reorient with an applied magnetic field or mechanical strain. We discuss the possible roles played by nanoscale magnetic heterogeneities in the mechanism for magnetostriction in this material.

  16. Magnetostriction and Magnetic Heterogeneities in Iron-Gallium

    SciTech Connect

    Laver, M.; Mudivarthi, C.; Cullen, J. R.; Wuttig, M.; Flatau, A. B.; Chen, W.-C.; Watson, S. M.

    2010-07-09

    Iron-gallium alloys Fe{sub 1-x}Ga{sub x} exhibit an exceptional increase in magnetostriction with gallium content. We present small-angle neutron scattering investigations on a Fe{sub 0.81}Ga{sub 0.19} single crystal. We uncover heterogeneities with an average spacing of 15 nm and with magnetizations distinct from the matrix. The moments in and around the heterogeneities are observed to reorient with an applied magnetic field or mechanical strain. We discuss the possible roles played by nanoscale magnetic heterogeneities in the mechanism for magnetostriction in this material.

  17. A review of magnetostrictive iron-gallium alloys

    NASA Astrophysics Data System (ADS)

    Atulasimha, Jayasimha; Flatau, Alison B.

    2011-04-01

    A unique combination of low hysteresis, moderate magnetostriction at low magnetic fields, good tensile strength, machinability and recent progress in commercially viable methods of processing iron-gallium alloys make them well poised for actuator and sensing applications. This review starts with a brief historical note on the early developments of magnetostrictive materials and moves to the recent work on FeGa alloys and their useful properties. This is followed by sections addressing the challenges specific to the characterization and processing of FeGa alloys and the state of the art in modeling their actuation and sensing behavior.

  18. Development of a novel polymeric fiber-optic magnetostrictive metal detector.

    PubMed

    Hua, Wei-Shu; Hooks, Joshua Rosenberg; Wu, Wen-Jong; Wang, Wei-Chih

    2010-01-01

    The purpose this paper is the development a novel polymeric fiber-optic magnetostrictive metal detector, using a fiber-optic Mach-Zehnder interferometer and polymeric magnetostrictive material. Metal detection is based on the strain-induced optical path length change steming from the ferromagnetic material introduced in the magnetic field. Varied optical phase shifts resulted largely from different metal objects. In this paper, the preliminary results on the different metal material detection will be discussed.

  19. Development of a novel polymeric fiber-optic magnetostrictive metal detector

    NASA Astrophysics Data System (ADS)

    Hua, Wei-Shu; Hooks, Joshua Rosenberg; Wu, Wen-Jong; Wang, Wei-Chih

    2010-03-01

    The purpose this paper is the development a novel polymeric fiber-optic magnetostrictive metal detector, using a fiber- optic Mach-Zehnder interferometer and polymeric magnetostrictive material. Metal detection is based on the straininduced optical path length change steming from the ferromagnetic material introduced in the magnetic field. Varied optical phase shifts resulted largely from different metal objects. In this paper, the preliminary results on the different metal material detection will be discussed.

  20. Development of a novel polymeric fiber-optic magnetostrictive metal detector

    PubMed Central

    Hua, Wei-Shu; Hooks, Joshua Rosenberg; Wu, Wen-Jong

    2011-01-01

    The purpose this paper is the development a novel polymeric fiber-optic magnetostrictive metal detector, using a fiber–optic Mach-Zehnder interferometer and polymeric magnetostrictive material. Metal detection is based on the strain-induced optical path length change steming from the ferromagnetic material introduced in the magnetic field. Varied optical phase shifts resulted largely from different metal objects. In this paper, the preliminary results on the different metal material detection will be discussed. PMID:22140300

  1. Nebular and Interstellar Materials in a Giant Cluster IDP of Probable Cometary Origin

    NASA Technical Reports Server (NTRS)

    Messenger, S.; Brownlee, D. E.; Joswiak, D. J.; Nguyen, A. N.

    2015-01-01

    Comets contain a complex mixture of materials with presolar and Solar System origins. Chondritic porous interplanetary dust particles (CP-IDPs) are associated with comets by their fragile nature, unequilibrated anhydrous mineralogy and high abundances of circumstellar grains and isotopically anomalous organic materials. Comet 81P/Wild 2 samples returned by the Stardust spacecraft contain presolar materials as well as refractory 16O-rich Ca-Al-rich inclusion- (CAI), chondrule-, and AOA-like materials. We are conducting coordinated chemical, mineralogical, and isotopic studies of a giant cluster CP-IDP (U2-20-GCA) to determine the proportions of inner Solar System and interstellar materials. We previously found that this IDP contains abundant presolar silicates (approx. 1,800 ppm) and 15N-rich hotspots [6].

  2. Synthesis of high-performance magnetostrictive Tb0.3Dy0.7Fe2 by unidirectional solidification in microgravity.

    PubMed

    Okutani, Takeshi; Nagai, Hideaki; Mamiya, Mikito

    2009-04-01

    Giant magnetostrictive materials, Tb(0.297)Dy(0.679)Fe(2), were synthesized by unidirectional solidification of a mixture of Tb(0.99)Fe(2) and Dy(0.97)Fe(2) alloys in microgravity with magnetic field of 0-0.12 T. Tb(0.297)Dy(0.679)Fe(2) is a mixed crystal of TbFe(2) and DyFe(2). Tb(0.297)Dy(0.679)Fe(2) synthesized in microgravity with no magnetic field had sheet dendrites structure with 300 (cooling direction) x 200 x 30 microm (thickness) and Fe-rich layer between the sheet dendrites, and they exhibited a tendency for crystalline orientation of <110> and <111> with the cooling direction. The magnetostriction with the cooling direction was 9000 ppm at an external magnetic field of 120 mT. In contrast, Tb(0.297)Dy(0.679)Fe(2) synthesized by unidirectional solidification in normal gravity with no magnetic field had a dendrite structure with a 30-mum diameter x 250-microm length growing in the cooling direction and no preferred orientation. The magnetostriction along the cooling direction was 2000 ppm at an external magnetic field of 120 mT. Analysis of the solidification in microgravity with magnetic field revealed that the dendrites oriented along the cooling direction and that the tendency for crystalline orientation of <110> and <111> with the cooling direction increased with magnetic field. Examination of the solidification in normal gravity with magnetic field indicated that Tb(0.297)Dy(0.679)Fe(2) consisted of sheet dendrites without orientation and revealed no preferred orientation. The magnetostriction along the cooling direction increased with increases in the magnetic field. The effects of microgravity and magnetic field on the structure and crystalline orientation were considered.

  3. Novel techniques for characterisation and control of magnetostriction in G.O.S.S

    NASA Astrophysics Data System (ADS)

    Klimczyk, Piotr

    magnetostriction sensitivity of the final material..

  4. Magnetostriction of field-structured magnetoelastomers.

    SciTech Connect

    Gulley, Gerald L. (Dominican University, River Forest, IL); Read, Douglas H.; Martin, James Ellis; Huber, Dale L.; Anderson, Robert Alan; Frankamp, Benjamin L.

    2005-12-01

    Field-structured magnetic particle composites are an important new class of materials that have great potential as both sensors and actuators. These materials are synthesized by suspending magnetic particles in a polymeric resin and subjecting these to magnetic fields while the resin polymerizes. If a simple uniaxial magnetic field is used, the particles will form chains, yielding composites whose magnetic susceptibility is enhanced along a single direction. A biaxial magnetic field, comprised of two orthogonal ac fields, forms particle sheets, yielding composites whose magnetic susceptibility is enhanced along two principal directions. A balanced triaxial magnetic field can be used to enhance the susceptibility in all directions, and biased heterodyned triaxial magnetic fields are especially effective for producing composites with a greatly enhanced susceptibility along a single axis. Magnetostriction is quadratic in the susceptibility, so increasing the composite susceptibility is important to developing actuators that function well at modest fields. To investigate magnetostriction in these field-structured composites we have constructed a sensitive, constant-stress apparatus capable of 1 ppm strain resolution. The sample geometry is designed to minimize demagnetizing field effects. With this apparatus we have demonstrated field-structured composites with nearly 10,000 ppm strain.

  5. Composition and crystallinity in electrochemically deposited magnetostrictive galfenol (FeGa)

    SciTech Connect

    Estrine, Eliot C. Hein, Matt; Robbins, William P.; Stadler, Bethanie J. H.

    2014-05-07

    Here, we report the first measurements of magnetostriction as a function of composition for electrodeposited iron-gallium alloys, also known as galfenol. Galfenol is an exciting material due to its large magnetostriction constant (up to 400 ppm) and robust mechanical properties. A wide range of sensors, actuators, and other transducers can be fabricated by taking advantage of galfenol's unique mix of magnetic and mechanical properties. Electrodeposition allows galfenol to be easily integrated into a variety of applications, such as toque sensors with conformal, monolithic active layers. In this work, we examine the underlying factors that influence magnetostriction in electrodeposited galfenol, including crystallinity and composition. Here, we have controlled the film composition, as measured by energy dispersive x-ray spectroscopy, over the range of 5–25% gallium using a single plating bath by varying deposition parameters. This composition range corresponds to the region of largest expected magnetostriction for iron gallium alloys. However, our measured magnetostriction values were significantly lower than the values for single crystal galfenol from literature. The electrodeposited films in this work appeared polycrystalline when measured using x-ray diffraction. When the texture of the film is taken into account, the magnetostriction results closely matched the predicted values. These results show that it is possible to achieve magnetostrictive galfenol thin films over a wide range of compositions using electrodeposition.

  6. Composition and crystallinity in electrochemically deposited magnetostrictive galfenol (FeGa)

    NASA Astrophysics Data System (ADS)

    Estrine, Eliot C.; Hein, Matt; Robbins, William P.; Stadler, Bethanie J. H.

    2014-05-01

    Here, we report the first measurements of magnetostriction as a function of composition for electrodeposited iron-gallium alloys, also known as galfenol. Galfenol is an exciting material due to its large magnetostriction constant (up to 400 ppm) and robust mechanical properties. A wide range of sensors, actuators, and other transducers can be fabricated by taking advantage of galfenol's unique mix of magnetic and mechanical properties. Electrodeposition allows galfenol to be easily integrated into a variety of applications, such as toque sensors with conformal, monolithic active layers. In this work, we examine the underlying factors that influence magnetostriction in electrodeposited galfenol, including crystallinity and composition. Here, we have controlled the film composition, as measured by energy dispersive x-ray spectroscopy, over the range of 5-25% gallium using a single plating bath by varying deposition parameters. This composition range corresponds to the region of largest expected magnetostriction for iron gallium alloys. However, our measured magnetostriction values were significantly lower than the values for single crystal galfenol from literature. The electrodeposited films in this work appeared polycrystalline when measured using x-ray diffraction. When the texture of the film is taken into account, the magnetostriction results closely matched the predicted values. These results show that it is possible to achieve magnetostrictive galfenol thin films over a wide range of compositions using electrodeposition.

  7. Enhancement in the magnetostriction of sintered cobalt ferrite by making self-composites from nanocrystalline and bulk powders.

    PubMed

    Mohaideen, Kamal Khaja; Joy, Pattayil Alias

    2012-12-01

    Sintered polycrystalline cobalt ferrite is a potential magnetostrictive smart material for applications as sensors and actuators. A novel concept of enhancing the magnetostrictive strain of sintered cobalt ferrite by making self-composites from nanosized and bulk powders with different particle sizes of the same material as components is reported. The self-composites give higher magnetostriction coefficient and strain derivative when compared to the sintered products obtained from the individual powders. The individual components give a maximum magnetostriction up to ~310 ppm, whereas up to ~370 ppm is obtained for a two-component system consisting of powders of two different sizes. On the other hand, a three-component self-composite made from starting powders of 3 nm, 40 nm and >1 μm give very high magnetostriction of ~400 ppm at 800 kA/m, suitable for making devices.

  8. Understanding strong magnetostriction in Fe100−xGax alloys

    PubMed Central

    Wang, Hui; Zhang, Y. N.; Wu, R. Q.; Sun, L. Z.; Xu, D. S.; Zhang, Z. D.

    2013-01-01

    Magnetostriction of ferromagnetic materials describes the change of their shape or dimension in response to the reorientation of magnetization under the influence of external magnetic field. Fe100−xGax binary alloys (Galfenol) have large magnetostriction and excellent ductility; and they are very promising rare-earth free materials for applications in sensors, actuators, energy-harvesters and spintronic devices. Here we report results of large-scale ab initio molecular dynamics (AIMD) simulations for Galfenol, especially regarding the mechanism that leads to the sudden drop of tetragonal magnetostriction at x ~ 19, a long-standing puzzle for the community. Based on rigid band analysis, we propose possible ways to further optimize the performance of Galfenol for device applications. For example, we found that the substitution of a small amount of Cu for Ga (1.6%) in certain configuration may double the magnetostriction of Galfenol. PMID:24343479

  9. Understanding strong magnetostriction in Fe(100-x)Ga(x) alloys.

    PubMed

    Wang, Hui; Zhang, Y N; Wu, R Q; Sun, L Z; Xu, D S; Zhang, Z D

    2013-12-17

    Magnetostriction of ferromagnetic materials describes the change of their shape or dimension in response to the reorientation of magnetization under the influence of external magnetic field. Fe(100-x)Ga(x) binary alloys (Galfenol) have large magnetostriction and excellent ductility; and they are very promising rare-earth free materials for applications in sensors, actuators, energy-harvesters and spintronic devices. Here we report results of large-scale ab initio molecular dynamics (AIMD) simulations for Galfenol, especially regarding the mechanism that leads to the sudden drop of tetragonal magnetostriction at x ~ 19, a long-standing puzzle for the community. Based on rigid band analysis, we propose possible ways to further optimize the performance of Galfenol for device applications. For example, we found that the substitution of a small amount of Cu for Ga (1.6%) in certain configuration may double the magnetostriction of Galfenol.

  10. Magnetostrictive contribution to Poisson ratio of galfenol

    NASA Astrophysics Data System (ADS)

    Paes, V. Z. C.; Mosca, D. H.

    2013-09-01

    In this work we present a detailed study on the magnetostrictive contribution to Poisson ratio for samples under applied mechanical stress. Magnetic contributions to strain and Poisson ratio for cubic materials were derived by accounting elastic and magneto-elastic anisotropy contributions. We apply our theoretical results for a material of interest in magnetomechanics, namely, galfenol (Fe1-xGax). Our results show that there is a non-negligible magnetic contribution in the linear portion of the curve of stress versus strain. The rotation of the magnetization towards [110] crystallographic direction upon application of mechanical stress leads to an auxetic behavior, i.e., exhibiting Poisson ratio with negative values. This magnetic contribution to auxetic behavior provides a novel insight for the discussion of theoretical and experimental developments of materials that display unusual mechanical properties.

  11. Broadband giant-refractive-index material based on mesoscopic space-filling curves

    PubMed Central

    Chang, Taeyong; Kim, Jong Uk; Kang, Seung Kyu; Kim, Hyowook; Kim, Do Kyung; Lee, Yong-Hee; Shin, Jonghwa

    2016-01-01

    The refractive index is the fundamental property of all optical materials and dictates Snell's law, propagation speed, wavelength, diffraction, energy density, absorption and emission of light in materials. Experimentally realized broadband refractive indices remain <40, even with intricately designed artificial media. Herein, we demonstrate a measured index >1,800 resulting from a mesoscopic crystal with a dielectric constant greater than three million. This gigantic enhancement effect originates from the space-filling curve concept from mathematics. The principle is inherently very broad band, the enhancement being nearly constant from zero up to the frequency of interest. This broadband giant-refractive-index medium promises not only enhanced resolution in imaging and raised fundamental absorption limits in solar energy devices, but also compact, power-efficient components for optical communication and increased performance in many other applications. PMID:27573337

  12. Broadband giant-refractive-index material based on mesoscopic space-filling curves

    NASA Astrophysics Data System (ADS)

    Chang, Taeyong; Kim, Jong Uk; Kang, Seung Kyu; Kim, Hyowook; Kim, Do Kyung; Lee, Yong-Hee; Shin, Jonghwa

    2016-08-01

    The refractive index is the fundamental property of all optical materials and dictates Snell's law, propagation speed, wavelength, diffraction, energy density, absorption and emission of light in materials. Experimentally realized broadband refractive indices remain <40, even with intricately designed artificial media. Herein, we demonstrate a measured index >1,800 resulting from a mesoscopic crystal with a dielectric constant greater than three million. This gigantic enhancement effect originates from the space-filling curve concept from mathematics. The principle is inherently very broad band, the enhancement being nearly constant from zero up to the frequency of interest. This broadband giant-refractive-index medium promises not only enhanced resolution in imaging and raised fundamental absorption limits in solar energy devices, but also compact, power-efficient components for optical communication and increased performance in many other applications.

  13. Nanomechanical measurement of magnetostriction and magnetic anisotropy in (Ga,Mn)As.

    PubMed

    Masmanidis, S C; Tang, H X; Myers, E B; Li, Mo; De Greve, K; Vermeulen, G; Van Roy, W; Roukes, M L

    2005-10-28

    A GaMnAs nanoelectromechanical resonator is used to obtain the first measurement of magnetostriction in a dilute magnetic semiconductor. Resonance frequency shifts induced by field-dependent magnetoelastic stress are used to simultaneously map the magnetostriction and magnetic anisotropy constants over a wide range of temperatures. Owing to the central role of carriers in controlling ferromagnetic interactions in this material, the results appear to provide insight into a unique form of magnetoelastic behavior mediated by holes.

  14. Instrumentation Acquisition for Research and Education in Additive Manufacturing and Advanced Material Fabrication

    DTIC Science & Technology

    2015-08-18

    Triangle Park, NC 27709-2211 Final Report, Instrument acquisition, Selective Laser Melting REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT...Description 1 Renishaw AM 250 Selective Laser Melting Machine Renishaw $585,305 This vendor was selected for purchase due to lower acquisition... selective laser melting of Tefenol – D giant magnetostricitve material. Terfenol‐D has the advantage of achieving magnetostriction comparable

  15. Vibration control via stiffness switching of magnetostrictive transducers

    NASA Astrophysics Data System (ADS)

    Scheidler, Justin J.; Asnani, Vivake M.; Dapino, Marcelo J.

    2016-04-01

    In this paper, a computational study is presented of structural vibration control that is realized by switching a magneto-strictive transducer between high and low stiffness states. Switching is accomplished by either changing the applied magnetic field with a voltage excitation or changing the shunt impedance on the transducer's coil (i.e., the magneto-strictive material's magnetic boundary condition). Switched-stiffness vibration control is simulated using a lumped mass supported by a damper and the magneto-strictive transducer (mount), which is represented by a nonlinear, electromechanical model. Free vibration of the mass is calculated while varying the mount's stiffness according to a reference switched-stiffness vibration control law. The results reveal that switching the magnetic field produces the desired change in stiffness, but also an undesired actuation force that can significantly degrade the vibration control. Hence, a modified switched-stiffness control law that accounts for the actuation force is proposed and implemented for voltage-controlled stiffness switching. The influence of the magneto-mechanical bias condition is also discussed. Voltage-controlled stiffness switching is found to introduce damping equivalent to a viscous damping factor up to about 0.13; this is shown to primarily result from active vibration reduction caused by the actuation force. The merit of magneto-strictive switched-stiffness vibration control is then quantified by comparing the results of voltage- and shunt-controlled stiffness switching to the performance of optimal magneto-strictive shunt damping. For the cases considered, optimal resistive shunt damping performed considerably better than both voltage- and shunt-controlled stiffness switching.

  16. Vibration Control via Stiffness Switching of Magnetostrictive Transducers

    NASA Technical Reports Server (NTRS)

    Scheidler, Justin J.; Asnani, Vivake M.; Dapino, Marcelo J.

    2016-01-01

    In this paper, a computational study is presented of structural vibration control that is realized by switching a magnetostrictive transducer between high and low stiffness states. Switching is accomplished by either changing the applied magnetic field with a voltage excitation or changing the shunt impedance on the transducer's coil (i.e., the magnetostrictive material's magnetic boundary condition). Switched-stiffness vibration control is simulated using a lumped mass supported by a damper and the magnetostrictive transducer (mount), which is represented by a nonlinear, electromechanical model. Free vibration of the mass is calculated while varying the mount's stiffness according to a reference switched-stiffness vibration control law. The results reveal that switching the magnetic field produces the desired change in stiffness, but also an undesired actuation force that can significantly degrade the vibration control. Hence, a modified switched-stiffness control law that accounts for the actuation force is proposed and implemented for voltage-controlled stiffness switching. The influence of the magneto-mechanical bias condition is also discussed. Voltage-controlled stiffness switching is found to introduce damping equivalent to a viscous damping factor up to about 0.13; this is shown to primarily result from active vibration reduction caused by the actuation force. The merit of magnetostrictive switched-stiffness vibration control is then quantified by comparing the results of voltage- and shunt-controlled stiffness switching to the performance of optimal magnetostrictive shunt damping. For the cases considered, optimal resistive shunt damping performed considerably better than both voltage- and shunt-controlled stiffness switching.

  17. Donor-site giant cell reaction following backfill with synthetic bone material during osteochondral plug transfer.

    PubMed

    Fowler, Donald E; Hart, Joseph M; Hart, Jennifer A; Miller, Mark D

    2009-10-01

    Osteochondral defects are common in younger, active patients. Multiple strategies have been used to treat these lesions, including microfracture and osteochondral plug transfer. We describe a patient experiencing chronic knee pain and a full-thickness cartilage defect on the lateral femoral condyle. After failing conservative management and microfracture surgery, the patient underwent osteochondral autograft plug transfer, with backfilling of the donor sites using synthetic bone graft substitute. Initial recovery was uncomplicated until the patient experienced pain following a twist of the knee. Magnetic resonance imaging for the subsequent knee injury revealed poor healing at the donor sites. The donor sites were debrided, and specimens revealed a foreign body giant cell reaction. Donor-site morbidity is of primary concern during osteochondral plug transfer; however, insufficient data exist to support the use of synthetic bone graft material. Our results indicate that off-label use of synthetic bone graft substitute during a primary procedure requires further investigation.

  18. Multinucleated giant cells in the implant bed of bone substitutes are foreign body giant cells-New insights into the material-mediated healing process.

    PubMed

    Barbeck, Mike; Booms, Patrick; Unger, Ronald; Hoffmann, Verena; Sader, Robert; Kirkpatrick, Charles James; Ghanaati, Shahram

    2017-04-01

    In addition to macrophages, multinucleated giant cells (MNGCs) are involved in the tissue reaction to a variety of biomaterials. Especially in the case of bone substitute materials it has been assumed that the MNGCs are osteoclasts, based on the chemical and physical similarity of many materials to the calcified matrix and the bony environment in which they are used. However, many studies indicate that these cells belong to the cell line of the foreign body giant cells (FBGCs), which are of "inflammatory origin", although they have been shown to possess both a pro- and also anti-inflammatory phenotype. Moreover, no information is available about their role in the tissue reaction to bone substitute materials. The present study was conducted to analyze the origin of MNGCs in the implant beds of a synthetic and a xenogeneic bone substitute and focused on the application of immunohistochemical methods. Two antibodies against integrin molecules specific for osteoclasts (β-3 integrin) or FBGCs (β-2 integrin) were used to distinguish both giant cell types. The results of the present study indicate that the MNGCs induced by both kinds of bone substitutes are FBGCs, as they express only β-2 integrin in contrast to the osteoclasts outside of the immediate implantation areas, which only demonstrate β-3 integrin expression. These data give new insight into the tissue reaction to both xenogeneic and synthetic bone substitutes. Based on this new knowledge further research concerning the proteomic profile of the FBGCs especially based on the different physicochemical properties of bone substitutes is necessary. This may show that specific characteristics of bone substitutes may exhibit a substantial influence on the regeneration process via the expression of anti-inflammatory molecules by FBGCs. Based on this information it may be possible to formulate and choose bone substitutes that can guide the process of bone tissue regeneration on the molecular level. © 2017 Wiley

  19. Developing Electrocaloric (EC) Materials with Giant EC Response and Chip-Scale EC Cooling Devices

    NASA Astrophysics Data System (ADS)

    Zhang, Qiming

    2015-03-01

    The direct and efficient coupling between the electric signals and the elastic, thermal, optical and magnetic signals in ferroelectric based electroactive materials makes them attractive for exploiting a broad range of cross-coupling phenomena which have great promise for new device technologies. This talk will present the recent advances at Penn State in developing electrocaloric materials which may provide alternative cooling technology to replace the century old vapor compression cycle (VCC) based cooling which employs strong greenhouse gases as the refrigerants. Electrocaloric effect (ECE), which is the temperature and entropy change of insulating dielectric materials under electric fields, is attractive to realize efficient cooling devices. However, the relatively small ECE observed in dielectrics in the last century make it unimpressive for any practical applications. Experimental results on the ECE in the relaxor ferroelectric polymers and general theoretical considerations for achieving large ECE will be presented. This talk will also discuss considerations on and present recent works in using nanocomposites to further enhancing the ECE beyond the pure relaxor polymers, on the giant ECE in a class of dielectric liquid, and in bulk ferroelectric ceramics near the invariant critical point. The works related to developing the chip-scale EC cooling devices, exploiting the newly discovered large ECE in ferroelectric materials and featuring high cooling power density and high efficiency, will also be presented. This work has been supported by DoE BES and by ARO.

  20. Single-particle mechanism of magnetostriction in magnetoactive elastomers

    NASA Astrophysics Data System (ADS)

    Kalita, Viktor M.; Snarskii, Andrei A.; Zorinets, Denis; Shamonin, Mikhail

    2016-06-01

    Magnetoactive elastomers (MAEs) are composite materials comprised of micrometer-sized ferromagnetic particles in a nonmagnetic elastomer matrix. A single-particle mechanism of magnetostriction in MAEs, assuming the rotation of a soft magnetic, mechanically rigid particle with uniaxial magnetic anisotropy in magnetic fields is identified and considered theoretically within the framework of an alternative model. In this mechanism, the total magnetic anisotropy energy of the filling particles in the matrix is the sum over single particles. Matrix displacements in the vicinity of the particle and the resulting direction of the magnetization vector are calculated. The effect of matrix deformation is pronounced well if the magnetic anisotropy coefficient K is much larger than the shear modulus µ of the elastic matrix. The feasibility of the proposed magnetostriction mechanism in soft magnetoactive elastomers and gels is elucidated. The magnetic-field-induced internal stresses in the matrix lead to effects of magnetodeformation and may increase the elastic moduli of these composite materials.

  1. Large magnetostriction from morphotropic phase boundary in ferromagnets.

    PubMed

    Yang, Sen; Bao, Huixin; Zhou, Chao; Wang, Yu; Ren, Xiaobing; Matsushita, Yoshitaka; Katsuya, Yoshio; Tanaka, Masahiko; Kobayashi, Keisuke; Song, Xiaoping; Gao, Jianrong

    2010-05-14

    For more than half of a century, morphotropic phase boundary (MPB) in ferroelectric materials has drawn constant interest because it can significantly enhance the piezoelectric properties. However, MPB has been studied merely in ferroelectric systems, not in another large class of ferroic systems, the ferromagnets. In this Letter, we report the existence of an MPB in a ferromagnetic system TbCo2-DyCo2. Such a magnetic MPB involves a first-order magnetoelastic transition, at which both magnetization direction and crystal structure change simultaneously. The MPB composition demonstrates a 3-6 times larger "figure of merit" of magnetostrictive response compared with that of the off-MPB compositions. The finding of MPB in ferromagnets may help to discover novel high-performance magnetostrictive and even magnetoelectric materials.

  2. Single-particle mechanism of magnetostriction in magnetoactive elastomers.

    PubMed

    Kalita, Viktor M; Snarskii, Andrei A; Zorinets, Denis; Shamonin, Mikhail

    2016-06-01

    Magnetoactive elastomers (MAEs) are composite materials comprised of micrometer-sized ferromagnetic particles in a nonmagnetic elastomer matrix. A single-particle mechanism of magnetostriction in MAEs, assuming the rotation of a soft magnetic, mechanically rigid particle with uniaxial magnetic anisotropy in magnetic fields is identified and considered theoretically within the framework of an alternative model. In this mechanism, the total magnetic anisotropy energy of the filling particles in the matrix is the sum over single particles. Matrix displacements in the vicinity of the particle and the resulting direction of the magnetization vector are calculated. The effect of matrix deformation is pronounced well if the magnetic anisotropy coefficient K is much larger than the shear modulus µ of the elastic matrix. The feasibility of the proposed magnetostriction mechanism in soft magnetoactive elastomers and gels is elucidated. The magnetic-field-induced internal stresses in the matrix lead to effects of magnetodeformation and may increase the elastic moduli of these composite materials.

  3. Giant piezoelectric voltage coefficient in grain-oriented modified PbTiO3 material.

    PubMed

    Yan, Yongke; Zhou, Jie E; Maurya, Deepam; Wang, Yu U; Priya, Shashank

    2016-10-11

    A rapid surge in the research on piezoelectric sensors is occurring with the arrival of the Internet of Things. Single-phase oxide piezoelectric materials with giant piezoelectric voltage coefficient (g, induced voltage under applied stress) and high Curie temperature (Tc) are crucial towards providing desired performance for sensing, especially under harsh environmental conditions. Here, we report a grain-oriented (with 95% <001> texture) modified PbTiO3 ceramic that has a high Tc (364 °C) and an extremely large g33 (115 × 10(-3) Vm N(-1)) in comparison with other known single-phase oxide materials. Our results reveal that self-polarization due to grain orientation along the spontaneous polarization direction plays an important role in achieving large piezoelectric response in a domain motion-confined material. The phase field simulations confirm that the large piezoelectric voltage coefficient g33 originates from maximized piezoelectric strain coefficient d33 and minimized dielectric permittivity ɛ33 in [001]-textured PbTiO3 ceramics where domain wall motions are absent.

  4. Giant piezoelectric voltage coefficient in grain-oriented modified PbTiO3 material

    PubMed Central

    Yan, Yongke; Zhou, Jie E.; Maurya, Deepam; Wang, Yu U.; Priya, Shashank

    2016-01-01

    A rapid surge in the research on piezoelectric sensors is occurring with the arrival of the Internet of Things. Single-phase oxide piezoelectric materials with giant piezoelectric voltage coefficient (g, induced voltage under applied stress) and high Curie temperature (Tc) are crucial towards providing desired performance for sensing, especially under harsh environmental conditions. Here, we report a grain-oriented (with 95% <001> texture) modified PbTiO3 ceramic that has a high Tc (364 °C) and an extremely large g33 (115 × 10−3 Vm N−1) in comparison with other known single-phase oxide materials. Our results reveal that self-polarization due to grain orientation along the spontaneous polarization direction plays an important role in achieving large piezoelectric response in a domain motion-confined material. The phase field simulations confirm that the large piezoelectric voltage coefficient g33 originates from maximized piezoelectric strain coefficient d33 and minimized dielectric permittivity ɛ33 in [001]-textured PbTiO3 ceramics where domain wall motions are absent. PMID:27725634

  5. Foreign Body Giant Cell-Related Encapsulation of a Synthetic Material Three Years After Augmentation.

    PubMed

    Lorenz, Jonas; Barbeck, Mike; Sader, Robert A; Kirkpatrick, Charles J; Russe, Philippe; Choukroun, Joseph; Ghanaati, Shahram

    2016-06-01

    Bone substitute materials of different origin and chemical compositions are frequently used in augmentation procedures to enlarge the local bone amount. However, relatively little data exist on the long-term tissue reactions. The presented case reports for the first time histological and histomorphometrical analyses of a nanocrystaline hydroxyapatite-based bone substitute material implanted in the human sinus cavity after an integration period of 3 years. The extracted biopsy was analyzed histologically and histomorphometrically with focus on the tissue reactions, vascularization, new bone formation, and the induction of a foreign body reaction. A comparably high rate of connective tissue (48.25%) surrounding the remaining bone substitute granules (42.13%) was observed. Accordingly, the amount of bone tissue (9.62%) built the smallest fraction within the biopsy. Further, tartrate-resistant acid phosphatase-positive and -negative multinucleated giant cells (4.35 and 3.93 cells/mm(2), respectively) were detected on the material-tissue interfaces. The implantation bed showed a mild vascularization of 10.03 vessels/mm(2) and 0.78%. The present case report shows that after 3 years, a comparable small amount of bone tissue was observable. Thus, the foreign body response to the bone substitute seems to be folded without further degradation or regeneration.

  6. Giant piezoelectric voltage coefficient in grain-oriented modified PbTiO3 material

    NASA Astrophysics Data System (ADS)

    Yan, Yongke; Zhou, Jie E.; Maurya, Deepam; Wang, Yu U.; Priya, Shashank

    2016-10-01

    A rapid surge in the research on piezoelectric sensors is occurring with the arrival of the Internet of Things. Single-phase oxide piezoelectric materials with giant piezoelectric voltage coefficient (g, induced voltage under applied stress) and high Curie temperature (Tc) are crucial towards providing desired performance for sensing, especially under harsh environmental conditions. Here, we report a grain-oriented (with 95% <001> texture) modified PbTiO3 ceramic that has a high Tc (364 °C) and an extremely large g33 (115 × 10-3 Vm N-1) in comparison with other known single-phase oxide materials. Our results reveal that self-polarization due to grain orientation along the spontaneous polarization direction plays an important role in achieving large piezoelectric response in a domain motion-confined material. The phase field simulations confirm that the large piezoelectric voltage coefficient g33 originates from maximized piezoelectric strain coefficient d33 and minimized dielectric permittivity ε33 in [001]-textured PbTiO3 ceramics where domain wall motions are absent.

  7. Thin-layer magnetostrictive composite films for turbomachinery fan blade damping

    NASA Astrophysics Data System (ADS)

    Pulliam, Wade J.; Lee, Donggun; Carman, Gregory P.; McKnight, Geoffrey P.

    2003-08-01

    Recently, there have been significant advances in using magnetostrictive particles in a polymer matrix; finding uses in many applications, both as an active transducer and a passive dumper. Termed magnetostrictive particulate composites (MPC), the material provides capabilities identical or superior to the monolithic material. Fortis Technologies has been pursuing improvements in the applications and fabrication of this innovative material. Specifically, this MPC technology provides a passive, broadband, large temperature range, high stiffness, damping material to be used where current technologies fall short. A novel manufacturing technique based on magnetic fields has been developed to distribute magnetostrictive particulates in a polymer resin and apply it in thin-layer on surfaces for vibration damping in environments typical of turbomachinery fan blades. These magnetostrictive particulates provide damping through domain wall switching, a non-conservative action which provides a high loss factor, and, in turn, significant vibration mitigation. The magnetostrictive damping composites can be easily fabricated into thin films, provide stiffness and strength while also incorporating damping capabilities which exceed in performance and temperature range viscoelastic materials, the current state of the art for applied blade damping. Analytical studies, a finite element analysis and experimental study of the new material in a typical turbomachinery blade loading condition has been conducted and has demonstrated the benefits of this technology.

  8. Magnetostrictive vibration damper and energy harvester for rotating machinery

    NASA Astrophysics Data System (ADS)

    Deng, Zhangxian; Asnani, Vivake M.; Dapino, Marcelo J.

    2015-04-01

    Vibrations generated by machine driveline components can cause excessive noise and structural dam- age. Magnetostrictive materials, including Galfenol (iron-gallium alloys) and Terfenol-D (terbium-iron- dysprosium alloys), are able to convert mechanical energy to magnetic energy. A magnetostrictive vibration ring is proposed, which generates electrical energy and dampens vibration, when installed in a machine driveline. A 2D axisymmetric finite element (FE) model incorporating magnetic, mechanical, and electrical dynamics is constructed in COMSOL Multiphysics. Based on the model, a parametric study considering magnetostrictive material geometry, pickup coil size, bias magnet strength, flux path design, and electrical load is conducted to maximize loss factor and average electrical output power. By connecting various resistive loads to the pickup coil, the maximum loss factors for Galfenol and Terfenol-D due to electrical energy loss are identified as 0.14 and 0.34, respectively. The maximum av- erage electrical output power for Galfenol and Terfenol-D is 0.21 W and 0.58 W, respectively. The loss factors for Galfenol and Terfenol-D are increased to 0.59 and 1.83, respectively, by using an L-C resonant circuit.

  9. Magnetostrictive Vibration Damper and Energy Harvester for Rotating Machinery

    NASA Technical Reports Server (NTRS)

    Deng, Zhangxian; Asnani, Vivake M.; Dapino, Marcelo J.

    2015-01-01

    Vibrations generated by machine driveline components can cause excessive noise and structural damage. Magnetostrictive materials, including Galfenol (iron-gallium alloys) and Terfenol-D (terbium-iron-dysprosium alloys), are able to convert mechanical energy to magnetic energy. A magnetostrictive vibration ring is proposed, which generates electrical energy and dampens vibration, when installed in a machine driveline. A 2D axisymmetric finite element (FE) model incorporating magnetic, mechanical, and electrical dynamics is constructed in COMSOL Multiphysics. Based on the model, a parametric study considering magnetostrictive material geometry, pickup coil size, bias magnet strength, flux path design, and electrical load is conducted to maximize loss factor and average electrical output power. By connecting various resistive loads to the pickup coil, the maximum loss factors for Galfenol and Terfenol-D due to electrical energy loss are identified as 0.14 and 0.34, respectively. The maximum average electrical output power for Galfenol and Terfenol-D is 0.21 W and 0.58 W, respectively. The loss factors for Galfenol and Terfenol-D are increased to 0.59 and 1.83, respectively, by using an L-C resonant circuit.

  10. Detection of Salmonella typhimurium using phage-based magnetostrictive sensor

    NASA Astrophysics Data System (ADS)

    Lakshmanan, Ramji S.; Hu, Jing; Guntupalli, Rajesh; Wan, Jiehui; Huang, Shichu; Yang, Hong; Petrenko, Valery A.; Barbaree, James M.; Chin, Bryan A.

    2006-05-01

    This article presents a contactless, remote sensing Salmonella typhimurium sensor based on the principle of magnetostriction. Magnetostrictive materials have been used widely for various types of sensor systems. In this work, the use of a magnetostrictive material for the detection of Salmonella typhimurium has been established. The mass of the bacteria attached to the sensor causes changes in the resonance frequency of the sensor. Filamentous bacteriophage was used as a probe order to ensure specific and selective binding of the bacteria onto the sensor surface. Thus changes in response of the sensor due to the mass added onto the sensor caused by specific attachment of bacteria can be monitored in absence of any contact to the sensor. The response of the sensor due to increasing concentrations (from 5x101 to 5x10 8 cfu/ml) of the bacteria was studied. A reduction in the physical dimensions enhances the sensitivity of these sensors and hence different dimensions of the sensor ribbons were studied. For a 2mm x 0.1mm x 0.02mm the detection limit was observed to be of the order of 10 4 cfu/mL and for a sensor of 1mm x 0.2mm x 0.02mm a reduced detection limit of 10 3 cfu/mL was achieved.

  11. Design of a Magnetostrictive-Hydraulic Actuator Considering Nonlinear System Dynamics and Fluid-Structure Coupling

    NASA Astrophysics Data System (ADS)

    Larson, John Philip

    Smart material electro-hydraulic actuators (EHAs) utilize fluid rectification via one-way check valves to amplify the small, high-frequency vibrations of certain smart materials into large motions of a hydraulic cylinder. Although the concept has been demonstrated in previously, the operating frequency of smart material EHA systems has been limited to a small fraction of the available bandwidth of the driver materials. The focus of this work is to characterize and model the mechanical performance of a magnetostrictive EHA considering key system components: rectification valves, smart material driver, and fluid-system components, leading to an improved actuator design relative to prior work. The one-way valves were modeled using 3-D finite element analysis, and their behavior was characterized experimentally by static and dynamic experimental measurement. Taking into account the effect of the fluid and mechanical conditions applied to the valves within the pump, the dynamic response of the valve was quantified and applied to determine rectification bandwidth of different valve configurations. A novel miniature reed valve, designed for a frequency response above 10~kHz, was fabricated and tested within a magnetostrictive EHA. The nonlinear response of the magnetostrictive driver, including saturation and hysteresis effects, was modeled using the Jiles-Atherton approach to calculate the magnetization and the resulting magnetostriction based on the applied field calculated within the rod from Maxwell's equations. The dynamic pressure response of the fluid system components (pumping chamber, hydraulic cylinder, and connecting passages) was measured over a range of input frequencies. For the magnetostrictive EHA tested, the peak performance frequency was found to be limited by the fluid resonances within the system. A lumped-parameter modeling approach was applied to model the overall behavior of a magnetostrictive EHA, incorporating models for the reed valve response

  12. Micromotors using magnetostrictive thin films

    NASA Astrophysics Data System (ADS)

    Claeyssen, Frank; Le Letty, Ronan; Barillot, Francois; Betz, Jochen; MacKay, Ken; Givord, Dominique; Bouchilloux, Philippe

    1998-07-01

    This study deals with a micromotor based on the use of magnetostrictive thin films. This motor belongs to the category of the Standing Wave Ultrasonic Motors. The active part of the motor is the rotor, which is a 100 micrometers thick ring vibrating in a flexural mode. Teeth (300 micrometers high) are placed on special positions of the rotor and produce an oblique motion which can induce the relative motion of any object in contact with them. The magnetic excitation field is radial and uses the transverse coupling of the 4 micrometers thick magnetostrictive film. The film, deposited by sputtering on the ring, consists of layers of different rare-earth/iron alloys and was developed during a European Brite-Euram project. The finite element technique was used in order to design a prototype of the motor and to optimize the active rotor and the energizer coil. The prototype we built delivered a speed of 30 turns per minute with a torque of 2 (mu) N.m (without prestress applied on the rotor). Our experimental results show that the performance of this motor could easily be increased by a factor of 5. The main advantage of this motor is the fact that it is remotely powered and controlled. The excitation coil, which provides both power and control, can be placed away from the active rotor. Moreover, the rotor is completely wireless and is not connected to its support or to any other part. It is interesting to note that it would not be possible to build this type of motor using piezoelectric technology. Medical applications of magnetostrictive micromotors could be found for internal microdistributors of medication (the coil staying outside the body). Other applications include remote control micropositioning, micropositioning of optical components, and for the actuation of systems such as valves, electrical switches, and relays.

  13. Bioprospecting Finds the Toughest Biological Material: Extraordinary Silk from a Giant Riverine Orb Spider

    PubMed Central

    Agnarsson, Ingi; Kuntner, Matjaž; Blackledge, Todd A.

    2010-01-01

    Background Combining high strength and elasticity, spider silks are exceptionally tough, i.e., able to absorb massive kinetic energy before breaking. Spider silk is therefore a model polymer for development of high performance biomimetic fibers. There are over 41.000 described species of spiders, most spinning multiple types of silk. Thus we have available some 200.000+ unique silks that may cover an amazing breadth of material properties. To date, however, silks from only a few tens of species have been characterized, most chosen haphazardly as model organisms (Nephila) or simply from researchers' backyards. Are we limited to ‘blindly fishing’ in efforts to discover extraordinary silks? Or, could scientists use ecology to predict which species are likely to spin silks exhibiting exceptional performance properties? Methodology We examined the biomechanical properties of silk produced by the remarkable Malagasy ‘Darwin's bark spider’ (Caerostris darwini), which we predicted would produce exceptional silk based upon its amazing web. The spider constructs its giant orb web (up to 2.8 m2) suspended above streams, rivers, and lakes. It attaches the web to substrates on each riverbank by anchor threads as long as 25 meters. Dragline silk from both Caerostris webs and forcibly pulled silk, exhibits an extraordinary combination of high tensile strength and elasticity previously unknown for spider silk. The toughness of forcibly silked fibers averages 350 MJ/m3, with some samples reaching 520 MJ/m3. Thus, C. darwini silk is more than twice tougher than any previously described silk, and over 10 times better than Kevlar®. Caerostris capture spiral silk is similarly exceptionally tough. Conclusions Caerostris darwini produces the toughest known biomaterial. We hypothesize that this extraordinary toughness coevolved with the unusual ecology and web architecture of these spiders, decreasing the likelihood of bridgelines breaking and collapsing the web into the river

  14. A comparison of and the compensation for magnetostrictive core inductances in magnetic transducer systems

    NASA Astrophysics Data System (ADS)

    Bartlett, P. A.; Meydan, T.; Lea, S. C.; Moses, A. J.; Williams, P. I.; Landini, G.; Walmsley, A. D.

    Magnetostrictive materials have been utilized for the production of ultrasonic frequency vibrations for a number of years. This has particularly been the case in laminated nickel-based ultrasonic dental-scaler cleaning systems. In this study, a comparison has been made between the impedances of a number of magnetostrictive stacks of 50 mm×4 mmט0.3 mm strips at frequencies in the range of 10-50 kHz in a coil used for the excitation of a stack in a dental-scaler system. The magnetostrictive stacks tested comprised of potential replacement materials for standard nickel ones. The study showed that it was possible to compensate for the inductive 'imaginary' components of the impedance through the use of a tuned, series capacitance so that only the 'real' resistive component of the impedance remained. This reduced the electrical losses associated with the excitation of the magnetostrictive stacks as a result of the frequency-dependent inductance of the coil system. Consequently, the maximum power transfer from an amplifier to the transducer was increased. Also, the investigation showed how the 'real' component of impedance of the different stacks varied with frequency. In a tuned resonant electrical circuit, the resistive component of the impedance, if considered as a loss, would be the lowest that could be achieved with such a magnetic circuit. Consequently, the losses associated with resonant magnetostrictive devices, like dental scalers, can be reduced.

  15. Application of high-temperature superconducting wires to magnetostrictive transducers for underwater sonar

    SciTech Connect

    Voccio, J.P.; Joshi, C.H.; Lindberg, J.F.

    1994-07-01

    Recently discovered cryogenic magnetostrictive materials show maximum strains greater than any room temperature materials. These cryogenic magnetostrictors can be combined with high-temperature superconducting (HTS) coils to create a sonar transducer with high efficiency and high acoustic power density. A prototype low-frequency (< 1,000 Hz) magnetostrictive transducer is described. This transducer uses a terbium-dysprosium (TbDy) magnetostrictor rod with HTS coils cooled to 50--80 K using a single-stage cryocooler. The device is designed for operation at water depths of 100 m and is believed to be the first fully integrated prototype demonstration of HTS.

  16. An Anisotropic Model for Magnetostriction and Magnetization Computing for Noise Generation in Electric Devices.

    PubMed

    Mbengue, Serigne Saliou; Buiron, Nicolas; Lanfranchi, Vincent

    2016-04-16

    During the manufacturing process and use of ferromagnetic sheets, operations such as rolling, cutting, and tightening induce anisotropy that changes the material's behavior. Consequently for more accuracy in magnetization and magnetostriction calculations in electric devices such as transformers, anisotropic effects should be considered. In the following sections, we give an overview of a macroscopic model which takes into account the magnetic and magnetoelastic anisotropy of the material for both magnetization and magnetostriction computing. Firstly, a comparison between the model results and measurements from a Single Sheet Tester (SST) and values will be shown. Secondly, the model is integrated in a finite elements code to predict magnetostrictive deformation of an in-house test bench which is a stack of 40 sheets glued together by the Vacuum-Pressure Impregnation (VPI) method. Measurements on the test bench and Finite Elements results are presented.

  17. Direct measurement of intrinsic atomic scale magnetostriction.

    PubMed

    Ruffoni, M P; Pascarelli, S; Grössinger, R; Turtelli, R Sato; Bormio-Nunes, C; Pettifer, R F

    2008-10-03

    Using differential x-ray absorption spectroscopy (DiffXAS) we have measured and quantified the intrinsic, atomic-scale magnetostriction of Fe81Ga19. By exploiting the chemical selectivity of DiffXAS, the Fe and Ga local environments have been assessed individually. The enhanced magnetostriction induced by the addition of Ga to Fe was found to originate from the Ga environment, where lambda;{gamma,2}( approximately (3/2)lambda_{100}) is 390+/-40 ppm. In this environment, 001 Ga-Ga pair defects were found to exist, which mediate the magnetostriction by inducing large strains in the surrounding Ga-Fe bonds. For the first time, intrinsic, chemically selective magnetostrictive strain has been measured and quantified at the atomic level, allowing true comparison with theory.

  18. Magnetostriction in a Co-30%Fe alloy

    SciTech Connect

    Chen, L.H.; Mavoori, H.; Klemmer, T.; Jin, S.

    1999-09-01

    The authors have studied the magnetostriction and magnetic properties of a deformed and annealed Co-30%Fe alloy. The cold-rolled and annealed (at 820 C for 40 min) sample exhibits a substantial magnetostriction of {approximately}110 x 10{sup {minus}6} at a practical, low field of {approximately}100 Oe, while only {approximately}10 x 10{sup {minus}6} for the same applied field is obtained for the as-cold-rolled sample. The saturation magnetostriction of the annealed Co-30%Fe alloy was {approximately}140 x 10{sup {minus}6}, which is significantly affected by the cold-rolling and annealing processes. This drastic dependence of the magnetostriction behavior on the alloy processing is believed to be a result of the microstructure and residual stress changes brought about by the heat treatment processing.

  19. Temperature-dependent magnetostriction as the key factor for martensite reorientation in magnetic field

    NASA Astrophysics Data System (ADS)

    L'vov, Victor A.; Kosogor, Anna

    2016-09-01

    The magnetic field application leads to spatially inhomogeneous magnetostriction of twinned ferromagnetic martensite. When the increasing field and magnetostrictive strain reach certain threshold values, the motion of twin boundaries and magnetically induced reorientation (MIR) of twinned martensite start. The MIR leads to giant magnetically induced deformation of twinned martensite. In the present article, the threshold field (TF) and temperature range of observability of MIR were calculated for the Ni-Mn-Ga martensite assuming that the threshold strain (TS) is temperature-independent. The calculations show that if the TS is of the order of 10-4, the TF strongly depends on temperature and MIR can be observed only above the limiting temperature (~220 K). If the TS is of the order of 10-6, the TF weakly depends on temperature and MIR can be observed at extremely low temperatures. The obtained theoretical results are in agreement with available experimental data.

  20. Thermo-magnetic history effects in the giant magnetostriction across the first-order transition and minor hysteresis loops modeling in Fe0.955Ni0.045Rh alloy.

    PubMed

    Manekar, Meghmalhar; Sharma, V K; Roy, S B

    2012-05-30

    Results of temperature- and magnetic field-dependent strain measurements across the first-order antiferromagnetic to ferromagnetic phase transition in Fe(0.955)Ni(0.045)Rh are presented. Distinct thermal and magnetic field hystereses are observed in the measured strain across the phase transition. The minor hysteresis loops inside the hysteretic regime across the temperature-driven transition are modeled using the Preisach model of hysteresis. The applicability of the Preisach model to explain the general features of minor hysteresis loops is discussed for a disorder influenced first-order transition. The minor hysteresis loops show the property of retaining the memory of the starting or end point of the temperature cycle followed within the hysteretic region. A larger temperature excursion within the hysteretic region wipes out the memory of a smaller temperature cycle which contains one of the extrema of the larger cycle. The end-point memory and the wiping-out property of the minor hysteresis loops can be described quite well within the Preisach model, irrespective of the temperature history followed to reach a particular starting point. Thermo-magnetic history effects across the magnetic field-induced transition are explained, which will enable the choice of the starting point of an experimental cycle in the field-temperature phase space so as to achieve the desired functionality. Our results highlight the necessity to understand the influence of disorder on a first-order phase transition so as to achieve a repeatable performance of materials whose functionalities are based on such a transition.

  1. An Anisotropic Model for Magnetostriction and Magnetization Computing for Noise Generation in Electric Devices

    PubMed Central

    Mbengue, Serigne Saliou; Buiron, Nicolas; Lanfranchi, Vincent

    2016-01-01

    During the manufacturing process and use of ferromagnetic sheets, operations such as rolling, cutting, and tightening induce anisotropy that changes the material’s behavior. Consequently for more accuracy in magnetization and magnetostriction calculations in electric devices such as transformers, anisotropic effects should be considered. In the following sections, we give an overview of a macroscopic model which takes into account the magnetic and magnetoelastic anisotropy of the material for both magnetization and magnetostriction computing. Firstly, a comparison between the model results and measurements from a Single Sheet Tester (SST) and values will be shown. Secondly, the model is integrated in a finite elements code to predict magnetostrictive deformation of an in-house test bench which is a stack of 40 sheets glued together by the Vacuum-Pressure Impregnation (VPI) method. Measurements on the test bench and Finite Elements results are presented. PMID:27092513

  2. Influence of Tb on easy magnetization direction and magnetostriction of ferromagnetic Laves phase GdFe2 compounds

    NASA Astrophysics Data System (ADS)

    Murtaza, Adil; Yang, Sen; Zhou, Chao; Song, Xiaoping

    2016-09-01

    The crystal structure, magnetization, and spontaneous magnetostriction of ferromagnetic Laves phase GdFe2 compound have been investigated. High resolution synchrotron x-ray diffraction (XRD) analysis shows that GdFe2 has a lower cubic symmetry with easy magnetization direction (EMD) along [100] below Curie temperature TC. The replacement of Gd with a small amount of Tb changes the EMD to [111]. The Curie temperature decreases while the field dependence of the saturation magnetization (Ms) measured in temperature range 5-300 K varies with increasing Tb concentration. Coercivity Hc increases with increasing Tb concentration and decays exponentially as temperature increases. The anisotropy in GdFe2 is so weak that some of the rare-earth substitution plays an important role in determining the easy direction of magnetization in GdFe2. The calculated magnetostrictive constant λ100 shows a small value of 37×10-6. This value agrees well with experimental data 30×10-6. Under a relatively small magnetic field, GdFe2 exhibits a V-shaped positive magnetostriction curve. When the field is further increased, the crystal exhibits a negative magnetostriction curve. This phenomenon has been discussed in term of magnetic domain switching. Furthermore, magnetostriction increases with increasing Tb concentration. Our work leads to a simple and unified mesoscopic explanation for magnetostriction in ferromagnets. It may also provide insight for developing novel functional materials. Project supported by the National Basic Research Program of China (Grant No. 2012CB619401).

  3. Giant electric-field-induced strain in lead-free piezoelectric materials

    PubMed Central

    Chen, Lan; Yang, Yurong; Meng, X. K.

    2016-01-01

    First-principles calculations are performed to investigate the structures, electrical, and magnetic properties of compressive BiFeO3 films under electric-field and pressure perpendicular to the films. A reversible electric-field-induced strain up 10% is achieved in the compressive BiFeO3 films. The giant strain originates from rhombohedral-tetragonal (R-T) phase transition under electric-filed, and is recoverable from tetragonal-rhombohedral (T-R) phase transition by compressive stress. Additionally, the weak ferromagnetism in BiFeO3 films is largely changed in R-T phase transition under electric-filed and T-R phase transition under pressure – reminiscent of magnetoelectric effect and magnetoelastic effect. These results suggest exciting device opportunities arising from the giant filed-induced strain, large magnetoelectric effect and magnetoelastic effect. PMID:27139526

  4. Power generation transducer from magnetostrictive materials

    NASA Astrophysics Data System (ADS)

    Zhang, Hui

    2011-06-01

    In this letter, on the basis of Stoner-Wohlfarth model, the changes in magnetization of Tb0.3Dy0.7Fe2 alloy have been calculated with a compressive stress along the [111] and [112] axes. The results have shown that the significant change in magnetization for Tb0.3Dy0.7Fe2 alloy can be induced by the compressive stress. A feasible application of power generation floor which can convert the energy from the vibration created by a walking person on it into electric energy has been proposed, and its structure and performance also have been revealed.

  5. Magnetostrictive Roller-Drive Stepping Motor

    NASA Technical Reports Server (NTRS)

    Vranish, John M.

    1993-01-01

    Proposed motor based on magnetostrictive effect provides stepped angular motion with angular increments of order of 100 microradians. Driven to repeat stepping cycle rapidly enough to achieve maximum speed of about 20 rpm, provides torque an order of magnitude greater than electric motors, and brakes itself when power turned off. Magnetostrictive rods in electromagnet coils push against drive plate, causing it to rotate slightly. This slight rotation jams conical rollers between cam surfaces on outer drive ring and split drum, so rollers transmit rotation to drum. Suitable for precise, high-torque, fail-safe-braking, direct drive of robot joint, without bulk and weight of additional brake mechanism and gear train.

  6. Giant enhancement of the controllable in-plane anisotropy of biased isotropic noncentrosymmetric materials with epsilon-negative multilayers

    NASA Astrophysics Data System (ADS)

    Valagiannopoulos, C. A.; Tsitsas, N. L.; Lakhtakia, A.

    2017-02-01

    Giant in-plane anisotropy can be exhibited by a finitely thick periodic multilayer comprising bilayers of an isotropic noncentrosymmetric material and a non-dissipative isotropic medium of negative permittivity, when a dc electric field is applied in the thickness direction. Compared to a homogeneous layer of the noncentrosymmetric material with the same thickness as the periodic multilayer, the latter exhibits an effective in-plane anisotropy that can be three orders larger in magnitude. This enhancement gets more substantial at higher frequencies and is electrically controllable. The incorporation of dissipation reduces the enhancement of the effective in-plane anisotropy, which nevertheless remains significant. We expect the finitely thick periodic multilayer to be useful as a polarization transformer or a modulator in the terahertz regime fully controllable via external dc bias.

  7. Tailoring magnetostriction sign of ferromagnetic composite by increasing magnetic field strength

    NASA Astrophysics Data System (ADS)

    Gou, Junming; Liu, Xiaolian; Wu, Kaiyun; Wang, Yue; Hu, Shanshan; Zhao, Hui; Xiao, Andong; Ma, Tianyu; Yan, Mi

    2016-08-01

    The unitary deformation of single-phase ferromagnets by a magnetic field, i.e., either positive or negative linear magnetostriction, allows only monotonous control. Here we report a proof-of-principle ferromagnetic composite Fe73Ga27, for which the magnetostriction sign changes from positive to negative by increasing the magnetic field strength. Based on the transformation from body-centered-cubic (BCC) to face-centered-cubic (FCC) phases in this binary system, Fe73Ga27 composite is prepared by aging the BCC averaged precursor for 3 days at 803 K. Magnetic measurements indicate that the BCC phase exhibits smaller magnetocrystalline anisotropy constant than the FCC phase. The offset effect between BCC and FCC phases produces positive net magnetostriction at low magnetic fields but negative net magnetostriction at high magnetic fields. By tuning the field strength, such composites can mediate compressive and tensile strains to other functional materials, e.g., piezoelectric material or optic-fibers, which is beneficial to design multifunctional devices.

  8. Effects of intrinsic magnetostriction on tube-topology magnetoelectric sensors with high magnetic field sensitivity

    SciTech Connect

    Gillette, Scott M.; Fitchorov, Trifon; Obi, Ogheneyunume; Chen, Yajie Harris, Vincent G.; Jiang, Liping; Hao, Hongbo; Wu, Shuangxia

    2014-05-07

    Three quasi-one-dimensional magnetoelectric (ME) magnetic field sensors, each with a different magnetostrictive wire material, were investigated in terms of sensitivity and noise floor. Magnetostrictive Galfenol, iron-cobalt-vanadium, and iron-nickel wires were examined. Sensitivity profiles, hysteresis effects, and noise floor measurements for both optimally biased and zero-biased conditions are presented. The FeNi wire (FN) exhibits high sensitivity (5.36 mV/Oe) at bias fields below 22 Oe and an optimal bias of 10 Oe, whereas FeGa wire (FG) exhibits higher sensitivity (6.89 mW/Oe) at bias fields >22 Oe. The sensor of FeCoV wire (FC) presents relatively low sensitivity (2.12 mV/Oe), due to low magnetostrictive coefficient. Each ME tube-topology sensor demonstrates relatively high sensitivity at zero bias field, which results from a magnetic shape anisotropy and internal strain of the thin magnetostrictive wire.

  9. The effect of the condensation of ice materials in the atmosphere on the thermal evolution of ice giants

    NASA Astrophysics Data System (ADS)

    Kurosaki, Kenji; Ikoma, Masahiro

    2015-12-01

    Though Uranus and Neptune are similar in mass and radius, the former is significantly fainter than the latter. As previous theoretical studies of thermal evolution of the ice giants demonstrated, the faintness of Uranus is not explained by simple three-layer models that are composed of a H/He-dominated envelope, an ice mantle and a rocky core. Namely, the observed effective temperature of Uranus is lower than theoretically predicted (e.g., Fortney et al., 2011; Nettelmann et al., 2013). Since the speed of the thermal evolution is determined by how efficiently the planetary atmosphere radiates energy, the atmospheric structure is important. If the atmosphere contains ice materials such as water, ammonia and methane, those materials have been condensed and removed from the atmosphere during the cooling. In this study, we quantify the impact of the condensation of ice components in the atmosphere on the thermal evolution, which previous studies ignore, to explain the current luminosity of Uranus. To do so, we simulate the thermal cooling of ice giants, based on three layer models with a relatively ice-component-rich, H/He-dominated atmosphere on top of a water mantle that surrounds a rocky core. We demonstrate that the effect of the condensation makes the timescale of the thermal cooling of the planet shorter by an order of magnitude than in the case without condensation. Such accelerated cooling is shown to be fast enough to explain the current faintness of Uranus. We also discuss what caused the difference in current luminosity between Uranus and Neptune.

  10. Development of highly magnetostrictive composites for applications in magnetomechanical torque sensors

    SciTech Connect

    Chen, Yonghua

    1999-12-01

    The objective of this work was to investigate and develop a magnetomechanical material with high magnetomechanical response and low hysteresis. This material will be used in electronic torque sensors for advanced steering systems in automobiles which will replace the costly and fuel inefficient hydraulic steering systems currently in use. Magnetostruction and the magnetomechanical effect under torsional stress of magnetostrictive composites have been investigated in the present study.

  11. Exchange-Coupling in Magnetic Nanoparticles to Enhance Magnetostrictive Properties

    SciTech Connect

    Radousky, H; McElfresh, M; Berkowitz, A; Carman, G P

    2002-01-31

    Spark erosion is a versatile and economical method for producing particles of virtually any type of material that has a nominal conductivity: particles can be prepared in sizes ranging from a few nm to tens of {micro}m. The purpose of this feasibility study was to demonstrate the capability of making spherical particles of specific magnetic materials. We chose (Tb Dy)Fe{sub 2} (Terfenol-D) due to its potential use as the magnetostrictive component in magneto-elastomer composites. We also chose to work with pure Ni as a model system. Improvements in the properties of magneto-elastomer composites have broad applications in the areas of sensor development, enhanced actuators and damping systems.

  12. A Cryogenic Magnetostrictive Actuator Using a Persistent High Temperature Superconducting Magnet. Part 1; Concept and Design

    NASA Technical Reports Server (NTRS)

    Horner, Garnett; Bromberg, Leslie; Teter, J. P.

    2000-01-01

    Cryogenic magnetostrictive materials, such as rare earth zinc crystals, offer high strains and high forces with minimally applied magnetic fields, making the material ideally suited for deformable optics applications. For cryogenic temperature applications the use of superconducting magnets offer the possibility of a persistent mode of operation, i.e., the magnetostrictive material will maintain a strain field without power. High temperature superconductors (HTS) are attractive options if the temperature of operation is higher than 10 degrees Kelvin (K) and below 77 K. However, HTS wires have constraints that limit the minimum radius of winding, and even if good wires can be produced, the technology for joining superconducting wires does not exist. In this paper, the design and capabilities of a rare earth zinc magnetostrictive actuator using bulk HTS is described. Bulk superconductors can be fabricated in the sizes required with excellent superconducting properties. Equivalent permanent magnets, made with this inexpensive material, are persistent, do not require a persistent switch as in HTS wires, and can be made very small. These devices are charged using a technique which is similar to the one used for charging permanent magnets, e.g., by driving them into saturation. A small normal conducting coil can be used for charging or discharging. Because of the magnetic field capability of the superconductor material, a very small amount of superconducting magnet material is needed to actuate the rare earth zinc. In this paper, several designs of actuators using YBCO and BSCCO 2212 superconducting materials are presented. Designs that include magnetic shielding to prevent interaction between adjacent actuators will also be described. Preliminary experimental results and comparison with theory for BSCCO 2212 with a magnetostrictive element will be discussed.

  13. Progress towards developing neutron tolerant magnetostrictive and piezoelectric transducers

    SciTech Connect

    Reinhardt, Brian; Tittmann, Bernhard; Rempe, Joy; Daw, Joshua; Kohse, Gordon; Carpenter, David; Ames, Micheal; Ostrovsky, Yakov; Ramuhalli, Pradeep; Montgomery, Robert; Chien, Hualte; Wernsman, Bernard

    2014-07-01

    Current generation light water reactors (LWRs), sodium cooled fast reactors (SFRs), small modular reactors (SMRs), and next generation nuclear plants (NGNPs) provide harsh environments in and near the core that can severely test material performance and limit their operational life. To address this issue, several Department of Energy Office of Nuclear Energy (DOE-NE) research programs are evaluating the long duration radiation performance of fuels and materials. In To reduce the amount of Material and Test Reactor (MTR) irradiations required, DOE is also funding development of enhanced instrumentation that will be able to obtain data, with unprecedented accuracy and resolution, that are required to validate new multi-scale multiphysics modeling tools . It is not feasible to obtain such data with the current state of instrumentation technology. To address this need, PSU and collaborators have started an experiment to test the potential for utilizing ultrasonic instruments in-pile. Ultrasonic sensors must be resistant to high neutron flux, high gamma radiation, and high temperature. PSU and collaborators have designed, fabricated, and started to irradiate piezoelectric and magnetostrictive transducers designed to perform in such harsh environments. Three piezoelectric transducers were fabricated with aluminum nitride, zinc oxide, and bismuth titanate as the active element. The transducers are coupled kovar and aluminum waveguides of which pulse-echo ultrasonic measurements are made in-situ. Two magnetostrictive transducers were fabricated with Remendur and Arnokrome as the active elements. These devices will be pulsed and monitored in-situ. (1) Selection of candidate sensor materials as well as optimization of test assembly parameters (2) High temperature benchmark testing and (3) initial data from the irradiation will be reported.

  14. Pinning induced magnetostriction in ceramic high temperature superconductors

    NASA Astrophysics Data System (ADS)

    Nabiałek, A.; Szymczak, H.; Piotrowski, K.; Chabanenko, V.; Pakieła, Z.

    1999-08-01

    Transverse and longitudinal magnetostriction was measured in ceramic YBa 2Cu 3O 7- δ and Hg 0.8Pb 0.2Ba 2Ca 2Cu 3O 8+ δ superconductors by the strain gauge technique. The measurements were performed in an external magnetic field up to 12 T. The observed magnetostriction was shown to consist of two components. The first one is connected with the intragrain - and the second one with the intergrain screening currents. Both components of the magnetostriction were analyzed independently in frames of an isotropic theory of the pinning induced magnetostriction.

  15. Origin of large magnetostriction in FeGa alloys

    NASA Astrophysics Data System (ADS)

    Wu, Ruqian

    2002-05-01

    Using the highly precise full potential linearized augmented plane wave method, the phase stability, magnetism, and magnetostriction of Fe3Ga alloys were investigated. The magnetostrictive coefficients strongly depend on the atomic arrangement. The B2-like structure, although it is unstable in the small unit cell chosen here, appears to play a crucial rule for the large positive magnetostriction in the FeGa alloys as observed recently. Electronic origin of enhancement in magnetostriction is discussed in terms of density of states and band structures.

  16. Magnetic and magnetostrictive properties of RE-doped Cu-Co ferrite fabricated from spent lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Xi, Guoxi; Wang, Lu; Zhao, Tingting

    2017-02-01

    Magnetostrictive Cu0.1Co0.9RExFe2-xO4 (RE=Ho, Gd or Sm) was fabricated by a sol-gel auto-combustion technique using spent lithium-ion batteries as raw materials. X-ray diffraction analysis confirmed the spinel structure of the RE-incorporated samples with limited RE solubility. Field-emission scanning electron microscopy and Fourier transform infrared spectroscopy revealed a layered structure composed of particles and the cation distribution. Magnetic hysteresis loops and magnetostriction strain curves showed that the saturation magnetization, magnetostriction coefficient and strain derivative were significantly modified due to the substitution of larger ionic radius RE3+ ions for Fe3+ ions, influencing the interaction between the tetrahedral and octahedral sites.

  17. Magnetostrictive bending micro-actuator using iron gallium-alloy

    NASA Astrophysics Data System (ADS)

    Ueno, Toshiyuki; Higuchi, Toshiro

    2007-04-01

    We investigate a micro bending actuator based on unimorph, lamination of Galfenol (Iron-gallium alloy) and non-magnetic material. Galfenol C-shape yoke bonded with stainless plates (lamination) is wound coils, and is composed close magnetic loop with connected an iron plate. The magnetostriction in longitude direction is constrained by the stainless, thus, the laminations yield bending deformation with the current flowing. The advantage of the actuator is simple, compact and ease of assembling including winding coil, and high tolerance against bending, tensile and impact. We machined the yoke from a plate of 1mm thickness of polycrystalline Galfenol (Fe 81.4Ga 18.6 Research grade) using ultra high precision cutting technique. The prototype, thickness of 1mm and length of 10mm, was observed the displacement 13μm and 1st resonance at 1.6 kHz, and the high bending (tensile) tolerance withstanding suspended weight of 500g.

  18. First principles determination of the rhombohedral magnetostriction of Fe100-xGax and Fe100-xAlx (x<20) alloys

    NASA Astrophysics Data System (ADS)

    Wu, Ruqian; Zhang, Yanning

    2012-02-01

    Extensive efforts have been dedicated to investigate the extraordinary magnetostriction of Galfenol (Fe100-xGax) and Alfenal (Fe100-xAlx) alloys, which are very promising magnetostrictive materials for various applications such as sensors, transducers and spintronic devices. In contrast to the strong response of the tetragonal magnetostriction (λ100) to the Ga/Al concentration (x), the rhombohedral magnetostriction,λ111, vs. x curves for both FeGa and FeAl alloys show negative and steady values for 0magnetostriction anisotropy in these alloys. Possible reasons on the disagreement between the calculated and observed rhombohedral magnetostriction of bcc Fe will also be given.

  19. Testing Results of Magnetostrictive Ultrasonic Sensor Cables for Signal Loss

    SciTech Connect

    JT Evans

    2005-05-01

    The purpose of this test was to determine the signal strength and resolution losses of a magnetostrictive ultrasonic system with an extended signal cable. The cable of interest carries electrical signals between the pulse generator/receiver and the magnetostrictive transducer. It was desired to determine the loss introduced by different lengths of the signal cable (6', 100', and 200').

  20. Specific features of magnetostriction at electron topological transitions in metals

    NASA Astrophysics Data System (ADS)

    Mikitik, G. P.; Sharlai, Yu. V.

    2017-01-01

    The properties of magnetostriction in metals are studied in cases when the chemical potential of electrons is close to the critical energy of the electron energy spectrum, at which there is an electron topological transition of 2½ or 3½ kind. It is shown that the experimental study of magnetostriction can be an effective method for detecting these transitions in metals.

  1. Analysis of an operator-differential model for magnetostrictive energy harvesting

    NASA Astrophysics Data System (ADS)

    Davino, D.; Krejčí, P.; Pimenov, A.; Rachinskii, D.; Visone, C.

    2016-10-01

    We present a model of, and analysis of an optimization problem for, a magnetostrictive harvesting device which converts mechanical energy of the repetitive process such as vibrations of the smart material to electrical energy that is then supplied to an electric load. The model combines a lumped differential equation for a simple electronic circuit with an operator model for the complex constitutive law of the magnetostrictive material. The operator based on the formalism of the phenomenological Preisach model describes nonlinear saturation effects and hysteresis losses typical of magnetostrictive materials in a thermodynamically consistent fashion. We prove well-posedness of the full operator-differential system and establish global asymptotic stability of the periodic regime under periodic mechanical forcing that represents mechanical vibrations due to varying environmental conditions. Then we show the existence of an optimal solution for the problem of maximization of the output power with respect to a set of controllable parameters (for the periodically forced system). Analytical results are illustrated with numerical examples of an optimal solution.

  2. Giant amplification of light in non-hermitian photonic materials (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Tureci, Hakan E.; Makris, Konstantinos G.; Ge, Li

    2015-09-01

    In photonics and quantum optics, a key challenge facing any technological application has traditionally been the mitigation of optical losses. Recent work has shown that a new class of optical materials, called Parity-Time symmetric materials, that consist of a precisely balanced distribution of loss and gain can be exploited to engineer novel functionalities for propagating and filtering electromagnetic radiation. Here we show a generic property of optical systems that feature an arbitrary distribution of loss and gain, described by non-Hermitian operators, namely that overall lossy optical systems can transiently amplify certain input signals by several orders of magnitude. We present a mathematical framework to analyze the dynamics of wave propagation in media with an arbitrary distribution of loss and gain and construct the initial conditions to engineer such non-Hermitian power amplifiers.

  3. Presolar Materials in a Giant Cluster IDP of Probable Cometary Origin

    NASA Technical Reports Server (NTRS)

    Messenger, S.; Brownlee, D. E.; Joswiak, D. J.; Nguyen, A. N.

    2015-01-01

    Chondritic porous interplanetary dust particles (CP-IDPs) have been linked to comets by their fragile structure, primitive mineralogy, dynamics, and abundant interstellar materials. But differences have emerged between 'cometary' CP-IDPs and comet 81P/Wild 2 Stardust Mission samples. Particles resembling Ca-Al-rich inclusions (CAIs), chondrules, and amoeboid olivine aggregates (AOAs) in Wild 2 samples are rare in CP-IDPs. Unlike IDPs, presolar materials are scarce in Wild 2 samples. These differences may be due to selection effects, such as destruction of fine grained (presolar) components during the 6 km/s aerogel impact collection of Wild 2 samples. Large refractory grains observed in Wild 2 samples are also unlikely to be found in most (less than 30 micrometers) IDPs. Presolar materials provide a measure of primitive-ness of meteorites and IDPs. Organic matter in IDPs and chondrites shows H and N isotopic anomalies attributed to low-T interstellar or protosolar disk chemistry, where the largest anomalies occur in the most primitive samples. Presolar silicates are abundant in meteorites with low levels of aqueous alteration (Acfer 094 approximately 200 ppm) and scarce in altered chondrites (e.g. Semarkona approximately 20 ppm). Presolar silicates in minimally altered CP-IDPs range from approximately 400 ppm to 15,000 ppm, possibly reflecting variable levels of destruction in the solar nebula or statistical variations due to small sample sizes. Here we present preliminary isotopic and mineralogical studies of a very large CP-IDP. The goals of this study are to more accurately determine the abundances of presolar components of CP-IDP material for comparison with comet Wild 2 samples and meteorites. The large mass of this IDP presents a unique opportunity to accurately determine the abundance of pre-solar grains in a likely cometary sample.

  4. Progress Report 2011: Understanding compound phase transitions in Heusler alloy giant magnetocaloric materials

    SciTech Connect

    Stadler, Shane

    2011-12-13

    Our goal is to gain insight into the fundamental physics that is responsible for magnetocaloric effects (MCE) and related properties at the atomic level. We are currently conducting a systematic study on the effects of atomic substitutions in Ni2MnGa-based alloys, and also exploring related full- and half-Heusler alloys, for example Ni-Mn-X (X=In, Sn, Sb), that exhibit a wide variety of interesting and potentially useful physical phenomena. It is already known that the magnetocaloric effect in the Heusler alloys is fundamentally connected to other interesting phenomena such as shape-memory properties. And the large magnetic entropy change in Ni2Mn0.75Cu0.25Ga has been attributed to the coupling of the first-order, martensitic transition with the second-order ferromagnetic paramagnetic (FM-PM) transition. Our research to this point has focused on understanding the fundamental physics at the origin of these complex, compound phase transitions, and the novel properties that emerge. We synthesize the materials using a variety of techniques, and explore their material properties through structural, magnetic, transport, and thermo-magnetic measurements.

  5. Sound Generation Using a Magnetostrictive Microactuator

    NASA Astrophysics Data System (ADS)

    S. Albach, Thorsten; Horn, Peter; Sutor, Alexander; Lerch, Reinhard

    2011-04-01

    In this paper, we present the design and performance of a MEMS-device based on the magnetostrictive effect, which can be used as a micro-loudspeaker. The device basically consists of a comb structure of monomorph bending cantilevers with an active area up to 3.0×2.5 mm2. It produces a sound-pressure-level up to 101 dB at 400 Hz in a standard 2 ccm measurement volume. We show our measurement setup as well as a mechanic-acoustic-coupled lumped element model to calculate sound pressure. The model incorporates finite element results for mechanical behavior. Measurement results validate our model assumptions.

  6. Magnetostrictive GMR spin valves with composite FeGa/FeCo free layers

    NASA Astrophysics Data System (ADS)

    Liu, Luping; Zhan, Qingfeng; Yang, Huali; Li, Huihui; Zhang, Shuanglan; Liu, Yiwei; Wang, Baomin; Tan, Xiaohua; Li, Run-Wei

    2016-03-01

    We have fabricated strain-sensitive spin valves on flexible substrates by utilizing the large magnetostrictive FeGa alloy to promote the strain sensitivity and the composite free layer of FeGa/FeCo to avoid the drastic reduction of giant magnetoresistance (GMR) ratio. This kind of spin valve (SV-FeGa/FeCo) displays a MR ratio about 5.9%, which is comparable to that of the conventional spin valve (SV-FeCo) with a single FeCo free layer. Different from the previously reported works on magnetostrictive spin valves, the SV-FeGa/FeCo displays an asymmetric strain dependent GMR behavior. Upon increasing the lateral strain, the MR ratio for the ascending branch decreases more quickly than that for the descending branch, which is ascribed to the formation of a spiraling spin structure around the FeGa/FeCo interface under the combined influences of both magnetic field and mechanical strain. A strain sensitivity of GF = 7.2 was achieved at a magnetic bias field of -30 Oe in flexible SV-FeGa/FeCo, which is significantly larger than that of SV-FeCo.

  7. Magnetostriction of some rare earth-aluminum Laves phase compounds

    NASA Technical Reports Server (NTRS)

    Pourarian, F.; Wallace, W. E.

    1979-01-01

    Measurements of the linear and volume magnetostriction of RAl2 cubic Laves compounds in which R is one of the rare earth elements Gd, Dy, Ho or Er, at temperatures between 4.2 K and the Curie temperature of each compound, are reported. Magnetic fields up to 2.5 Tesla were applied, and magnetostriction was measured using standard strain gage techniques. Saturation magnetostrictions of 17 x 10 to the -6th, -1420 x 10 to the -6th, 60 x 10 to the -6th and -920 x 10 to the -6th are determined at 4.2 K for GdAl2, DyAl2, HoAl2 and ErAl2, respectively. Large forced magnetostriction is observed in GdAl2 above the saturation field and the strain temperature dependence shows a decrease in magnitude below 40 K. A linear dependence of magnetostriction on magnetic field was observed for DyAl2 above 40 K, and the observed temperature dependence is interpreted in terms of the lowest order single-ion magnetoelastic theory. An observed decrease in the magnitude of the strain of HoAl2 below 15 K is associated with a change of the easy direction of magnetization, while in the case of ErAl2, magnetostriction is observed to occur normally up to the Curie temperature. Large volume magnetostriction is obtained for all the compounds with the exception of GdAl2.

  8. Progress towards developing neutron tolerant magnetostrictive and piezoelectric transducers

    NASA Astrophysics Data System (ADS)

    Reinhardt, Brian; Tittmann, Bernhard; Rempe, Joy; Daw, Joshua; Kohse, Gordon; Carpenter, David; Ames, Michael; Ostrovsky, Yakov; Ramuhalli, Pradeep; Montgomery, Robert; Chien, Hualte; Wernsman, Bernard

    2015-03-01

    Current generation light water reactors (LWRs), sodium cooled fast reactors (SFRs), small modular reactors (SMRs), and next generation nuclear plants (NGNPs) produce harsh environments in and near the reactor core that can severely tax material performance and limit component operational life. To address this issue, several Department of Energy Office of Nuclear Energy (DOE-NE) research programs are evaluating the long duration irradiation performance of fuel and structural materials used in existing and new reactors. In order to maximize the amount of information obtained from Material Testing Reactor (MTR) irradiations, DOE is also funding development of enhanced instrumentation that will be able to obtain in-situ, real-time data on key material characteristics and properties, with unprecedented accuracy and resolution. Such data are required to validate new multi-scale, multi-physics modeling tools under development as part of a science-based, engineering driven approach to reactor development. It is not feasible to obtain high resolution/microscale data with the current state of instrumentation technology. However, ultrasound-based sensors offer the ability to obtain such data if it is demonstrated that these sensors and their associated transducers are resistant to high neutron flux, high gamma radiation, and high temperature. To address this need, the Advanced Test Reactor National Scientific User Facility (ATR-NSUF) is funding an irradiation, led by PSU, at the Massachusetts Institute of Technology Research Reactor to test the survivability of ultrasound transducers. As part of this effort, PSU and collaborators have designed, fabricated, and provided piezoelectric and magnetostrictive transducers that are optimized to perform in harsh, high flux, environments. Four piezoelectric transducers were fabricated with either aluminum nitride, zinc oxide, or bismuth titanate as the active element that were coupled to either Kovar or aluminum waveguides and two

  9. Progress towards developing neutron tolerant magnetostrictive and piezoelectric transducers

    SciTech Connect

    Reinhardt, Brian; Tittmann, Bernhard; Rempe, Joy; Daw, Joshua; Kohse, Gordon; Carpenter, David; Ames, Michael; Ostrovsky, Yakov; Ramuhalli, Pradeep; Montgomery, Robert; Chien, Hualte; Wernsman, Bernard

    2015-03-31

    Current generation light water reactors (LWRs), sodium cooled fast reactors (SFRs), small modular reactors (SMRs), and next generation nuclear plants (NGNPs) produce harsh environments in and near the reactor core that can severely tax material performance and limit component operational life. To address this issue, several Department of Energy Office of Nuclear Energy (DOE-NE) research programs are evaluating the long duration irradiation performance of fuel and structural materials used in existing and new reactors. In order to maximize the amount of information obtained from Material Testing Reactor (MTR) irradiations, DOE is also funding development of enhanced instrumentation that will be able to obtain in-situ, real-time data on key material characteristics and properties, with unprecedented accuracy and resolution. Such data are required to validate new multi-scale, multi-physics modeling tools under development as part of a science-based, engineering driven approach to reactor development. It is not feasible to obtain high resolution/microscale data with the current state of instrumentation technology. However, ultrasound-based sensors offer the ability to obtain such data if it is demonstrated that these sensors and their associated transducers are resistant to high neutron flux, high gamma radiation, and high temperature. To address this need, the Advanced Test Reactor National Scientific User Facility (ATR-NSUF) is funding an irradiation, led by PSU, at the Massachusetts Institute of Technology Research Reactor to test the survivability of ultrasound transducers. As part of this effort, PSU and collaborators have designed, fabricated, and provided piezoelectric and magnetostrictive transducers that are optimized to perform in harsh, high flux, environments. Four piezoelectric transducers were fabricated with either aluminum nitride, zinc oxide, or bismuth titanate as the active element that were coupled to either Kovar or aluminum waveguides and two

  10. Orbital engineering of two-dimensional materials with hydrogenation: A realization of giant gap and strongly correlated topological insulators

    NASA Astrophysics Data System (ADS)

    Pham, Anh; Gil, Carmen J.; Smith, Sean C.; Li, Sean

    2015-07-01

    Orbital interaction plays an important role in topological insulators. Using first-principles calculations, we demonstrate that hydrogenation can change two-dimensional (2D) trivial insulator/semimetal-like Pb, Mo, and W to a Z2 topological insulator with giant gaps by filtering unwanted orbitals such as the pz orbital in Pb, and the d3 z2-r2 in Mo and W. For PbH, the large intrinsic spin-orbit coupling (SOC) confined in the in-plane orbitals px ,y results in a bulk gap of 1.07 eV. For the case of MoH and WH, hydrogenation results in a novel s d4 hybridization with a Dirac cone formed by the out-of-plane orbital dy z /x z orbitals. Furthermore, due to the electron-electron interaction and the strong SOC in the 4 d and 5 d elements, the bulk band gap is significantly enhanced with a value of 1.28 eV for MoH and 0.30 eV for WH. The strong correlation effect also induces several topological phase transitions in WH like the Dirac semimetal and Mott insulating phase, while MoH remains a topological insulator even with large correlation effect. We propose that these new strongly correlated 2D materials can be realized experimentally by using substrate such as the boron nitride sheet, which can exhibit various novel properties such as the Dirac semimetal phase with large spin-orbit energy splitting as well as the quantum spin Hall property.

  11. Translatory and wobbling micro magnetostrictive actuator

    NASA Astrophysics Data System (ADS)

    Ueno, Toshiyuki; Saito, Chihiro; Imaizumi, Nobuo; Higuchi, Toshiro

    2008-03-01

    We propose a three-DOF magnetostrictive micro actuator using Iron-Gallium alloy (Galfenol). The actuator consists of two parallel beam structure having a Galfenol core, located at either end of a Galfenol rod of 1 mm square cross-section and length 11 mm, with two orthogonal ditches cut down it of width 0.3 mm. Around the resulting prongs are wound, and the prongs are bonded to an iron end cap to close the magnetic circuit. When current is passed through a coil wound round one of the orthogonal parallel beams, the resulting magnetostriction enables the actuator to bend in two directions. In addition, longitudinal displacement with high frequency bandwidth can be generated by excitation of two or of all four coils. Maximum displacements were observed of 8 to 10 μm in bending and 2.2 μm in the longitudinal direction. This actuator is potentially applicable in machining (drilling), positioning, and in a micro-motor using wobbling or translational motion when powered by a small power supply.

  12. Performance of improved magnetostrictive vibrational power generator, simple and high power output for practical applications

    SciTech Connect

    Ueno, Toshiyuki

    2015-05-07

    Vibration based power generation technology is utilized effectively in various fields. Author has invented novel vibrational power generation device using magnetostrictive material. The device is based on parallel beam structure consisting of a rod of iron-gallium alloy wound with coil and yoke accompanied with permanent magnet. When bending force is applied on the tip of the device, the magnetization inside the rod varies with induced stress due to the inverse magnetostrictive effect. In vibration, the time variation of the magnetization generates voltage on the wound coil. The magnetostrictive type is advantageous over conventional such using piezoelectric or moving magnet types in high efficiency and high robustness, and low electrical impedance. Here, author has established device configuration, simple, rigid, and high power output endurable for practical applications. In addition, the improved device is lower cost using less volume of Fe-Ga and permanent magnet compared to our conventional, and its assembly by soldering is easy and fast suitable for mass production. Average power of 3 mW/cm{sup 3} under resonant vibration of 212 Hz and 1.2 G was obtained in miniature prototype using Fe-Ga rod of 2 × 0.5× 7 mm{sup 3}. Furthermore, the damping effect was observed, which demonstrates high energy conversion of the generator.

  13. Magnetostriction and its inverse effect in Tb0.3Dy0.7Fe2 alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Zeng, Dechang

    2010-06-01

    Magnetostriction and its inverse effect (also referred to as a magnetomechanical effect) in the Tb0.3Dy0.7Fe2 alloy have been investigated based on the three dimensional Stoner-Wohlfarth model in this paper. The solutions of direction cosines of magnetization under a compressive stress and a field both applied along the [112] axis have been obtained by following a conventional minimization procedure in which the nonlinear equations for equilibrium conditions have been solved numerically. With a more accurate computation presented here, some new theoretical results have been achieved. These results are in good agreement with experimental observations reported previously. In the demagnetized state the resultant anisotropy for the alloy is determined by the combination of the magnetocrystalline and stress-induced anisotropy energies, and degenerates from cubic into uniaxial at a critical stress. When a field is applied to the alloy along the [112] axis, the alloy under the compressive stress is more difficult to magnetize and can attain a maximum change in bulk magnetostriction at the critical stress. The main reason for the large bulk magnetostriction is that the fractional occupancy of the [1¯1¯1] or [111¯]-oriented domains increases from 1/8 to 1/2 with the stress. This more accurate computation has been proposed for similar investigations and the results will also be helpful for a better understanding of the magnetostriction in materials such as the FeGa alloys.

  14. A model to predict the ultrasonic field radiated by magnetostrictive effects induced by EMAT in ferromagnetic parts

    NASA Astrophysics Data System (ADS)

    Clausse, B.; Lhémery, A.; Walaszek, H.

    2017-01-01

    An Electro-Magnetic Acoustic Transducer (EMAT) is a non-contact source used in Ultrasonic Testing (UT) which generates three types of dynamic excitations into a ferromagnetic part: Lorentz force, magnetisation force, and magnetostrictive effect. This latter excitation is a strain resulting from a magnetoelastic interaction between the external magnetic field and the mechanical part. Here, a tensor model is developed to transform this effect into an equivalent body force. It assumes weak magnetoelastic coupling and a dynamic magnetic field much smaller than the static one. This approach rigorously formulates the longitudinal Joule’s magnetostriction, and makes it possible to deal with arbitrary material geometries and EMAT configurations. Transduction processes induced by an EMAT in ferromagnetic media are then modelled as equivalent body forces. But many models developed for efficiently predicting ultrasonic field radiation in solids assume source terms given as surface distributions of stress. To use these models, a mathematical method able to accurately transform these body forces into equivalent surface stresses has been developed. By combining these formalisms, the magnetostrictive strain is transformed into equivalent surface stresses, and the ultrasonic field radiated by magnetostrictive effects induced by an EMAT can be both accurately and efficiently predicted. Numerical examples are given for illustration.

  15. Two-dimensional magnetostriction under vector magnetic characteristic

    NASA Astrophysics Data System (ADS)

    Wakabayashi, D.; Enokizono, M.

    2015-05-01

    This paper presents two-dimensional magnetostriction of electrical steel sheet under vector magnetic characteristic. In conventional measurement method using Single Sheet Tester, the magnetic flux density, the magnetic field strength, and the magnetostriction have been measured in one direction. However, an angle between the magnetic flux density vector and the magnetic field strength vector exists because the magnetic property is vector quantity. An angle between the magnetic flux density vector and the direction of maximum magnetostriction also exists. We developed a new measurement method, which enables measurement of these angles. The vector magnetic characteristic and the two-dimensional magnetostriction have been measured using the new measurement method. The BH and Bλ curves considering the angles are shown in this paper. The analyzed results considering the angles are also made clear.

  16. Recent development in grain-oriented electrical steel with low magnetostriction

    SciTech Connect

    Yabumoto, M.; Arai, S.; Kawamata, R.; Mizokami, M.; Kubota, T.

    1997-12-01

    For precise evaluations of magnetostriction properties, a new magnetostriction measuring system using a laser vibrometer was developed. Frequency analysis of magnetostriction under non-sinusoidal magnetization revealed a nonlinear relation between harmonics in flux and those in magnetostriction. Transformer core vibration was investigated in order to clarify the relations between magnetostriction and transformer noise and to realize low-noise transformers. Resonance was proved to have an important role for core vibration. Domain-refined, grain-oriented electrical steel, which fulfills low loss and low magnetostriction properties simultaneously, is also explained.

  17. Evaluation of steel shafts for magnetostrictive torque sensors (abstract)

    SciTech Connect

    Koga, F.; Yoshida, K.; Sasada, I.

    1997-04-01

    Based on the magnetostrictive effect in steel, a robust, noncontacting shaft torque sensor can be obtained. A fundamental problem is compatibility between mechanical strength required for a shaft and a magnetic one needed for a torque sensor. To find shaft material accommodating these two requirements, we investigated basic characteristics, such as hysteresis, linearity, and zero-level fluctuation associated with shaft rotation, of the magnetostrictive torque sensor for various nickel chromium molybdenum steel shafts (SNCM in Japanese Industrial Standard) subjected to case hardening. We prepared three kinds of shafts of 25 mm in diameter: SNCM 420 (Ni=1.69{percent}, C=0.2{percent}), SNCM 616 (Ni=2.91{percent}, C=0.15{percent}), and SNCM 447 (Ni=1.67{percent}, C=0.49{percent}). Shafts of the first two materials were carburized, whereas those of the last one were quenched. We used a magnetic head-type torque sensor consisting of a pair of cross-coupled figure-eight coils (14 turn). The hysteresis in the input{endash}output relationship was measured for the excitation current from 0.1 to 1.0 A at 60 kHz. The hysteresis of the SNCM 420 shaft changes from negative to positive with the increase in excitation current and that of the SNCM 616 shaft decreases monotonically but never reaches zero, whereas that of the SNCM 447 shaft exhibits minimum. The smallest values obtained are nearly zero for the SNCM 420 shaft at 0.3 A, 1.5{percent}/(full scale (FS)=400 Nm) for the SNCM 616 shaft at 1.0 A and 0.7{percent}/FS for the SNCM 447 shaft at 0.8 A, respectively. The linearity measured for the SNCM 420 shaft, which has the smallest hysteresis of the three, at 0.3 A and 60 kHz was virtually straight for the applied torque range {minus}400{endash}400 Nm and 0.8{percent} of nonlinearity error for the range {minus}1000{endash}1000 Nm. The zero-level fluctuation was measured for the SNCM 420 shaft by rotating the shaft without applying torque. (Abstract Truncated)

  18. Vertical positioning surveillance by magnetostrictive transducer

    NASA Astrophysics Data System (ADS)

    Carvalho, A. S.; Lopes, C.; Pinto, O. O.; Nunes, C. D.; Borges, M. F.; Strohaecker, T. R.

    2015-10-01

    This work purpose is to create a positioning automated system of a tailstock to perform impact resistance tests on silicone mammary implants. This system is capable to measure and oversight the positioning through interrelation between three main components: programmable logic controller, human-machine interface and magnetostrictive transducer. Together, these components form an operational closed loop that ensures an appropriate positioning for the impact device. The paper describes how the closed loop works and also the algorithm implemented in the programmable logic controller which surveys the positioning. As a last topic, the paper presents the operator work on the machine's operation in conjunction with human-machine interface. The results were satisfactory and in accordance with the limits determined on ABNT NBR ISO 14607 for this method of tests.

  19. Development of a magnetostrictive borehole seismic source

    SciTech Connect

    Cutler, R.P.; Sleefe, G.E.; Keefe, R.G.

    1997-04-01

    A magnetostrictive borehole seismic source was developed for use in high resolution crosswell surveys in environmental applications. The source is a clamped, vertical-shear, swept frequency, reaction-mass shaker design consisting of a spring pre-loaded magnetostrictive rod with permanent magnet bias, drive coils to induce an alternating magnetic field, and an integral tungsten reaction mass. The actuator was tested extensively in the laboratory. It was then incorporated into an easily deployable clamped downhole tool capable of operating on a standard 7 conductor wireline in borehole environments to 10,000{degrees} deep and 100{degrees}C. It can be used in either PVC or steel cased wells and the wells can be dry or fluid filled. It has a usable frequency spectrum of {approx} 150 to 2000 Hz. The finished tool was successfully demonstrated in a crosswell test at a shallow environmental site at Hanford, Washington. The source transmitted signals with a S/N ratio of 10-15 dB from 150-720 Hz between wells spaced 239 feet apart in unconsolidated gravel. The source was also tested successfully in rock at an oil field test site, transmitting signals with a S/N ratio of 5-15 dB over the full sweep spectrum from 150-2000 Hz between wells spaced 282 feet apart. And it was used successfully on an 11,000{degrees} wireline at a depth of 4550{degrees}. Recommendations for follow-on work include improvements to the clamp, incorporation of a higher sample rate force feedback controller, and increases in the force output of the tool.

  20. Electroluminescence of Giant Stretchability.

    PubMed

    Yang, Can Hui; Chen, Baohong; Zhou, Jinxiong; Chen, Yong Mei; Suo, Zhigang

    2016-06-01

    A new type of electroluminescent device achieves giant stretchability by integrating electronic and ionic components. The device uses phosphor powders as electroluminescent materials, and hydrogels as stretchable and transparent ionic conductors. Subject to cyclic voltage, the phosphor powders luminesce, but the ionic conductors do not electrolyze. The device produces constant luminance when stretched up to an area strain of 1500%.

  1. Validated linear dynamic model of electrically-shunted magnetostrictive transducers with application to structural vibration control

    NASA Astrophysics Data System (ADS)

    Scheidler, Justin J.; Asnani, Vivake M.

    2017-03-01

    This paper presents a linear model of the fully-coupled electromechanical behavior of a generally-shunted magnetostrictive transducer. The impedance and admittance representations of the model are reported. The model is used to derive the effect of the shunt’s electrical impedance on the storage modulus and loss factor of the transducer without neglecting the inherent resistance of the transducer’s coil. The expressions are normalized and then shown to also represent generally-shunted piezoelectric materials that have a finite leakage resistance. The generalized expressions are simplified for three shunts: resistive, series resistive-capacitive, and inductive, which are considered for shunt damping, resonant shunt damping, and stiffness tuning, respectively. For each shunt, the storage modulus and loss factor are plotted for a wide range of the normalized parameters. Then, important trends and their impact on different applications are discussed. An experimental validation of the transducer model is presented for the case of resistive and resonant shunts. The model closely predicts the measured response for a variety of operating conditions. This paper also introduces a model for the dynamic compliance of a vibrating structure that is coupled to a magnetostrictive transducer for shunt damping and resonant shunt damping applications. This compliance is normalized and then shown to be analogous to that of a structure that is coupled to a piezoelectric material. The derived analogies allow for the observations and equations in the existing literature on structural vibration control using shunted piezoelectric materials to be directly applied to the case of shunted magnetostrictive transducers.

  2. Real Time Digital Control of a Magnetostrictive Actuator

    NASA Technical Reports Server (NTRS)

    Zrostlik, Rick L.; Hall, David L.; Flatau, Alison B.

    1996-01-01

    The use of the magnetostrictive material Terfenol-D as a motion source in active vibration control (AVC) systems are being studied. Currently it is of limited use due to the nonlinear nature of the strain versus magnetization curve and the magnetic hysteresis in the Terfenol-D. One manifestation of these nonlinearities is waveform distortion in the output velocity of the transducer. For Terfenol-D to be used in ever greater numbers of AVC systems, these nonlinearities must be addressed. In this study the nonlinearities are treated as disturbances to a linear system. The acceleration output is used in simple analog and digital feedback control schemes to improve linearity of the transducer. In addition, the use of a Terfenol-D actuator in an AVC system is verified. Both analog and digital controllers are implemented and results compared. A cantilever beam system is considered for AVC applications. The second thrust of this presentation is the reduction of harmonic distortions. Two conclusions can be reached from this work. One, the linearization of Terfenol-D transducers is possible with the use of feedback controllers, both digital and analog. Second, Terfenol-D is a viable motion source in active vibration control systems utilizing either analog or digital controllers.

  3. An Innocent Giant

    PubMed Central

    Solanki, Lakhan Singh; Dhingra, Mandeep; Raghubanshi, Gunjan; Thami, Gurvinder Pal

    2014-01-01

    A cutaneous horn (cornu cutaneum) is a protrusion from the skin composed of a cornified material. It may be associated with a benign, premalignant, or malignant lesion at the base, masking numerous dermatoses. In a 24-year-old female, a giant cutaneous horn arising from a seborrheic keratosis located on the leg is presented. This case has been reported to emphasize that a giant cutaneous horn may also occur in young patients, even in photoprotected areas, and are not always associated with malignancy. PMID:25484426

  4. A Nonlinear Optimal Control Design using Narrowband Perturbation Feedback for Magnetostrictive Actuators

    DTIC Science & Technology

    2010-07-01

    A Nonlinear Optimal Control Design using Narrowband Perturbation Feedback for Magnetostrictive Actuators William S. Oates1, Rick Zrostlik2, Scott...Abstract Nonlinear optimal and narrowband feedback control designs are developed and experimentally implemented on a magnetostrictive Terfenol-D...utilizing narrowband feedback. A narrowband filter is implemented by treating the nonlinear and hysteretic magnetostrictive constitutive behavior as

  5. Review of magnetostrictive transducers (MsT) utilizing reversed Wiedemann effect

    NASA Astrophysics Data System (ADS)

    Vinogradov, Sergey; Cobb, Adam; Light, Glenn

    2017-02-01

    Magnetostrictive transduction has been widely utilized in NDE applications, specifically for generation and reception of guided waves for long-range inspection of components such as pipes, vessels, and small tubes. Transverse-motion guided wave modes (e.g., torsional vibrations in pipes) are the most typical choice for long-range inspection applications because the wave motion is in the plane of the structure. Magnetostrictive-based sensors have been available for several years for these wave modes based on the Wiedemann effect. For these sensors, a permanent magnetic bias is applied that is perpendicular to the direction of the propagated guided wave. This bias field strains the material that the guided wave is generated in preferentially in the desired particle motion direction. A time-varying magnetic field oriented parallel to the direction of guided wave propagation is also induced in the material. This time-varying field is induced using an electric coil located near the material surface. The interaction of these two fields produces the guided waves; an inverse effect is used for the receive process. An alternative configuration of a sensor for generating and receiving these traverse-motion guided waves is to swap the biasing and time-varying magnetic fields directions. Since transverse-motion guided wave sensors are typically much longer in the particle motion direction than in the bias field direction, the net effect of this alternative design is that the magnetic biasing length is shorter and different coil designs can be used. Because of this, the alternative design, known as a magnetostrictive transducer (MsT), exhibits a number of unique features compared to the Wiedemann sensor described above, such as: 1) the ability to use smaller rare earth permanent magnets and achieve uniform and self-sustained bias field strengths, 2) the choice of more efficient electric coil arrangements to induce a stronger time-varying magnetic field for a given coil

  6. Wiedemann effect of Fe—Ga based magnetostrictive wires

    NASA Astrophysics Data System (ADS)

    Li, Ji-Heng; Gao, Xue-Xu; Zhu, Jie; Bao, Xiao-Qian; Cheng, Liang; Xie, Jian-Xin

    2012-08-01

    (Fe83Ga17)98Cr2 wires each with a diameter of 0.7 mm are prepared by hot swaging and warm drawing from the casting rods directly, because the ductility of Fe83Ga17 alloy is improved by adding Cr element. The Wiedemann twists and dependences on magnetostrictions of Fe83Ga17 and (Fe83Ga17)98Cr2 wires are investigated. The largest observed Wiedemann twists of 245 s·cm-1 and 182 s·cm-1 are detected in the annealed Fe83Ga17 and (Fe83Ga17)98Cr2 wires, respectively. The magnetostrictions of the annealed Fe83Ga17 and (Fe83Ga17)98Cr2 wires are 160 ppm and 107 ppm, respectively. The maximum of the Wiedemann twist increases with magnetostriction increasing. However the magnetostriction is just one important factor that affects the Wiedemann effect of alloy wire, and the relationship between magnetostriction and Wiedemann effect is a complex function rather than a simple function.

  7. Magnetic structure and local lattice distortion in giant negative thermal expansion material Mn3Cu1-xGexN

    NASA Astrophysics Data System (ADS)

    Iikubo, S.; Kodama, K.; Takenaka, K.; Takagi, H.; Shamoto, S.

    2010-11-01

    Magnetic and local structures in an antiperovskite system, Mn3Cu1-xGexN, with a giant negative thermal expansion have been studied by neutron powder diffraction measurement. We discuss (1) an importance of an averaged cubic crystal structure and a ΓG5g antiferromagnetic spin structure for the large magneto-volume effect (MVE) in this itinerant electron system, (2) an unique role of a local lattice distortion well described by the low temperature tetragonal structure of Mn3GeN for the broadening of MVE.

  8. Feasibility of Magnetostrictive Sensor Inspection of Containments

    SciTech Connect

    Kwun, H.

    1999-03-01

    This report describes the results of a study on the feasibility of using guided waves for long-range global inspection of containment metallic pressure boundaries (i.e., steel containments and liners of reinforced concrete containments) in nuclear power plants. Of particular concern in this study was the potential of the guided-wave approach for remotely inspecting the regions that are inaccessible; for example, regions where the metallic pressure boundary is backed by concrete on one or both sides. The study includes a literature review on long-range guided-wave inspection techniques, a modeling study of the behavior of guided waves in plates with different boundary conditions (e.g., freestanding and backed by concrete on one or both sides), and an experimental investigation of the feasibility of a guided-wave technique called ''magnetostrictive sensor (MsS)'' for (1) generating and detecting guided waves in plates and (2) detecting a defect over a long range. Results of the study showed (1) that it is feasible to achieve long-range global inspection of plates, including regions that are inaccessible, using low-frequency guided waves and (2) that the MsS technique is well suited for this application. Recommendations are made to further test and develop the MsS technique for practical implementation for containment inspection in nuclear power plants.

  9. The nature of photoinduced changes in the magnetostriction of yttrium-iron garnet single crystals

    SciTech Connect

    Vorob'eva, N. V.

    2011-05-15

    A model of the occurrence of photoinduced changes in linear magnetostriction is proposed based on a complex experimental study of magnetostrictive strains in yttrium-iron garnets Y{sub 3}Fe{sub 5}O{sub 12} with low contents of different impurities. Analytical expressions for calculating the magnetostriction in yttrium-iron garnet single crystals with different types of doping are presented. The correlation of the photoinduced change in the magnetostriction with the crystallographic features of the samples is demonstrated. The changes in the magnetostriction constants are analyzed quantitatively for samples prepared in different ways.

  10. Switching the conductance of Dy nanocontacts by magnetostriction.

    PubMed

    Müller, Marc; Montbrun, Richard; Marz, Michael; Fritsch, Veronika; Sürgers, Christoph; v Löhneysen, Hilbert

    2011-02-09

    The electrical conductance G of mechanical break-junctions fabricated from the rare-earth metal dysprosium has been investigated at 4.2 K where Dy is in the ferromagnetic state. In addition to the usual variation of the conductance while breaking the wire mechanically, the conductance can be changed reproducibly by variation of the magnetic field H, due to the large magnetostriction of Dy. For a number of contacts, we observe discrete changes in G(H) in the range of several G(0) = 2e(2)/h. The behavior of G(H) and its angular dependence can be quantitatively understood by taking into account the magnetostrictive properties of Dy. This realization of a magnetostrictive few-atom switch demonstrates the possibility of reproducibly tuning the conductance of magnetic nanocontacts by a magnetic field.

  11. Elastic and magnetostrictive properties of Tb6Fe1-xCioBi2 (0 < x < 0.375)

    SciTech Connect

    Koehler, Michael R.; Jia, Lin; McCarthy, David; McGuire, Michael A; Keppens, Veerle

    2011-01-01

    Elastic moduli and magnetostriction data are reported for polycrystalline Tb{sub 6}Fe{sub 1-x}Co{sub x}Bi{sub 2} (0 {le} x {le} 0.375). The elastic moduli c{sub 11} and c{sub 44} have been measured as a function of temperature (5-300 K) and magnetic field (0-5 T), and reflect the ferromagnetic transition observed in these materials around 250 K. A remarkable elastic softening, which is partially suppressed upon application of a magnetic field, is observed at low temperatures and is believed to be linked to a structural transition that takes place in the Co-doped samples. The soft elastic moduli lead to large magnetostriction below 50 K, reaching a value of 700 ppm at 20 kOe for Tb{sub 6}Fe{sub 0.75}Co{sub 0.25}Bi{sub 2}.

  12. Mirroring the dynamic magnetic behavior of magnetostrictive Co/(Ag,Cu,Ta) multilayers grown onto rigid and flexible substrates

    NASA Astrophysics Data System (ADS)

    Agra, K.; Gomes, R. R.; Della Pace, R. D.; Dorneles, L. S.; Bohn, F.; Corrêa, M. A.

    2015-11-01

    We investigate the magnetoimpedance effect in a wide frequency range in magnetostrictive Co/(Ag,Cu,Ta) multilayers grown onto rigid and flexible substrates. We observe a direct correlation between structural and quasi-static magnetic properties and the magnetoimpedance effect, since they are directly dependent on the nature of the spacer material. Moreover, we verify that all these properties are insensitive to the kind of employed substrate. We compare the magnetoimpedance results measured for multilayers in rigid and flexible substrates and discuss them in terms of different mechanisms that govern the impedances changes, magnetic anisotropy, structural character, and of numerical calculation results found in the literature. The fact that magnetostrictive multilayers can be reproduced in distinct kinds of substrates corresponds to an important advance for their applicability. The results place multilayers grown onto flexible substrates as attractive candidates for application as probe element in the development of MI-based sensor devices.

  13. Giant magneto-impedance and its relaxation in Co{endash}Fe{endash}Si{endash}B amorphous ribbons

    SciTech Connect

    Sartorelli, M.L.; Knobel, M.; Schoenmaker, J.; Gutierrez, J.; Barandiaran, J.M.

    1997-10-01

    Systematic measurements of giant magneto-impedance (GMI) and its relaxation (magneto-impedance aftereffect) have been carried out in a series of Co-rich amorphous ribbons ranging in magnetostriction values from {minus}3.5 to +3.5thinspppm. The value of GMI is a maximum for the alloy with the lowest value of magnetostriction, corresponding to a maximum of the transverse permeability. The impedance relaxation between two fixed times depends on the magnetostriction constant ({lambda}{sub s}) of the samples, and the observed trend is consistent with the theories which predict a direct relationship of the conventional permeability aftereffect (MAE) with the square of {lambda}{sub s}. Furthermore, the variation of the impedance aftereffect with the driving current resembles the behavior of MAE, and a connection between both effects can be established. {copyright} {ital 1997 American Institute of Physics.}

  14. Design, test and model of a hybrid magnetostrictive hydraulic actuator

    NASA Astrophysics Data System (ADS)

    Chaudhuri, Anirban; Yoo, Jin-Hyeong; Wereley, Norman M.

    2009-08-01

    The basic operation of hybrid hydraulic actuators involves high frequency bi-directional operation of an active material that is converted to uni-directional motion of hydraulic fluid using valves. A hybrid actuator was developed using magnetostrictive material Terfenol-D as the driving element and hydraulic oil as the working fluid. Two different lengths of Terfenol-D rod, 51 and 102 mm, with the same diameter, 12.7 mm, were used. Tests with no load and with load were carried out to measure the performance for uni-directional motion of the output piston at different pumping frequencies. The maximum no-load flow rates were 24.8 cm3 s-1 and 22.7 cm3 s-1 with the 51 mm and 102 mm long rods respectively, and the peaks were noted around 325 Hz pumping frequency. The blocked force of the actuator was close to 89 N in both cases. A key observation was that, at these high pumping frequencies, the inertial effects of the fluid mass dominate over the viscous effects and the problem becomes unsteady in nature. In this study, we also develop a mathematical model of the hydraulic hybrid actuator in the time domain to show the basic operational principle under varying conditions and to capture phenomena affecting system performance. Governing equations for the pumping piston and output shaft were obtained from force equilibrium considerations, while compressibility of the working fluid was taken into account by incorporating the bulk modulus. Fluid inertia was represented by a lumped parameter approach to the transmission line model, giving rise to strongly coupled ordinary differential equations. The model was then used to calculate the no-load velocities of the actuator at different pumping frequencies and simulation results were compared with experimental data for model validation.

  15. Magnetostriction-driven cantilevers for dynamic atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Penedo, M.; Fernández-Martínez, I.; Costa-Krämer, J. L.; Luna, M.; Briones, F.

    2009-10-01

    An actuation mode is presented to drive the mechanical oscillation of cantilevers for dynamic atomic force microscopy. The method is based on direct mechanical excitation of the cantilevers coated with amorphous Fe-B-N thin films, by means of the film magnetostriction, i.e., the dimensional change in the film when magnetized. These amorphous magnetostrictive Fe-B-N thin films exhibit soft magnetic properties, excellent corrosion resistance in liquid environments, nearly zero accumulated stress when properly deposited, and good chemical stability. We present low noise and high resolution topographic images acquired in liquid environment to demonstrate the method capability.

  16. Magnetostriction and palæomagnetism of igneous rocks

    USGS Publications Warehouse

    Graham, John W.; Buddington, A.F.; Balsley, James R.

    1959-01-01

    IN a recent communication, Stott and Stacey1 report on a “crucial experiment” from which they conclude: “This excellent agreement between the dip and the directions of artificial thermoremanent magnetization of the stressed and unstressed rocks indicates that large systematic errors due to magnetostriction are most improbable in igneous rocks of types normally used for palæomagnetic work”. This experiment was intended to test the proposals2 and measurements3 bearing on the role of magnetostriction in rock magnetism. We present here our reasons for believing that the experiment was not crucial and that the conclusion is not justified.

  17. Continuous method for manufacturing grain-oriented magnetostrictive bodies

    DOEpatents

    Gibson, Edwin D.; Verhoeven, John D.; Schmidt, Frederick A.; McMasters, O. Dale

    1988-01-01

    The invention comprises a continuous casting and crystallization method for manufacturing grain-oriented magnetostrictive bodies. A magnetostrictive alloy is melted in a crucible having a bottom outlet. The melt is discharged through the bottom of the crucible and deposited in an elongated mold. Heat is removed from the deposited melt through the lower end portion of the mold to progressively solidify the melt. The solid-liquid interface of the melt moves directionally upwardly from the bottom to the top of the mold, to produce the axial grain orientation.

  18. Local Lattice Distortion in the Giant Negative Thermal Expansion Material Mn3Cu1-xGexN

    NASA Astrophysics Data System (ADS)

    Iikubo, S.; Kodama, K.; Takenaka, K.; Takagi, H.; Takigawa, M.; Shamoto, S.

    2008-11-01

    Giant negative thermal expansion is achieved in antiperovskite manganese nitrides when the sharp volume change associated with magnetic ordering is broadened by substitution. In this Letter, we address the unique role of the ‘‘magic” element, Ge, for such broadening in Mn3Cu1-xGexN. We present evidence for a local lattice distortion well described by the low-temperature tetragonal (T4) structure of Mn3GeN for a range of x, where the overall structure remains cubic. This structural instability shows a strong correlation with the broadness of the growth of the ordered magnetic moment and, hence, is considered to trigger the broadening of the volume change.

  19. The time-dependent magneto-visco-elastic behavior of a magnetostrictive fiber actuated viscoelastic polymer matrix composite.

    PubMed

    Hogea, Cosmina S; Armstrong, William D

    2002-11-01

    The paper develops a one-dimensional magneto-elastic model of a magnetostrictive fiber actuated polymer matrix composite material which accounts for a strong viscoelastic response in the polymer matrix. The viscoelastic behavior of the composite polymer matrix is modeled with a three parallel Maxwell element viscoelastic model, the magnetoelastic behavior of the composite fibers is modeled with an anhysteric directional potential based domain occupation theory. Example calculations are performed to identify and explain the dynamical behavior of the composite. These calculations assume that a constant stress and the oscillating magnetic field are applied in the fiber longitudinal direction. The inclusion of matrix viscosity results in an apparent hysteresis loop in the magnetization and magnetostriction curves even though the model does not include magnetoelastic hysteresis in the fibers. The apparent hysteresis is a consequence of the interaction of the time varying fiber stress caused by matrix viscosity with a multidomain state in the fiber. The small increase in fiber longitudinal compressive stress due to matrix viscosity under increasing field inhibits the occupation of domains with magnetization orientations near the fiber longitudinal [112] direction. As a consequence, the summed longitudinal magnetization and magnetostriction is reduced as compared to the decreasing field limb.

  20. New details of the Fermi surface of 2H-NbSe2 revealed by quantum oscillations in the magnetostriction

    NASA Astrophysics Data System (ADS)

    Sirenko, V.; Gasparini, A.; de Visser, A.; Eremenko, V.; Ibulaev, V.; Bruk, V.

    2009-03-01

    The layered charge-density wave (CDW) superconductor 2H-NbSe2 (TS=7.2 K) is the very first material in which quantum oscillations have been observed in the mixed state by means of magnetization and magnetostriction measurements. The magnetostriction technique offers the advantage that quantum oscillations are particularly pronounced, which is due to pressure sensitivity of the relevant cross-section of the Fermi surface. Moreover, measurements can be performed for a field oriented along the crystallographic axis in contrast to the torque technique that is routinely used. Here we present magnetostriction measurement on a high-quality single-crystalline sample for temperatures 0.25-8.0 K using a sensitive capacitance dilatometer. Two oscillation frequencies are observed at the lowest temperatures for the in-plane orientation of the applied magnetic field. These new data reveal that the Fermi-surface sheet in the first Brillouin zone has two cross-sections, rather than the conventional pan-cake shape.

  1. Unique magnetostriction of Fe68.8Pd31.2 attributable to twinning.

    PubMed

    Steiner, Jake; Lisfi, Abdellah; Kakeshita, Tomoyuki; Fukuda, Takashi; Wuttig, Manfred

    2016-09-30

    Fe68.8Pd31.2 exhibits an anomalously large magnetostriction of ~400 ppm at room temperature as well as linear, isotropic, and hysteresis free magnetization behavior. This near perfectly reversible magnetic response is attributable to the presence of a large number of premartensitic magnetoelastic twin clusters present in the system made possible through the elastic softening that occurs near a martensitic transformation temperature of 252 K. It is proposed that the twin clusters in the material reduce both internal elastic and magnetic energy, causing the elastic and magnetic behavior of the material to be intimately linked. In such a framework, the anisotropy energy becomes extremely low causing the material to bear no crystalline dependence on magnetization, and application of a magnetic field causes simultaneous magnetic and twin domain movement which relaxes the system.

  2. Unique magnetostriction of Fe68.8Pd31.2 attributable to twinning

    NASA Astrophysics Data System (ADS)

    Steiner, Jake; Lisfi, Abdellah; Kakeshita, Tomoyuki; Fukuda, Takashi; Wuttig, Manfred

    2016-09-01

    Fe68.8Pd31.2 exhibits an anomalously large magnetostriction of ~400 ppm at room temperature as well as linear, isotropic, and hysteresis free magnetization behavior. This near perfectly reversible magnetic response is attributable to the presence of a large number of premartensitic magnetoelastic twin clusters present in the system made possible through the elastic softening that occurs near a martensitic transformation temperature of 252 K. It is proposed that the twin clusters in the material reduce both internal elastic and magnetic energy, causing the elastic and magnetic behavior of the material to be intimately linked. In such a framework, the anisotropy energy becomes extremely low causing the material to bear no crystalline dependence on magnetization, and application of a magnetic field causes simultaneous magnetic and twin domain movement which relaxes the system.

  3. Unique magnetostriction of Fe68.8Pd31.2 attributable to twinning

    PubMed Central

    Steiner, Jake; Lisfi, Abdellah; Kakeshita, Tomoyuki; Fukuda, Takashi; Wuttig, Manfred

    2016-01-01

    Fe68.8Pd31.2 exhibits an anomalously large magnetostriction of ~400 ppm at room temperature as well as linear, isotropic, and hysteresis free magnetization behavior. This near perfectly reversible magnetic response is attributable to the presence of a large number of premartensitic magnetoelastic twin clusters present in the system made possible through the elastic softening that occurs near a martensitic transformation temperature of 252 K. It is proposed that the twin clusters in the material reduce both internal elastic and magnetic energy, causing the elastic and magnetic behavior of the material to be intimately linked. In such a framework, the anisotropy energy becomes extremely low causing the material to bear no crystalline dependence on magnetization, and application of a magnetic field causes simultaneous magnetic and twin domain movement which relaxes the system. PMID:27688053

  4. Co-Fe-B-Si-Nb bulk glassy alloys with superhigh strength and extremely low magnetostriction

    SciTech Connect

    Chang Chuntao; Shen Baolong; Inoue, Akihisa

    2006-01-02

    Co-based bulk glassy alloys with diameters up to 4 mm were formed in a [(Co{sub 1-x}Fe{sub x}){sub 0.75}B{sub 0.2}Si{sub 0.05}]{sub 96}Nb{sub 4} system. The bulk glassy alloys exhibit a superhigh fracture strength of 3980-4170 MPa and Young's modulus of 190-210 GPa. The bulk glassy alloys also exhibit excellent soft-magnetic properties, i.e., high saturation magnetization of 0.71-0.97 T, low coercive force of 0.7-1.8 A/m, high permeability of 1.48-3.25x10{sup 4}, and extremely low saturation magnetostriction of 0.55-5.76x10{sup -6}. The first successful synthesis of the Co-Fe-B-Si-based bulk glassy alloys exhibiting superhigh fracture strength and excellent soft-magnetic properties with extremely low magnetostriction is encouraging for future development of Co-based bulk glassy alloys as new engineering and functional materials.

  5. Giant isotropic magnetostrain of GaCMn3

    NASA Astrophysics Data System (ADS)

    Guo, X. G.; Tong, P.; Lin, J. C.; Yang, C.; Zhang, K.; Lin, S.; Song, W. H.; Sun, Y. P.

    2017-02-01

    Normal magnetostriction (MS), which comes from the gradual rotation of magnetic domains in ferromagnets, is anisotropic and smoothly dependent on the applied magnetic field. In cubic antiperovskite compound GaCMn3, a sharp shrink of lattice volume takes place at the antiferromagnetic (AFM) to intermediate magnetic (IM) phase transition. Below the Neel temperature (˜143 K), the AFM-IM transformation can be driven by external magnetic field, leading to a giant isotropic MS of ˜1700 ppm comparable to that of commercial Terfenol-D. In contrast to normal MS, the field-induced magnetostrain exhibits a rapid switch behavior at the critical field. Furthermore, good reversibility and stability were demonstrated for the giant MS of GaCMn3 compound.

  6. Frequency control of a spin-torque oscillator using magnetostrictive anisotropy

    SciTech Connect

    Park, Min Gyu Albert; Lee, Seok-Hee E-mail: shlee@kaist.edu; Baek, Seung-heon Chris; Park, Byong-Guk E-mail: shlee@kaist.edu

    2016-01-11

    We report the working principle of a spin-torque oscillator, of which the frequency is efficiently controlled by manipulating the magnetostrictive anisotropy. To justify the scheme, we simulate a conventional magnetic-tunnel junction-based oscillator which is fabricated on a piezoelectric material. By applying mechanical stress to a free layer using a piezoelectric material, the oscillation frequency can be controlled to ensure a broad tuning range without a significant reduction of the dynamic resistance variation. Such controllability, which appears in the absence of an external magnetic field, will not only enable the integration of spin-torque oscillators and conventional complimentary metal-oxide semiconductor technology but will also broaden the applicability of spin-torque oscillators.

  7. U-shape magnetostrictive vibration based power generator for universal use

    NASA Astrophysics Data System (ADS)

    Ueno, T.

    2016-04-01

    Vibrational power generator extracts electrical energy from ambient vibration. Author invented novel configuration using magnetostrictive material. The device is based on parallel beams of iron-gallium alloy and magnetic material, and features high efficiency, high robustness, and low electrical impedance. In this paper, author proposes U-shape generator for universal use. It consists of the parallel beams and fixed and free end beams forming U-shape frame flexibly modified for variety of mechanical input. Miniature U-shape prototype using Fe-Ga rod 6 by 0.5 by 13 mm3 exhibited average power of 3.7 mW under vibration of 166 Hz and 2.5 G. L-shape type was demonstrated to generate electromotive force by two directional vibrations. In switch type, maximum energy of 0.7 mJ was retrieved by one pushing force. The performances are sufficient to drive wireless module for heath monitoring and remote control.

  8. Influence of interdiffusion layer on magnetostriction of Fe/CoNbZr multilayers

    NASA Astrophysics Data System (ADS)

    Ż; uberek, R.; Szymczak, H.; Krishnan, R.; Tessier, M.

    1994-05-01

    The results of measurements of the magnetostriction constant λ S of multilayer Fe/CoNbZr sputtered films are reported, performed at room temperature using the strain-modulated ferromagnetic resonance method. Experimental evidence for an interdiffusion layer in the multilayer with iron layer thickness of 12 nm is demonstrated. The magnetostriction of the total multilayer is determined by the balance in magnetostriction among Fe, CoNbZr and the interdiffusion layer.

  9. Experimental Exploration of the Origin of Magnetostriction in Single Crystal Iron

    SciTech Connect

    Xing, Q.; Lograsso, T.A.; Ruffoni, M.P.; Azimonte, C.; Pascarelli, S.; Miller, D.J.

    2010-08-19

    The magnetostrictive atomic strain in a pure Fe single crystal was measured by differential x-ray absorption spectroscopy. The obtained tetragonal magnetostriction constant, (3/2){lambda}{sub 100}, was determined to be 45 ppm, consistent with the previously reported theoretical value calculated from a spin-orbit coupling theory. These results provide a foundation for understanding the origin of magnetostriction in pure Fe as well as Fe-based binary alloys.

  10. Experimental exploration of the origin of magnetostriction in single crystalline iron.

    SciTech Connect

    Xing, Q.; Lograsso, T. A.; Ruffoni, M. P.; Azimonte, C.; Pascarelli, S.; Miller, D. J.; Materials Science Division; Ames Lab.; European Synchrotron Radiation Facility

    2010-01-01

    The magnetostrictive atomic strain in a pure Fe single crystal was measured by differential x-ray absorption spectroscopy. The obtained tetragonal magnetostriction constant, (3/2){lambda}{sub 100}, was determined to be 45 ppm, consistent with the previously reported theoretical value calculated from a spin-orbit coupling theory. These results provide a foundation for understanding the origin of magnetostriction in pure Fe as well as Fe-based binary alloys.

  11. Evaluation of Magnetostrictive Shunt Damper Performance Using Iron (Fe)-Gallium (Ga) Alloy

    DTIC Science & Technology

    2013-09-01

    Evaluation of Magnetostrictive Shunt Damper Performance Using Iron (Fe)-Gallium (Ga) Alloy by Andrew James Murray and Dr. JinHyeong Yoo...Aberdeen Proving Ground, MD 21005 ARL-TN-0566 September 2013 Evaluation of Magnetostrictive Shunt Damper Performance Using Iron (Fe... Magnetostrictive Shunt Damper Performance Using Iron (Fe)- Gallium (Ga) Alloy 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6

  12. Sintered rare earth-iron Laves phase magnetostrictive alloy product and preparation thereof

    DOEpatents

    Malekzadeh, Manoochehr; Pickus, Milton R.

    1979-01-01

    A sintered rare earth-iron Laves phase magnetostrictive alloy product characterized by a grain oriented morphology. The grain oriented morphology is obtained by magnetically aligning powder particles of the magnetostrictive alloy prior to sintering. Specifically disclosed are grain oriented sintered compacts of Tb.sub.x Dy.sub.1-x Fe.sub.2 and their method of preparation. The present sintered products have enhanced magnetostrictive properties.

  13. A Cryogenic Magnetostrictive Actuator using a Persistent High Temperature Superconducting Magnet, Part 1: Concept and Design. Part 1; Concept and Design

    NASA Technical Reports Server (NTRS)

    Horner, Garnett C.; Bromberg, Leslie; Teter, J. P.

    2001-01-01

    Cryogenic magnetostrictive materials, such as rare earth zinc crystals, offer high strains and high forces with minimally applied magnetic fields, making the material ideally suited for deformable optics applications. For cryogenic temperature applications, such as Next Generation Space Telescope (NGST), the use of superconducting magnets offer the possibility of a persistent mode of operation, i.e., the magnetostrictive material will maintain a strain field without power. High temperature superconductors (HTS) are attractive options if the temperature of operation is higher than 10 degrees Kelvin (K) and below 77 K. However, HTS wires have constraints that limit the minimum radius of winding, and even if good wires can be produced, the technology for joining superconducting wires does not exist. In this paper, the design and capabilities of a rare earth zinc magnetostrictive actuator using bulk HTS is described. Bulk superconductors can be fabricated in the sizes required with excellent superconducting properties. Equivalent permanent magnets, made with this inexpensive material, are persistent, do not require a persistent switch as in HTS wires, and can be made very small. These devices are charged using a technique which is similar to the one used for charging permanent magnets, e.g., by driving them into saturation. A small normal conducting coil can be used for charging or discharging. Very fast charging and discharging of HTS tubes, as short as 100 microseconds, has been demonstrated. Because of the magnetic field capability of the superconductor material, a very small amount of superconducting magnet material is needed to actuate the rare earth zinc. In this paper, several designs of actuators using YBCO and BSCCO 2212 superconducting materials are presented. Designs that include magnetic shielding to prevent interaction between adjacent actuators will also be described. Preliminary experimental results and comparison with theory for BSSCO 2212 with a

  14. Development of novel acoustic wave biosensor platforms based on magnetostriction and fabrication of magnetostrictive nanowires

    NASA Astrophysics Data System (ADS)

    Li, Suiqiong

    There is an urgent need for biosensors that are able to detect and quantify the presence of a small amount of biological threat agents in a real-time manner. Acoustic wave (AW) devices, whose performance is defined by mass sensitivity (Sm) and merit quality factor (Q value), have been extensively studied as high performance biosensor platforms. However, current AW devices face some challenges in practical applications. In this research, two types of AW devices---magnetostrictive microcantilever (MSMC) and completely free-standing magnetostrictive particle (MSP)---were developed. The research consists of two parts: (1) Design and the feasibility study of MSMC and MSP based sensor technology; (2) Fabrication and characterization of micro/nano MSPs made of amorphous Fe-B alloy. Both MSMC and MSP based sensors are wireless/remote and work well in liquid, which makes the sensors good candidates for in-situ detection. The performance of MSMC was simulated and compared with the state of art AW devices: microcantilevers. The MSMC exhibits the following advantages: (1) remote/wireless driving and sensing; (2) ease of fabrication; (3) works well in liquid; (4) exhibits a high Q value (> 500 in air); (5) well suited for sensor array development. MSMCs in milli/micro sizes were fabricated and their performance was characterized in air and liquid. The experimental results confirm the advantages of MSMC mentioned above. The in situ detection of the yeast cells and Bacillus anthracis spores in water were performed using MSMC biosensors. MSPs in the shape of strip and bar were investigated. Strip-shape MSPs in milli/micro sizes were fabricated. The resonance behaviors of MSPs at the even and odd vibration modes were analyzed. MSP exhibits a Sm about 100 times greater, and a Q value about 10 times greater, than MCs. A multiple-sensor and a multiple-target approach were developed to further enhance the performance of MSP-based sensors. A unique methodology was created to detect the

  15. Optimization on magnetic transitions and magnetostriction in TbxDyyNdz(Fe0.9Co0.1)1.93 compounds

    NASA Astrophysics Data System (ADS)

    Hu, C. C.; Shi, Y. G.; Shi, D. N.; Zhou, X. G.; Fan, J. Y.; Lv, L. Y.; Tang, S. L.

    2013-10-01

    The structure, magnetic transitions, and magnetostriction of TbxDyyNdz(Fe0.9Co0.1)1.93 polycrystalline compounds have been investigated, with the ratio of x, y, and z spanning the line of minimum magnetic anisotropy. Anisotropy compensation with lower Tb content was realized in Tb0.253Dy0.657Nd0.09(Fe0.9Co0.1)1.93 compound. The spin configuration diagram accompanied with different crystal structures was constructed to illustrate the arrangement for the easy magnetization direction and crystal structure. An optimized effect on magnetostriction especially at the relatively low field of 1 kOe (197 ppm) was observed in Tb0.253Dy0.657Nd0.09(Fe0.9Co0.1)1.93 compound, which is about two times larger than that of the sample free of Nd (62 ppm). Meanwhile, the polycrystalline saturation magnetostriction (λs=945 ppm) of Tb0.253Dy0.657Nd0.09(Fe0.9Co0.1)1.93 is even much larger than that of the Ho-doped multicomponent single crystal compound Tb0.2Dy0.22Ho0.58Fe2 (λs=530 ppm). Low content of heavy rare earth Tb, high Curie temperature, and large ratio between magnetostriction and the absolute value of the first anisotropy constant λa/|K1| were obtained in Tb0.253Dy0.657Nd0.09(Fe0.9Co0.1)1.93 compound, which may make it a potential material for magnetostrictive application.

  16. Effect of nonsuperconducting particles on the effective magnetostriction of bulk superconductors

    NASA Astrophysics Data System (ADS)

    Yong, Hua-Dong; Zhou, You-He

    2008-08-01

    In this article, the dependence of effective magnetostriction of the bulk superconductors on the parameters including the elastic moduli and volume fraction is investigated. For a bulk superconductor of nonsuperconducting particles dispersed in a superconducting matrix, a simple and approximate model for effective magnetostriction is described. Based on the plane strain approach, the two-dimensional magnetostriction is obtained by implementing the continuity conditions of displacement and stress at the interface between the particle and the matrix. The results obtained show that the elastic moduli and volume fraction have obvious effects on the magnetostriction of bulk superconductors, which may explain why the experimental and the theoretical results have small differences.

  17. Quasi-static characterization and modeling of the bending behavior of single crystal galfenol for magnetostrictive sensors and actuators

    NASA Astrophysics Data System (ADS)

    Datta, Supratik

    2009-12-01

    Iron-gallium alloys (Galfenol) are structural magnetostrictive materials that exhibit high free-strain at low magnetic fields, high stress-sensitivity and useful thermo-mechanical properties. Galfenol, like smart materials in general, is attractive for use as a dynamic actuator and/or sensor material and can hence find use in active shape and vibration control, real-time structural health monitoring and energy harvesting applications. Galfenol possesses significantly higher yield strength and greater ductility than most smart materials, which are generally limited to use under compressive loads. The unique structural attributes of Galfenol introduce opportunities for use of a smart material in applications that involve tension, bending, shear or torsion. A principal motivation for the research presented in this dissertation is that bending and shear loads lead to development of non-uniform stress and magnetic fields in Galfenol which introduce significantly more complexity to the considerations to be modeled, compared to modeling of purely axial loads. This dissertation investigates the magnetostrictive response of Galfenol under different stress and magnetic field conditions which is essential for understanding and modeling Galfenol's behavior under bending, shear or torsion. Experimental data are used to calculate actuator and sensor figures of merit which can aid in design of adaptive structures. The research focuses on the bending behavior of Galfenol alloys as well as of laminated composites having Galfenol attached to other structural materials. A four-point bending test under magnetic field is designed, built and conducted on a Galfenol beam to understand its performance as a bending sensor. An extensive experimental study is conducted on Galfenol-Aluminum laminated composites to evaluate the effect of magnetic field, bending moment and Galfenol-Aluminum thickness ratio on actuation and sensing performance. A generalized recursive algorithm is presented for

  18. Magnetization of polydisperse colloidal ferrofluids: effect of magnetostriction.

    PubMed

    Huang, J P; Holm, C

    2004-12-01

    We exploit magnetostriction in polydisperse ferrofluids in order to generate nonlinear responses and apply a thermodynamical method to derive the desired nonlinear magnetic susceptibility. For an ideal gas, this method has been demonstrated to be in excellent agreement with a statistical method. In the presence of a sinusoidal ac magnetic field, the magnetization of the polydisperse ferrofluid contains higher-order harmonics, which can be extracted analytically by using a perturbation approach. We find that the harmonics are sensitive to the particle distribution and the degree of field-induced anisotropy of the system. In addition, we find that the magnetization is higher in the polydisperse system than in the monodisperse one, as also found by a recent Monte Carlo simulation. Thus, it seems possible to detect the size distribution in a polydisperse ferrofluid by measuring the harmonics of the magnetization under the influence of magnetostriction.

  19. Enhanced converse magnetoelectric effect in cylindrical piezoelectric-magnetostrictive composites

    NASA Astrophysics Data System (ADS)

    Wu, Gaojian; Zhang, Ru; Zhang, Ning

    2016-10-01

    Enhanced converse magnetoelectric (ME) effect has been experimentally observed in cylindrical PZT-Terfenol-D piezoelectric-magnetostrictive bilayered composites, where the piezoelectric and magnetostrictive components are coupled through normal stresses instead of shear stresses that act in most of previous multiferroic composites. A theoretical model based on elastodynamics analysis has been proposed to describe the frequency response of converse ME effect for axial and radial modes in the bilayered cylindrical composites. The theory shows good agreement with the experimental results. The different variation tendency of resonant converse ME coefficient, as well as different variation rate of resonance frequency with bias magnetic field for axial and radial modes is interpreted in terms of demagnetizing effect. This work is of theoretical and technological significance for the application of converse ME effect as magnetic sensor, transducers, coil-free flux switch, etc.

  20. Magnetic Domains in Magnetostrictive Fe-Ga Alloys

    SciTech Connect

    Q. Xing; T.A. Lograsso

    2008-11-03

    Lorentz microscopy was applied to the observation of magnetic domains in iron-gallium (Fe-Ga) alloys. Results did not show any link between the magnetic domains and the magnetostriction enhancement by Ga addition, but did reveal that the drastic decrease in magnetostriction for Fe-31.2 at. % Ga was due to the presence of large scale precipitates. Magnetic domain features did not change in the alloys of A2, D0{sub 3}, A2+D0{sub 3}, A2+B2+D0{sub 3}, and A2+fine scale precipitates. Large scale precipitates within the slow-cooled Fe-31.2 at. % Ga affected both the distribution and wall motion of magnetic domains.

  1. A magnetostrictive composite-fiber Bragg Grating sensor.

    PubMed

    Quintero, Sully M M; Braga, Arthur M B; Weber, Hans I; Bruno, Antonio C; Araújo, Jefferson F D F

    2010-01-01

    This paper presents a light and compact optical fiber Bragg Grating sensor for DC and AC magnetic field measurements. The fiber is coated by a thick layer of a magnetostrictive composite consisting of particles of Terfenol-D dispersed in a polymeric matrix. Among the different compositions for the coating that were tested, the best magnetostrictive response was obtained using an epoxy resin as binder and a 30% volume fraction of Terfenol-D particles with sizes ranging from 212 to 300 μm. The effect of a compressive preload in the sensor was also investigated. The achieved resolution was 0.4 mT without a preload or 0.3 mT with a compressive pre-stress of 8.6 MPa. The sensor was tested at magnetic fields of up to 750 mT under static conditions. Dynamic measurements were conducted with a magnetic unbalanced four-pole rotor.

  2. Atmosphere expansion and mass loss of close-orbit giant exoplanets heated by stellar XUV. I. Modeling of hydrodynamic escape of upper atmospheric material

    SciTech Connect

    Shaikhislamov, I. F.; Khodachenko, M. L.; Sasunov, Yu. L.; Lammer, H.; Kislyakova, K. G.; Erkaev, N. V.

    2014-11-10

    In the present series of papers we propose a consistent description of the mass loss process. To study in a comprehensive way the effects of the intrinsic magnetic field of a close-orbit giant exoplanet (a so-called hot Jupiter) on atmospheric material escape and the formation of a planetary inner magnetosphere, we start with a hydrodynamic model of an upper atmosphere expansion in this paper. While considering a simple hydrogen atmosphere model, we focus on the self-consistent inclusion of the effects of radiative heating and ionization of the atmospheric gas with its consequent expansion in the outer space. Primary attention is paid to an investigation of the role of the specific conditions at the inner and outer boundaries of the simulation domain, under which different regimes of material escape (free and restricted flow) are formed. A comparative study is performed of different processes, such as X-ray and ultraviolet (XUV) heating, material ionization and recombination, H{sub 3}{sup +} cooling, adiabatic and Lyα cooling, and Lyα reabsorption. We confirm the basic consistency of the outcomes of our modeling with the results of other hydrodynamic models of expanding planetary atmospheres. In particular, we determine that, under the typical conditions of an orbital distance of 0.05 AU around a Sun-type star, a hot Jupiter plasma envelope may reach maximum temperatures up to ∼9000 K with a hydrodynamic escape speed of ∼9 km s{sup –1}, resulting in mass loss rates of ∼(4-7) · 10{sup 10} g s{sup –1}. In the range of the considered stellar-planetary parameters and XUV fluxes, that is close to the mass loss in the energy-limited case. The inclusion of planetary intrinsic magnetic fields in the model is a subject of the follow-up paper (Paper II).

  3. Measurement of magnetostriction coefficients of epitaxial garnet films.

    PubMed

    Vella-Coleiro, G P

    1979-09-01

    A technique for measuring the magnetostriction coefficients of epitaxial garnet films on 50-mm-diam wafers is described. The measurement is based on the shift of the microwave ferrimagnetic resonance produced by stressing the film, which is achieved by supporting the wafer around its circumference and reducing the atmospheric pressure on one side. A simple, nonresonant transmission microwave spectrometer which is well suited for measurements on large wafers is also described.

  4. Incoherent magnetization dynamics in strain mediated switching of magnetostrictive nanomagnets

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Dhritiman; Mamun Al-Rashid, Md; D'Souza, Noel; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

    2017-01-01

    Micromagnetic studies of the magnetization change in magnetostrictive nanomagnets subjected to stress are performed for nanomagnets of different sizes. The interplay between demagnetization, exchange and stress anisotropy energies is used to explain the rich physics of size-dependent magnetization dynamics induced by modulating stress anisotropy in planar nanomagnets. These studies have important implications for strain mediated ultralow energy magnetization control in nanomagnets and its application in energy-efficient nanomagnetic computing devices.

  5. A magnetostrictive acceleration sensor for registration of chest wall displacements

    NASA Astrophysics Data System (ADS)

    Kaniusas, E.; Mehnen, L.; Krell, C.; Pfützner, H.

    2000-06-01

    The present study concerns a novel acceleration sensor built up using a bimetallic strip with one freely oscillating end. The strip consists of a magnetostrictive amorphous ribbon glued on a nonmagnetic metal ribbon. The sensor's effectiveness is demonstrated for the case of chest wall displacements as resulting from cardiorespiratory activity. The cheap and easy-to-handle novel sensor offers multiple information on the so-called sleep apnea syndrome.

  6. Magnetic and magnetostrictive properties of Cu substituted Co-ferrites

    NASA Astrophysics Data System (ADS)

    Chandra Sekhar, B.; Rao, G. S. N.; Caltun, O. F.; Dhana Lakshmi, B.; Parvatheeswara Rao, B.; Subba Rao, P. S. V.

    2016-01-01

    Copper substituted cobalt ferrite, Co1-xCuxFe2O4 (x=0.00-0.25), nanoparticles were synthesized by sol-gel autocombustion method. X-ray diffraction analysis on the samples was done to confirm the cubic spinel structures and Scherrer equation was used to estimate the mean crystallite size as 40 nm. Using the obtained nanoparticles, fabrication of the sintered pellets was done by standard ceramic technique. Magnetic and magnetostrictive measurements on the samples were made by strain gauge and vibrating sample magnetometer techniques, respectively. Maximum magnetostriction and strain derivative values were deduced from the field dependent magnetostriction curves while the magnetic parameters such as saturation magnetization (51.7-61.9 emu/g) and coercivity (1045-1629 Oe) on the samples were estimated from the obtained magnetic hysteresis loops. Curie temperature values (457-315 °C) were measured by a built in laboratory set-up. Copper substituted cobalt ferrites have shown improved strain derivative values as compared to the pure cobalt ferrite and thus making them suitable for stress sensing applications. The results have been explained on the basis of cationic distributions, strength of exchange interactions and net decreased anisotropic contributions due to the increased presence of Co2+ ions in B-sites as a result of Cu substitutions.

  7. Detection of Salmonella typhimurium using polyclonal antibody immobilized magnetostrictive biosensors

    NASA Astrophysics Data System (ADS)

    Guntupalli, R.; Hu, Jing; Lakshmanan, Ramji S.; Wan, Jiehui; Huang, Shichu; Yang, Hong; Barbaree, James M.; Huang, T. S.; Chin, Bryan A.

    2006-05-01

    Novel mass-sensitive, magnetostrictive sensors have a characteristic resonant frequency that can be determined by monitoring the magnetic flux emitted by the sensor in response to an applied, time varying, magnetic field. This magnetostrictive platform has a unique advantage over conventional sensor platforms in that measurement is wireless or remote. These biosensors can thus be used in-situ for detecting pathogens and biological threat agents. In this work, we have used a magnetostrictive platform immobilized with a polyclonal antibody (the bio-molecular recognition element) to form a biosensor for the detection of Salmonella typhimurium. Upon exposure to solutions containing Salmonella typhimurium bacteria, the bacteria were bound to the sensor and the additional mass of the bound bacteria caused a shift in the sensor's resonant frequency. Responses of the sensors to different concentrations of S. typhimurium were recorded and the results correlated with those obtained from scanning electron microscopy (SEM) images of samples. Good agreement between the measured number of bound bacterial cells (attached mass) and frequency shifts were obtained. The longevity and specificity of the selected polyclonal antibody were also investigated and are reported.

  8. Omnidirectional Lamb waves by axisymmetrically-configured magnetostrictive patch transducer.

    PubMed

    Lee, Joo Kyung; Kim, Hoe Woong; Kim, Yoon Young

    2013-09-01

    This work presents the generation of omnidirectional Lamb waves by a new magnetostrictive patch transducer (MPT) and investigates its generation mechanism. Although MPTs have been widely used for wave transduction in plates and pipes, no investigation reports the generation of omnidirectional Lamb waves in a plate by an MPT. For the generation, we propose an axisymmetrically-configured MPT that installs multiple axisymmetric turns of coil outside of a permanent cylindrical magnet located above the center of a circular magnetostrictive patch. After confirming the omnidirectivity of the proposed MPT experimentally, the mechanism of the Lamb wave generation and its frequency characteristics are investigated. It is also shown that the Lamb wave is most efficiently generated in a test plate when its wavelength is equal to two-thirds of the magnetostrictive patch diameter. If this wavelength¿patch diameter relation holds, the second radial extensional vibration mode of the patch of the proposed MPT is shown to be the mode responsible for generating the Lamb wave in a plate.

  9. A uniaxial stress capacitive dilatometer for high-resolution thermal expansion and magnetostriction under multiextreme conditions.

    PubMed

    Küchler, R; Stingl, C; Gegenwart, P

    2016-07-01

    Thermal expansion and magnetostriction are directional dependent thermodynamic quantities. For the characterization of novel quantum phases of matter, it is required to study materials under multi-extreme conditions, in particular, down to very low temperatures, in very high magnetic fields or under high pressure. We developed a miniaturized capacitive dilatometer suitable for temperatures down to 20 mK and usage in high magnetic fields, which exerts a large spring force between 40 to 75 N on the sample. This corresponds to a uniaxial stress up to 3 kbar for a sample with cross section of (0.5 mm)(2). We describe design and performance test of the dilatometer which resolves length changes with high resolution of 0.02 Å at low temperatures. The miniaturized device can be utilized in any standard cryostat, including dilution refrigerators or the commercial physical property measurement system.

  10. Model-Based Robust Control Design for Magnetostrictive Transducers Operating in Hysteretic and Nonlinear Regimes

    DTIC Science & Technology

    2003-01-01

    ag ne tiz at io n (A /m ) Data Model −1.5 −1 −0.5 0 0.5 1 1.5 x 10 5 0 0.2 0.4 0.6 0.8 1 1.2 1.4 x 10 −3 Field (A/m) S tr ai n Data Model (a) (b...31] R.C. Smith, M.J. Dapino and S . Seelecke, “A Free Energy Model for Hysteresis in Magnetostrictive Transducers,” Journal of Applied Physics, 93(1...of Intelligent Material Systems and Structures, 11(1), pp. 62-79, 2000. [35] R.C. Smith, S . Seelecke, M.J. Dapino and Z. Ounaies, “A Unified Model

  11. Method of forming magnetostrictive rods from rare earth-iron alloys

    DOEpatents

    McMasters, O.D.

    1986-09-02

    Rods of magnetostrictive alloys of iron with rare earth elements are formed by flowing a body of rare earth-iron alloy in a crucible enclosed in a chamber maintained under an inert gas atmosphere, forcing such molten rare-earth-iron alloy into a hollow mold tube of refractory material positioned with its lower end portion within the molten body by means of a pressure differential between the chamber and mold tube and maintaining a portion of the molten alloy in the crucible extending to a level above the lower end of the mold tube so that solid particles of higher melting impurities present in the alloy collect at the surface of the molten body and remain within the crucible as the rod is formed in the mold tube. 5 figs.

  12. Magnetic Materials

    DTIC Science & Technology

    1985-03-01

    Defense supported the development of microwave ferrites , and today 85 percent of that market is still military. Magnetostrictive sensors for sonar...or hard ferrite , Although both cobalt and samarium are expensive and the production process is difficult v4,*-°’. because of the strong tendency of...plentiful materials supply and low magnet cost. This calls for automated mass-production methods for ferrites and, perhaps, Nd-Fe-based REPMs. But for

  13. Thermal treatment for increasing magnetostrictive response of rare earth-iron alloy rods

    DOEpatents

    Verhoeven, John D.; McMasters, O. D.

    1989-07-18

    Magnetostrictive rods formed from rare earth-iron alloys are subjected to a short time heat treatment to increase their Magnetostrictive response under compression. The heat treatment is preferably carried out at a temperature of from 900.degree. to 1000.degree. C. for 20 minutes to six hours.

  14. Thermal treatment for increasing magnetostrictive response of rare earth-iron alloy rods

    DOEpatents

    Verhoeven, J.D.; McMasters, O.D.

    1989-07-18

    Magnetostrictive rods formed from rare earth-iron alloys are subjected to a short time heat treatment to increase their magnetostrictive response under compression. The heat treatment is preferably carried out at a temperature of from 900 to 1,000 C for 20 minutes to six hours.

  15. Influence of Be and Al on the magnetostrictive behavior of FeGa alloys

    SciTech Connect

    Mungsantisuk, Pinai; Corson, Robert P.; Guruswamy, Sivaraman

    2005-12-15

    The rare-earth-free body-centered-cubic FeGa-based alloys have an attractive combination of large low-field magnetostriction at room temperature, good mechanical properties, low hysteresis, and relatively low cost for use in sensor and actuator devices. This paper examines the influence of partially substituting Ga in FeGa alloys with Be and Al on their magnetostrictive behavior. Magnetic and magnetostrictive properties of the various ternary FeGaAl and FeGaBe alloys prepared by directional growth process are presented. It is shown that substitution of Ga with Al and Be can be made in FeGa alloys in certain composition ranges without a significant reduction in magnetostriction. Minimal reductions in magnetostriction when Ga is partially substituted by smaller Be or larger Al atoms in certain composition ranges indicate that local electronic environments are more important and that the effects of Ga and Be are additive.

  16. The effect of magnetic annealing on the magnetostriction for Sm-Dy-Fe rod alloys

    NASA Astrophysics Data System (ADS)

    Wang, Bowen; Wang, Zhihua; Weng, Ling; Huang, Wenmei; Sun, Ying; Cui, Baozhi

    2013-05-01

    The Sm0.86Dy0.14Fex (x = 1.85-2.05) magnetostrictive alloys have been prepared with arc-melting and then cast into a copper mold with a diameter of 8 mm. It is found that the magnetostriction (λ// - λ⊥) increases from -900 × 10-6 for untreated rod alloys to -1200 × 10-6 for magnetically annealed rod alloys at the magnetic field of 640 kA/m. In the magnetic annealing temperature range of 483-643 K, the magnetostriction value exhibits a peak at 543 K. The variation of magnetostriction and magnetization with magnetic fields has been determined and the mechanism of domains' movements has been discussed. This result is very important to improve the magnetostrictive property of Sm-Dy-Fe rod alloys.

  17. Influence of Be and Al on the magnetostrictive behavior of FeGa alloys

    NASA Astrophysics Data System (ADS)

    Mungsantisuk, Pinai; Corson, Robert P.; Guruswamy, Sivaraman

    2005-12-01

    The rare-earth-free body-centered-cubic FeGa-based alloys have an attractive combination of large low-field magnetostriction at room temperature, good mechanical properties, low hysteresis, and relatively low cost for use in sensor and actuator devices. This paper examines the influence of partially substituting Ga in FeGa alloys with Be and Al on their magnetostrictive behavior. Magnetic and magnetostrictive properties of the various ternary FeGaAl and FeGaBe alloys prepared by directional growth process are presented. It is shown that substitution of Ga with Al and Be can be made in FeGa alloys in certain composition ranges without a significant reduction in magnetostriction. Minimal reductions in magnetostriction when Ga is partially substituted by smaller Be or larger Al atoms in certain composition ranges indicate that local electronic environments are more important and that the effects of Ga and Be are additive.

  18. Giant Magnons Meet Giant Gravitons

    SciTech Connect

    Hofman, Diego M.

    2008-07-28

    We study the worldsheet reflection matrix of a string attached to a D-brane in AdS{sub 5}xS{sup 5}. The D-brane corresponds to a maximal giant graviton that wraps an S{sup 3} inside S{sup 5}. In the gauge theory, the open string is described by a spin chain with boundaries. We focus on open strings with a large SO(6) charge and define an asymptotic boundary reflection matrix. Using the symmetries of the problem, we review the computation of the boundary reflection matrix, up to a phase. We also discuss weak and strong coupling computations where we obtain the overall phase factor and test our exact results.

  19. Asymmetric torsion stress giant magnetoimpedance in nearly zero magnetostrictive amorphous wires

    NASA Astrophysics Data System (ADS)

    Blanco, J. M.; Zhukov, A.; Gonzalez, J.

    2000-05-01

    The effect of the torsion strain on the electrical impedance in (Co0.95Fe0.05)72.5Si12.5B15 amorphous wire has been investigated. The torsion stress impedance ratio, defined as (ΔZ/Z)ξ=[(Z(ξ)-Z(ξmax)]/Z(ξmax), has an asymmetric character with a broad maximum at around 20 rad/m. After Joule heating without torsion (ΔZ/Z)ξ has a tendency to achieve finally a sharp and nearly symmetric shape. Maximum changes of (ΔZ/Z)ξ, of 270% is obtained after optimal conditions of current annealing. Besides, GMI ratio, (ΔZ/Z)H=[(Z(H)-Z(Hmax)]/Z(Hmax) can be significantly improved too reaching 350% in the particular case of current annealing at 550 mA for 0.5 min. The asymmetry of the (ΔZ/Z)ξ in the as-cast state and after torsion annealing could be ascribed to the spontaneous or induced helical anisotropy.

  20. Design and Testing of a Dynamically-Tuned Magnetostrictive Spring with Electrically-Controlled Stiffness

    NASA Technical Reports Server (NTRS)

    Scheidler, Justin; Asnani, Vivake M.; Dapino, Marcelo J.

    2015-01-01

    This paper details the development of an electrically-controlled, variable-stiffness spring based on magnetostrictive materials. The device, termed a magnetostrictive Varispring, can be applied as a semi-active vibration isolator or switched stiffness vibration controller for reducing transmitted vibrations. The Varispring is designed using 1D linear models that consider the coupled electrical response, mechanically-induced magnetic diffusion, and the effect of internal mass on dynamic stiffness. Modeling results illustrate that a Terfenol-D-based Varispring has a rise time almost an order of magnitude smaller and a magnetic diffusion cut-off frequency over two orders of magnitude greater than a Galfenol-based Varispring. The results motivate the use of laminated Terfenol-D rods for a greater stiffness tuning range and increased bandwidth. The behavior of a prototype Varispring is examined under vibratory excitation up to 6 MPa and 25 Hz using a dynamic load frame. For this prototype, stiffness is indirectly varied by controlling the excitation current. Preliminary measurements of continuous stiffness tuning via sinusoidal currents up to 1 kHz are presented. The measurements demonstrate that the Young's modulus of the Terfenol-D rod inside the Varispring can be continuously varied by up to 21.9 GPa. The observed stiffness tuning range is relatively constant up to 500 Hz, but significantly decreases thereafter. The stiffness tuning range can be greatly increased by improving the current and force control such that a more consistent current can be applied and the Varispring can be accurately tested at a more optimal bias stress.

  1. Elastic and magnetostrictive properties of Tb{sub 6}Fe{sub 1-x}Co{sub x}Bi{sub 2} (0 {<=} x {<=} 0.375)

    SciTech Connect

    Koehler, Michael R.; Jia Lin; McCarthy, David; Keppens, Veerle; McGuire, Michael A.

    2011-04-01

    Elastic moduli and magnetostriction data are reported for polycrystalline Tb{sub 6}Fe{sub 1-x}Co{sub x}Bi{sub 2} (0 {<=} x {<=} 0.375). The elastic moduli c{sub 11} and c{sub 44} have been measured as a function of temperature (5-300 K) and magnetic field (0-5 T), and reflect the ferromagnetic transition observed in these materials around 250 K. A remarkable elastic softening, which is partially suppressed upon application of a magnetic field, is observed at low temperatures and is believed to be linked to a structural transition that takes place in the Co-doped samples. The soft elastic moduli lead to large magnetostriction below 50 K, reaching a value of 700 ppm at 20 kOe for Tb{sub 6}Fe{sub 0.75}Co{sub 0.25}Bi{sub 2}.

  2. Shape anisotropy in zero-magnetostrictive rapidly solidified amorphous nanowires

    NASA Astrophysics Data System (ADS)

    Rotărescu, C.; Atitoaie, A.; Stoleriu, L.; Óvári, T.-A.; Lupu, N.; Chiriac, H.

    2016-04-01

    The magnetic behavior of zero-magnetostrictive rapidly solidified amorphous nanowires has been investigated in order to understand their magnetic bistability. The study has been performed both experimentally - based on inductive hysteresis loop measurements - and theoretically, by means of micromagnetic simulations. Experimental hysteresis loops have shown that the amorphous nanowires display an axial magnetic bistability, characterized by a single-step magnetization reversal when the applied field reaches a critical value called switching field. The simulated loops allowed us to understand the effect of shape anisotropy on coercivity. The results are key for understanding and controlling the magnetization processes in these novel nanowires, with important application possibilities in new miniaturized sensing devices.

  3. Magnetostriction and ferroelectric state in AgCrS₂.

    PubMed

    Streltsov, Sergey V; Poteryaev, Alexander I; Rubtsov, Alexey N

    2015-04-29

    The band structure calculations in the GGA+U approximation show the presence of additional lattice distortions in the magnetically ordered phase of AgCrS2. The magnetostriction leads to the formation of long and short Cr-Cr bonds in the case when the respective Cr ions have the same or opposite spin projections. These changes in the Cr lattice are accompanied by distortions of the CrS6 octahedra, which in turn lead to the development of spontaneous electric polarization.

  4. Temperature dependence of the magnetostriction in polycrystalline PrFe{sub 1.9} and TbFe{sub 2} alloys: Experiment and theory

    SciTech Connect

    Tang, Y. M.; Chen, L. Y.; Huang, H. F.; Xia, W. B.; Zhang, S. Y.; Wei, J.; Tang, S. L. Du, Y. W.; Zhang, L.

    2014-05-07

    A remarkable magnetostriction λ{sub 111} as large as 6700 ppm was found at 70 K in PrFe{sub 1.9} alloy. This value is even larger than the theoretical maximum of 5600 ppm estimated by the Steven's equivalent operator method. The temperature dependence of λ{sub 111} for PrFe{sub 1.9} and TbFe{sub 2} alloys follows well with the single-ion theory rule, which yields giant estimated λ{sub 111} values of about 8000 and 4200 ppm for PrFe{sub 1.9} and TbFe{sub 2} alloys, respectively, at 0 K. The easy magnetization direction of PrFe{sub 1.9} changes from [111] to [100] as temperature decreases, which leads to the abnormal decrease of the magnetostriction λ. The rare earth sublattice moment increases sharply in PrFe{sub 1.9} alloy with decreasing temperature, resulting in the remarkably largest estimated value of λ{sub 111} at 0 K according to the single-ion theory.

  5. Dynamics, Bifurcations and Normal Forms in Arrays of Magnetostrictive Energy Harvesters with All-to-All Coupling

    NASA Astrophysics Data System (ADS)

    Matus-Vargas, Antonio; González-Hernandez, Hugo G.; Chan, Bernard S.; Palacios, Antonio; Buono, Pietro-Luciano; in, Visarath; Naik, Suketu; Phipps, Alex; Longhini, Patrick

    Modeling and bifurcation analysis of an energy harvesting system composed of coupled resonators using the Galfenol-based magnetostrictive material are presented. The analysis in this work should be broad enough to be applicable to a large class of vibratory-based energy harvesting systems since various types of vibratory harvesters share the same normal forms, e.g. magnetostrictive and piezoelectric materials. A combined model of the mechanical and electrical domains of a single energy harvester is discussed first. Building on this model, the governing equations of the coupled system are derived, leading to a system of differential equations with an all-to-all coupling between the resonators. A bifurcation analysis of the system equations reveals different patterns of collective oscillations. Among the many different patterns, a synchronous state exists and it is stable over a broad region of parameter space. This pattern has the potential to yield significant increases in power output and it will be used as a starting point to guide future experimental work. A Hamiltonian approach is employed to study analytically the nature of the bifurcations and to calculate an expression for the onset of synchronization valid for any number of harvesters.

  6. Transforming giants.

    PubMed

    Kanter, Rosabeth Moss

    2008-01-01

    Large corporations have long been seen as lumbering, inflexible, bureaucratic--and clueless about global developments. But recently some multinationals seem to be transforming themselves: They're engaging employees, moving quickly, and introducing innovations that show true connection with the world. Harvard Business School's Kanter ventured with a research team inside a dozen global giants--including IBM, Procter & Gamble, Omron, CEMEX, Cisco, and Banco Real--to discover what has been driving the change. After conducting more than 350 interviews on five continents, she and her colleagues came away with a strong sense that we are witnessing the dawn of a new model of corporate power: The coordination of actions and decisions on the front lines now appears to stem from widely shared values and a sturdy platform of common processes and technology, not from top-down decrees. In particular, the values that engage the passions of far-flung workforces stress openness, inclusion, and making the world a better place. Through this shift in what might be called their guidance systems, the companies have become as creative and nimble as much smaller ones, even while taking on social and environmental challenges of a scale that only large enterprises could attempt. IBM, for instance, has created a nonprofit partnership, World Community Grid, through which any organization or individual can donate unused computing power to research projects and see what is being done with the donation in real time. IBM has gained an inspiring showcase for its new technology, helped business partners connect with the company in a positive way, and offered individuals all over the globe the chance to contribute to something big.

  7. Giant Cell Arteritis

    MedlinePlus

    Giant cell arteritis is a disorder that causes inflammation of your arteries, usually in the scalp, neck, and arms. ... arteries, which keeps blood from flowing well. Giant cell arteritis often occurs with another disorder called polymyalgia ...

  8. Large magnetostriction in directionally solidified FeGa and FeGaAl alloys

    NASA Astrophysics Data System (ADS)

    Srisukhumbowornchai, N.; Guruswamy, S.

    2001-12-01

    The magnetostriction of Fe-x at. % Ga (x=15, 20, and 27.5) was measured, for alloys processed under different directional solidification conditions, and the effect of partial substitution of Ga with Al on the magnetostriction of the alloys was examined. Magnetostriction measurements were carried out at different prestress levels varying from 0 to 55 MPa. Ga additions in the range of 15-27.5 at. % Ga in Fe were found to improve the magnetostriction of the disordered bcc phase of Fe by as much as 1 order of magnitude. The applied fields for saturation magnetostriction and the hysteresis observed were small. Magnetostriction values as high as 271×10-6 were obtained in polycrystalline Fe-27.5 at. % Ga rods prepared using a directional growth (DG) process at a growth rate of 22.5 mm/h. This process, which is essentially a seedless vertical Bridgman technique, resulted in near [001] textured polycrystalline Fe-Ga alloys. The preferred [001] crystallographic orientation of the DG alloys was approximately 14° away from the rod direction. For Ga contents between 15 and 27.5 at. % in Fe, the Ga atoms increase the Fe-Fe spacing in the disordered bcc (A2) phase and reduce the magnetic moment of Fe. Substitution of Ga with Al has a significant effect on the magnetostriction of the Fe-Ga alloys. Small substitution of 5 at. % Al for Ga in the Fe-20 at. % Ga alloy increases the magnetostriction in Fe, and the value is slightly larger than that of the Fe-20 at. % Ga alloy. A higher substitution amount of Al tends to decrease the magnetostriction.

  9. Green Giants.

    ERIC Educational Resources Information Center

    Wright, Michaella; Maine, Bruce

    2001-01-01

    Explains how designing and constructing sustainable, environmentally friendly school buildings does not have to be a costly venture. Provides advice for selecting building materials, developing energy efficiency, and minimizing toxins. Reviews the status of national sustainable design standards. (GR)

  10. Giant impacts on giant planets

    NASA Astrophysics Data System (ADS)

    de Pater, Imke

    2013-10-01

    The 2009 impact and recent superbolides on Jupiter caught the world by surprise and cast doubt on impactor flux estimates for the outer solar system. Enhanced amateur planetary imaging techniques yield both high spatial resolution {enabling the 2009 impact debris field detection} and rapid frame rates {enabling the 2010/2012 impact flash detections and lightcurve measurements}.We propose a ToO program to image future impacts on Jupiter and Saturn. To remove the possibility of impact cloud non-detections, the program will be triggered only if an existing impact debris field is seen, an object on a collision course with Jupiter or Saturn is discovered, or an impact light curve is measured with an estimated total energy large enough to generate an impact cloud in a giant planet atmosphere {10^20 J}.HST provides the only way to image these events in the ultraviolet, providing information on aerosol altitudes and on smaller particles that are less visible to ground-based infrared observations. High-resolution imaging with proper timing {not achievable from the ground} is required to measure precisely both the velocity fields of impact sites and the optical spectrum of impact debris. HST observations of past impacts on Jupiter have also served both as cornerstones of science investigations at other wavelengths and as vehicles for effective public outreach.Large outer solar system impacts are governed by the same physics as in the terrestrial events that dominate the impact threat to humans. Studying the behavior of impactors of various sizes and compositions, as they enter the atmosphere at varying angles and speeds, will better quantify terrestrial impact hazards.

  11. Giant impacts on giant planets

    NASA Astrophysics Data System (ADS)

    de Pater, Imke

    2014-10-01

    The 2009 impact and recent superbolides on Jupiter caught the world by surprise and cast doubt on impactor flux estimates for the outer solar system. Enhanced amateur planetary imaging techniques yield both high spatial resolution (enabling the 2009 impact debris field detection) and rapid frame rates (enabling the 2010/2012 impact flash detections and lightcurve measurements).We propose a ToO program to image future impacts on Jupiter and Saturn. To remove the possibility of impact cloud non-detections, the program will be triggered only if an existing impact debris field is seen, an object on a collision course with Jupiter or Saturn is discovered, or an impact light curve is measured with an estimated total energy large enough to generate an impact cloud in a giant planet atmosphere (10^20 J).HST provides the only way to image these events in the ultraviolet, providing information on aerosol altitudes and on smaller particles that are less visible to ground-based infrared observations. High-resolution imaging with proper timing (not achievable from the ground) is required to measure precisely both the velocity fields of impact sites and the optical spectrum of impact debris. HST observations of past impacts on Jupiter have also served both as cornerstones of science investigations at other wavelengths and as vehicles for effective public outreach.Large outer solar system impacts are governed by the same physics as in the terrestrial events that dominate the impact threat to humans. Studying the behavior of impactors of various sizes and compositions, as they enter the atmosphere at varying angles and speeds, will better quantify terrestrial impact hazards.

  12. Giant impacts on giant planets

    NASA Astrophysics Data System (ADS)

    de Pater, Imke

    2012-10-01

    The 2009 impact on Jupiter caught the world by surprise and cast doubt on impactor flux estimates for the outer solar system. Enhanced amateur planetary imaging techniques yield both high spatial resolution {enabling the 2009 impact debris field detection} and rapid frame rates {enabling the 2010 impact flash detections and lightcurve measurements}.We propose a Target of Opportunity program to image future impacts on Jupiter and Saturn. To remove the possibility of impact cloud non-detections, the program will be triggered only if an existing impact debris field is seen, an object on a collision course with Jupiter or Saturn is discovered, or an impact light curve is measured with an estimated total energy large enough to generate an impact cloud in a giant planet atmosphere.HST provides the only way to image these events in the ultraviolet, providing information on aerosol altitudes and on smaller particles that are less visible to ground-based infrared observations. High-resolution imaging with proper timing {not achievable from the ground} is required to measure precisely both the velocity fields of impact sites and the optical spectrum of impact debris. HST observations of past impacts on Jupiter have also served both as cornerstones of science investigations at other wavelengths and as vehicles for effective public outreach.Large outer solar system impacts are governed by the same physics as in the terrestrial events that dominate the impact threat to humans. Studying the behavior of impactors of various sizes and compositions, as they enter the atmosphere at varying angles and speeds, will better quantify terrestrial impact hazards.

  13. Nano-magnetism of magnetostriction in Fe{sub 35}Co{sub 65}

    SciTech Connect

    Lisfi, A.; Ren, T.; Wuttig, M.; Khachaturyan, A.

    2014-03-03

    The nature of the large magnetostriction in body-centered Fe-based solid solutions has been widely discussed in the literature. Here, we use a combination of magnetostriction, magnetization, torque, and transmission electron microscopy measurements of specially annealed Co{sub 65}Fe{sub 35} to show that the magnetostriction is caused by coherent uniaxial nano-precipitates. We show further that these nano-precipitates lower the magnetocrystalline anisotropy in these alloys to K{sub 1} = −2.16 × 10{sup 4} J/m{sup 3}.

  14. Saturation and forced volume magnetostriction of Fe-rich FeZr amorphous alloys

    NASA Astrophysics Data System (ADS)

    Tange, H.; Tanaka, Y.; Goto, M.; Fukamichi, K.

    1989-10-01

    AC susceptibility, saturation and forced volume magnetostriction were studied on iron-rich zirconium amorphous alloys a-Fe 100- xZr x (8 at% ≤ x ≤ 12 at%). The experimental results are discussed in relation to the re-entrant spin glass state. It is found that the transverse magnetostriction accompanies a remarkable magnetic aftereffect in the spin glass phase, and that the forced volume magnetostriction shows an apparent peak at the ferromagnet to spin glass transition where the ac susceptibility has a cusp.

  15. Hysteresis modelling and experimental verification of a Fe–Ga alloy magnetostrictive actuator

    NASA Astrophysics Data System (ADS)

    Wei, Zhu; Lei Xiang, Bian; Gangli, Chen; Shuxin, Liu; Qinbo, Zhou; Xiaoting, Rui

    2017-03-01

    In order to accurately describe the asymmetric rate-bias-dependent hysteresis of a Fe–Ga alloy magnetostrictive actuator, a comprehensive model, which is composed of a phenomenon model, describing hysteresis by the modified Bouc–Wen hysteresis operator, and a theoretical model, representing the dynamics characteristics, is put forward. The experimental system is setup to verify the performance of the comprehensive model. Results show that the modified Bouc–Wen model can effectively describe the dynamics and hysteresis characteristics of the Fe–Ga alloy magnetostrictive actuator. The results highlight significantly improved accuracy in the modelling of the magnetostrictive actuator.

  16. Suppressing magneto-mechanical vibrations and noise in magnetostriction variation for three-phase power transformers

    NASA Astrophysics Data System (ADS)

    Hsu, Chang-Hung; Liu, Jui-Jung; Fu, Chao-Ming; Huang, Yi-Mei; Chang, Chia-Wen; Cheng, Shan-Jen

    2015-05-01

    This study investigated the effect of magnetostriction-induced core magnetomechanical vibrations and noise on the magnetic properties of power transformers. The magnetostriction of grain-oriented Si steels was found to be extremely sensitive to compressive stress applied along the rolling direction and to tensile stress applied along the transverse direction. The compressive stress increased the variation in the magnitude of magnetostriction, which is correlated with core vibration and noise. A 2D model of the power transformer was used to simulate the noise and vibration variables through a finite element analysis.

  17. The magnetostriction in a superconductor-magnet system under non-uniform magnetic field

    NASA Astrophysics Data System (ADS)

    Li, Xueyi; Jiang, Lang; Wu, Hao; Gao, Zhiwen

    2017-03-01

    This paper describes a numerical model to examine the magnetostriction of bulk high-temperature superconductor (HTS) under non-uniform magnetic field in conjunction with finite element analysis. Through this model, the magnetostriction of homogeneous and nonhomogeneous HTS can be implemented under non-uniform magnetic field. Further, the effects of critical current density, applied field frequency and amplitude are also considered. The computational study can provide a fundamental mechanistic understanding the effects of non-uniform magnetic field on magnetostriction of HTS.

  18. Magnetostrictive influence on the bistability of amorphous wires

    SciTech Connect

    Madurga, V.; Costa, J.L.; Inoue, A.; Rao, K.V. )

    1990-08-01

    We have studied the effect of tension and external field on the magnetization process in amorphous positive magnetostrictive Fe-Si-B wires. The radial stress created during the in-rotating water quenching technique of producing these wires causes a radial anisotropy. Using a simple phenomenological model which assumes a continuous distribution for the values of these radial stresses, we fit the observed values of the remanence as a function of the applied longitudinal stress and obtain information about the stress distribution. We also explain in a consistent manner the dependence of the magnetization process on the applied longitudinal stress. On doing so, a value of the saturation magnetostriction constant {lambda}{sub {ital s}}=28{times}10{sup {minus}6} is obtained for a Fe{sub 77.5}Si{sub 7.5}B{sub 15} amorphous wire. In the stress dependence of the nucleation field for the Barkhausen jump we observe a minimum. A quantitative explanation for this minimum is given.

  19. Dynamically tuned magnetostrictive spring with electrically controlled stiffness

    NASA Astrophysics Data System (ADS)

    Scheidler, Justin J.; Asnani, Vivake M.; Dapino, Marcelo J.

    2016-03-01

    This paper presents the design and testing of an electrically controllable magnetostrictive spring that has a dynamically tunable stiffness (i.e., a magnetostrictive Varispring). The device enables in situ stiffness tuning or stiffness switching for vibration control applications. Using a nonlinear electromechanical transducer model and an analytical solution of linear, mechanically induced magnetic diffusion, Terfenol-D is shown to have a faster rise time to stepped voltage inputs and a significantly higher magnetic diffusion cut-off frequency relative to Galfenol. A Varispring is manufactured using a laminated Terfenol-D rod. Further rise time reductions are achieved by minimizing the rod’s diameter and winding the electromagnet with larger wire. Dynamic tuning of the Varispring’s stiffness is investigated by measuring the Terfenol-D rod’s strain response to dynamic, compressive, axial forces in the presence of sinusoidal or square wave control currents. The Varispring’s rise time is \\lt 1 ms for 1 A current switches. Continuous modulus changes up to 21.9 GPa and 500 Hz and square wave modulus changes (dynamic {{Δ }}E effect) up to 12.3 GPa and 100 Hz are observed. Stiffness tunability and tuning bandwidth can be considerably increased by operating about a more optimal bias stress and improving the control of the electrical input.

  20. Displacement sensors using soft magnetostrictive alloys

    NASA Astrophysics Data System (ADS)

    Hristoforou, E.; Reilly, R. E.

    1994-09-01

    We report results on the response of a family of displacement sensors, which are based on the magentostrictive delay line (MDL) technique, using current conductors orthogonal to the MDL. Such sensing technique is based on the change of the magnetic circuit at the acoustic stress point of origin due to the displacement of a soft magnetic material above it. Integrated arrays of sensors can be obtained due to the acoustic delay line technique and they can be used as tactile arrays, digitizers or devices for medical applications (gait analysis etc.), while absence of hysteresis and low cost of manufacturing make them competent in this sector of sensor market.

  1. Effect of thermal deformation on giant magnetoresistance of flexible spin valves grown on polyvinylidene fluoride membranes

    NASA Astrophysics Data System (ADS)

    Luping, Liu; Qingfeng, Zhan; Xin, Rong; Huali, Yang; Yali, Xie; Xiaohua, Tan; Run-wei, Li

    2016-07-01

    We fabricated flexible spin valves on polyvinylidene fluoride (PVDF) membranes and investigated the influence of thermal deformation of substrates on the giant magnetoresistance (GMR) behaviors. The large magnetostrictive Fe81Ga19 (FeGa) alloy and the low magnetostrictive Fe19Ni81 (FeNi) alloy were selected as the free and pinned ferromagnetic layers. In addition, the exchange bias (EB) of the pinned layer was set along the different thermal deformation axes α 31 or α 32 of PVDF. The GMR ratio of the reference spin valves grown on Si intrinsically increases with lowering temperature due to an enhancement of spontaneous magnetization. For flexible spin valves, when decreasing temperature, the anisotropic thermal deformation of PVDF produces a uniaxial anisotropy along the α 32 direction, which changes the distribution of magnetic domains. As a result, the GMR ratio at low temperature for spin valves with EB∥ α 32 becomes close to that on Si, but for spin valves with EB∥ α 31 is far away from that on Si. This thermal effect on GMR behaviors is more significant when using magnetostrictive FeGa as the free layer. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374312, 51401230, 51522105, and 51471101) and the Ningbo Science and Technology Innovation Team, China (Grant No. 2015B11001).

  2. Experimental study and analytical model of deformation of magnetostrictive films as applied to mirrors for x-ray space telescopes.

    PubMed

    Wang, Xiaoli; Knapp, Peter; Vaynman, S; Graham, M E; Cao, Jian; Ulmer, M P

    2014-09-20

    The desire for continuously gaining new knowledge in astronomy has pushed the frontier of engineering methods to deliver lighter, thinner, higher quality mirrors at an affordable cost for use in an x-ray observatory. To address these needs, we have been investigating the application of magnetic smart materials (MSMs) deposited as a thin film on mirror substrates. MSMs have some interesting properties that make the application of MSMs to mirror substrates a promising solution for making the next generation of x-ray telescopes. Due to the ability to hold a shape with an impressed permanent magnetic field, MSMs have the potential to be the method used to make light weight, affordable x-ray telescope mirrors. This paper presents the experimental setup for measuring the deformation of the magnetostrictive bimorph specimens under an applied magnetic field, and the analytical and numerical analysis of the deformation. As a first step in the development of tools to predict deflections, we deposited Terfenol-D on the glass substrates. We then made measurements that were compared with the results from the analytical and numerical analysis. The surface profiles of thin-film specimens were measured under an external magnetic field with white light interferometry (WLI). The analytical model provides good predictions of film deformation behavior under various magnetic field strengths. This work establishes a solid foundation for further research to analyze the full three-dimensional deformation behavior of magnetostrictive thin films.

  3. Q-switched all-fiber laser based on magnetostriction modulation of a Bragg grating.

    PubMed

    Pérez-Millán, P; Díez, A; Andrés, M; Zalvidea, D; Duchowicz, R

    2005-06-27

    We report an actively Q-switched all-fiber laser based on magnetostriction modulation of a Bragg grating. The laser employs a pair of Bragg gratings as reflective mirrors, one of which is bonded to a magnetostrictive element. Lengthening of the magnetostrictive element when a magnetic field is applied shifts the Bragg wavelength of the grating, allowing control of the Q-factor of the cavity and, thus, performing active Q-switching. The magnetostrictive modulator is small, compact and requires less than 300 mW electrical drive power. Using erbium-doped fiber and a maximum pump power of 120 mW, Q-switch pulses of more than 1 W peak power were obtained, with a pulse repetition rate that can be continuously varied from 1 Hz to 125 kHz.

  4. Controllable magnetic and magnetostrictive properties of FeGa films electrodeposited on curvature substrates

    NASA Astrophysics Data System (ADS)

    Cao, Derang; Wang, Zhenkun; Pan, Lining; Feng, Hongmei; Cheng, Xiaohong; Zhu, Zengtai; Wang, Jianbo; Liu, Qingfang; Han, Genliang

    2016-11-01

    Magnetic properties of magnetostrictive FeGa films deposited by electrodeposition method on flexible curvature substrates were investigated under various mechanical stresses. The stresses of the bowed substrates were realized by series of different concentric circles. FeGa films exhibit a significant uniaxial magnetic anisotropy after the application of tensile or compressive stress, and the anisotropy of the film can be regulated by the residual stress. In addition, the magnetostriction of FeGa films is estimated through approximate calculation, indicating that the saturation magnetostrictive constant of films is enhanced with the increased tensile and compressive strains. These results provide another way to tune the magnetic properties and magnetostriction of flexible thin films, which is particularly important for the development of the flexible magneto-electronic devices.

  5. Large magnetostriction and structural characteristics of Fe83Ga17 wires

    NASA Astrophysics Data System (ADS)

    Li, J. H.; Gao, X. X.; Xie, J. X.; Zhu, J.; Bao, X. Q.; Yu, R. B.

    2012-04-01

    The columnar-grained structure induced by directional solidification was beneficial to improve the deformability of Fe83Ga17 alloy. Fe83Ga17 wires with diameter of 0.5∼0.9 mm were prepared successfully by hot rotary swaging and warm drawing from the directional solidified rods. The magnetostriction and microstructure of the as-drawn and the annealed Fe83Ga17 wires with diameter of 0.6 mm were investigated. Results demonstrated that the magnetostriction of Fe83Ga17 wires depended on the microstructure and the fiber texture, which were controlled by heat treatment process. The maximum magnetostriction of 160 ppm was detected in the annealed wire, which has the ideal <100> fiber texture. The phase mixture of A2 containing heterogeneous modified-DO3 phase has beneficial effect on magnetostriction.

  6. The compressive stress effect on the magnetostriction and magnetization for Sm-Dy-Fe composites

    NASA Astrophysics Data System (ADS)

    Wang, Bowen; Wang, Zhihua; Hao, Yanming; Weng, Ling; Huang, Wenmei; Yan, Weili

    2012-04-01

    Sm0.88Dy0.12Fe2 rod composites were fabricated under a compaction pressure of 800 MPa along the rod direction and in a magnetic field of 200 kA/m along the direction, perpendicular to the rod axis. It is found that the magnetostriction λ|| parallel to the rod direction is almost unchanged with increasing the compressive stress up to 20 MPa and shows a large unsaturated magnetostriction value of -620 × 10-6 at 600 kA/m. The magnetostriction λ⊥ perpendicular to rod axis increases with increasing the compressive stress when the magnetic field is larger than 300 kA/m. The variation of the magnetostriction and magnetization with compressive stress has been discussed. This result is very important to application of Sm-Dy-Fe composites.

  7. Development of phage/antibody immobilized magnetostrictive biosensors

    NASA Astrophysics Data System (ADS)

    Fu, Liling

    There is an urgent need for biosensors that are able to detect and quantify the presence of a small amount of pathogens in a real-time manner accurately and quickly to guide prevention efforts and assay food and water quality. Acoustic wave (AW) devices, whose performance is defined by mass sensitivity (Sm) and quality factor (Q value), have been extensively studied as high performance biosensor platforms. However, current AW devices still face some challenges such as the difficulty to be employed in liquid and low Q value in practical applications. The objective of this research is to develop magnetostrictive sensors which include milli/microcantilever type (MSMC) and particle type (MSP). Compared to other AW devices, MSMC exhibits the following advantages: (1) wireless/remote driving and sensing; (2) easy to fabricate; (3) works well in liquid; (4) exhibits a high Q value (> 500 in air). The fundamental study of the damping effect on MSMCs from the surrounding media including air and liquids were conducted to improve the Q value of MSMCs. The experiment results show that the Q value is dependent on the properties of surrounding media (e.g. viscosity, density), the geometry of the MSMCs, and the harmonic mode on the resonance behavior of MSMCs, etc. The phage-coated MSMC has high specificity and sensitivity even while used in water with a low concentration of targeted bacteria. Two currently developed phages, JRB7 and E2, respectively respond to Bacillus anthracis spores and Salmonella typhimurium, were employed as bio-recognition elements in this research. The phage-immobilized MSMC biosensors exhibited high performance and detection of limit was 5 x 104 cfu/ml for the MSMC in size of 1.4 x 0.8 x 0.035 mm. The MSMC-based biosensors were indicated as a very potential method for in-situ monitoring of the biological quality in water. The MSP combine antibody was used to detect Staphylococcus aureus in this experiment. The interface between MSPs and antibody was

  8. Influence of ordering phenomena on the magnetostriction of high Si alloys for electrical applications

    SciTech Connect

    Ros-Yanez, Tanya; Ruiz, Daniel; Lopez, Diego; Hilgert, Tom; Dupre, Luc; Vandenberghe, Robert E.; Houbaert, Yvan

    2005-05-15

    The present work attempts to assess the influence of order phenomena on the magnetostriction of high Fe-Si alloys for electrical applications. The magnetostriction of high silicon electrical steels in the range of 4 to 6 wt. % Si was studied regarding the effect of processing and thermal treatment. In addition, power losses and saturation magnetization measurements were performed and {sup 57}Fe Moessbauer spectroscopy was used to evaluate and quantify the degree of order.

  9. Method of increasing magnetostrictive response of rare earth-iron alloy rods

    DOEpatents

    Verhoeven, J.D.; McMasters, O.D.; Gibson, E.D.; Ostenson, J.E.; Finnemore, D.K.

    1989-04-04

    This invention comprises a method of increasing the magnetostrictive response of rare earth-iron (RFe) magnetostrictive alloy rods by a thermal-magnetic treatment. The rod is heated to a temperature above its Curie temperature, viz. from 400 to 600 C; and, while the rod is at that temperature, a magnetic field is directionally applied and maintained while the rod is cooled, at least below its Curie temperature. 2 figs.

  10. Method of increasing magnetostrictive response of rare earth-iron alloy rods

    DOEpatents

    Verhoeven, John D.; McMasters, O. Dale; Gibson, Edwin D.; Ostenson, Jerome E.; Finnemore, Douglas K.

    1989-04-04

    This invention comprises a method of increasing the magnetostrictive response of rare earth-iron (RFe) magnetostrictive alloy rods by a thermal-magnetic treatment. The rod is heated to a temperature above its Curie temperature, viz. from 400.degree. to 600.degree. C.; and, while the rod is at that temperature, a magnetic field is directionally applied and maintained while the rod is cooled, at least below its Curie temperature.

  11. The Electric Giant Resonances

    NASA Astrophysics Data System (ADS)

    van der Woude, A.

    The following sections are included: * Introduction * Experimental Methods to Study Giant Resonances * Introduction * The Tools * Introduction * Tools for Isoscalar Scattering * INELASTIC α-SCATTERING * INELASTIC PROTON SCATTERING * Tools for Isovector Excitations * γ-ABSORPTION AND PARTICLE CAPTURE REACTIONS * CHARGE EXCHANGE REACTIONS - THE (π+, π0) REACTION * Tools For Isoscalar And Isovector Excitations * INELASTIC ELECTRON SCATTERING * GIANT RESONANCE EXCITATION BY FAST HEAVY IONS * From Multipole Cross Section To Multipole Strength * The Electric Isoscalar Resonances * The Isoscalar Giant Monopole Resonance * Systematics on the GMR * Compressibility and the Giant Monopole Resonance * Introduction * The Compressibility of nuclear matter from the GMR energies * Discussion * The Isoscalar Giant Quadrupole Resonance * General Trends In Medium-Heavy and Heavy Nuclei * The GQR In Light Nuclei * The Isoscalar 3- Strength, LEOR and HEOR * Isoscalar 4+ Strength * Miscellaneous; Isoscalar 1- and L > 4-Strength * The Electric Isovector Giant Resonances * The Isovector Giant Dipole Resonance: GDR * The Isovector Giant Monopole Resonances: IVGMR * The Isovector Quadrupole Resonance: IVGQR * The Effect of Ground State Deformation on the Shape of Giant Resonance: Microscopic Picture * Giant Resonances Built on Excited States * Introduction * Capture Reactions on Light Nuclei * Statistical decay of GDR γ Emission in Heavy Compound Systems * Introduction * Theoretical Predictions * Some Experimental Results * Summary and Outlook * Acknowledgements * General References * References

  12. Effects of stress on the magnetostriction of 2% Mn pipeline steel

    SciTech Connect

    Makar, J.M.; Atherton, D.L. . Dept. of Physics)

    1994-07-01

    The effects of varying the order of the application of stress and a demagnetization procedure on the magnetostrictive behavior of a 2% Mn pipeline steel sample are studied and compared to the predictions of recent theory. Plots of magnetostriction versus both magnetic field and magnetization are given. Significant differences were found in the behavior of the magnetostrictive initial curve when the sample was both demagnetized and the measurements made under a constant stress as compared to the results when the sample was demagnetized and then stressed. Tension was also found to decrease the range and the hysteresis of the sample's saturation major magnetostrictive loops, while compression had the opposite effect. This behavior appeared to be independent of whether the stress was applied before or after the demagnetization process, and was found to be due to changes in magnetostriction at low magnetization values. Comparison of the sample's magnetostrictive behavior of theory showed that only some of the features seen experimentally were correctly predicted by theory.

  13. Saturation and forced volume magnetostrictions of Fe-rich FeZr and FeNiZr amorphous alloys

    NASA Astrophysics Data System (ADS)

    Tange, H.; Kamimori, T.; Goto, M.; Fukamichi, K.

    1990-12-01

    The saturation and forced volume magnetostrictions, ac susceptibility have been investigated for Fe 90Zr 10 and Fe 90-xNi xZr 10 amorphous alloys. The linear magnetostriction in the re-entrant spin glass state exhibits a hysteresis due to a remarkable magnetic after effect. The temperature dependence of the forced volume magnetostriction shows a peak at the spin freezing temperature.

  14. Fully coupled, dynamic model of a magnetostrictive amorphous ribbon and its validation

    SciTech Connect

    Bergmair, Bernhard Huber, Thomas; Bruckner, Florian; Vogler, Christoph; Fuger, Markus; Suess, Dieter

    2014-01-14

    Magnetostrictive amorphous ribbons are widely used in electronic article surveillance as well as for magnetoelastic sensors. Both applications utilize the fact that the ribbons' resonant frequency can be read out remotely by applying external magnetic AC fields. This paper proposes a magnetomechanical model to simulate the dynamics of such ribbons. The goal was to only use general material properties as input parameters, which are usually denoted in the data sheet of amorphous metals. Thus, only the magnetization curve at zero stress has to be gained via measurement. The magnetization under stress is calculated thereof. The equation of motion for a longitudinally oscillating ribbon is derived and coupled to Maxwell's equations for magnetostatics. The fully coupled initial value problem is solved simultaneously by a finite difference approach. The model is validated by comparing calculated and measured resonant frequencies of various amorphous ribbons, which turned out to be in good agreement. When slightly adapting single material properties from the data sheet, the match is almost perfect. The model is then used to calculate the local magnetic and mechanical properties inside static and vibrating ribbons. These local distributions can be directly linked to the field dependence of the resonant frequency and its higher harmonics.

  15. Nonlinear Optimal Control of Plate Structures Using Magnetostrictive Actuators

    DTIC Science & Technology

    2005-01-01

    Hamiltonian , and λ(t) ∈ lR2Nω is a set of Lagrange multipliers. The Hamiltonian is, H(y, λ, u, t) = L(y, u, t) + λT f(y, u, t) = 1 2 [ yT (t)Qy(t...uT (t)Ru(t) ] + λT f(y, u, t) (13) where the Lagrangian L includes the penalities on the states and inputs through the semi-definite maxtrix Q and the...magnetostrictive transducers,” EDGE Technologies, Inc. Ames, IA. [6] F.T. Calkins , R.C. Smith, and A.B. Flatau, “An energy-based hysteresis model for

  16. Ab initio studies of the effect of nanoclusters on magnetostriction of Fe1-xGax alloys

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Zhang, Y. N.; Yang, Teng; Zhang, Z. D.; Sun, L. Z.; Wu, R. Q.

    2010-12-01

    Using the density functional calculations, we investigated the effect of nanoprecipitation on the magnetostriction of Fe1-xGax alloys. While the B2-like FeGa clusters undergo slight tetragonal distortion, D03-like FeGa clusters remain cubic in the Fe matrix. Moreover, we found that B2-like nanostructures produce negative magnetostriction, whereas D03-like nanostructures give small positive magnetostriction in the hypothetical inhomogeneous structures. Therefore, the formation of nanoscale precipitates cannot be the reason for the extraordinary enhancement of magnetostriction of Fe1-xGax alloys.

  17. Giant strain with ultra-low hysteresis and high temperature stability in grain oriented lead-free K₀̣₅Bi₀̣₅TiO₃-BaTiO₃-Na₀̣₅Bi₀̣₅TiO₃ piezoelectric materials

    DOE PAGES

    Maurya, Deepam; Zhou, Yuan; Wang, Yaojin; ...

    2015-02-26

    We synthesized grain-oriented lead-free piezoelectric materials in (K₀̣₅Bi₀̣₅TiO₃-BaTiO₃-xNa₀̣₅Bi₀̣₅TiO₃ (KBT-BT-NBT) system with high degree of texturing along the [001]c (c-cubic) crystallographic orientation. We demonstrate giant field induced strain (~0.48%) with an ultra-low hysteresis along with enhanced piezoelectric response (d₃₃ ~ 190pC/N) and high temperature stability (~160°C). Transmission electron microscopy (TEM) and piezoresponse force microscopy (PFM) results demonstrate smaller size highly ordered domain structure in grain-oriented specimen relative to the conventional polycrystalline ceramics. The grain oriented specimens exhibited a high degree of non-180° domain switching, in comparison to the randomly axed ones. These results indicate the effective solution to the lead-free piezoelectricmore » materials.« less

  18. Fate of a giant {Mo72Fe30}-type polyoxometalate cluster in an aqueous solution at higher temperature: understanding related Keplerate chemistry, from molecule to material.

    PubMed

    Mekala, Raju; Supriya, Sabbani; Das, Samar K

    2013-09-03

    When the giant icosahedral {Mo72Fe30} cluster containing compound [Mo72Fe30O252(CH3COO)12{Mo2O7(H2O)}2{H2Mo2O8(H2O)}(H2O)91]·150H2O (1) is refluxed in water for 36 h, it results in the formation of nanoiron molybdate, Fe2(MoO4)3, in the form of a yellow precipitate; this simple approach not only generates nanoferric molybdate at a moderate temperature but also helps to understand the stability of {Mo72Fe30} in terms of the linker-pentagon complementary relationship.

  19. Critical Behavior of Thermal Expansion and Magnetostriction in the Vicinity of the First order transition at the Curie Point of Gd5(SixGe1-x)4

    SciTech Connect

    Han, Mangui

    2004-01-01

    Thermal expansion (TE) and magnetostriction (MS) measurements have been conducted for Gd5(SixGe1-x)4 with a series of x values to study its critical behavior in the vicinity of transition temperatures. It was found that the Curie temperature of Gd5(SixGe1-x)4 for x 0 ~ 0.5 is dependent on magnetic field, direction of change of temperature (Tc on cooling was lower than Tc on heating), purity of Gd starting material, compositions, material preparation methods, and also can be triggered by the external magnetic field with a different dT/dB rate for different x values. For Gd5(Si1.95Ge2.05), Gd5(Si2Ge2), Gd5(Si2.09Ge1.91), it was also found that the transition is a first order magneto-structural transition, which means the magnetic transition and crystalline structure transition occur simultaneously, and completely reversible. Temperature hysteresis and phase coexistence have been found to confirm that it is a first order transformation. While for Gd5(Si0.15Ge3.85), it is partially reversible at some temperature range between the antiferromagnetic and the ferromagnetic state. For Gd5(Si2.3Ge1.7) and Gd5(Si3Ge1), it was a second order transformation between the paramagnetic and ferromagnetic state, because no ΔT have been found. Giant magnetostriction was only found on Gd5(Si1.95Ge2.05), Gd5(Si2Ge2), Gd5(Si2.09Ge1.91) in their vicinity of first order transformation. MFM images have also been taken on polycrystal sample Gd5(Si2.09Ge1.91) to investigate the transformation process. The results also indicates that the Curie temperature was lower and the thermally

  20. The Giant Magnetocaloric Effect

    NASA Astrophysics Data System (ADS)

    Pecharsky, Vitalij K.

    1998-03-01

    Since the discovery of the magnetocaloric effect in pure iron by E.Warburg in 1881, it has been measured experimentally on many magnetic metals and compounds. The majority of the materials studied order magnetically undergoing a second order phase transformation. The magnetocaloric effect, typically peaking near the Curie or the Néel temperature, generally ranges from 0.5 to 2 K (in terms of adiabatic temperature change) or at 1 to 4 J/kg K (in terms of isothermal magnetic entropy change) per 1 T magnetic field change. The giant magnetocaloric effect recently discovered in Gd_5(Si_xGe_1-x)4 alloys, where x <= 0.5, is associated with a first order magnetic phase transition and it reaches values of 3 to 4 K and 6 to 10 J/kg K per 1 T field change, respectively. The refrigerant capacity, which is the measure of how much heat can be transferred from a cold to a hot reservoir in one ideal thermodynamic cycle, is larger than that of the best second order phase transition materials by 25 to 100%. When the Gd_5(Si_xGe_1-x)4 alloys are compared with other known materials, which show first order magnetic phase transition, such as Dy, Ho, Er, HoCo_2, NdMn_2Si_2, Fe_0.49Rh_0.51, and (Hf_0.83Ta_0.17)Fe_2+x, only Fe_0.49Rh_0.51 has comparable magnetocaloric properties. However, the first order magnetic phase transition in Fe_0.49Rh_0.51 is irreversible, and the magnetocaloric effect disappears after one magnetizing/demagnetizing cycle. A study of the crystal structure, thermodynamics, and magnetism of the Gd_5(Si_xGe_1-x)4 alloys, where 0 <= x <= 1 allowed us to obtain a qualitative understanding of the basic relations between the composition, the crystal structure, and the change in thermodynamics and magnetocaloric properties, which occur in the Gd_5(Si_xGe_1-x)4 system, and which brings about the giant magnetocaloric effect when x <= 0.5.

  1. Magnetostrictive gradient in Tb0.27Dy0.73Fe1.95 induced by high magnetic field gradient applied during solidification

    NASA Astrophysics Data System (ADS)

    Gao, Pengfei; Liu, Tie; Dong, Meng; Yuan, Yi; Wang, Kai; Wang, Qiang

    2016-09-01

    We investigated how high magnetic field gradients affected the magnetostrictive performance of Tb0.27Dy0.73Fe1.95 during solidification. At high applied magnetic field gradients, the magnetostriction exhibited a gradient distribution throughout the alloy. Increasing the magnetic field gradient also increased the magnetostriction gradient. We attributed the graded magnetostrictive performance to the gradient distribution of (Tb, Dy)Fe2 phase in the alloy and its orientation.

  2. Magnetic tunnel junction on a magnetostrictive substrate: An ultrasensitive magnetic-field sensor

    NASA Astrophysics Data System (ADS)

    Pertsev, N. A.

    2016-09-01

    The concept of a magnetic tunnel junction (MTJ) fabricated on an active substrate made of a highly magnetostrictive ferromagnetic material is described theoretically. It is shown that, under certain conditions, such hybrid device exhibits strongly enhanced sensitivity of the tunnel current to the external magnetic field. This feature results from the field-induced substrate deformations, which create lattice strains in the MTJ due to the interfacial mechanical interaction. If the free electrode of MTJ is made of a cubic ferromagnet like Co40Fe60 having strong magnetoelastic coupling between the magnetization and strains, the field-induced magnetization reorientation here may be enhanced by the strain effect drastically. This reorientation should lead to a change in the junction's electrical conductance because the magnetization of the reference electrode may be pinned by adjacent antiferromagnetic layer to keep its initial direction. Taking into account additional strain effects on the height and width of the tunnel barrier and the effective mass of tunneling electrons, we performed numerical calculations of the conductance magnetosensitivity for the CoFe/MgO/CoFeB junctions mechanically coupled to the FeGaB film grown on Si and found that such hybrid device is promising as an ultrasensitive room-temperature magnetic-field sensor.

  3. Wide operation frequency band magnetostrictive vibration power generator using nonlinear spring constant by permanent magnet

    NASA Astrophysics Data System (ADS)

    Furumachi, S.; Ueno, T.

    2016-04-01

    We study magnetostrictive vibration based power generator using iron-gallium alloy (Galfenol). The generator is advantages over conventional, such as piezoelectric material in the point of high efficiency highly robust and low electrical impedance. Generally, the generator exhibits maximum power when its resonant frequency matches the frequency of ambient vibration. In other words, the mismatch of these frequencies results in significant decrease of the output. One solution is making the spring characteristics nonlinear using magnetic force, which distorts the resonant peak toward higher or lower frequency side. In this paper, vibrational generator consisting of Galfenol plate of 6 by 0.5 by 13 mm wound with coil and U shape-frame accompanied with plates and pair of permanent magnets was investigated. The experimental results show that lean of resonant peak appears attributed on the non-linear spring characteristics, and half bandwidth with magnets is 1.2 times larger than that without. It was also demonstrated that the addition of proof mass is effective to increase the sensitivity but also the bandwidth. The generator with generating power of sub mW order is useful for power source of wireless heath monitoring for bridge and factory machine.

  4. Thermal expansion and magnetostriction of pure doped RAgSb2 (R = Y, Sm, La) single crystals

    SciTech Connect

    Bud'ko, S.; Law, S.; Canfield, P.; Samolyuk, G.; Torikachvili, M.; Schmiedeshoff, G.

    2008-02-20

    Data on temperature-dependent, anisotropic thermal expansion in pure and doped RAgSb{sub 2} (R = Y, Sm, La) single crystals are presented. Using the Ehrenfest relation and heat capacity measurements, uniaxial pressure derivatives for long range magnetic ordering and charge density wave transition temperatures are evaluated and compared with the results of the direct measurements under hydrostatic pressure. In-plane and c-axis pressure have opposite effects on the phase transitions in these materials, with in-plane effects being significantly weaker. Quantum oscillations in magnetostriction were observed for the three pure compounds, with the possible detection of new frequencies in SmAgSb{sub 2} and LaAgSb{sub 2}. The uniaxial (along the c-axis) pressure derivatives of the dominant extreme orbits ({beta}) were evaluated for YAgSb{sub 2} and LaAgSb{sub 2}.

  5. Thermal expansion and magnetostriction of pure and doped RAgSb(2) (R = Y, Sm, La) single crystals.

    PubMed

    Bud'ko, S L; Law, S A; Canfield, P C; Samolyuk, G D; Torikachvili, M S; Schmiedeshoff, G M

    2008-03-19

    Data on temperature-dependent, anisotropic thermal expansion in pure and doped RAgSb(2) (R = Y, Sm, La) single crystals are presented. Using the Ehrenfest relation and heat capacity measurements, uniaxial pressure derivatives for long range magnetic ordering and charge density wave transition temperatures are evaluated and compared with the results of the direct measurements under hydrostatic pressure. In-plane and c-axis pressure have opposite effects on the phase transitions in these materials, with in-plane effects being significantly weaker. Quantum oscillations in magnetostriction were observed for the three pure compounds, with the possible detection of new frequencies in SmAgSb(2) and LaAgSb(2). The uniaxial (along the c-axis) pressure derivatives of the dominant extreme orbits (β) were evaluated for YAgSb(2) and LaAgSb(2).

  6. Inverse-magnetostriction-induced switching current reduction of STT-MTJs and its application for low-voltage MRAM

    NASA Astrophysics Data System (ADS)

    Takamura, Yota; Shuto, Yusuke; Yamamoto, Shu'uichiro; Funakubo, Hiroshi; Kurosawa, Minoru Kuribayashi; Nakagawa, Shigeki; Sugahara, Satoshi

    2017-02-01

    A new spin-transfer torque (STT) magnetic tunnel junction (MTJ) using an inverse magnetostriction (IMS) material for the free layer is proposed for low-voltage MRAMs. The MTJ is surrounded by a piezoelectric gate structure so that a pressure for introducing the IMS effect can efficiently be applied to the free layer without any high-yield-strength support structure. During STT-induced magnetization switching, the energy barrier height for the switching can be lowered by the IMS effect, and thus a critical current density (JC) for the magnetization switching can dramatically be reduced. Energy performance of a low-voltage STT-MRAM cell using the proposed MTJ and a FinFET is also demonstrated.

  7. Exotic Earths: forming habitable worlds with giant planet migration.

    PubMed

    Raymond, Sean N; Mandell, Avi M; Sigurdsson, Steinn

    2006-09-08

    Close-in giant planets (e.g., "hot Jupiters") are thought to form far from their host stars and migrate inward, through the terrestrial planet zone, via torques with a massive gaseous disk. Here we simulate terrestrial planet growth during and after giant planet migration. Several-Earth-mass planets also form interior to the migrating jovian planet, analogous to recently discovered "hot Earths." Very-water-rich, Earth-mass planets form from surviving material outside the giant planet's orbit, often in the habitable zone and with low orbital eccentricities. More than a third of the known systems of giant planets may harbor Earth-like planets.

  8. Spin-phonon and magnetostriction phenomena in CaMn{sub 7}O{sub 12} helimagnet probed by Raman spectroscopy

    SciTech Connect

    Nonato, A.; Araujo, B. S.; Ayala, A. P.; Maciel, A. P.; Yanez-Vilar, S.; Sanchez-Andujar, M.; Senaris-Rodriguez, M. A.; Paschoal, C. W. A.

    2014-12-01

    In this letter, we investigated the temperature-dependent Raman spectra of CaMn{sub 7}O{sub 12} helimagnet from room temperature down to 10 K. The temperature dependence of the Raman mode parameters shows remarkable anomalies for both antiferromagnetic and incommensurate transitions that this compound undergoes at low temperatures. The anomalies observed at the magnetic ordering transition indicate a spin-phonon coupling at higher-temperature magnetic transition in this material, while a magnetostriction effect at the lower-temperature magnetic transition.

  9. Formation of Giant Planets and Brown Dwarves

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    2003-01-01

    According to the prevailing core instability model, giant planets begin their growth by the accumulation of small solid bodies, as do terrestrial planets. However, unlike terrestrial planets, the growing giant planet cores become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. Models predict that rocky planets should form in orbit about most stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large enough to gravitationally trap substantial quantities of gas. Ongoing theoretical modeling of accretion of giant planet atmospheres, as well as observations of protoplanetary disks, will help decide this issue. Observations of extrasolar planets around main sequence stars can only provide a lower limit on giant planet formation frequency . This is because after giant planets form, gravitational interactions with material within the protoplanetary disk may cause them to migrat inwards and be lost to the central star. The core instability model can only produce planets greater than a few jovian masses within protoplanetary disks that are more viscous than most such disks are believed to be. Thus, few brown dwarves (objects massive enough to undergo substantial deuterium fusion, estimated to occur above approximately 13 jovian masses) are likely to be formed in this manner. Most brown dwarves, as well as an unknown number of free-floating objects of planetary mass, are probably formed as are stars, by the collapse of extended gas/dust clouds into more compact objects.

  10. Inverse effect of morphotropic phase boundary on the magnetostriction of ferromagnetic Tb1-xGdxCo2

    NASA Astrophysics Data System (ADS)

    Zhou, Chao; Ren, Shuai; Bao, Huixin; Yang, Sen; Yao, Yonggang; Ji, Yuanchao; Ren, Xiaobing; Matsushita, Yoshitaka; Katsuya, Yoshio; Tanaka, Masahiko; Kobayashi, Keisuke

    2014-03-01

    The morphotropic phase boundary (MPB) has been utilized extensively in ferroelectrics and recently has attracted interest in ferromagnets [S. Yang, H. Bao, C. Zhou, Y. Wang, X. Ren, Y. Matsushita, Y. Katsuya, M. Tanaka, K. Kobayashi, X. Song, and J. Gao, Phys. Rev. Lett. 104, 197201 (2010), 10.1103/PhysRevLett.104.197201; R. Bergstrom, M. Wuttig, J. Cullen, P. Zavalij, R. Briber, C. Dennis, V. O. Garlea, and M. Laver, Phys. Rev. Lett. 111, 017203 (2013), 10.1103/PhysRevLett.111.017203] for obtaining enhanced large field-induced strain. Here we report that the MPB can also lead to weakening (the inverse effect as compared to the known MPB materials) of field-induced strain, as exhibited in the Tb1-xGdxCo2 system. With synchrotron x-ray diffractometry, the structure symmetry of TbCo2-rich compositions is detected to be rhombohedral below TC and that of GdCo2-rich compositions is tetragonal. The MPB composition Tb0.1Gd0.9Co2, corresponding to the two phases (rhombohedral and tetragonal) of coexistence, shows the exotic minimum (near zero) magnetostriction as well as the largest magnetic susceptibility among all samples. Further analysis suggests that whether MPB can enhance or weaken magnetostriction is determined by the degree of magnetic ordering of two end members that form ferromagnetic MPBs, which was not considered previously. Our work not only reveals a new type of ferromagnetic MPB, but also provides a new recipe for designing functional high-susceptibility and low-strain magnetic materials.

  11. Magnetostrictive Fe73Ga27 nanocontacts for low-field conductance switching

    NASA Astrophysics Data System (ADS)

    Kannan, U. M.; Kuntz, S.; Berg, O.; Kittler, W.; Basumatary, H.; Arout Chelvane, J.; Sürgers, C.; Narayana Jammalamadaka, S.

    2016-06-01

    The electrical conductance G of magnetostrictive nanocontacts made from Galfenol (Fe73Ga27) can be reproducibly switched between "on" and "off" states in a low magnetic field of ˜20-30 mT at 10 K. The switching behavior is in agreement with the magnetic field dependence of the magnetostriction inferred from the magnetization behavior, causing a positive magnetostrictive strain along the magnetic field. The repeated magnetic-field cycling leads to a stable contact geometry and to a robust contact configuration with a very low hysteresis of ˜1 mT between opening and closing the contact due to a training effect. Non-integral multiples of the conductance quantum G0 observed for G > G0 are attributed to electron backscattering at defect sites in the electrodes near the contact interface. When the contact is closed either mechanically or by magnetic field, the conductance shows an exponential behavior below G0 due to electron tunneling. This allows to estimate the magnetostriction λ = 4 × 10-5 at 10 K. The results demonstrate that such magnetostrictive devices are suitable for the remote control of the conductance by low magnetic fields in future nanotechnology applications.

  12. Studies of magnetostriction and spin polarized band structures of rare earth intermetallics

    NASA Technical Reports Server (NTRS)

    Wallace, W. E.

    1979-01-01

    Anisotropic magnetostriction measurements of R6Fe23, R = (Tb, Dy, Ho, and Er) were carried out from 77 K to room temperature. Magnetic fields up to 2.1 Tesla were applied. All the compounds exhibited large magnetostrictions at 77 K, the largest effect being obtained for Tb6Fe23. Saturation magnetostriction values for the compounds were also determined for 77 K and room temperature. Results of the temperature dependence of magnetostriction for Er6Fe23 are in good agreement with Callen and Callen's single ion theory. Therefore, the main sources of magnetostriction in this compound is the Er ion. The spin-up and spin-down electronic energy bands, the density of states and the magnetic moments of YCo5, SmCo5, and GdCo5 were calculated by the spin polarized augmented plane wave technique. The calculations obtained show the origin of the moment, provide good estimates of its magnitude and variation, and the reasons for those variations. They also show the important role of partial charge transfer and of d-d electronic coupling. Calculations for LaNi5 and GdNi5 systems are discussed.

  13. Short range ordering and magnetostriction in Fe-Ga and other Fe alloy single crystals

    NASA Astrophysics Data System (ADS)

    Guruswamy, Sivaraman; Jayaraman, Tanjore V.; Corson, Robert P.; Garside, Gavin; Thuanboon, Swieng

    2008-12-01

    The magnetostrictive behaviors of Fe-Ga, Fe-Mo, Fe-W, and other Fe alloys have been observed to be sensitive to their thermal history. In this work, the changes in the structure with thermal history and how they correlate with the observed magnetostriction values in Fe-Ga, Fe-W, and Fe-Mo single crystals are examined. Single crystals were grown using the vertical Bridgman crystal growth technique. The magnetostriction constant (3/2)λ100 measured in (i) as-grown and air-cooled (DG) and (ii) annealed and water quenched single crystal samples of Fe-Ga and Fe-W alloys clearly indicate that annealing in the α-phase region followed by rapid quenching improves the magnetostriction values. High-resolution x-ray diffraction (XRD) studies on [100]-oriented Fe-Ga as well as other Fe alloy single crystals show (i) a diffuse scattering peak indicative of short range ordering, the extent of which depends on composition and thermal history, and (ii) (200) peak splitting and broadening indicative of the presence of long range ordered coherent second phases and associated coherency strains. A detailed examination of the XRD patterns suggests that the changes in magnetostriction with composition and thermal history are related to the local strain modulations associated with the solutes, short range order, long range ordered coherent second phases, incoherent precipitates, and other structural defects.

  14. Epitaxial photostriction-magnetostriction coupled self-assembled nanostructures.

    PubMed

    Liu, Heng-Jui; Chen, Long-Yi; He, Qing; Liang, Chen-Wei; Chen, Yu-Ze; Chien, Yung-Shun; Hsieh, Ying-Hui; Lin, Su-Jien; Arenholz, Elke; Luo, Chih-Wei; Chueh, Yu-Lun; Chen, Yi-Chun; Chu, Ying-Hao

    2012-08-28

    Self-assembled vertical nanostructures take advantage of high interface-to-volume ratio and can be used to design new functionalities by the choice of a proper combination of constituents. However, most of the studies to date have emphasized the functional controllability of the nanostructures using external electric or magnetic fields. In this study, to introduce light (or photons) as an external control parameter in a self-assembled nanostructure system, we have successfully synthesized oxide nanostructures with CoFe(2)O(4) nanopillars embedded in a SrRuO(3) matrix. The combination of photostrictive SrRuO(3) and magnetostrictive CoFe(2)O(4) in the intimately assembled nanostructures leads to a light-induced, ultrafast change in magnetization of the CoFe(2)O(4) nanopillars. Our work demonstrates a novel concept on oxide nanostructure design and opens an alternative pathway for the explorations of diverse functionalities in heteroepitaxial self-assembled oxide nanostructures.

  15. Magnetostrictive and structural properties of FeCoGa films

    SciTech Connect

    Jen, S. U.; Chi, W. L.; Tsai, T. L.; Kuo, P. C.; Cheng, W. C.

    2010-01-15

    Fe{sub 81-x}Co{sub x}Ga{sub 19} (with x ranging from 0 to 19 at. % Co) films were made by the dc magnetron sputtering method. We have studied the structural (phases, texturing, and grain size D), magnetic (saturation magnetostriction {lambda}{sub S} and coercivity H{sub C}), mechanical (Young's modulus E{sub f} and hardness H{sub f}), and electrical (electrical resistivity {rho}) properties of these films. The main results are as follows: (i) all the films are (110) textured; (ii) the bct phase (with twinned grains) coexists with the bcc phase only in the case of x{<=}3 at. % Co; (iii) {lambda}{sub S} increases steadily from 42 to 86 ppm, as x increases from 0 to 19 at. % Co; and (iv) {rho} reaches the saturation limit, about 200 {mu}{Omega} cm, when 19{>=}x{>=}15 at. % Co. In conclusion, we report that the Fe{sub 62}Co{sub 19}Ga{sub 19} film has the optimal magnetic, mechanical, and electrical properties among all the FeCoGa films measured.

  16. Tunnel Magnetoresistance Sensors with Magnetostrictive Electrodes: Strain Sensors.

    PubMed

    Tavassolizadeh, Ali; Rott, Karsten; Meier, Tobias; Quandt, Eckhard; Hölscher, Hendrik; Reiss, Günter; Meyners, Dirk

    2016-11-11

    Magnetostrictive tunnel magnetoresistance (TMR) sensors pose a bright perspective in micro- and nano-scale strain sensing technology. The behavior of TMR sensors under mechanical stress as well as their sensitivity to the applied stress depends on the magnetization configuration of magnetic tunnel junctions (MTJ)s with respect to the stress axis. Here, we propose a configuration resulting in an inverse effect on the tunnel resistance by tensile and compressive stresses. Numerical simulations, based on a modified Stoner-Wohlfarth (SW) model, are performed in order to understand the magnetization reversal of the sense layer and to find out the optimum bias magnetic field required for high strain sensitivity. At a bias field of -3.2 kA/m under a 0.2 × 10 - 3 strain, gauge factors of 2294 and -311 are calculated under tensile and compressive stresses, respectively. Modeling results are investigated experimentally on a round junction with a diameter of 30 ± 0.2 μ m using a four-point bending apparatus. The measured field and strain loops exhibit nearly the same trends as the calculated ones. Also, the gauge factors are in the same range. The junction exhibits gauge factors of 2150 ± 30 and -260 for tensile and compressive stresses, respectively, under a -3.2 kA/m bias magnetic field. The agreement of the experimental and modeling results approves the proposed configuration for high sensitivity and ability to detect both tensile and compressive stresses by a single TMR sensor.

  17. Unstable giant gravitons

    SciTech Connect

    Mello Koch, Robert de; Ives, Norman; Smolic, Jelena; Smolic, Milena

    2006-03-15

    We find giant graviton solutions in Frolov's three parameter generalization of the Lunin-Maldacena background. The background we study has {gamma}-tilde{sub 1}=0 and {gamma}-tilde{sub 2}={gamma}-tilde{sub 3}={gamma}-tilde. This class of backgrounds provides a nonsupersymmetric example of the gauge theory/gravity correspondence that can be tested quantitatively, as recently shown by Frolov, Roiban, and Tseytlin. The giant graviton solutions we find have a greater energy than the point gravitons, making them unstable states. Despite this, we find striking quantitative agreement between the gauge theory and gravity descriptions of open strings attached to the giant.

  18. Magnetostriction and magnetism of rare earth intermetallic compounds: First principle study

    SciTech Connect

    Gavrilenko, V. I.; Wu, R. Q.

    2001-06-01

    Magnetism and magnetostriction of rare earth intermetallic compounds, GdCo{sub 2}, GdFe{sub 2}, NdCo{sub 2}, SmCo{sub 2}, and ErCo{sub 2}, have been studied by using the first principles full-potential linearized augmented plane-wave method with the generalized gradient approximation. The calculated magnetostriction coefficients agree well with experiment. The itinerant electrons of transition metal elements are found to play a significant role in magnetoelastic coupling. The strong anisotropy of magnetostriction in GdCo{sub 2} is explained. Contributions due to spatial anisotropic charge distribution of the incomplete 4f shells are calculated and discussed. {copyright} 2001 American Institute of Physics.

  19. Large Barkhausen discontinuities in Co-based amorphous wires with negative magnetostriction

    SciTech Connect

    Yamasaki, J.; Humphrey, F.B.; Mohri, K.; Kawamura, H.; Takamure, H.; Maelmhaell, R.

    1988-04-15

    Magnetic properties, such as domain patterns and anisotropy, were measured for negative magnetostrictive Co-Si-B amorphous wires exhibiting large Barkhausen discontinuities and the results are compared to those of Fe-Si-B wires with positive magnetostriction. The Co-based wire was found to have a bamboolike domain structure at the wire surface. It was also shown that the amorphous wires prepared by the in-water quenching technique store tensile stress in the radial direction. The magnetostrictive anisotropy due to residual stress will produce an axial component of magnetization in conjunction with the two-dimensional geometry of wires making both Co- and Fe-based wires exhibit large Barkhausen discontinuities along the axis of the wire.

  20. Voltage induced magnetostrictive switching of nanomagnets: Strain assisted strain transfer torque random access memory

    SciTech Connect

    Khan, Asif Nikonov, Dmitri E.; Manipatruni, Sasikanth; Ghani, Tahir; Young, Ian A.

    2014-06-30

    A spintronic device, called the “strain assisted spin transfer torque (STT) random access memory (RAM),” is proposed by combining the magnetostriction effect and the spin transfer torque effect which can result in a dramatic improvement in the energy dissipation relative to a conventional STT-RAM. Magnetization switching in the device which is a piezoelectric-ferromagnetic heterostructure via the combined magnetostriction and STT effect is simulated by solving the Landau-Lifshitz-Gilbert equation incorporating the influence of thermal noise. The simulations show that, in such a device, each of these two mechanisms (magnetostriction and spin transfer torque) provides in a 90° rotation of the magnetization leading a deterministic 180° switching with a critical current significantly smaller than that required for spin torque alone. Such a scheme is an attractive option for writing magnetic RAM cells.

  1. Crystal growth of high magnetostrictive polycrystalline Fe 81Ga 19 alloys

    NASA Astrophysics Data System (ADS)

    Li, Chuan; Liu, Jinghua; Wang, Zhibin; Jiang, Chengbao

    2012-03-01

    High magnetostrictive Fe81Ga19 alloy was prepared by induction heating zone melting method. The microstructure, solute partition behaviour, orientation evolution and magnetostriction are investigated. During the crystal growth process, the initial small grains gradually grow into large columnar crystals, and the solid-liquid interface shows slightly concave morphology. The equilibrium solute partition coefficient (k0), effective solute partition coefficient (ke) and solution diffusion coefficient (D) are calculated to be 0.74, 0.76 and 1.04×10-9 m2/s, respectively. In the steady growth stage, the composition distribution of the FeGa rod is uniform with average level about 18.50 at% Ga, which is close to the nominal composition. The deviation of the <001> orientation from the axial direction evolves from about 8° to 3° along the growth direction, and the corresponding magnetostriction increases from the initial 180 ppm to the final 305 ppm.

  2. Ultra sensitive magnetic sensors integrating the giant magnetoelectric effect with advanced microelectronics

    NASA Astrophysics Data System (ADS)

    Fang, Zhao

    This dissertation investigates approaches to enhance the performance, especially the sensitivity and signal to noise ratio of magnetoelectric sensors, which exploits the magnetoelectric coupling in magnetostrictive and piezoelectric laminate composites. A magnetic sensor is a system or device that can measure the magnitude of a magnetic field or each of its vector components. Usually the techniques encompass many aspects of physics and electronics. The common technologies used for magnetic field sensing include induction coil sensors, fluxgate, SQUID (superconducting quantum interference device), Hall effect, giant magnetoresistance, magnetostrictive/piezoelectric composites, and MEMS (microelectromechanical systems)-based magnetic sensors. Magnetic sensors have found a broad range of applications for many decades. For example, ultra sensitive magnetic sensors are able to detect tiny magnetic fields produced outside the brain by the neuronal currents which can be used for diagnostic application. Measuring the brain's magnetic field is extremely challenging because they are so weak, have strengths of 0.1--1 pT and thus requiring magnetic sensors with sub-picotesla sensitivity. In fact, to date, these measurements can only performed with the most sensitive magnetic sensors, i.e., SQUID. However, such detectors need expensive and cumbersome cryogenics to operate. Additionally, the thermal insulation of the sensors prevents them from being placed very closed to the tissues under study, thereby preventing high-resolution measurement capability. All of these severely limit their broad usage and proliferation for biomedical imaging, diagnosis, and research. A novel ultra-sensitive magnetic sensor capable of operating at room temperature is investigated in this thesis. Magnetoelectric effect is a material phenomenon featuring the interchange between the magnetic and electric energies or signals. The large ME effect observed in ME composites, especially the ME laminates

  3. Sharp Goss texture and magnetostriction in binary Fe81Ga19 sheets

    NASA Astrophysics Data System (ADS)

    He, Zhenghua; Sha, Yuhui; Fu, Quan; Lei, Fan; Jin, Bokai; Zhang, Fang; Zuo, Liang

    2016-11-01

    Goss ({110}<001>) texture development and magnetostriction in binary Fe81Ga19 sheet were investigated. Millimeters-sized Goss grains, covering 80% area of the annealed sheet surface, are produced by secondary recrystallization without effects of inhibitor and surface energy. The micro-texture analysis demonstrates that primarily recrystallized Goss grains have an evident advantage in size and number to be potential secondary nuclei. The grain size distribution of primary Goss grains can induce the continuable abnormal growth until the completion of secondary recrystallization. The obtained magnetostriction coefficient is close to those with the help of inhibitor or surface energy.

  4. Large Barkhausen effect and Matteucci effect in cold-drawn and torsion annealed amorphous magnetostrictive wires

    SciTech Connect

    Kawamura, H.; Mohri, K.; Yamasaki, J.; Ogasawara, I. )

    1988-07-01

    Amorphous magnetostrictive wires fabricated by super-rapid quenching in water exhibit a remarkably stable Barkhausen effect and Matteucci effect in the as-prepared state. The Matteucci effect in as-prepared wire is under 1 mV. When the wire is drawn or made shorter than 70 mm, the Barkhausen effect vanishes. In this work, the amorphous magnetostrictive wire was cold drawn and then annealed under torsional stress; the wires obtained had a large Matteucci effect, as well as a large Barkhausen effect even when as short as 25 mm. These wires were used as devices for pulse generation. Their magnetic properties are studied.

  5. Uniformity of direct and converse magnetoelectric effects in magnetostrictive-piezoelectric composites

    NASA Astrophysics Data System (ADS)

    Liu, Guoxi; Dong, Shuxiang

    2014-09-01

    In this paper, we theoretically and experimentally confirmed the uniformity of magnetoelectric (ME) coupling coefficients for the direct and converse ME (DME and CME) effects in longitudinal-transverse (L-T) mode magnetostrictive-piezoelectric two-phase composites, both at low frequencies and in the electromechanical resonance region. We also discussed the flaws in previous measurements of the ME coupling coefficients, which led to misunderstandings in the uniformity between the DME and CME effects. Our current work provided a correct method to correctly understand ME coupling in magnetostrictive-piezoelectric two-phase composites.

  6. Single sheet tester having open magnetic path for measurement of magnetostriction of electrical steel sheet

    SciTech Connect

    Nakase, Tomoya; Nakano, Masanori; Fujiwara, Koji; Takahashi, Norio

    1999-09-01

    A single sheet tester having closed magnetic path (a closed type of SST) has a problem that measurement accuracy of magnetostriction is considerably affected by electromagnetic force between specimen and yoke. Therefore, an open type has been developed. In order to get uniform flux distribution in sufficiently large region, a compensating magnetizing winding is installed, and a method of waveform control is investigated, in which applied voltages to main and compensating windings are adjusted individually. The effectiveness of the newly developed open type is demonstrated by measuring magnetostrictions of thin amorphous sheet as well as highly grain-oriented silicon steel sheet.

  7. Coagulation sensors based on magnetostrictive delay lines for biomedical and chemical engineering applications

    NASA Astrophysics Data System (ADS)

    Maliaritsi, E.; Zoumpoulakis, L.; Simitzis, J.; Vassiliou, P.; Hristoforou, E.

    2006-04-01

    Coagulation sensors based on the magnetostrictive delay line technique are presented in this paper. They are based on magnetostrictive ribbons and are used for measuring the coagulation, curing or solidification time of different liquids. Experimental results indicate that the presented sensing elements can determine the blood coagulation with remarkable repeatability, thus allowing their use as blood coagulation sensors. Additionally, results indicate that they can also measure curing time of resins, solidification of fluids and coagulation of chemical substances, therefore allowing their implementation in chemical engineering applications.

  8. The Next Giant Step

    NASA Video Gallery

    Artist Robert McCall painted "The Next Giant Step" in 1979 to commemorate the heroism and courage of spaceflight pioneers. Located in the lobby of Johnson's building 2, the mural depicts America's ...

  9. The Giant Cell.

    ERIC Educational Resources Information Center

    Stockdale, Dennis

    1998-01-01

    Provides directions for the construction of giant plastic cells, including details for building and installing the organelles. Also contains instructions for preparing the ribosomes, nucleolus, nucleus, and mitochondria. (DDR)

  10. EDITORIAL: Materially speaking!

    NASA Astrophysics Data System (ADS)

    Cornwall, Malcolm G.

    1997-05-01

    areas of physics-based science and technology. Can materials science be made intellectually more exciting and mind-stretching for our students? In this special issue we present several articles by researchers in less-than-familiar but important areas of materials science and technology. Following a review by Mathew Philip of some of the basic atomic theory which underlies materials science, Jose Silva looks at how artificial diamonds can be made and at how we can apply this exotic material (other than on fingers and around necks). Alan Piercy reviews the field of giant magnetostrictive materials, which, when magnetized, change dimensions hundreds or even thousands of times more than traditional ferromagnetics. David Pettifor provides a nicely interdisciplinary overview of how computer simulations, from the subatomic to the macroscopic level, can be used to help in the design of new materials for such things as turbine blades. Adrian Rennie offers a much-requested written version of the entertaining 1995/6 IOP Schools Lecture on the physics of polymers. (We had hoped to include an article by Professor Colin Gough of Birmingham University on High Temperatue Superconductors, but for technical reasons this has had to be postponed until a future issue.) Finally, there are two articles describing an initiative which will have a direct practical impact on the teaching and learning of `Materials' in the UK. Karen Davies describes the exciting new Materials Gallery due to be opened at the Science Museum as this issue goes to press in May 1997 (no coincidence!), and David Sang provides details of how the new gallery has been linked directly with the GNVQ curriculum, and can certainly be exploited more widely in our physics and technology teaching. Perhaps this can help provide the missing 'zing' that materials science at present seems to lack.

  11. Tunnel Magnetoresistance Sensors with Magnetostrictive Electrodes: Strain Sensors

    PubMed Central

    Tavassolizadeh, Ali; Rott, Karsten; Meier, Tobias; Quandt, Eckhard; Hölscher, Hendrik; Reiss, Günter; Meyners, Dirk

    2016-01-01

    Magnetostrictive tunnel magnetoresistance (TMR) sensors pose a bright perspective in micro- and nano-scale strain sensing technology. The behavior of TMR sensors under mechanical stress as well as their sensitivity to the applied stress depends on the magnetization configuration of magnetic tunnel junctions (MTJ)s with respect to the stress axis. Here, we propose a configuration resulting in an inverse effect on the tunnel resistance by tensile and compressive stresses. Numerical simulations, based on a modified Stoner–Wohlfarth (SW) model, are performed in order to understand the magnetization reversal of the sense layer and to find out the optimum bias magnetic field required for high strain sensitivity. At a bias field of −3.2 kA/m under a 0.2×10-3 strain, gauge factors of 2294 and −311 are calculated under tensile and compressive stresses, respectively. Modeling results are investigated experimentally on a round junction with a diameter of 30±0.2μm using a four-point bending apparatus. The measured field and strain loops exhibit nearly the same trends as the calculated ones. Also, the gauge factors are in the same range. The junction exhibits gauge factors of 2150±30 and −260 for tensile and compressive stresses, respectively, under a −3.2 kA/m bias magnetic field. The agreement of the experimental and modeling results approves the proposed configuration for high sensitivity and ability to detect both tensile and compressive stresses by a single TMR sensor. PMID:27845708

  12. Combining large magnetostriction and large magnetostrictive susceptibility in TbFeCo/Y{sub x}Fe{sub 1-x} exchange-spring-type multilayers

    SciTech Connect

    Huong Giang, D.T.; Duc, N.H.; Thuc, V.N.; Vu, L.V.; Chau, N.

    2004-08-30

    An approach to obtain both large magnetostriction and large magnetostrictive susceptibility is developed. It is applied to sputtered {l_brace}Tb(Fe{sub 0.55}Co{sub 0.45}){sub 1.5}/(Y{sub x}Fe{sub 1-x}){r_brace} (x=0, 0.1 and 0.2) multilayers. In the as-deposited samples, the TbFeCo layers are in the amorphous state, but the microstructure of the Y{sub x}Fe{sub 1-x} layers is not the same: A crystalline state is observed in pure Fe layers (x=0), whereas body-centered-cubic-Fe nanocrystals coexist within an YFe amorphous matrix in Y{sub 0.1}Fe{sub 0.9} layers. A parallel magnetostrictive susceptibility {chi}{sub {lambda}}{sub parallel} as large as 29.4x10{sup -2} T{sup -1}, which is almost half of that (79.6x10{sup -2} T{sup -1}) of the Metglas 2605SC was obtained for x=0.1. This is attributed to the exchange coupling between sandwiched TbFeCo layers and nanostructured YFe layers.

  13. Role of nanoscale precipitates on the enhanced magnetostriction of heat-treated galfenol (Fe1-xGax) alloys.

    PubMed

    Cao, H; Gehring, P M; Devreugd, C P; Rodriguez-Rivera, J A; Li, J; Viehland, D

    2009-03-27

    We report neutron diffuse scattering measurements on highly magnetostrictive Fe1-xGax alloys (0.14magnetostriction and exhibits asymmetric peaks at the (100) and (300) reciprocal lattice positions that are consistent with the coexistence of short-range ordered, coherent nanometer-scale precipitates embedded in a long-range ordered, body-centered cubic matrix. A large peak splitting is observed at (300) for x=0.19, which indicates that the nanoprecipitates are not cubic and have a large elastic strain. This implies a structural origin for the enhanced magnetostriction.

  14. Novel quantum criticality in CeRu2Si2 near absolute zero observed by thermal expansion and magnetostriction.

    PubMed

    Yoshida, J; Abe, S; Takahashi, D; Segawa, Y; Komai, Y; Tsujii, H; Matsumoto, K; Suzuki, H; Onuki, Y

    2008-12-19

    We report linear thermal expansion and magnetostriction measurements for CeRu2Si2 in magnetic fields up to 52.6 mT and at temperatures down to 1 mK. At high temperatures, this compound showed Landau-Fermi-liquid behavior: The linear thermal expansion coefficient and the magnetostriction coefficient were proportional to the temperature and magnetic field, respectively. In contrast, a pronounced non-Fermi-liquid effect was found below 50 mK. The negative contribution of thermal expansion and magnetostriction suggests the existence of an additional quantum critical point.

  15. Circumferential phased array of shear-horizontal wave magnetostrictive patch transducers for pipe inspection.

    PubMed

    Kim, Hoe Woong; Lee, Joo Kyung; Kim, Yoon Young

    2013-02-01

    Several investigations report effective uses of magnetostrictive patch transducers to generate and measure longitudinal and torsional guided waves in a pipe. They can be used to form a phased array for the circumferential inspection of pipes. Although there are circumferential phased arrays employing piezoelectric transducers or EMAT's, no magnetostrictive patch transducer based array system has been attempted. In this investigation, we aim to develop a circumferential phased magnetostrictive patch transducer (PMPT) array that can focus shear-horizontal waves at any target point on a cylindrical surface of a pipe. For the development, a specific configuration of a PMPT array employing six magnetostrictive patch transducers is proposed. A wave simulation model is also developed to determine time delays and amplitudes of signals generated by the transducers of the array. This model should be able to predict accurately the angular profiles of shear-horizontal waves generated by the transducers. For wave focusing, the time reversal idea will be utilized. The wave focusing ability of the developed PMPT array is tested with multiple-crack detection experiments. Imaging of localized surface inspection regions is also attempted by using wave signals measured by the developed PMPT array system.

  16. Magnetostriction Measured by Holographic Interferometry with the Simple and Inexpensive "Arrowhead" Setup

    ERIC Educational Resources Information Center

    Ladera, Celso L.; Donoso, Guillermo; Contreras, Johnny H.

    2012-01-01

    Double-exposure holographic interferometry is applied to measure the "linear" or "longitudinal" magnetostriction constant of a soft-ferrite rod. This high-accuracy measurement is done indirectly, by measuring the small rotations of a lever in contact with the rod using double-exposure holographic interferometry implemented with a robust…

  17. Electrodeposition and characterization of magnetostrictive galfenol (FeGa) thin films for use in microelectromechanical systems

    NASA Astrophysics Data System (ADS)

    Estrine, Eliot C.; Robbins, William P.; Maqableh, Mazin M.; Stadler, Bethanie J. H.

    2013-05-01

    In this paper, we investigate the challenges related to electrodeposition and characterization of magnetostrictive galfenol thin films as well as techniques used to overcome these issues. Successful deposition and evaluation of galfenol thin films is necessary for the design of galfenol based microelectromechanical devices. Stress is a primary concern because thick films and poor adhesion to substrates (e.g., silicon oxide) can lead to delamination and peeling. In addition, magnetostriction measurements require films that are uniform in thickness and composition over the sample area. Various adhesion layers were tested, and delamination was eliminated with Cr/Cu, which provided robust adhesion to the glass substrates used in capacitance bridge measurements. Uniformity and composition were controlled by the use of a rotating disk electrode for electrodeposition, which created a uniform boundary condition across the sample during deposition. The capacitance bridge technique was calibrated with Ni/glass samples, after which a magnetostriction of 140 ppm was measured for Fe83Ga17 films. These results represent the first magnetostriction measurements of electrodeposited galfenol.

  18. Ultrasonic IR thermographic inspection of graphite epoxy composite: a comparative study of piezoelectric and magnetostrictive stimulation

    NASA Astrophysics Data System (ADS)

    Swiderski, W.; Vavilov, V.

    2015-03-01

    In this paper the experimental results of piezoelectric and magnetostrictive ultrasonic stimulation are comparatively analyzed in the evaluation of impact damage in a graphite epoxy composite sample chosen for a round robin test. By comparing theoretical and experimental results, it is shown that the equivalent power of internal friction can reach some hundreds mill watt per a single crack.

  19. Giant congenital melanocytic nevus*

    PubMed Central

    Viana, Ana Carolina Leite; Gontijo, Bernardo; Bittencourt, Flávia Vasques

    2013-01-01

    Giant congenital melanocytic nevus is usually defined as a melanocytic lesion present at birth that will reach a diameter ≥ 20 cm in adulthood. Its incidence is estimated in <1:20,000 newborns. Despite its rarity, this lesion is important because it may associate with severe complications such as malignant melanoma, affect the central nervous system (neurocutaneous melanosis), and have major psychosocial impact on the patient and his family due to its unsightly appearance. Giant congenital melanocytic nevus generally presents as a brown lesion, with flat or mammilated surface, well-demarcated borders and hypertrichosis. Congenital melanocytic nevus is primarily a clinical diagnosis. However, congenital nevi are histologically distinguished from acquired nevi mainly by their larger size, the spread of the nevus cells to the deep layers of the skin and by their more varied architecture and morphology. Although giant congenital melanocytic nevus is recognized as a risk factor for the development of melanoma, the precise magnitude of this risk is still controversial. The estimated lifetime risk of developing melanoma varies from 5 to 10%. On account of these uncertainties and the size of the lesions, the management of giant congenital melanocytic nevus needs individualization. Treatment may include surgical and non-surgical procedures, psychological intervention and/or clinical follow-up, with special attention to changes in color, texture or on the surface of the lesion. The only absolute indication for surgery in giant congenital melanocytic nevus is the development of a malignant neoplasm on the lesion. PMID:24474093

  20. Giant congenital melanocytic nevus.

    PubMed

    Viana, Ana Carolina Leite; Gontijo, Bernardo; Bittencourt, Flávia Vasques

    2013-01-01

    Giant congenital melanocytic nevus is usually defined as a melanocytic lesion present at birth that will reach a diameter ≥ 20 cm in adulthood. Its incidence is estimated in <1:20,000 newborns. Despite its rarity, this lesion is important because it may associate with severe complications such as malignant melanoma, affect the central nervous system (neurocutaneous melanosis), and have major psychosocial impact on the patient and his family due to its unsightly appearance. Giant congenital melanocytic nevus generally presents as a brown lesion, with flat or mammilated surface, well-demarcated borders and hypertrichosis. Congenital melanocytic nevus is primarily a clinical diagnosis. However, congenital nevi are histologically distinguished from acquired nevi mainly by their larger size, the spread of the nevus cells to the deep layers of the skin and by their more varied architecture and morphology. Although giant congenital melanocytic nevus is recognized as a risk factor for the development of melanoma, the precise magnitude of this risk is still controversial. The estimated lifetime risk of developing melanoma varies from 5 to 10%. On account of these uncertainties and the size of the lesions, the management of giant congenital melanocytic nevus needs individualization. Treatment may include surgical and non-surgical procedures, psychological intervention and/or clinical follow-up, with special attention to changes in color, texture or on the surface of the lesion. The only absolute indication for surgery in giant congenital melanocytic nevus is the development of a malignant neoplasm on the lesion.

  1. Strong anisotropy and magnetostriction in the two-dimensional Stoner ferromagnet Fe3GeTe2

    DOE PAGES

    Zhuang, Houlong L.; Kent, P. R. C.; Hennig, Richard G.

    2016-04-06

    Comore » mputationally characterizing magnetic properies of novel two-dimensional (2D) materials serves as an important first step of exploring possible applications. Using density-functional theory, we show that single-layer Fe3GeTe2 is a potential 2D material with sufficiently low formation energy to be synthesized by mechanical exfoliation from the bulk phase with a van der Waals layered structure. In addition, we calculated the phonon dispersion demonstrating that single-layer Fe3GeTe2is dynamically stable. Furthermore, we find that similar to the bulk phase, 2D Fe3GeTe2 exhibits amagnetic moment that originates from a Stoner instability. In contrast to other 2D materials, we find that single-layer Fe3GeTe2 exhibits a significant uniaxial magnetocrystalline anisotropy energy of 920μ eV per Fe atom originating from spin-orbit coupling. In conclusion, we show that applying biaxial tensile strains enhances the anisotropy energy, which reveals strong magnetostriction in single-layer Fe3GeTe2 with a sizable magneostrictive coefficient. Our results indicate that single-layer Fe3GeTe2 is potentially useful for magnetic storage applications.« less

  2. Magnetostrictive properties of the heavy-rare-earth-free Sm1-xNdxFe2 compounds

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Ren, W. J.; Yang, Y. H.; Li, B.; Li, J.; Zhang, Z. D.

    2013-04-01

    In this work, we report the magnetostrictive properties of Sm1-xNdxFe2 compounds, which are free of (expensive) heavy rare earths. Anomalies are observed in the temperature dependence of both the magnetization and the magnetostriction of these compounds, which are ascribed to spin-reorientation transitions. At low fields, the quasi-static magnetostriction and the piezomagnetic coefficient d33 of Sm0.88Nd0.12Fe2 are larger than those of SmFe2, which is due to the compensation of the anisotropy of the Sm3+ and Nd3+ ions. At a magnetic-field strength of 6 kOe, the static magnetostriction of Sm0.88Nd0.12Fe2 is -1244 ppm at 225 K and -1022 ppm at 290 K and, at a bias magnetic field of 700 Oe, the d33 equals 0.55 ppm/Oe (6.8 nm/A).

  3. Warm Disks from Giant Impacts

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-10-01

    In the process of searching for exoplanetary systems, weve discovered tens of debris disks close around distant stars that are especially bright in infrared wavelengths. New research suggests that we might be looking at the late stages of terrestrial planet formation in these systems.Forming Terrestrial PlanetsAccording to the widely-accepted formation model for our solar-system, protoplanets the size of Mars formed within a protoplanetary disk around our Sun. Eventually, the depletion of the gas in the disk led the orbits of these protoplanets to become chaotically unstable. Finally, in the giant impact stage, many of the protoplanets collided with each other ultimately leading to the formation of the terrestrial planets and their moons as we know them today.If giant impact stages occur in exoplanetary systems, too leading to the formation of terrestrial exoplanets how would we detect this process? According to a study led by Hidenori Genda of the Tokyo Institute of Technology, we might be already be witnessing this stage in observations of warm debris disks around other stars. To test this, Genda and collaborators model giant impact stages and determine what we would expect to see from a system undergoing this violent evolution.Modeling CollisionsSnapshots of a giant impact in one of the authors simulations. The collision causes roughly 0.05 Earth masses of protoplanetary material to be ejected from the system. Click for a closer look! [Genda et al. 2015]The collaborators run a series of simulations evolving protoplanetary bodies in a solar system. The simulations begin 10 Myr into the lifetime of the solar system, i.e., after the gas from the protoplanetary disk has had time to be cleared and the protoplanetary orbits begin to destabilize. The simulations end when the protoplanets are done smashing into each other and have again settled into stable orbits, typically after ~100 Myr.The authors find that, over an average giant impact stage, the total amount of

  4. Enhancing the strain sensitivity of CoFe₂O₄ at low magnetic fields without affecting the magnetostriction coefficient by substitution of small amounts of Mg for Fe.

    PubMed

    Anantharamaiah, P N; Joy, P A

    2016-04-21

    Attaining high magnetostrictive strain sensitivity (dλ/dH) with high magnetostriction strain (λ) is desirable for sintered polycrystalline cobalt ferrite for various applications. It is shown that substitution of a small amount of Fe(3+) by Mg(2+) in CoMgxFe2-xO4 (x < 0.1) gives a comparable maximum magnetostriction coefficient to that of the unsubstituted counterpart, with large improvement in the strain sensitivity at relatively low magnetic fields. A large increase in the magnetostriction coefficient is obtained at low magnetic fields for the substituted compositions. The magnetostriction parameters are further enhanced by magnetic field annealing of the sintered products. The results are analyzed based on powder XRD, Raman spectroscopy, XPS and magnetic measurements and based on the results from these studies, the changes in the magnetostriction parameters are correlated with the changes in the cation distribution, magnetic anisotropy and microstructure.

  5. Giant scrotal elephantiasis.

    PubMed

    Kuepper, Daniel

    2005-02-01

    How much can a man carry? Penoscrotal elephantiasis is a debilitating syndrome. This is a case report of a patient with giant genital elephantiasis secondary to long-standing lymphogranuloma venereum infection in Ethiopia. Complete surgical resection of the pathologic tissue and penile reconstruction was undertaken with good cosmetic and functional results.

  6. Rotational giant magnetoimpedance in soft magnetic wires: Modelization through Fourier harmonic contribution

    NASA Astrophysics Data System (ADS)

    Gómez-Polo, C.; Vázquez, M.; Knobel, M.

    2001-01-01

    A method to investigate the giant magnetoimpedance effect based on Fourier analysis is introduced. The study is carried out on a FeCoSiB amorphous wire with vanishing magnetostriction subjected to joule heating (current annealing) treatment that induces an enhancement of circumferential magnetic anisotropy and modifies the magnetoimpedance response of the samples. Experimental results are interpreted within the framework of the classical electrodynamical model, where the circumferential permeability plays the dominant role in the field dependence of the complex impedance of the sample. A rotational magnetization model is employed to determine the circular magnetization process, and a mean value of the circumferential permeability is obtained through the harmonic components obtained through Fourier analysis of the time derivative of the circular magnetization. This simple model is able to reproduce the observed experimental behavior, i.e., evolution of the field dependence of the complex impedance with annealing and the asymmetrical field dependence under a dc biased electrical current.

  7. Stress-induced magnetic hysteresis in amorphous microwires probed by microwave giant magnetoimpedance measurements

    NASA Astrophysics Data System (ADS)

    Popov, V. V.; Berzhansky, V. N.; Gomonay, H. V.; Qin, F. X.

    2013-05-01

    We report the results of a detailed study of the effects of tensile and torsional stresses on the giant magnetoimpedance (GMI) characteristics of vanishing-magnetostrictive Co-rich microwires at microwave frequency. A complex stress-induced hysteresis behaviour is identified in the GMI response in the presence of tensile and torsional stresses. It is also revealed that there exists a competition between these two kinds of stresses on the critical field via the interactions with the intrinsic anisotropy. An "enhanced core-shell" model is proposed here to resolve the physical origin of the low-field hysteresis and the dependence of induced anisotropy field on the applied tensile and/or torsional stress. Our results are of both technical importance to the design of non-contact stress sensors exploiting the GMI of microwires and fundamental significance to the understanding of the microwave GMI characteristics of soft magnetic microwires in the presence of external stresses.

  8. Magnetostriction and texture development in binary and ternary iron-gallium-based alloys

    NASA Astrophysics Data System (ADS)

    Mungsantisuk, Pinai

    2005-07-01

    The rare earth-free bcc FeGa-based alloys have an excellent combination of large low-field magnetostriction at room temperature, good mechanical properties, low hysteresis, and relatively low cost. These alloys are attractive for use in numerous sensor and actuator devices. The first part of this dissertation examines the influence of partial substitutions of Ga with Al, Be, Si, Ge, and Sn and partial substitutions of Fe with Co and Ni. The work involved directional growth of [001] textured rods of these ternary alloys using a Vertical Bridgman process, X-ray diffraction analysis, magnetic property measurements using vibrating sample magnetometry, and magnetostriction measurements. It is shown that substitution of Ga with Al can be made in FeGa alloys in certain composition ranges without a reduction in magnetostriction, and the additions of Si, Ge, and Sn results in a sharp decrease of magnetostriction. The addition or substitute of Be, due to its smaller size than Fe, resulted in only a slight decrease of magnetostriction. Substitution of Fe with Ni and Co results in a significant decrease of the magnetostriction. The work also evaluated the elastic properties of Fe-x at. % Ga and Fe-(20-y) at. % Ga-y at. % Al polycrystalline alloys using resonant ultrasound spectroscopy. Young's modulus obtained for FeGa and FeGaAl alloys were in the range of 110 to 170 GPa which are several times that for Terfenol-D alloys. Thus, large-force delivery is possible from FeGa alloy based actuators even though saturation strain values are smaller than that of Terfenol-D. The second part of this work examined the development of an inexpensive thermomechanical processing method to obtain [001] textured polycrystalline Fe-15 at. % Ga alloys. The processing involved a sequence of controlled hot rolling, two-stage warm rolling with intermediate anneal, and texture anneal. Roll forces measured and the extent of reductions feasible indicated an excellent processability. Texture evolution

  9. A Cascaded Magnetostrictive Vibration Source System for Underground Construction Applications

    NASA Astrophysics Data System (ADS)

    Hock, S.; Polom, U.; Mikulla, S.; Krüger, K.; Giese, R.; Lüth, S.

    2009-04-01

    For underground construction seismic measurements can contribute knowledge to geology and relevant geotechnical parameters. Within the cooperative project OnSITE - Online Seismic Imaging System for Tunnel Excavation - a new seismic source is in development. The design of the seismic source takes into account the special requirements for such an application: high signal frequency (up to several kHz) to obtain resolution in the order of few meters (1-2 m), generation of repeatable signals at short time intervals to implement a large measuring point density, and a high signal/noise ratio. In the first step, two magnetostrictive actuators in similar fashion - custom-made by ETREMA Products, Inc. (USA) - were used for a cascaded seismic vibration source system. The bandwidth of the pilot signal for this vibration source system covers the range from 300 Hz up to 6 kHz. After principally testing the source system in the research and teaching mine Reiche Zeche in Freiberg (Germany), further field measurements at this test site showed a high-grade signal repeatability for frequencies above 600 Hz for the head signal and good signal repeatability in the near field (Hock et al. 2008). To avoid 1) feedback effects between vibrator and medium - causing resonance at certain frequencies, e.g. around 3000 Hz and around 5500 Hz - and 2) unwanted phase shifts between the two vibrator signals at frequencies above 3000 Hz, an signal excitation with an open loop control for amplitude and phase is necessary in combination with only one real-time processor for controlling both actuators. In a second step, a source system was constructed consisting of 2 nearly identical (90%) actuators - again custom-made by ETREMA Products, Inc. (USA) - which are approximately one third lighter than the actuators in the first prototype. This new prototype was applied for the first time during a seismic survey in the Piora adit (above the Gotthard base tunnel near Faido, CH) in November 2008 with success

  10. Insights on a Giant Aneurysm Treated Endovascularly.

    PubMed

    Graziano, Francesca; Iacopino, Domenico Gerardo; Ulm, Arthur John

    2016-07-01

    Background Endovascular treatment with stent-assisted Guglielmi detachable coils is an accepted method for treating intracranial giant aneurysms that otherwise would require more invasive or destructive treatment or could not be treated at all. Nevertheless, there is a paucity of information concerning inner postcoiling aneurysmal changes in human subjects over the long term. We report a postmortem analysis of a patient with a giant aneurysm at the vertebrobasilar junction (VBJ) who was treated endovascularly and studied pathologically 24 months after treatment. Materials and Method The head was removed at autopsy and prefixed in a 10% neutral buffered formalin solution. The brain was gently removed from the skull base after cutting the intracranial nerves and vascular structures. The giant VBJ aneurysm and its relationship with the brainstem, cranial nerves, and vessels were captured photographically and analyzed. Afterward, under operating microscope guidance, the vertebrobasilar system with the aneurysm was gently and carefully detached from the brainstem and carefully analyzed. Results No complete fibrous obliteration of the aneurysm lumen could be detected in our case, and no endothelialization had taken place 24 months after treatment. Conclusions Our findings agree with those of previous similar reports. Coiling, in particular in large or giant aneurysms, may be burdened by the risk of coil compaction and recanalization, but it has the advantage of not affecting the flow in the perforating arteries.

  11. Structural flexibility in magnetocaloric RE5T4 (RE = rare-earth; T = silicon, germanium, gallium) materials: Effect of chemical substitution on structure, bonding and properties

    NASA Astrophysics Data System (ADS)

    Misra, Sumohan

    The binary, ternary and multicomponent intermetallic compounds of rare-earth metals (RE) with group 14 elements (Tt) at the RE5 Tt4 stoichiometry have been known for over 30 years, but only in the past decade have these materials become a gold mine for solid-state chemistry, materials science and condensed matter physics. It all started with the discovery of a giant magnetocaloric effect in Gd5Si 2Ge2, along with other extraordinary magnetic properties, such as a colossal magnetostriction and giant magnetoresistance. The distinctiveness of this series is in the remarkable flexibility of the chemical bonding between well-defined, subnanometer-thick slabs and the resultant magnetic, transport, and thermodynamic properties of these materials. This can be controlled by varying either or both RE and Tt elements, including mixed rare-earth elements on the RE sites and different group 14 (or T = group 13 or 15) elements occupying the Tt sites. In addition to chemical means, the interslab interactions are also tunable by temperature, pressure, and magnetic field. Thus, this system provides a splendid "playground" to investigate the interrelationships among composition, structure, physical properties, and chemical bonding. The work presented in this dissertation involving RE5T4 materials has resulted in the successful synthesis, characterization, property measurements, and theoretical analyses of various new intermetallic compounds. The results provide significant insight into the fundamental magnetic and structural behavior of these materials and help us better understand the complex link between a compound's composition, its observed structure, and its properties.

  12. Soft magnetism, magnetostriction, and microwave properties of FeGaB thin films

    SciTech Connect

    Lou, J.; Insignares, R. E.; Cai, Z.; Ziemer, K. S.; Liu, M.; Sun, N. X.

    2007-10-29

    A series of (Fe{sub 100-y}Ga{sub y}){sub 1-x}B{sub x} (x=0-21 and y=9-17) films were deposited; their microstructure, soft magnetism, magnetostrictive behavior, and microwave properties were investigated. The addition of B changes the FeGaB films from polycrystalline to amorphous phase and leads to excellent magnetic softness with coercivity <1 Oe, high 4{pi}M{sub s}, self-biased ferromagnetic resonance (FMR) frequency of 1.85 GHz, narrow FMR linewidth (X band) of 16-20 Oe, and a high saturation magnetostriction constant of 70 ppm. The combination of these properties makes the FeGaB films potential candidates for tunable magnetoelectric microwave devices and other rf/microwave magnetic device applications.

  13. The stress components effect on the Fe-based microwires magnetostatic and magnetostrictive properties

    NASA Astrophysics Data System (ADS)

    Rodionova, V.; Baraban, I.; Chichay, K.; Litvinova, A.; Perov, N.

    2017-01-01

    For glass-coated amorphous ferromagnetic Fe-based microwires both joint and separate effect of metallic nucleus diameter, d, and the ratio of metallic nucleus diameter to the total diameter of microwire in glass shell, d/D, on magnetic properties is investigated. Thereby the contribution of both shell-induced stresses, associated with the ratio of diameters, and internal nucleus stresses (residual, quenching), associated with the diameter of the nucleus are estimated. A strong and non-monotonic effect of the metallic nucleus diameter and metallic nucleus diameter/total microwire diameter ratio on magnetostatic and magnetostrictive properties was established. For analysis, we considered magnetically bi-stable microwires of "classic" Fe77.5Si7.5B15 alloy with positive magnetostriction coefficient.

  14. Magnetostriction and Magnetostructural Domains in Antiferromagnetic YBa2Cu3O6.

    PubMed

    Náfrádi, B; Keller, T; Hardy, F; Meingast, C; Erb, A; Keimer, B

    2016-01-29

    We use high-resolution neutron Larmor diffraction and capacitative dilatometry to investigate spontaneous and forced magnetostriction in undoped, antiferromagnetic YBa_{2}Cu_{3}O_{6.0}, the parent compound of a prominent family of high-temperature superconductors. Upon cooling below the Néel temperature T_{N}=420  K, Larmor diffraction reveals the formation of magnetostructural domains of characteristic size ∼240  nm. In the antiferromagnetic state, dilatometry reveals a minute (4×10^{-6}) orthorhombic distortion of the crystal lattice in external magnetic fields. We attribute these observations to exchange striction and spin-orbit coupling induced magnetostriction, respectively, and show that they have an important influence on the thermal and charge transport properties of undoped and lightly doped cuprates.

  15. Thermal expansion, heat capacity and magnetostriction of RAl3 (R = Tm, Yb, Lu) single crystals

    SciTech Connect

    Bud'ko, S.; Frenerick, J.; Mun, E.; Canfield, P.; Schmiedeshoff, G.

    2007-12-13

    We present thermal expansion and longitudinal magnetostriction data for cubic RAl{sub 3} (R = Tm, Yb, Lu) single crystals. The thermal expansion coefficient for YbAl{sub 3} is consistent with an intermediate valence of the Yb ion, whereas the data for TmAl{sub 3} show crystal electric field contributions and have strong magnetic field dependences. de Haas-van Alphen like oscillations were observed in the magnetostriction data for YbAl{sub 3} and LuAl{sub 3}, several new extreme orbits were measured and their effective masses were estimated. Specific heat data taken at 0 and 140 kOe for both LuAl{sub 3} and TmAl{sub 3} for T {le} 200 K allow for the determination of a crystal electric field splitting scheme for TmAl{sub 3}.

  16. Bulk ultrasonic NDE of metallic components at high temperature using magnetostrictive transducers

    NASA Astrophysics Data System (ADS)

    Ashish, Antony Jacob; Rajagopal, Prabhu; Balasubramaniam, Krishnan; Kumar, Anish; Rao, B. Purnachandra; Jayakumar, Tammana

    2017-02-01

    Online ultrasonic NDE at high-temperature is of much interest to the power, process and automotive industries in view of possible savings in downtime. This paper describes a novel approach to developing ultrasonic transducers capable of high-temperature in-situ operation using the principle of magnetostriction. Preliminary design from previous research by the authors [1] is extended for operation at 1 MHz, and at elevated temperatures by amorphous metallic strips as the magnetostrictive core. Ultrasonic signals in pulse-echo mode are experimentally obtained from the ultrasonic transducer thus developed, in a simulated high-temperature environment of 350 °C for 10 hours. Advantages and challenges for practical deployment of this approach are discussed.

  17. Phage-based magnetostrictive-acoustic microbiosensors for detecting bacillus anthracis spores

    NASA Astrophysics Data System (ADS)

    Wan, J.; Yang, H.; Lakshmanan, R. S.; Guntupalli, R.; Huang, S.; Hu, J.; Petrenko, V. A.; Chin, B. A.

    2006-05-01

    Magnetostrictive particles (MSPs) as biosensor platform have been developed recently. The principle of MSPs as sensor platform is the same as that of other acoustic wave devices, such as quartz crystal microbalance. In this paper, the fabrication, characterization and performance of phage-based MSP biosensors for detecting Bacillus anthracis spores are reported. A commercially available magnetostrictive alloy was utilized to fabricate the sensor platform. The phage was immobilized onto the MSPs using physical adsorption technology. The following performance of the phage-based MSP sensors will be presented: sensitivity, response time, longevity, specificity and binding efficacy. The performance of the sensors at static and dynamic conditions was characterized. The experimental results are confirmed by microscopy photographs. The excellent performance including high sensitivity and rapid response is demonstrated. More importantly, it is experimentally found that the phage-based MSP sensors have a much better longevity than antibody-based sensors.

  18. Design of Compensation Coils for EMI Suppression in Magnetostrictive Linear Position Sensors

    PubMed Central

    Zhang, Yongjie; Liu, Weiwen; Yang, Jinfeng; Lv, Chunfeng; Zhao, Hui

    2012-01-01

    This paper presents recent development on magnetostrictive linear position sensors (MLPS). A new compensation coil structure improves the EMI suppression and accuracy considerably. Furthermore, experimental results indicate that the new structure can improve the accuracy to ±0.13 mm nearly double the ±0.2 mm obtained with traditional structures. As another design continuation after the differential waveguide structure, this new structure is a practical and reliable implementation technique for the commercialization of MLPS. PMID:22778648

  19. Nursery of Giants

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Hidden behind a shroud of dust in the constellation Cygnus is a stellar nursery called DR21, which is giving birth to some of the most massive stars in our galaxy. Visible light images reveal no trace of this interstellar cauldron because of heavy dust obscuration. In fact, visible light is attenuated in DR21 by a factor of more than 10,000,000,000,000,000,000,000,000,000,000,000,000,000 (ten thousand trillion heptillion).

    New images from NASA's Spitzer Space Telescope allow us to peek behind the cosmic veil and pinpoint one of the most massive natal stars yet seen in our Milky Way galaxy. The never-before-seen star is 100,000 times as bright as the Sun. Also revealed for the first time is a powerful outflow of hot gas emanating from this star and bursting through a giant molecular cloud.

    This image is a large-scale mosaic assembled from individual photographs obtained with the InfraRed Array Camera (IRAC) aboard Spitzer. The image covers an area about two times that of a full moon. The mosaic is a composite of images obtained at mid-infrared wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red). The brightest infrared cloud near the top center corresponds to DR21, which presumably contains a cluster of newly forming stars at a distance of 10,000 light-years.

    Protruding out from DR21 toward the bottom left of the image is a gaseous outflow (green), containing both carbon monoxide and molecular hydrogen. Data from the Spitzer spectrograph, which breaks light into its constituent individual wavelengths, indicate the presence of hot steam formed as the outflow heats the surrounding molecular gas. Outflows are physical signatures of processes that create supersonic beams, or jets, of gas. They are usually accompanied by discs of material around the new star, which likely contain the materials from which future planetary systems are formed. Additional newborn stars, depicted in green, can be seen surrounding the

  20. Giant magneto radio frequency absorption in magneto-resistive materials La{sub 0.7}(Sr,Ca){sub 0.3}MnO{sub 3}

    SciTech Connect

    Owens, F.J. |

    1997-09-01

    The dc magnetic field, frequency, and temperature dependence of electromagnetic absorption at rf frequencies of 335 kHz and 10 MHz are measured in the as sintered samples of colossal magneto resistive materials La{sub 0.7}Sr{sub 0.3}MnO{sub 3} and La{sub 0.7}Ca{sub 0.3}MnO{sub 3} by measuring the penetration depth using the method of Schawlow and Devlin. Very large magneto-electromagnetic absorption effects, much larger than the magneto resistive effects, are observed. A dc magnetic field of 1000 G changes the penetration depth at 350 kHz by 53{percent} at room temperature in La{sub 0.7}Sr{sub 0.3}MnO{sub 3}, whereas the resistance of the sample only decreases by 0.75{percent} for the same field. The effects are primarily a result of the decrease of the permeability of the sample with dc magnetic field in the ferromagnetic state. A simple dc magnetometer employing the as sintered La{sub 0.7}Sr{sub 0.3}MnO{sub 3} contained in the coil of an LC oscillator as the sensing element is described.

  1. Giant negative thermal expansion in magnetic nanocrystals.

    PubMed

    Zheng, X G; Kubozono, H; Yamada, H; Kato, K; Ishiwata, Y; Xu, C N

    2008-12-01

    Most solids expand when they are heated, but a property known as negative thermal expansion has been observed in a number of materials, including the oxide ZrW2O8 (ref. 1) and the framework material ZnxCd1-x(CN)2 (refs 2,3). This unusual behaviour can be understood in terms of low-energy phonons, while the colossal values of both positive and negative thermal expansion recently observed in another framework material, Ag3[Co(CN)6], have been explained in terms of the geometric flexibility of its metal-cyanide-metal linkages. Thermal expansion can also be stopped in some magnetic transition metal alloys below their magnetic ordering temperature, a phenomenon known as the Invar effect, and the possibility of exploiting materials with tuneable positive or negative thermal expansion in industrial applications has led to intense interest in both the Invar effect and negative thermal expansion. Here we report the results of thermal expansion experiments on three magnetic nanocrystals-CuO, MnF2 and NiO-and find evidence for negative thermal expansion in both CuO and MnF2 below their magnetic ordering temperatures, but not in NiO. Larger particles of CuO and MnF2 also show prominent magnetostriction (that is, they change shape in response to an applied magnetic field), which results in significantly reduced thermal expansion below their magnetic ordering temperatures; this behaviour is not observed in NiO. We propose that the negative thermal expansion effect in CuO (which is four times larger than that observed in ZrW2O8) and MnF2 is a general property of nanoparticles in which there is strong coupling between magnetism and the crystal lattice.

  2. Two-dimensional numerical simulation of acoustic wave phase conjugation in magnetostrictive elastic media

    NASA Astrophysics Data System (ADS)

    Voinovich, Peter; Merlen, Alain

    2005-12-01

    The effect of parametric wave phase conjugation (WPC) in application to ultrasound or acoustic waves in magnetostrictive solids has been addressed numerically by Ben Khelil et al. [J. Acoust. Soc. Am. 109, 75-83 (2001)] using 1-D unsteady formulation. Here the numerical method presented by Voinovich et al. [Shock waves 13(3), 221-230 (2003)] extends the analysis to the 2-D effects. The employed model describes universally elastic solids and liquids. A source term similar to Ben Khelil et al.'s accounts for the coupling between deformation and magnetostriction due to external periodic magnetic field. The compatibility between the isotropic constitutive law of the medium and the model of magnetostriction has been considered. Supplementary to the 1-D simulations, the present model involves longitudinal/transversal mode conversion at the sample boundaries and separate magnetic field coupling with dilatation and shear stress. The influence of those factors in a 2-D geometry on the potential output of a magneto-elastic wave phase conjugator is analyzed in this paper. The process under study includes propagation of a wave burst of a given frequency from a point source in a liquid into the active solid, amplification of the waves due to parametric resonance, and formation of time-reversed waves, their radiation into liquid, and focusing. The considered subject is particularly important for ultrasonic applications in acoustic imaging, nondestructive testing, or medical diagnostics and therapy.

  3. A Magnetic Flux Leakage and Magnetostrictive Guided Wave Hybrid Transducer for Detecting Bridge Cables

    PubMed Central

    Xu, Jiang; Wu, Xinjun; Cheng, Cheng; Ben, Anran

    2012-01-01

    Condition assessment of cables has gained considerable attention for the bridge safety. A magnetic flux leakage and magnetostrictive guided wave hybrid transducer is provided to inspect bridge cables. The similarities and differences between the two methods are investigated. The hybrid transducer for bridge cables consists of an aluminum framework, climbing modules, embedded magnetizers and a ribbon coil. The static axial magnetic field provided by the magnetizers meets the needs of the magnetic flux leakage testing and the magnetostrictive guided wave testing. The magnetizers also provide the attraction for the climbing modules. In the magnetic flux leakage testing for the free length of cable, the coil induces the axial leakage magnetic field. In the magnetostrictive guided wave testing for the anchorage zone, the coil provides a pulse high power variational magnetic field for generating guided waves; the coil induces the magnetic field variation for receiving guided waves. The experimental results show that the transducer with the corresponding inspection system could be applied to detect the broken wires in the free length and in the anchorage zone of bridge cables. PMID:22368483

  4. Enhanced sensitivity of temperature-compensated SAW-based current sensor using the magnetostrictive effect

    NASA Astrophysics Data System (ADS)

    Wang, Wen; Jia, Yana; Liu, Xinlu; Liang, Yong; Xue, Xufeng; Du, Zaofu

    2017-02-01

    A temperature-compensated surface acoustic wave (SAW)-based current sensor was proposed in this contribution, composed of a sensor chip made by SAW delay line patterns on a SiO2/128° YX LiNbO3 piezoelectric substrate, a magnetostrictive FeCo film deposited on the SAW propagation path, and a corresponding differential oscillation configuration. The FeCo coating produced magnetostrictive strain under the magnetic field generated by the applied current, leading to linearity changes in the SAW propagation in the form of velocity change. The corresponding differential oscillation frequency shift was used to evaluate the tested current. By solving the coupled electromechanical field equation in a layered structure while considering the magnetostrictive effect, the optimal FeCo film thickness, and sensor operation frequency yielding high current sensitivity, were determined, and then confirmed experimentally by evaluating the developed SAW current sensor system utilizing a Helmholtz coil. A high sensitivity of 16.6 KHz A-1 (8.3 KHz m-1 T-1), excellent linearity, and lower detection limit (˜0.2 mA) were achieved with our 300 MHz SAW sensor with a 500 nm FeCo coating and aspect ratio of 2:1.

  5. Anhysteretic magnetization and magnetostriction of thin NiFe films under stress and plastic deformation

    NASA Astrophysics Data System (ADS)

    Finkel, Peter; Garrity, Ed; Lofland, Sam

    2006-03-01

    The magnetic properties of thin samples of a thin film NiFe sample under tensile stress are investigated. The magnetostriction contribution to dc magnetization under elastic stress and the effect of the plastic strain on the hysteresis loops are discussed. Also, a role of the plastic deformation interrelated with the elastic stress in the magnetization process is established. An experimental system based on a conventional vibrating sample magnetometer equipped with the specially designed loading fixture and optical resonant spectroscopy tension monitoring technique is used to measure anhysteretic permeability and magnetization curve as a function of stress and temperature. This method used to measure anhysteretic permeability and magnetization curve of Ni-Fe as a function of stress and temperature. Anhysteretic permeability was extracted from the anhysteretic B-H curves constructed by degaussing the sample at given longitudinal (parallel to the stresses) dc field. The large positive magnetostriction constant of FeNi samples leads to higher susceptibility and lower coercivity with tensile stress while the large volume magnetostriction results in reduced saturation magnetization. Large stresses imposed on the sample result in plastic strain of the sample which induces increase in dislocation density and domain wall pinning. This causes the gain in hysteresis loss and coercivity to increase at the highest stresses. We also discuss the effect of the Ni composition on results of the measurements.

  6. Magnetostrictive helical array transducer for inspecting spiral welded pipes using flexural guided waves

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaowei; Tang, Zhifeng; Lv, Fuzai

    2017-02-01

    A wavefront analysis indicates that a flexural wave propagates at a helix angle with respect to the pipe axis. The expression for calculation of the helix angle for each flexural mode is given, and the helix angle dispersion curves for flexural modes are calculated. According to the new understanding of flexural guided waves, a magnetostrictive helical array transducer (MHAT) is proposed for selectively exciting a single predominant flexural torsional guided wave in a pipe and inspecting spiral welded pipes using flexural waves. A MHAT contains a pre-magnetized magnetostrictive patch that is helically coupled with the outer surface of a pipe, and an array of novel compound comb coils that are wrapped around the helical magnetostrictive patch. The proposed wideband MHAT possesses the direction control ability. A verification experiment indicates that flexural torsional mode T(3,1) at center frequency f=64kHz is effectively actuated by a MHAT with 13-degree helix angle. A 20-degree MHAT is adopted to inspect a spiral welded pipe, an artificial notch with cross section loss CSL=2.7% is effectively detected by using flexural waves.

  7. A magnetic flux leakage and magnetostrictive guided wave hybrid transducer for detecting bridge cables.

    PubMed

    Xu, Jiang; Wu, Xinjun; Cheng, Cheng; Ben, Anran

    2012-01-01

    Condition assessment of cables has gained considerable attention for the bridge safety. A magnetic flux leakage and magnetostrictive guided wave hybrid transducer is provided to inspect bridge cables. The similarities and differences between the two methods are investigated. The hybrid transducer for bridge cables consists of an aluminum framework, climbing modules, embedded magnetizers and a ribbon coil. The static axial magnetic field provided by the magnetizers meets the needs of the magnetic flux leakage testing and the magnetostrictive guided wave testing. The magnetizers also provide the attraction for the climbing modules. In the magnetic flux leakage testing for the free length of cable, the coil induces the axial leakage magnetic field. In the magnetostrictive guided wave testing for the anchorage zone, the coil provides a pulse high power variational magnetic field for generating guided waves; the coil induces the magnetic field variation for receiving guided waves. The experimental results show that the transducer with the corresponding inspection system could be applied to detect the broken wires in the free length and in the anchorage zone of bridge cables.

  8. Local structure in magnetostrictive melt-spun Fe80Ga20 alloys

    NASA Astrophysics Data System (ADS)

    Pascarelli, S.; Ruffoni, M. P.; Sato Turtelli, R.; Kubel, F.; Grössinger, R.

    2008-05-01

    We perform a detailed investigation of the local atomic structure in highly magnetostrictive α-FeGa melt-spun ribbons. By using extended x-ray absorption fine structure (EXAFS) analysis at the Fe and GaK edges coupled to x-ray diffraction (XRD) and to ab initio full multiple scattering calculations of the x-ray absorption near edge structure (XANES), we test for the presence of different local defect structures proposed in literature as being responsible for the large magnetostriction in these alloys. XRD shows that the ribbons crystallize in the A2 phase. Invisible by XRD, the presence of small Ga clusters is excluded by both EXAFS and XANES since no first shell Ga-Ga bonds are detected. However, EXAFS analysis of the second coordination shell around Ga clearly provides evidence for the presence of one highly strained (+4%) Ga-Ga pair and five Ga-Fe pairs, among the six crystallographically equivalent ⟨001⟩ atomic pairs. This conclusion supports recent total energy calculations that assign the large magnetostriction in these alloys to the strain caused by the rotation of the magnetization in the vicinity of such defects.

  9. Electrodeposition of high magnetostrictive cobalt-iron alloy films for smart tags and sensor applications

    SciTech Connect

    Pillars, Jamin Ryan

    2015-12-01

    Magnetostrictive CoFe films were investigated for use as magnetoelastic tags or sensors. The ability to electrodeposit these films enables batch fabrication processes to pattern a variety of geometries while controlling the film stoichiometry and crystallography. In current research looking at CoFe, improved magnetostriction was achieved using a co-sputtering, annealing, and quenching method1. Other current research has reported electrodeposited CoFe films using a sulfate based chemistry resulting in film compositions that are Fe rich in the range of Co0.3-0.4Fe0.7-0.6 and have problems of codeposition of undesirables that can have a negative impact on magnetic properties. The research presented here focused on maximizing magnetostriction at the optimal stoichiometry range of Co0.7-0.75Fe0.3-0.25, targeting the (fcc+bcc)/bcc phase boundary, and using a novel chemistry and plating parameters to deposit films without being limited to “line of sight” deposition.

  10. Ice Giant Exploration

    NASA Astrophysics Data System (ADS)

    Rymer, A. M.; Arridge, C. S.; Masters, A.; Turtle, E. P.; Simon, A. A.; Hofstadter, M. D.; Turrini, D.; Politi, R.

    2015-12-01

    The Ice Giants in our solar system, Uranus and Neptune, are fundamentally different from their Gas Giant siblings Jupiter and Saturn, from the different proportions of rock and ice to the configuration of their planetary magnetic fields. Kepler space telescope discoveries of exo-planets indicate that planets of this type are among the most ubiquitous universally and therefore a future mission to explore the nature of the Ice Giants in our own solar system will provide insights into the nature of extra-solar system objects in general. Uranus has the smallest self- luminosity of all the planets, potentially related to catastrophic events early in the planet's history, which also may explain Uranus' large obliquity. Uranus' atmosphere is subject to extreme seasonal forcing making it unique in the Solar System. Neptune is also unique in a number of ways, notably its large moon Triton which is likely a captured Kuiper Belt Object and one of only two moons in the solar system with a robustly collisional atmosphere. Similar to Uranus, the angle between the solar wind and the magnetic dipole axis is subject to large-amplitude variations on both diurnal and seasonal timescales, but peculiarly it has one of the quietest magnetospheres of the solar system, at least according to Voyager 2, the only spacecraft to encounter Neptune to date. A comprehensive mission, as advocated in the Decadal Survey, would provide enormous science return but is also challenging and expensive. In this presentation we will discuss mission scenarios and suggest how collaboration between disciplines and internationally can help us to pursue a mission that includes Ice Giant exploration.

  11. Giant cell arteritis

    PubMed Central

    Calvo-Romero, J

    2003-01-01

    Giant cell arteritis (GCA), temporal arteritis or Horton's arteritis, is a systemic vasculitis which involves large and medium sized vessels, especially the extracranial branches of the carotid arteries, in persons usually older than 50 years. Permanent visual loss, ischaemic strokes, and thoracic and abdominal aortic aneurysms are feared complications of GCA. The treatment consists of high dose steroids. Mortality, with a correct treatment, in patients with GCA seems to be similar that of controls. PMID:13679546

  12. Giant Cell Arteritis.

    PubMed

    Hoffman, Gary S

    2016-11-01

    This issue provides a clinical overview of giant cell arteritis, focusing on diagnosis, treatment, and practice improvement. The content of In the Clinic is drawn from the clinical information and education resources of the American College of Physicians (ACP), including MKSAP (Medical Knowledge and Self-Assessment Program). Annals of Internal Medicine editors develop In the Clinic in collaboration with the ACP's Medical Education and Publishing divisions and with the assistance of additional science writers and physician writers.

  13. Tunability of band structures in a two-dimensional magnetostrictive phononic crystal plate with stress and magnetic loadings

    NASA Astrophysics Data System (ADS)

    Zhang, Shunzu; Shi, Yang; Gao, Yuanwen

    2017-03-01

    Considering the magneto-mechanical coupling of magnetostrictive material, the tunability of in-plane wave propagation in two-dimensional Terfenol-D/epoxy phononic crystal (PC) plate is investigated theoretically by the plane wave expansion method. Two Schemes, i.e. magnetic field is rotated in x-y plane and x-z plane, are studied, respectively. The effects of amplitude and direction of magnetic field, pre-stress and geometric parameters are discussed. For Scheme-I, band gap reaches the maximum at an optimal angle 45° of magnetic field. However, the optimal angle is 0° for Scheme-II, because band gap decreases monotonically until disappears with the increasing angle. For both cases, higher-order band gaps generate and become stronger as magnetic field amplitude increases, while increasing compressive pre-stress has the opposite effect. Meanwhile, filling fraction plays a key role in controlling band gaps. These results provide possibility for intelligent regulation and optimal design of PC plates.

  14. Enhanced off-resonance magnetoelectric response in laser annealed PZT thick film grown on magnetostrictive amorphous metal substrate

    SciTech Connect

    Palneedi, Haribabu; Maurya, Deepam; Priya, Shashank; Kim, Gi-Yeop; Choi, Si-Young; Kang, Suk-Joong L.; Kim, Kwang-Ho; Ryu, Jungho

    2015-07-06

    A highly dense, 4 μm-thick Pb(Zr,Ti)O{sub 3} (PZT) film is deposited on amorphous magnetostrictive Metglas foil (FeBSi) by granule spray in vacuum process at room temperature, followed by its localized annealing with a continuous-wave 560 nm ytterbium fiber laser radiation. This longer-wavelength laser radiation is able to anneal the whole of thick PZT film layer without any deteriorative effects, such as chemical reaction and/or atomic diffusion, at the interface and crystallization of amorphous Metglas substrate. Greatly enhanced dielectric and ferroelectric properties of the annealed PZT are attributed to its better crystallinity and grain growth induced by laser irradiation. As a result, a colossal off-resonance magnetoelectric (ME) voltage coefficient that is two orders of magnitude larger than previously reported output from PZT/Metglas film-composites is achieved. The present work addresses the problems involved in the fabrication of PZT/Metglas film-composites and opens up emerging possibilities in employing piezoelectric materials with low thermal budget substrates (suitable for integrated electronics) and designing laminate composites for ME based devices.

  15. Analytical solution of the strain-controlled magnetic domain wall motion in bilayer piezoelectric/magnetostrictive nanostructures

    NASA Astrophysics Data System (ADS)

    Consolo, Giancarlo; Valenti, Giovanna

    2017-01-01

    The one-dimensional propagation of magnetic domain walls in an isotropic, linearly elastic, magnetostrictive material is investigated in the framework of the extended Landau-Lifshitz-Gilbert equation where the effects of a spin-polarized current and a rate-independent dry-friction dissipation are taken into account. In our analysis, it is assumed that the ferromagnet is subject to a spatially uniform biaxial in-plain stress generated by a piezoelectric substrate combined with the former in a multiferroic heterostructure. Moreover, a possible connection between the dry-friction mechanism and the piezo-induced strains is conjectured. By adopting the traveling waves ansatz, the effect of such a stress on the domain wall dynamics is explored in both steady and precessional regimes. In particular, it is proved that the magnetoelastic contribution, while it does not formally modify the classical solution, affects both the propagation threshold and the Walker Breakdown conditions involved in the steady regime, in agreement with recent experimental results. In the precessional regime, it is shown that the existence of a correlation between the piezo-induced strains and dry-friction leads to an upward shift of the domain wall velocity.

  16. Assimilation of planets by red giant stars

    NASA Astrophysics Data System (ADS)

    Carlberg, Joleen Karen

    The typical red giant star rotates slowly. This characteristic is expected from the conservation of angular momentum as these stars expand during their evolution. Nevertheless, a small percentage of red giant stars are rapidly rotating. One possible source of these stars' excess angular momenta is the orbital angular momentum of a planetary companion. The transfer of orbital angular momentum to the stellar envelope decays the planet's orbit, ultimately leading to the rapid in-spiral of the planet into the star. Using the known sample of exoplanets around main sequence host stars, I simulated both the future evolution of these stars and the expected interactions with their planets and found that Jupiter-mass planets residing at inner solar system distances---relatively common in exoplanetary systems---can contribute enough angular momentum to cause rapid rotation in their host stars during the red giant phase. Gas giant planets are also massive enough to alter the chemical composition of their host stars' envelopes when they are accreted. The central experiment of this thesis is to search for abundance anomalies in the rapid rotators that could be indicative of planet accretion. Hypothetical anomalies include the replenishment of light elements that are diluted by giant stars during first dredge-up (such as the stellar surface abundance of lithium), changes in isotopic abundance ratios that were altered by nucleosynthesis (such as increasing the stellar surface 12C/13C), and the preferential enhancement of refractory elements (indicative of the accretion of chemically fractionated material such as a planet). To increase the total number of known rapid rotators, I measured rotational velocities in a large database of spectra collected for the Grid Giant Star Survey developed for NASA's Space Interferometry Mission's astrometric grid. The 28 new rapid rotators discovered in this sample were combined with rapid rotators from the literature and a control sample of slow

  17. Giant viruses in the environment: their origins and evolution.

    PubMed

    Yamada, Takashi

    2011-07-01

    The recent identification of giant viruses has raised important questions, not only regarding their origin and evolution, but also regarding the differentiation between viruses and living organisms. These viruses possess large genomes encoding genes potentially involved in various metabolic processes and even protein synthesis, indicating their putative autonomy. Giant viruses of the Phycodnaviridae and Mimiviridae families appear to share a common evolutionary ancestor with members of the nucleo-cytoplasmic large DNA viruses. Many giant viruses are associated with protists in aquatic environments and might have evolved in protist cells. They may therefore play important roles in material cycling in natural ecosystems. With the advent of environmental metagenomic projects, there will be more chances to encounter novel giant viruses in the future.

  18. Magnetostriction and corrosion studies in single crystals of iron-gallium alloys

    NASA Astrophysics Data System (ADS)

    Jayaraman, Tanjore V.

    Iron-gallium alloys have an excellent combination of large low-field magnetostriction, good mechanical properties, low hysteresis, and relatively low cost. This dissertation focuses on the magneto striction and corrosion behaviors of single crystals of Fe-Ga alloys. In the first part, the variation of magnetostrictive coefficient: (3/2) lambda100, with composition and heat treatment conditions of Fe-Ga alloys, is examined. Single crystals with compositions Fe-15 at.% Ga, Fe-20 at.% Ga, and Fe-27.5 at.% Ga were obtained by (a) vertical Bridgman technique (DG) and (b) vertical Bridgman technique followed by long-term annealing (LTA) and quenching. Rapid quenching from a phase region improves the (3/2) lambda 100 value in these alloys. X-ray diffraction characterization showed for the first time the direct evidence of short-range ordering in these alloys. The second part reports the first study of alpha" ordering heat treatment on the elastic properties and magnetostriction of Fe-27.5 at.% Ga alloy single crystals. The elastic constants were measured using resonant ultrasound spectroscopy (RUS), and the elastic properties and magneto-elastic coupling constant were calculated. The (3/2) lambda100 and B1 values obtained for a phase were higher than alpha" phase. The third part examines the first study of corrosion behavior of as-cast FeGa and Fe-Ga-Al alloys in acidic, basic, and simulated seawater environments. Corrosion measurements were performed by Tafel scan and polarization resistance method and in general exhibited good corrosion resistance. The fourth part examines the first study of corrosion behavior of Fe-15 at.% Ga, Fe-20 at.% Ga, and Fe-27.5 at.% Ga DG and LTA alloy single crystals and the dependence of corrosion rates on the crystal orientations. The corrosion resistance was better in basic environments followed by simulated seawater and acidic environments. The fifth part examines the effect of magnetostriction on the corrosion behavior of [100]-oriented

  19. Giant thoracic osteophyte: a distinct clinical entity.

    PubMed

    Coumans, Jean-Valery C E; Neal, Jonathan B; Grottkau, Brian E; Nahed, Brian V; Shin, John H; Walcott, Brian P

    2014-09-01

    Calcified lesions described within the neural axis are classified as either an ossification of the posterior longitudinal ligament, diffuse idiopathic skeletal hyperostosis, or ossification of the ligamentum flavum. We aim to describe a unique pathologic entity: the giant thoracic osteophyte. We identified four patients who were surgically treated at the Massachusetts General Hospital from 2006 to 2012 with unusual calcified lesions in the ventral aspect of the spinal canal. In order to differentiate giant thoracic osteophytes from calcified extruded disc material, disc volumetrics were performed on actual and simulated disc spaces. All patients underwent operative resection of the calcific lesion as they had signs and/or symptoms of spinal cord compression. The lesions were found to be isolated, large calcific masses that originated from the posterior aspect of adjacent thoracic vertebral bodies. Pathological examination was negative for tumor. Adjacent disc volumes were not significantly different from the index disc (p=0.91). A simulated calculation hypothesizing that the calcific mass was extruded disc material demonstrated a significant difference (p=0.01), making this scenario unlikely. In conclusion, giant thoracic osteophyte is a unique and rare entity that can be found in the thoracic spine. The central tenant of surgical treatment is resection to relieve spinal cord compression.

  20. Stress-anneal-induced magnetic anisotropy in highly textured Fe-Ga and Fe-Al magnetostrictive strips for bending-mode vibrational energy harvesters

    NASA Astrophysics Data System (ADS)

    Park, Jung Jin; Na, Suok-Min; Raghunath, Ganesh; Flatau, Alison B.

    2016-05-01

    Magnetostrictive Fe-Ga and Fe-Al alloys are promising materials for use in bending-mode vibrational energy harvesters. For this study, 50.8 mm × 5.0 mm × 0.5 mm strips of Fe-Ga and Fe-Al were cut from 0.50-mm thick rolled sheet. An atmospheric anneal was used to develop a Goss texture through an abnormal grain growth process. The anneal lead to large (011) grains that covered over 90% of sample surface area. The resulting highly-textured Fe-Ga and Fe-Al strips exhibited saturation magnetostriction values (λsat = λ∥ - λ⊥) of ˜280 ppm and ˜130 ppm, respectively. To maximize 90° rotation of magnetic moments during bending of the strips, we employed compressive stress annealing (SA). Samples were heated to 500°C, and a 100-150 MPa compressive stress was applied while at 500°C for 30 minutes and while being cooled. The effectiveness of the SA on magnetic moment rotation was inferred by comparing post-SA magnetostriction with the maximum possible yield of rotated magnetic moments, which is achieved when λ∥ = λsat and λ⊥ = 0. The uniformity of the SA along the sample length and the impact of the SA on sensing/energy harvesting performance were then assessed by comparing pre- and post-SA bending-stress-induced changes in magnetization at five different locations along the samples. The SA process with a 150 MPa compressive load improved Fe-Ga actuation along the sample length from 170 to 225 ppm (from ˜60% to within ˜80% of λsat). The corresponding sensing/energy harvesting performance improved by as much as a factor of eight in the best sample, however the improvement was not at all uniform along the sample length. The SA process with a 100 MPa compressive load improved Fe-Al actuation along the sample length from 60 to 73 ppm (from ˜46% to ˜56% of λsat, indicating only a marginally effective SA and suggesting the need for modification of the SA protocol. In spite of this, the SA was effective at improving the sensing/energy harvesting

  1. Imaging Extrasolar Giant Planets

    NASA Astrophysics Data System (ADS)

    Bowler, Brendan P.

    2016-10-01

    High-contrast adaptive optics (AO) imaging is a powerful technique to probe the architectures of planetary systems from the outside-in and survey the atmospheres of self-luminous giant planets. Direct imaging has rapidly matured over the past decade and especially the last few years with the advent of high-order AO systems, dedicated planet-finding instruments with specialized coronagraphs, and innovative observing and post-processing strategies to suppress speckle noise. This review summarizes recent progress in high-contrast imaging with particular emphasis on observational results, discoveries near and below the deuterium-burning limit, and a practical overview of large-scale surveys and dedicated instruments. I conclude with a statistical meta-analysis of deep imaging surveys in the literature. Based on observations of 384 unique and single young (≈5-300 Myr) stars spanning stellar masses between 0.1 and 3.0 M ⊙, the overall occurrence rate of 5-13 M Jup companions at orbital distances of 30-300 au is {0.6}-0.5+0.7 % assuming hot-start evolutionary models. The most massive giant planets regularly accessible to direct imaging are about as rare as hot Jupiters are around Sun-like stars. Dividing this sample into individual stellar mass bins does not reveal any statistically significant trend in planet frequency with host mass: giant planets are found around {2.8}-2.3+3.7 % of BA stars, <4.1% of FGK stars, and <3.9% of M dwarfs. Looking forward, extreme AO systems and the next generation of ground- and space-based telescopes with smaller inner working angles and deeper detection limits will increase the pace of discovery to ultimately map the demographics, composition, evolution, and origin of planets spanning a broad range of masses and ages.

  2. A Giant Urethral Calculus.

    PubMed

    Sigdel, G; Agarwal, A; Keshaw, B W

    2014-01-01

    Urethral calculi are rare forms of urolithiasis. Majority of the calculi are migratory from urinary bladder or upper urinary tract. Primary urethral calculi usually occur in presence of urethral stricture or diverticulum. In this article we report a case of a giant posterior urethral calculus measuring 7x3x2 cm in a 47 years old male. Patient presented with acute retention of urine which was preceded by burning micturition and dribbling of urine for one week. The calculus was pushed in to the bladder through the cystoscope and was removed by suprapubic cystolithotomy.

  3. Giant left ventricular pseudoaneurysm.

    PubMed

    Prakash, Sumi; Garg, Nadish; Xie, Gong-Yuan; Dellsperger, Kevin C

    2010-01-01

    Left ventricular (LV) pseudoaneurysm (PS) is an uncommon, often fatal complication associated with myocardial infarction, cardiothoracic surgery, trauma, and, rarely, infective endocarditis. A 28-year-old man with prior history of bioprosthetic mitral valve replacement presented with congestive heart failure and bacteremia with Abiotrophia granulitica. Transesophageal echocardiogram showed bioprosthesis dysfunction, large vegetations, mitral regurgitation, and probable PS. Cardiac and chest CT confirmed a PS communicating with the left ventricle Patient had pulseless electrical activity and died. Autopsy showed a giant PS with layered thrombus and pseudo-endothelialized cavity. Our case highlights the importance of multimodality imaging as an important tool in management of PS.

  4. Burst magnetostriction in Tb{sub 0.3}Dy{sub 0.7}Fe{sub 1.9}

    SciTech Connect

    Armstrong, W.D.

    1997-04-01

    The magnetostriction and magnetic induction calculated by a continuous, anisotropic, anhysteric, magnetization model are compared with magnetostriction and magnetic induction measurements on burst and nonburst magnetostrictive Tb{sub 0.3}Dy{sub 0.7}Fe{sub 1.9} twinned single crystal rods. The model shows that the magnetostriction and permeability suppression occurring at low applied field is the result of the rotation, and subsequent capture, of initial field antiparallel magnetization into field transverse [11{bar 1}] or [{bar 1}{bar 1}1] local magnetoelastic energy minima. The model further shows that the interval of high magnetostriction applied field derivative, d{lambda}/dH is the result of the rotation of field transverse [11{bar 1}] or [{bar 1}{bar 1}1] oriented magnetization into the [111] near field magnetocrystalline minima. The occurance of burst magnetostriction is therefore contingent on obtaining sufficient magnetocrystalline anisotropy and sufficiently tight magnetization energy distribution in experimental Tb{sub 0.3}Dy{sub 0.7}Fe{sub 1.9} twinned single crystal rods so as to minimize the applied field interval over which this magnetization rotation process occurs. The present model is able to correctly approximate the applied field dependence of the burst magnetostriction response and the applied field dependence of the simultaneous magnetostriction and permeability suppression with a single set of parameters for a range of constant [112] applied compressive stresses, and correct saturation magnetostrictions for a range of experimentally applied compressive stresses. However, the model fails to match the experimental behavior above a simultaneous d{lambda}/dH, permeability and field hysteresis transition, located approximately 1000 microstrain from the saturation magnetostriction. The experimental transition clearly indicates a change in magnetization mechanism not accommodated by the present model. (Abstract Truncated)

  5. Giant papillary conjunctivitis.

    PubMed Central

    Donshik, P C

    1994-01-01

    Giant papillary conjunctivitis is a syndrome found frequently as a complication of contact lenses. Many variables can affect the onset and severity of the presenting signs and symptoms. Rigid gas permeable contact lenses appear to result in less severe signs and symptoms, with a longer time before the development of giant papillary conjunctivitis. Nonionic, low-water-content soft contact lenses tend to produce less severe signs and symptoms than ionic, low-water-content soft contact lenses. Enzymatic treatment appears to lessen the severity of signs and symptoms. The association of an allergy appears to play a role in the onset of the severity of the signs and symptoms but does not appear to affect the final ability of the individual to wear contact lenses. Using multiple treatment options, such as changing the polymer to a glyceryl methyl methacrylate or a rigid lens, or utilizing a soft lens on a frequent-replacement basis, can result in a success rate of over 90%. In individuals who still have a return of symptoms, the use of topical mast cell stabilizers or a nonsteroidal anti-inflammatory drug as an adjunctive therapy offers the added possibility of keeping these patients in contact lenses. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7 FIGURE 11 A FIGURE 11 B FIGURE 11 C FIGURE 11 D PMID:7886881

  6. Giant extragenital Bowen's disease.

    PubMed

    Bakardzhiev, Ilko; Chokoeva, Anastasiya Atanasova; Tchernev, Georgi

    2015-12-01

    Giant extragenital forms of Morbus Bowen are extremely rare. The already described cases in the word literature are most commonly with periungual localization, as well as located on the foot and neck area. The clinical manifestation is presented most commonly by non-specific erythematous to erythematous-squamous plaques or papules, which is confusing to the clinician. From the pathogenic point of view, it is important to be confirmed or rejected the presence of human papilloma viruses (HPVs) in each case of affected patient, as this information is mandatory in respect to the adequate selection of the subsequent regimen. If HPVs are detected, systemic antiviral therapy could be initiated to reduce the size of the lesions before subsequent surgical eradication. A postoperative prevention through vaccination could be also considered additionally. In cases of HPV-negative giant extragenital forms of Morbus Bowen (as in the described patient), the focus should be on local immunomodulation by substances such as imiquimod, which reduce the size of the lesions, thereby creating optimal opportunities for their future surgical eradication. Other possible options described in the literature include topical application of 5-fluorouracil, photodynamic therapy, cryotherapy, and laser therapy (carbon dioxide laser). The choice of the most appropriate regimen should have been an individual decision of the clinician, considering also the location and the extent of the lesion.

  7. Gas Giants Form Quickly

    NASA Technical Reports Server (NTRS)

    2007-01-01

    This is an artist's concept of a hypothetical 10-million-year-old star system. The bright blur at the center is a star much like our sun. The other orb in the image is a gas-giant planet like Jupiter. Wisps of white throughout the image represent traces of gas.

    Astronomers using NASA's Spitzer Space Telescope have found evidence showing that gas-giant planets either form within the first 10 million years of a sun-like star's life, or not at all. The lifespan for sun-like stars is about 10 billion years.

    The scientists came to this conclusion after searching for traces of gas around 15 different sun-like stars, most with ages ranging from 3 million to 30 million years. With the help of Spitzer's Infrared Spectrometer instrument, they were able to search for relatively warm gas in the inner regions of these star systems, an area comparable to the zone between Earth and Jupiter in our own solar system. They also used ground-based radio telescopes to search for cooler gas in the outer regions of these systems, an area comparable to the zone around Saturn and beyond.

  8. Giant Intradiverticular Bladder Tumor

    PubMed Central

    Noh, Mohamad Syafeeq Faeez Md; Aziz, Ahmad Fuad Abdul; Ghani, Khairul Asri Mohd; Siang, Christopher Lee Kheng; Yunus, Rosna; Yusof, Mubarak Mohd

    2017-01-01

    Patient: Male, 74 Final Diagnosis: Giant intradiverticular bladder tumor with metastasis Symptoms: Hematuria Medication:— Clinical Procedure: — Specialty: Urology Objective: Rare disease Background: Intradiverticular bladder tumors are rare. This renders diagnosis of an intradiverticular bladder tumor difficult. Imaging plays a vital role in achieving the diagnosis, and subsequently staging of the disease. Case Report: A 74-year-old male presented to our center with a few months history of constitutional symptoms. Upon further history, he reported hematuria two months prior to presentation, which stopped temporarily, only to recur a few days prior to coming to the hospital. The patient admitted to having lower urinary tract symptoms. However, there was no dysuria, no sandy urine, and no fever. Palpation of his abdomen revealed a vague mass at the suprapubic region, which was non tender. In view of his history and the clinical examination findings, an ultrasound of the abdomen and computed tomography (CT) was arranged. These investigations revealed a giant tumor that seemed to be arising from a bladder diverticulum, with a mass effect and hydronephrosis. He later underwent operative intervention. Conclusions: Intradiverticular bladder tumors may present a challenge to the treating physician in an atypical presentation; thus requiring a high index of suspicion and knowledge of tumor pathophysiology. As illustrated in our case, CT with its wide availability and multiplanar imaging capabilities offers a useful means for diagnosis, disease staging, operative planning, and follow-up. PMID:28246375

  9. Reinflating Giant Planets

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-01-01

    Two new, large gas-giant exoplanets have been discovered orbiting close to their host stars. A recent study examining these planets and others like them may help us to better understand what happens to close-in hot Jupiters as their host stars reach the end of their main-sequence lives.OversizedGiantsUnbinned transit light curves for HAT-P-65b. [Adapted from Hartman et al. 2016]The discovery of HAT-P-65b and HAT-P-66b, two new transiting hot Jupiters, is intriguing. These planets have periods of just under 3 days and masses of roughly 0.5 and 0.8 times that of Jupiter, but their sizes are whats really interesting: they have inflated radii of 1.89 and 1.59 times that of Jupiter.These two planets, discovered using the Hungarian-made Automated Telescope Network (HATNet) in Arizona and Hawaii, mark the latest in an ever-growing sample of gas-giant exoplanets with radii larger than expected based on theoretical planetary structure models.What causes this discrepancy? Did the planets just fail to contract to the expected size when they were initially formed, or were they reinflated later in their lifetimes? If the latter, how? These are questions that scientists are only now starting to be able to address using statistics of the sample of close-in, transiting planets.Unbinned transit light curves for HAT-P-66b. [Hartman et al. 2016]Exploring Other PlanetsLed by Joel Hartman (Princeton University), the team that discovered HAT-P-65b and HAT-P-66b has examined these planets observed parameters and those of dozens of other known close-in, transiting exoplanets discovered with a variety of transiting exoplanet missions: HAT, WASP, Kepler, TrES, and KELT. Hartman and collaborators used this sample to draw conclusions about what causes some of these planets to have such large radii.The team found that there is a statistically significant correlation between the radii of close-in giant planets and the fractional ages of their host stars (i.e., the stars age divided by its full

  10. Allometry indicates giant eyes of giant squid are not exceptional

    PubMed Central

    2013-01-01

    Background The eyes of giant and colossal squid are among the largest eyes in the history of life. It was recently proposed that sperm whale predation is the main driver of eye size evolution in giant squid, on the basis of an optical model that suggested optimal performance in detecting large luminous visual targets such as whales in the deep sea. However, it is poorly understood how the eye size of giant and colossal squid compares to that of other aquatic organisms when scaling effects are considered. Results We performed a large-scale comparative study that included 87 squid species and 237 species of acanthomorph fish. While squid have larger eyes than most acanthomorphs, a comparison of relative eye size among squid suggests that giant and colossal squid do not have unusually large eyes. After revising constants used in a previous model we found that large eyes perform equally well in detecting point targets and large luminous targets in the deep sea. Conclusions The eyes of giant and colossal squid do not appear exceptionally large when allometric effects are considered. It is probable that the giant eyes of giant squid result from a phylogenetically conserved developmental pattern manifested in very large animals. Whatever the cause of large eyes, they appear to have several advantages for vision in the reduced light of the deep mesopelagic zone. PMID:23418818

  11. Giant planet formation via pebble accretion

    NASA Astrophysics Data System (ADS)

    Guilera, O. M.

    2016-08-01

    In the standard model of core accretion, the formation of giant planets occurs by two main processes: first, a massive core is formed by the accretion of solid material; then, when this core exceeds a critical value (typically greater than ) a gaseous runaway growth is triggered and the planet accretes big quantities of gas in a short period of time until the planet achieves its final mass. Thus, the formation of a massive core has to occur when the nebular gas is still available in the disk. This phenomenon imposes a strong time-scale constraint in the giant planet formation due to the fact that the lifetimes of the observed protoplanetary disks are in general lower than 10 Myr. The formation of massive cores before 10 Myr by accretion of big planetesimals (with radii 10 km) in the oligarchic growth regime is only possible in massive disks. However, planetesimal accretion rates significantly increase for small bodies, especially for pebbles, particles of sizes between mm and cm, which are strongly coupled with the gas. In this work, we study the formation of giant planets incorporating pebble accretion rates in our global model of planet formation.

  12. Giant magnetoelectric effect at low frequencies in polymer-based thin film composites

    SciTech Connect

    Kulkarni, A.; Meurisch, K.; Strunskus, T.; Faupel, F.; Teliban, I.; Jahns, R.; Knöchel, R.; Piorra, A.

    2014-01-13

    A polymer-based magnetoelectric 2-2 composite was fabricated in a thin film approach by direct spin coating of polyvinylidenefluoride-co-trifluoroethylene onto a Metglas substrate without the usage of an adhesive for the mechanical coupling between the piezoelectric and magnetostrictive materials. For a prototype single-sided clamped cantilever, a magnetoelectric coefficient as high as 850 V cm{sup −1} Oe{sup −1} is observed at its fundamental bending mode resonance frequency at 27.8 Hz and a detection limit of 10 pTHz{sup −1/2} at its second bending mode resonance frequency at 169.5 Hz.

  13. Giant photoluminescence emission in crystalline faceted Si grains

    PubMed Central

    Faraci, Giuseppe; Pennisi, Agata R.; Alberti, Alessandra; Ruggeri, Rosa; Mannino, Giovanni

    2013-01-01

    Empowering an indirect band-gap material like Si with optical functionalities, firstly light emission, represents a huge advancement constantly pursued in the realization of any integrated photonic device. We report the demonstration of giant photoluminescence (PL) emission by a newly synthesized material consisting of crystalline faceted Si grains (fg-Si), a hundred nanometer in size, assembled in a porous and columnar configuration, without any post processing. A laser beam with wavelength 632.8 nm locally produce such a high temperature, determined on layers of a given thickness by Raman spectra, to induce giant PL radiation emission. The optical gain reaches the highest value ever, 0.14 cm/W, representing an increase of 3 orders of magnitude with respect to comparable data recently obtained in nanocrystals. Giant emission has been obtained from fg-Si deposited either on glass or on flexible, low cost, polymeric substrate opening the possibility to fabricate new devices. PMID:24056300

  14. Magnetostriction measuring device based on an optical fiber sensor with an annular photodiode.

    PubMed

    de Manuel, V; Del Real, R P; Alonso, J; Guerrero, H

    2007-09-01

    A new simple and sensitive dilatometer to measure magnetostriction of ribbons has been developed, based on an optical fiber sensor using an annular photodiode. The optical fiber is used bidirectionally, both for emission and detection of light, simplifying the access to the ribbon under test. The working principle is based on the measurement by reflection of the longitudinal displacement of the ribbon end. For a Vitroperm amorphous ribbon of 100 mm length, 21 microm thickness, and 8.3 mm width, a displacement of 2.571 microm with a maximum uncertainty of 8 nm has been obtained.

  15. Behavior of magnetic field and eddy current in a magnetostriction based bi-layered composite

    NASA Astrophysics Data System (ADS)

    Zhang, Kewei; Zhang, Kehao; Liu, Huifeng; Li, Junlin

    2016-12-01

    In this paper, we presented a theoretical method for studying the behavior of magnetic field intensity and eddy current inside a magnetostriction based bi-layered composite. Firstly, the mathematical model for the electromagnetic field in the composite was established. Then, the governing equation for determining the magnetic field intensity and eddy current was solved. Furthermore, the effect of the composite's conductivity on the magnetic field intensity and eddy current were discussed. Lastly, by comparing with the well known R.L. Stoll's equation, the magnetic field intensity calculated based on our equation showed a less than 0.5% error.

  16. High resolution magnetostriction measurements in pulsed magnetic fields using fiber Bragg gratings.

    PubMed

    Daou, Ramzy; Weickert, Franziska; Nicklas, Michael; Steglich, Frank; Haase, Ariane; Doerr, Mathias

    2010-03-01

    We report on a new high resolution apparatus for measuring magnetostriction suitable for use at cryogenic temperatures in pulsed high magnetic fields which we have developed at the Hochfeld-Magnetlabor Dresden. Optical fiber strain gauges based on fiber Bragg gratings are used to measure the strain in small (approximately 1 mm) samples. We describe the implementation of a fast measurement system capable of resolving strains in the order of 10(-7) with a full bandwidth of 47 kHz, and demonstrate its use on single crystal samples of GdSb and GdSi.

  17. Spontaneous volume magnetostriction and non-Stoner behavior of the valence band in pure hcp Gd

    NASA Astrophysics Data System (ADS)

    Khmelevskyi, S.; Turek, I.; Mohn, P.

    2004-10-01

    Employing the disordered local moment formalism in combination with first-principles band-structure calculations, we study the behavior of the valence band in pure hcp Gd upon disorder of the local 4f GD moments. We show that the large value of the spontaneous volume magnetostriction in Gd is entirely due to changes in the magnetic state of the valence band at Tc and can be calculated in good agreement with experiment. The local exchange splitting of the valence band persists above Tc , which is in strong disagreement with the conventional Stoner picture. The analysis of our results provides a theoretical background for the discussion of recent photoemission experiments.

  18. FMR and torque studies of highly stressed magnetostrictive polycrystalline CoPd alloy films

    SciTech Connect

    Dubowik, J.; Szymanski, B.

    1994-03-01

    Ferromagnetic resonance (FMR) and torque curves have been measured in electrodeposited CoPd alloy films with composition ranged from Co{sub 13}Pd{sub 83} to Co{sub 45}Pd{sub 55}. The authors show that the origin of the multimode structure of FMR spectra in these strongly magnetostrictive polycrystalline films can be satisfactory explained on the basis of the independent-grain-approach for a textured microstructure. The fourfold periodicity of the torque curves for the compositional range of 30--35 at% is assumed to be oriented by inhomogeneous distribution of the magnetization direction.

  19. Enhanced magnetocaloric effect material

    DOEpatents

    Lewis, Laura J. H.

    2006-07-18

    A magnetocaloric effect heterostructure having a core layer of a magnetostructural material with a giant magnetocaloric effect having a magnetic transition temperature equal to or greater than 150 K, and a constricting material layer coated on at least one surface of the magnetocaloric material core layer. The constricting material layer may enhance the magnetocaloric effect by restriction of volume changes of the core layer during application of a magnetic field to the heterostructure. A magnetocaloric effect heterostructure powder comprising a plurality of core particles of a magnetostructural material with a giant magnetocaloric effect having a magnetic transition temperature equal to or greater than 150 K, wherein each of the core particles is encapsulated within a coating of a constricting material is also disclosed. A method for enhancing the magnetocaloric effect within a giant magnetocaloric material including the step of coating a surface of the magnetocaloric material with a constricting material is disclosed.

  20. [Giant esophageal fibrovascular polyp].

    PubMed

    Palacios, Fernando; Contardo, Carlos; Guevara, Jorge; Vera, Augusto; Aguilar, Luis; Huamán, Manuel; Palomino, Américo; Yabar, Alejandro

    2003-01-01

    Fibrovascular polyps are extremely rare benign neoplasias of the esophagus, which usually originate in the lower cricoid area. They do not produce any discomfort in the patient for a long time, however it may make itself evident by the patient's regurgitation of the polyp, producing asphyxia or, more frequently, dysphagia. The case of a 58 year old male patient is presented herein, with a 9 month record of dysphagia, weight loss and intermittent melena. The barium x-ray showed a distended esophagus, with a tumor running from the upper esophageal sphincter to the cardia. The endoscopy confirmed the presence of a pediculated tumor, implanted in the cervical esophagus. Surgeons suspected the potential malignancy of the tumor and performed a transhiatal esophagectomy. The final pathologic diagnosis was giant fibrovascular esophageal polyp.

  1. Giant resonances: Progress, new directions, new challenges

    SciTech Connect

    Bertrand, J.R.; Beene, J.R.

    1989-01-01

    A review of some recent developments in the field of giant multipole resonances is presented. Particular emphasis is placed on directions that the authors feel will be followed in this field during the next several years. In particular, the use of high-energy heavy ions to excite the giant resonances is shown to provide exciting new capabilities for giant resonance studies. Among subjects covered are: Coulomb excitation of giant resonances, photon decay of giant resonances, the recent controversy over the identity of the giant monopole resonance, the most recent value for incompressibility of nuclear matter from analysis of giant monopole data, the isospin character of the 63 A/sup /minus/1/3/ GQR, agreement between (e,e/prime/) and (hadron, hadron/prime/) excitation of the giant quadrupole resonance, prospects for multiphonon giant resonance observation, and isolation of the isovector giant quadrupole resonance. 55 refs., 23 figs., 4 tabs.

  2. Giant Hedge-Hogs: Spikes on Giant Gravitons

    SciTech Connect

    Sadri, D

    2004-01-28

    We consider giant gravitons on the maximally supersymmetric plane-wave background of type IIB string theory. Fixing the light-cone gauge, we work out the low energy effective light-cone Hamiltonian of the three-sphere giant graviton. At first order, this is a U(1) gauge theory on R x S{sup 3}. We place sources in this effective gauge theory. Although non-vanishing net electric charge configurations are disallowed by Gauss' law, electric dipoles can be formed. From the string theory point of view these dipoles can be understood as open strings piercing the three-sphere, generalizing the usual BIons to the giant gravitons, BIGGons. Our results can be used to give a two dimensional (worldsheet) description of giant gravitons, similar to Polchinski's description for the usual D-branes, in agreement with the discussions of hep-th/0204196.

  3. A giant Ordovician anomalocaridid.

    PubMed

    Van Roy, Peter; Briggs, Derek E G

    2011-05-26

    Anomalocaridids, giant lightly sclerotized invertebrate predators, occur in a number of exceptionally preserved early and middle Cambrian (542-501 million years ago) biotas and have come to symbolize the unfamiliar morphologies displayed by stem organisms in faunas of the Burgess Shale type. They are characterized by a pair of anterior, segmented appendages, a circlet of plates around the mouth, and an elongate segmented trunk lacking true tergites with a pair of flexible lateral lobes per segment. Disarticulated body parts, such as the anterior appendages and oral circlet, had been assigned to a range of taxonomic groups--but the discovery of complete specimens from the middle Cambrian Burgess Shale showed that these disparate elements all belong to a single kind of animal. Phylogenetic analyses support a position of anomalocaridids in the arthropod stem, as a sister group to the euarthropods. The anomalocaridids were the largest animals in Cambrian communities. The youngest unequivocal examples occur in the middle Cambrian Marjum Formation of Utah but an arthropod retaining some anomalocaridid characteristics is present in the Devonian of Germany. Here we report the post-Cambrian occurrence of anomalocaridids, from the Early Ordovician (488-472 million years ago) Fezouata Biota in southeastern Morocco, including specimens larger than any in Cambrian biotas. These giant animals were an important element of some marine communities for about 30 million years longer than previously realized. The Moroccan specimens confirm the presence of a dorsal array of flexible blades attached to a transverse rachis on the trunk segments; these blades probably functioned as gills.

  4. Tetragonal magnetostriction and magnetoelastic coupling in Fe-Al, Fe-Ga, Fe-Ge, Fe-Si, Fe-Ga-Al, and Fe-Ga-Ge alloys

    NASA Astrophysics Data System (ADS)

    Restorff, J. B.; Wun-Fogle, M.; Hathaway, K. B.; Clark, A. E.; Lograsso, T. A.; Petculescu, G.

    2012-01-01

    This paper presents a comparative study on the tetragonal magnetostriction constant, λγ,2, [ = (3/2)λ100] and magnetoelastic coupling, b1, of binary Fe100-xZx (0 < x < 35, Z = Al, Ga, Ge, and Si) and ternary Fe-Ga-Al and Fe-Ga-Ge alloys. The quantities are corrected for magnetostrains due to sample geometry (the magnetostrictive form effect). Recently published elastic constant data along with magnetization measurements at both room temperature and 77 K make these corrections possible. The form effect correction lowers the magnetostriction by ˜10 ppm for high-modulus alloys and by as much as 30 ppm for low-modulus alloys. The elastic constants are also used to determine the values of the magnetoelastic coupling constant, b1. With the new magnetostriction data on the Fe-Al-Ga alloy, it is possible to show how the double peak magnetostriction feature of the binary Fe-Ga alloy flows into the single peak binary Fe-Al alloy. The corrected magnetostriction and magnetoelastic coupling data for the various alloys are also compared using the electron-per-atom ratio, e/a, as the common variable. The Hume-Rothery rules link the e/a ratio to the regions of phase stability, which appear to be intimately related to the magnetostriction versus the solute concentration curve in these alloys. Using e/a as the abscissa tends to align the peaks in the magnetostriction and magnetoelastic coupling for the Fe-Ga, Fe-Ge, Fe-Al, Fe-Ga-Al, and Fe-Ga-Ge alloys, but not for the Fe-Si alloys for which the larger atomic size difference may play a greater role in phase stabilization. Corrections for the form effect are also presented for the rhombohedral magnetostriction, λɛ,2, and the magnetoelastic coupling, b2, of Fe100-xGax (0 < x < 35) alloys.

  5. Pharma giants swap research programs.

    PubMed

    2014-07-01

    Pharmaceutical giants Novartis and GlaxoSmithKline (GSK) agreed in late April to swap some assets, with Novartis handing off its vaccine business to GSK and getting most of the British company's cancer portfolio in return.

  6. Theories of Giant Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Young, Richard E. (Technical Monitor)

    1998-01-01

    An overview of current theories of planetary formation, with emphasis on giant planets, is presented. The most detailed models are based upon observations of our own Solar System and of young stars and their environments. While these models predict that rocky planets should form around most single stars, the frequency of formation of gas giant planets is more difficult to predict theoretically. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth as do terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. Most models for extrasolar giant planets suggest that they formed as did Jupiter and Saturn (in nearly circular orbits, far enough from the star that ice could), and subsequently migrated to their current positions, although some models suggest in situ formation.

  7. Lichens On Galapagos Giant Tortoises.

    PubMed

    Hendrickson, J R; Weber, W A

    1964-06-19

    The association of Physcia picta with the giant Galdpagos tortoise is believed to be the first reported occurrence of lichens on land animals. The habitat is restricted to specific sites on the carapace of male tortoises.

  8. Landscape of the lost giants

    NASA Astrophysics Data System (ADS)

    2013-09-01

    The Pleistocene megafauna extinction erased a group of remarkable animals. Whether humans had a prominent role in the extinction remains controversial, but it is emerging that the disappearance of the giants has markedly affected the environment.

  9. Atmospheres of Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Marley, Mark

    2006-01-01

    The next decade will almost certainly see the direct imaging of extrasolar giant planets around nearby stars. Unlike purely radial velocity detections, direct imaging will open the door to characterizing the atmosphere and interiors of extrasola planets and ultimately provide clues on their formation and evolution through time. This process has already begun for the transiting planets, placing new constraints on their atmospheric structure, composition, and evolution. Indeed the key to understanding giant planet detectability, interpreting spectra, and constraining effective temperature and hence evolution-is the atmosphere. I will review the universe of extrasolar giant planet models, focusing on what we have already learned from modeling and what we will likely be able to learn from the first generation of direct detection data. In addition to these theoretical considerations, I will review the observations and interpretation of the - transiting hot Jupiters. These objects provide a test of our ability to model exotic atmospheres and challenge our current understanding of giant planet evolution.

  10. Giant Magnetoresistance: Basic Concepts, Microstructure, Magnetic Interactions and Applications

    PubMed Central

    Ennen, Inga; Kappe, Daniel; Rempel, Thomas; Glenske, Claudia; Hütten, Andreas

    2016-01-01

    The giant magnetoresistance (GMR) effect is a very basic phenomenon that occurs in magnetic materials ranging from nanoparticles over multilayered thin films to permanent magnets. In this contribution, we first focus on the links between effect characteristic and underlying microstructure. Thereafter, we discuss design criteria for GMR-sensor applications covering automotive, biosensors as well as nanoparticular sensors. PMID:27322277

  11. Forced Volume Magnetostriction in Composite Gd5Si2Ge2

    SciTech Connect

    Choe, W; McCall, S K; Radousky, H B; Nersessian, N; Or, S W; Carman, G P; Pecharsky, V K; Pecharsky, A O

    2004-04-01

    A -1200 ppm forced volume magnetostriction has been obtained in a [0-3], resin binder, Gd{sub 5}Si{sub 2}Ge{sub 2} particulate composite. The strain is a result of a magnetically induced phase transformation from a high volume (high temperature, low magnetic field) monoclinic phase to a low volume (low temperature, high magnetic field) orthorhombic phase. The particles used in the composite were ball-milled from a bulk sample and were sieved to obtain a size distribution of {approx}> 600 {micro}m. Bulk Gd{sub 5}Si{sub 2}Ge{sub 2} was manufactured via arc melting and subsequently annealed at 1300 C for 1 hour to produce a textured, polycrystalline sample. The transformation temperatures of the bulk sample, as measured using a Differential Scanning Calorimeter (DSC), were M{sub s}= -9.3 C, M{sub f}=-14.6 C, A{sub s}=-4.4 C, and A{sub f}=-1.2 C. The composite and the bulk samples were magnetically characterized using a SQUID magnetometer, and found to undergo a paramagnetic to ferromagnetic transition during the phase transformation, consistent with published results. The bulk sample was also found to possess a maximum linear magnetostriction -2500 ppm.

  12. Ordering, magnetostriction, and elastic properties in Fe-27.5 at. % Ga alloy single crystals

    SciTech Connect

    Jayaraman, Tanjore V.; Corson, Robert P.; Guruswamy, Sivaraman

    2007-09-01

    Fe-Ga alloys, with composition around 27.5 at. % Ga, can be heat treated to obtain {alpha} (A2, bcc), {alpha}{sup ''} (D0{sub 3}-like, ordered bcc), {beta}-Fe{sub 3}Ga (D0{sub 19}, ordered hexagonal), and {alpha}-Fe{sub 3}Ga (L1{sub 2} ordered fcc) phases. In this work, the influence of {alpha}{sup ''} ordering on the magnetostriction coefficient (3/2) {lambda}{sub 100}, elastic constants (C{sub 11}, C{sub 12}, and C{sub 44}), and the magnetomechanical coefficients (B{sub 1}) of the single crystals of {alpha}-Fe-27.5 at.% Ga and {alpha}{sup ''}-Fe-27.5 at. % Ga alloy is examined. Single crystals of Fe-27.5 at. % Ga were grown using the vertical Bridgman technique. Magnetostriction measurements were performed using [100]-oriented single crystals. Elastic constants were estimated using resonant ultrasound spectroscopy and analysis technique. It is shown that the {alpha}{sup ''} ordering in Fe-27.5 at. % Ga alloy decreases the (3/2) {lambda}{sub 100} value from that of {alpha} phase. This is consistent with our previous work on polycrystalline Fe-27.5 at. % Ga alloys. The {alpha}-Fe-27.5 at.% Ga alloy single crystal was found to have a higher magnetoelastic coupling constant than the {alpha}{sup ''}-Fe-27.5 at. % Ga alloy single crystal.

  13. Technique for measurement of magnetostriction in an individual nanowire using atomic force microscopy

    SciTech Connect

    Jin Park, Jung Flatau, Alison B.; Estrine, Eliot C.; Madhukar Reddy, Sai; Stadler, Bethanie J. H.

    2014-05-07

    We have investigated a method for measuring the dimensions of an individual multilayered Fe-Ga/Cu nanowire (NW) as it changes with induced magnetization. In this study, we demonstrate the proposed approach and establish this as a viable method for measuring the magnetostrictive behavior of an individual Fe-Ga/Cu NW using atomic force microscopy (AFM). When an external magnetic field (∼300 Oe) was applied perpendicular to the NW axis, the NW length appeared minimized. When a field (∼1000 Oe) was applied parallel to the NW axis, the height profile of the NW was found to be higher than in the case with no parallel external field. Since both ends of the NW were welded to the substrate, the magnetic field induced dimensional change of the NW caused deflection of the NW in the upward direction, which was significant enough to be detected by AFM. An average height difference of 15 nm was measured with and without an applied field which was then used to calculate the magnetostriction of the multilayered NW.

  14. Influence of volume magnetostriction on the thermodynamic properties of Ni-Mn-Ga shape memory alloys

    SciTech Connect

    Kosogor, Anna; L'vov, Victor A.; Cesari, Eduard

    2015-10-07

    In the present article, the thermodynamic properties of Ni-Mn-Ga ferromagnetic shape memory alloys exhibiting the martensitic transformations (MTs) above and below Curie temperature are compared. It is shown that when MT goes below Curie temperature, the elastic and thermal properties of alloy noticeably depend on magnetization value due to spontaneous volume magnetostriction. However, the separation of magnetic parts from the basic characteristics of MT is a difficult task, because the volume magnetostriction does not qualitatively change the transformational behaviour of alloy. This problem is solved for several Ni-Mn-Ga alloys by means of the quantitative theoretical analysis of experimental data obtained in the course of stress-strain tests. For each alloy, the entropy change and the transformation heat evolved in the course of MT are evaluated, first, from the results of stress-strain tests and, second, from differential scanning calorimetry data. For all alloys, a quantitative agreement between the values obtained in two different ways is observed. It is shown that the magnetic part of transformation heat exceeds the non-magnetic one for the Ni-Mn-Ga alloys undergoing MTs in ferromagnetic state, while the elevated values of transformation heat measured for the alloys undergoing MTs in paramagnetic state are caused by large MT strains.

  15. DC magnetic field sensor based on electric driving and magnetic tuning in piezoelectric/magnetostrictive bilayer

    NASA Astrophysics Data System (ADS)

    Zhang, Long; Wing Or, Siu; Ming Leung, Chung; Ho, S. L.

    2014-05-01

    A dc magnetic field sensor possessing an interestingly high electric voltage-driven, magnetic field-tuned dc magnetoelectric (ME) effect is developed based on a bilayer of Pb(Zr, Ti)O3 piezoelectric transformer and Tb0.3Dy0.7Fe1.92 magnetostrictive substrate. The dc ME effect in the sensor, as evaluated experimentally and theoretically, is induced by driving the bilayer at its zero-field longitudinal resonance frequency (fr0) using an ac electric voltage (Vac) referenced at the input of the piezoelectric transformer, as well as, by tuning the field-dependent compliance and resonance characteristics of the bilayer with the dc magnetic field to be measured (Hdc) upon the negative-ΔE effect intrinsic in the magnetostrictive substrate. The sensor shows a good linear negative response of ac ME voltage (VME) at the output of the piezoelectric transformer to a broad range of Hdc of 0-350 Oe under a small Vac of 2.5 V peak at the designated fr0 of 125.3 kHz. This gives a high negative dc magnetic field sensitivity (S) of -1.58 mV/Oe.

  16. Ordering, magnetostriction, and elastic properties in Fe-27.5 at. % Ga alloy single crystals

    NASA Astrophysics Data System (ADS)

    Jayaraman, Tanjore V.; Corson, Robert P.; Guruswamy, Sivaraman

    2007-09-01

    Fe-Ga alloys, with composition around 27.5at.% Ga, can be heat treated to obtain α (A2, bcc), α″ (D03-like, ordered bcc), β-Fe3Ga (D019, ordered hexagonal), and α-Fe3Ga (L12 ordered fcc) phases. In this work, the influence of α″ ordering on the magnetostriction coefficient (3/2) λ100, elastic constants (C11, C12, and C44), and the magnetomechanical coefficients (B1) of the single crystals of α-Fe-27.5at. % Ga and α″-Fe-27.5at.% Ga alloy is examined. Single crystals of Fe-27.5at.% Ga were grown using the vertical Bridgman technique. Magnetostriction measurements were performed using [100]-oriented single crystals. Elastic constants were estimated using resonant ultrasound spectroscopy and analysis technique. It is shown that the α″ ordering in Fe-27.5at.% Ga alloy decreases the (3/2) λ100 value from that of α phase. This is consistent with our previous work on polycrystalline Fe-27.5at.% Ga alloys. The α-Fe-27.5at. % Ga alloy single crystal was found to have a higher magnetoelastic coupling constant than the α″-Fe-27.5at.% Ga alloy single crystal.

  17. Anomalous Mössbauer fraction in small magnetic particles due to magnetostriction

    NASA Astrophysics Data System (ADS)

    Mohie-Eldin, M.-E. Y.; Gunther, L.

    1993-10-01

    The biological molecule ferritin and its proven synthetic counterpart polysaccharide iron complex (PIC) have been shown to contain small (< 100 Å in diameter) antiferrimagnetic cores at their centers. Mössbauer studies of these molecules have revealed an anomalous drop in the Mössbauer fraction (ƒ-factor) as the temperature rises above 30 K for mammalian ferritin and 60 K for PIC. Above the blocking temperature, superparamagnetic relaxation results in the disappearance of hyperfine splitting. Data that are treated with FFT procedures to eliminate the thickness effect still exhibit this anomaly. We have investigated the effect of superparamagnetic relaxation on the ƒ-factor. Spin-lattice relaxation was excluded based upon a calculation of the rate of energy transfer from the spin system to the lattice. We have found the following process as a plausible explanation of the anomaly: Superparamagnetic relaxation brings about a dynamical displacement of the Mössbauer nucleus through magnetostriction. These displacements produce a Doppler broadening of the Mössbauer spectrum that reduces the apparent ƒ-factor. The temperature dependence of the theoretically calculated ƒ-factor agrees qualitatively with experiment. Finally, there is semi-quantitative agreement if the as yet unknown dimensionless magnetostriction constant were to be on the order of 10 -3.

  18. Materialism.

    PubMed

    Melnyk, Andrew

    2012-05-01

    Materialism is nearly universally assumed by cognitive scientists. Intuitively, materialism says that a person's mental states are nothing over and above his or her material states, while dualism denies this. Philosophers have introduced concepts (e.g., realization and supervenience) to assist in formulating the theses of materialism and dualism with more precision, and distinguished among importantly different versions of each view (e.g., eliminative materialism, substance dualism, and emergentism). They have also clarified the logic of arguments that use empirical findings to support materialism. Finally, they have devised various objections to materialism, objections that therefore serve also as arguments for dualism. These objections typically center around two features of mental states that materialism has had trouble in accommodating. The first feature is intentionality, the property of representing, or being about, objects, properties, and states of affairs external to the mental states. The second feature is phenomenal consciousness, the property possessed by many mental states of there being something it is like for the subject of the mental state to be in that mental state. WIREs Cogn Sci 2012, 3:281-292. doi: 10.1002/wcs.1174 For further resources related to this article, please visit the WIREs website.

  19. Spin-lattice coupling in uranium dioxide probed by magnetostriction measurements at high magnetic fields (P08358-E001-PF)

    SciTech Connect

    Gofryk, K.; Jaime, M.

    2014-12-01

    Our preliminary magnetostriction measurements have already shown a strong interplay of lattice dynamic and magnetism in both antiferromagnetic and paramagnetic states, and give unambiguous evidence of strong spin- phonon coupling in uranium dioxide. Further studies are planned to address the puzzling behavior of UO2 in magnetic and paramagnetic states and details of the spin-phonon coupling.

  20. Dy substitution effect on the temperature dependences of magnetostriction in Pr1-x Dy x Fe1.9 alloys

    NASA Astrophysics Data System (ADS)

    Tang, Yan-Mei; Huang, Hai-Fu; Tang, Shao-Long; Du, You-Wei

    2016-11-01

    The temperature dependences of magnetostriction in Pr1-x Dy x Fe1.9 (0 ≤ x ≤ 1.0) alloys between 5 K and 300 K were investigated. An unusual decrease of magnetostriction with temperature decreasing was found in Pr-rich alloys (0 ≤ x ≤ 0.2), due to the change of the easy magnetization direction (EMD). Dy substitution reduces the magnetostriction in high-magnetic field (10 kOe ≤ H ≤ 90 kOe) at 5 K, while a small amount of Dy substitution (x = 0.05) is beneficial to increasing the magnetostriction in low-magnetic field between 10 K and 50 K. This makes the alloys a potential candidate for low temperature applications. Project supported by the National Natural Science Foundation of China (Grant No. U1232210), the Science Foundation of Guangxi Zhuang Autonomous Region, China (Grant No. 2015GXNSFBA139020), and the Enhancement of the Basic Ability of Teachers of Guangxi Zhuang Autonomous Region, China (Grant No. KY2016YB068).

  1. Structure and magnetic properties of mechanically alloyed Tb{sub 0.7}Pr{sub 0.3}(Fe{sub 0.9}B{sub 0.1}){sub 1.93} and the magnetostriction of its epoxy composites

    SciTech Connect

    Liu, J.J.; Ren, W.J.; Zhao, X.G.; Liu, W.; Zhang, Z.D.

    2005-05-15

    The C15 Laves phase with composition Tb{sub 0.7}Pr{sub 0.3}(Fe{sub 0.9}B{sub 0.1}){sub 1.93} has been synthesized by mechanical alloying and subsequent annealing process. The structure and magnetic properties of Tb{sub 0.7}Pr{sub 0.3}(Fe{sub 0.9}B{sub 0.1}){sub 1.93} have been investigated. The effect of the annealing on the magnetic properties has been studied. The samples annealed at 773 K are found to have a coercivity of 6.66 kOe at room temperature. The coercivity decreases monotonically with increase in the annealing temperature. The epoxy/Tb{sub 0.7}Pr{sub 0.3}(Fe{sub 0.9}B{sub 0.1}){sub 1.93} composites have been produced by a cold compression-molding technique. The magnetostriction of the epoxy/Tb{sub 0.7}Pr{sub 0.3}(Fe{sub 0.9}B{sub 0.1}){sub 1.93} composites with different weight ratios of epoxy resin to powder is measured by a standard strain technique. The Tb{sub 0.7}Pr{sub 0.3}(Fe{sub 0.9}B{sub 0.1}){sub 1.93} composites, with a weight ratio of epoxy resin to powder of 5:100, have a high magnetostriction of 810 ppm, at an applied magnetic field of 12 kOe. The Tb{sub 0.7}Pr{sub 0.3}(Fe{sub 0.9}B{sub 0.1}){sub 1.93} alloy combines a high magnetostriction with a low coercivity, which is a promising magnetostrictive material.

  2. Giants in the Local Region

    NASA Astrophysics Data System (ADS)

    Luck, R. Earle; Heiter, Ulrike

    2007-06-01

    We present parameter and abundance data for a sample of 298 nearby giants. The spectroscopic data for this work have a resolution of R~60,000, S/N>150, and spectral coverage from 475 to 685 nm. Overall trends in the Z>10 abundances are dominated by Galactic chemical evolution, while the light-element abundances are influenced by stellar evolution, as well as Galactic evolution. We find several super-Li stars in our sample and confirm that Li abundances in the first giant branch are related to mixing depths. Once astration of lithium on the main sequence along with the overall range of main-sequence lithium abundances are taken into account, the lithium abundances of the giants are not dramatically at odds with the predictions of standard stellar evolution. We find the giants to be carbon-diluted in accord with standard stellar evolution and that the carbon and oxygen abundances determined for the local giants are consistent with those found in local field dwarfs. We find that there is evidence for systematic carbon variations in the red giant clump in the sense that the blue side of the clump is carbon-poor (more diluted) than the red side.

  3. METALLICITIES OF PLANET-HOSTING STARS: A SAMPLE OF GIANTS AND SUBGIANTS

    SciTech Connect

    Ghezzi, L.; Cunha, K.; Schuler, S. C.; Smith, V. V.

    2010-12-10

    This work presents a homogeneous derivation of atmospheric parameters and iron abundances for a sample of giant and subgiant stars which host giant planets, as well as a control sample of subgiant stars not known to host giant planets. The analysis is done using the same technique as for our previous analysis of a large sample of planet-hosting and control sample dwarf stars. A comparison between the distributions of [Fe/H] in planet-hosting main-sequence (MS) stars, subgiants, and giants within these samples finds that the MS stars and subgiants have the same mean metallicity of ([Fe/H]){approx_equal} +0.11 dex, while the giant sample is typically more metal poor, having an average metallicity of [Fe/H] = -0.06 dex. The fact that the subgiants have the same average metallicities as the dwarfs indicates that significant accretion of solid metal-rich material onto the planet-hosting stars has not taken place, as such material would be diluted in the evolution from dwarf to subgiant. The lower metallicity found for the planet-hosting giant stars in comparison with the planet-hosting dwarfs and subgiants is interpreted as being related to the underlying stellar mass, with giants having larger masses and thus, on average, larger-mass protoplanetary disks. In core accretion models of planet formation, larger disk masses can contain the critical amount of metals necessary to form giant planets even at lower metallicities.

  4. Coordinated observations of interacting peculiar red giant binaries, 1

    NASA Technical Reports Server (NTRS)

    Ake, T.

    1995-01-01

    IUE Observations were begun for a two-year program to monitor the UV variability of three interacting peculiar red giant (PRG) binaries, HD 59643 (C6,s) HD 35155 (S3/2), and HR 1105 (S3.5/2.5). All of these systems were suspected to involve accretion of material from the PRG to a white-dwarf secondary, based mainly on previous IUE investigations. From our earlier surveys of PRG's, they were primary candidates to test the hypothesis that Tc-poor PRG's are formed as a result of mass transfer from a secondary component rather than from internal thermal pulsing while on the asymptotic red giant branch.

  5. The absence of circumstellar dust debris around G giants

    SciTech Connect

    Jura, M. )

    1990-12-01

    The IRAS data base has been searched for evidence for circumstellar dust around luminosity class III G giants, stars whose progenitors are mostly main-sequence A stars. While 20 percent of all main-sequence A dwarfs have dust which absorbs at least 5 x 10 to the -6th of the light from the star, less than 3 percent of all G giants have such clouds. One possible explanation for the absence of detectable dust debris around the G giants is that the Poynting-Robertson effect leads to the decay of the dust around the main-sequence A stars, and that the supply of these grains is not renewed indefinitely. In this case, the derived upper limit to the grain radius of about 0.2 cm for the bulk of the grains emitting the far-infrared emission is consistent with data derived from ground-based submillimeter observations. Another possible explanation for the lack of grains around at least some G giants is that the dust around the original A dwarf is mainly composed of relatively volatile material like water ice which thermally evaporates in a relatively short time during the giant phase of higher luminosity. 35 refs.

  6. The absence of circumstellar dust debris around G giants

    NASA Technical Reports Server (NTRS)

    Jura, M.

    1990-01-01

    The IRAS data base has been searched for evidence for circumstellar dust around luminosity class III G giants, stars whose progenitors are mostly main-sequence A stars. While 20 percent of all main-sequence A dwarfs have dust which absorbs at least 5 x 10 to the -6th of the light from the star, less than 3 percent of all G giants have such clouds. One possible explanation for the absence of detectable dust debris around the G giants is that the Poynting-Robertson effect leads to the decay of the dust around the main-sequence A stars, and that the supply of these grains is not renewed indefinitely. In this case, the derived upper limit to the grain radius of about 0.2 cm for the bulk of the grains emitting the far-infrared emission is consistent with data derived from ground-based submillimeter observations. Another possible explanation for the lack of grains around at least some G giants is that the dust around the original A dwarf is mainly composed of relatively volatile material like water ice which thermally evaporates in a relatively short time during the giant phase of higher luminosity.

  7. A unique advantage for giant eyes in giant squid.

    PubMed

    Nilsson, Dan-Eric; Warrant, Eric J; Johnsen, Sönke; Hanlon, Roger; Shashar, Nadav

    2012-04-24

    Giant and colossal deep-sea squid (Architeuthis and Mesonychoteuthis) have the largest eyes in the animal kingdom [1, 2], but there is no explanation for why they would need eyes that are nearly three times the diameter of those of any other extant animal. Here we develop a theory for visual detection in pelagic habitats, which predicts that such giant eyes are unlikely to evolve for detecting mates or prey at long distance but are instead uniquely suited for detecting very large predators, such as sperm whales. We also provide photographic documentation of an eyeball of about 27 cm with a 9 cm pupil in a giant squid, and we predict that, below 600 m depth, it would allow detection of sperm whales at distances exceeding 120 m. With this long range of vision, giant squid get an early warning of approaching sperm whales. Because the sonar range of sperm whales exceeds 120 m [3-5], we hypothesize that a well-prepared and powerful evasive response to hunting sperm whales may have driven the evolution of huge dimensions in both eyes and bodies of giant and colossal squid. Our theory also provides insights into the vision of Mesozoic ichthyosaurs with unusually large eyes.

  8. Formation of the giant planets

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    2006-01-01

    The observed properties of giant planets, models of their evolution and observations of protoplanetary disks provide constraints on the formation of gas giant planets. The four largest planets in our Solar System contain considerable quantities of hydrogen and helium, which could not have condensed into solid planetesimals within the protoplanetary disk. All three (transiting) extrasolar giant planets with well determined masses and radii also must contain substantial amounts of these light gases. Jupiter and Saturn are mostly hydrogen and helium, but have larger abundances of heavier elements than does the Sun. Neptune and Uranus are primarily composed of heavier elements. HD 149026 b, which is slightly more massive than is Saturn, appears to have comparable quantities of light gases and heavy elements. HD 209458 b and TrES-1 are primarily hydrogen and helium, but may contain supersolar abundances of heavy elements. Spacecraft flybys and observations of satellite orbits provide estimates of the gravitational moments of the giant planets in our Solar System, which in turn provide information on the internal distribution of matter within Jupiter, Saturn, Uranus and Neptune. Atmospheric thermal structure and heat flow measurements constrain the interior temperatures of planets. Internal processes may cause giant planets to become more compositionally differentiated or alternatively more homogeneous; high-pressure laboratory .experiments provide data useful for modeling these processes. The preponderance of evidence supports the core nucleated gas accretion model. According to this model, giant planets begin their growth by the accumulation of small solid bodies, as do terrestrial planets. However, unlike terrestrial planets, the growing giant planet cores become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. The primary questions regarding the core nucleated growth model is under what conditions

  9. Clump Giants in the Hyades

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard F. (Technical Monitor); Brickhouse, Nancy

    2003-01-01

    The project is entitled 'Clump Giants in the Hyades.' This observation of one of the late-type Hyades giants (Gamma Tau) has implications for understanding the formation of late-type stellar coronae as a function of the evolutionary state of the star. The Hyades giants are interesting because they are all clump giants in the Helium burning phase, similar to the cool primary of Capella. The Hyades giants show significantly more magnetic activity than expected from their state of evolution (and slowed-down rotation). Thus these systems provide an important clue to dynamo action. The data were obtained by the satellite on 13 March 2001 for a total RGS exposure of 58220 seconds. These data were delivered to the PI on 7 August 2001. The data could not be reprocessed until SAS Version 5.3.3 which became available 7 June 2002. Although the guidelines for assessing background rates suggested that half the data were contaminated, it does not appear that the spectral region of the RGS was adversely affected by unusually high background. The spectra show strong lines of Fe XVII and XVIII, O VII and VIII, Ne IX and X, along with numerous weaker lines. The emission measure distribution is highly reminiscent of Capella; if anything, the emission measure distribution is steeper at 6 million K than for Capella. Gamma Tau is the second brightest of the Hyades clump giants. Pallavicini et al. have shown that the luminosity of the brightest Hyades giant (Theta Tau) is remarkably similar to its luminosity as measured by Einstein. Short-term variability is also modest. We are addressing the variability issue now for Gamma Tau. Initial results were reported at the 2003 Seattle AAS meeting. A paper is in preparation for submission to the Astrophysical Journal.

  10. Multiferroic Nanopatterned Hybrid Material with Room-Temperature Magnetic Switching of the Electric Polarization.

    PubMed

    Cai, Ronggang; Antohe, Vlad-Andrei; Hu, Zhijun; Nysten, Bernard; Piraux, Luc; Jonas, Alain M

    2017-02-01

    A nanopatterned hybrid layer is designed, wherein the electric polarization can be flipped at room temperature by a magnetic field aided by an electrical field. This is achieved by embedding ferromagnetic nanopillars in a continuous organic ferroelectric layer, and amplifying the magnetostriction-generated stress gradients by scaling down the supracrystalline cell of the material.

  11. Giant strain with ultra-low hysteresis and high temperature stability in grain oriented lead-free K0.5Bi0.5TiO3-BaTiO3-Na0.5Bi0.5TiO3 piezoelectric materials

    PubMed Central

    Maurya, Deepam; Zhou, Yuan; Wang, Yaojin; Yan, Yongke; Li, Jiefang; Viehland, Dwight; Priya, Shashank

    2015-01-01

    We synthesized grain-oriented lead-free piezoelectric materials in (K0.5Bi0.5TiO3-BaTiO3-xNa0.5Bi0.5TiO3 (KBT-BT-NBT) system with high degree of texturing along the [001]c (c-cubic) crystallographic orientation. We demonstrate giant field induced strain (~0.48%) with an ultra-low hysteresis along with enhanced piezoelectric response (d33 ~ 190pC/N) and high temperature stability (~160°C). Transmission electron microscopy (TEM) and piezoresponse force microscopy (PFM) results demonstrate smaller size highly ordered domain structure in grain-oriented specimen relative to the conventional polycrystalline ceramics. The grain oriented specimens exhibited a high degree of non-180° domain switching, in comparison to the randomly axed ones. These results indicate the effective solution to the lead-free piezoelectric materials. PMID:25716551

  12. Giant strain with ultra-low hysteresis and high temperature stability in grain oriented lead-free K₀̣₅Bi₀̣₅TiO₃-BaTiO₃-Na₀̣₅Bi₀̣₅TiO₃ piezoelectric materials

    SciTech Connect

    Maurya, Deepam; Zhou, Yuan; Wang, Yaojin; Yan, Yongke; Li, Jiefang; Viehland, Dwight; Priya, Shashank

    2015-02-26

    We synthesized grain-oriented lead-free piezoelectric materials in (K₀̣₅Bi₀̣₅TiO₃-BaTiO₃-xNa₀̣₅Bi₀̣₅TiO₃ (KBT-BT-NBT) system with high degree of texturing along the [001]c (c-cubic) crystallographic orientation. We demonstrate giant field induced strain (~0.48%) with an ultra-low hysteresis along with enhanced piezoelectric response (d₃₃ ~ 190pC/N) and high temperature stability (~160°C). Transmission electron microscopy (TEM) and piezoresponse force microscopy (PFM) results demonstrate smaller size highly ordered domain structure in grain-oriented specimen relative to the conventional polycrystalline ceramics. The grain oriented specimens exhibited a high degree of non-180° domain switching, in comparison to the randomly axed ones. These results indicate the effective solution to the lead-free piezoelectric materials.

  13. Magnetostriction and complex permeability of [Fe62Co19Ga19/Py]5/glass multilayered films

    NASA Astrophysics Data System (ADS)

    Liu, Chi-Ching; Jen, Shien-Uang; Lin, Yu-Cha; Lai, Chih-Huang; Liao, Sheng-Chieh; Chien, Chia-Hua

    2015-07-01

    [Fe62Co19Ga19(x)/Py(40-x)]5/glass multilayered films, where x=0, 5, 10, 15, 20 nm, y=x(nm)/40(nm), and 0≤y≤1, were made by the magnetron sputtering method at room temperature. The total number of combined [Fe-Co-Ga/Py] unit-layers was five. The total film thickness (tf) was fixed at 200 nm. We have performed two kinds of experiments on these films: (i) the saturation magnetostriction (λS) measurement, and (ii) the complex permeability (μ=μR-jμI) experiment to find the resonance frequency (fR) as a function of external magnetic field (HE). By definition, the microwave power absorption Pabs at ferromagnetic resonance (FMR) for a metallic conductor is written as Pabs =[(μR2 + μI2)1/2 +μI ] 1 / 2 . We define the half-width of the absorption peak Δf as Δf ≣ ΔfS+ΔfA, where ΔfS and ΔfA are the symmetric and asymmetric parts in Δf. The degree of asymmetry, ΔfA/Δf, of each absorption peak is associated with the structural and/or magnetic inhomogeneity in the film. The main findings from this study are summarized as follows: (A) maximum λS occurs in the y=1 film, and as y increases, λS increases; (B) biasing field for magnetostriction decreases greatly by adding Py layers; (C) the magnetostriction sensitivity remains almost constant in the range 0.4

  14. Open questions about giant viruses.

    PubMed

    Claverie, Jean-Michel; Abergel, Chantal

    2013-01-01

    The recent discovery of giant viruses exhibiting double-stranded DNA genomes larger than a million base pairs, encoding more than a thousand proteins and packed in near micron-sized icosahedral particles, opened a new and unexpected chapter in virology. As of today, these giant viruses and their closest relatives of lesser dimensions infect unicellular eukaryotes found in aquatic environments, but belonging to a wide diversity of early branching phyla. This broad phylogenetic distribution of hosts is consistent with the hypothesis that giant viruses originated prior to the radiation of the eukaryotic domain and/or might have been involved in the partition of nuclear versus cytoplasmic functions in ancestral cells. The distinctive features of the known giant viruses, in particular the recurrent presence of components of the translation apparatus in their proteome, raise a number of fundamental questions about their origin, their mode of evolution, and the relationship they may entertain with other dsDNA viruses, the genome size of which exhibits the widest distribution among all biological entities, from less than 5 kb to more than 1.25 Mb (a ratio of 1:250). At a more conceptual level, the convergence between the discovery of increasingly reduced parasitic cellular organisms and that of giant viruses exhibiting a widening array of cellular-like functions may ultimately abolish the historical discontinuity between the viral and the cellular world.

  15. Warm Debris Disks Produced by Giant Impacts during Terrestrial Planet Formation

    NASA Astrophysics Data System (ADS)

    Genda, H.; Kobayashi, H.; Kokubo, E.

    2015-09-01

    In our solar system, Mars-sized protoplanets frequently collided with each other during the last stage of terrestrial planet formation, called the giant impact stage. Giant impacts eject a large amount of material from the colliding protoplanets into the terrestrial planet region, which may form debris disks with observable infrared excesses. Indeed, tens of warm debris disks around young solar-type stars have been observed. Here we quantitatively estimate the total mass of ejected materials during the giant impact stages. We found that ∼0.4 times the Earth’s mass is ejected in total throughout the giant impact stage. Ejected materials are ground down by collisional cascade until micron-sized grains are blown out by radiation pressure. The depletion timescale of these ejected materials is determined primarily by the mass of the largest body among them. We conducted high-resolution simulations of giant impacts to accurately obtain the mass of the largest ejected body. We then calculated the evolution of the debris disks produced by a series of giant impacts and depleted by collisional cascades to obtain the infrared excess evolution of the debris disks. We found that the infrared excess is almost always higher than the stellar infrared flux throughout the giant impact stage (∼100 Myr) and is sometimes ∼10 times higher immediately after a giant impact. Therefore, giant impact stages would explain the infrared excess from most observed warm debris disks. The observed fraction of stars with warm debris disks indicates that the formation probability of our solar-system-like terrestrial planets is approximately 10%.

  16. WARM DEBRIS DISKS PRODUCED BY GIANT IMPACTS DURING TERRESTRIAL PLANET FORMATION

    SciTech Connect

    Genda, H.; Kobayashi, H.; Kokubo, E.

    2015-09-10

    In our solar system, Mars-sized protoplanets frequently collided with each other during the last stage of terrestrial planet formation, called the giant impact stage. Giant impacts eject a large amount of material from the colliding protoplanets into the terrestrial planet region, which may form debris disks with observable infrared excesses. Indeed, tens of warm debris disks around young solar-type stars have been observed. Here we quantitatively estimate the total mass of ejected materials during the giant impact stages. We found that ∼0.4 times the Earth’s mass is ejected in total throughout the giant impact stage. Ejected materials are ground down by collisional cascade until micron-sized grains are blown out by radiation pressure. The depletion timescale of these ejected materials is determined primarily by the mass of the largest body among them. We conducted high-resolution simulations of giant impacts to accurately obtain the mass of the largest ejected body. We then calculated the evolution of the debris disks produced by a series of giant impacts and depleted by collisional cascades to obtain the infrared excess evolution of the debris disks. We found that the infrared excess is almost always higher than the stellar infrared flux throughout the giant impact stage (∼100 Myr) and is sometimes ∼10 times higher immediately after a giant impact. Therefore, giant impact stages would explain the infrared excess from most observed warm debris disks. The observed fraction of stars with warm debris disks indicates that the formation probability of our solar-system-like terrestrial planets is approximately 10%.

  17. Giant Magellan Telescope: overview

    NASA Astrophysics Data System (ADS)

    Johns, Matt; McCarthy, Patrick; Raybould, Keith; Bouchez, Antonin; Farahani, Arash; Filgueira, Jose; Jacoby, George; Shectman, Steve; Sheehan, Michael

    2012-09-01

    The Giant Magellan Telescope (GMT) is a 25-meter optical/infrared extremely large telescope that is being built by an international consortium of universities and research institutions. It will be located at the Las Campanas Observatory, Chile. The GMT primary mirror consists of seven 8.4-m borosilicate honeycomb mirror segments made at the Steward Observatory Mirror Lab (SOML). Six identical off-axis segments and one on-axis segment are arranged on a single nearly-paraboloidal parent surface having an overall focal ratio of f/0.7. The fabrication, testing and verification procedures required to produce the closely-matched off-axis mirror segments were developed during the production of the first mirror. Production of the second and third off-axis segments is underway. GMT incorporates a seven-segment Gregorian adaptive secondary to implement three modes of adaptive-optics operation: natural-guide star AO, laser-tomography AO, and ground-layer AO. A wide-field corrector/ADC is available for use in seeing-limited mode over a 20-arcmin diameter field of view. Up to seven instruments can be mounted simultaneously on the telescope in a large Gregorian Instrument Rotator. Conceptual design studies were completed for six AO and seeing-limited instruments, plus a multi-object fiber feed, and a roadmap for phased deployment of the GMT instrument suite is being developed. The partner institutions have made firm commitments for approximately 45% of the funds required to build the telescope. Project Office efforts are currently focused on advancing the telescope and enclosure design in preparation for subsystem- and system-level preliminary design reviews which are scheduled to be completed in the first half of 2013.

  18. Influence of the deposition-induced stress on the magnetic properties of magnetostrictive amorphous (Fe{sub 80}Co{sub 20}){sub 80}B{sub 20} multilayers with orthogonal anisotropy

    SciTech Connect

    Gonzalez-Guerrero, Miguel; Prieto, Jose Luis; Sanchez, Pedro; Aroca, Claudio

    2007-12-15

    In this work, we experimentally justify that the control of the mechanical stress induced during the deposition of sputtered amorphous magnetostrictive (Fe{sub 80}Co{sub 20}){sub 80}B{sub 20} allows a custom design of its magnetic properties. FeCoB multilayers have been sputtered on thermal oxide Si substrates with different buffer materials. The crystalline quality and the thermomechanical properties of the buffer layer influence both the coercive and the anisotropy field. Those buffer layers with both high rigidity and poor thermal conductivity do not allow the dissipation of energy of the incoming sputtered material. Therefore, the mechanical stresses related to the deposition process cannot be released, leading to magnetic layers with high easy-axis coercive field and low anisotropy field. This shows that the mechanical stresses accumulated during deposition are a key parameter for the control of coercivity.

  19. Polymyalgia Rheumatica and Giant Cell Arteritis

    MedlinePlus

    ... Clinical Trial Journal Articles Polymyalgia Rheumatica and Giant Cell Arteritis May 2016 Questions and Answers about Polymyalgia Rheumatica and Giant Cell Arteritis This publication contains general information about polymyalgia ...

  20. Giant lobelias exemplify convergent evolution

    PubMed Central

    2010-01-01

    Giant lobeliads on tropical mountains in East Africa and Hawaii have highly unusual, giant-rosette growth forms that appear to be convergent on each other and on those of several independently evolved groups of Asteraceae and other families. A recent phylogenetic analysis by Antonelli, based on sequencing the widest selection of lobeliads to date, raises doubts about this paradigmatic example of convergent evolution. Here I address the kinds of evidence needed to test for convergent evolution and argue that the analysis by Antonelli fails on four points. Antonelli's analysis makes several important contributions to our understanding of lobeliad evolution and geographic spread, but his claim regarding convergence appears to be invalid. Giant lobeliads in Hawaii and Africa represent paradigmatic examples of convergent evolution. PMID:20074322

  1. Atmospheres of Extrasolar Giant Planets

    NASA Astrophysics Data System (ADS)

    Marley, M. S.; Fortney, J.; Seager, S.; Barman, T.

    The key to understanding an extrasolar giant planet's spectrum - and hence its detectability and evolution - lies with its atmosphere. Now that direct observations of thermal emission from extrasolar giant planets (EGPs) are in hand, atmosphere models can be used to constrain atmospheric composition, thermal structure, and ultimately the formation and evolution of detected planets. We review the important physical processes that influence the atmospheric structure and evolution of EGPs and consider what has already been learned from the first generation of observations and modeling. We pay particular attention to the roles of cloud structure, metallicity, and atmospheric chemistry in affecting detectable properties through Spitzer Space Telescope observations of the transiting giant planets. Our review stresses the uncertainties that ultimately limit our ability to interpret EGP observations. Finally we will conclude with a look to the future as characterization of multiple individual planets in a single stellar system leads to the study of comparative planetary architectures.

  2. CMB lensing and giant rings

    SciTech Connect

    Rathaus, Ben; Itzhaki, Nissan E-mail: ben.rathaus@gmail.com

    2012-05-01

    We study the CMB lensing signature of a pre-inationary particle (PIP), assuming it is responsible for the giant rings anomaly that was found recently in the WMAP data. Simulating Planck-like data we find that generically the CMB lensing signal to noise ratio associated with such a PIP is quite small and it would be difficult to cross correlate the temperature giant rings with the CMB lensing signal. However, if the pre-inationary particle is also responsible for the bulk flow measured from the local large scale structure, which happens to point roughly at the same direction as the giant rings, then the CMB lensing signal to noise ratio is fairly significant.

  3. Structure of giant muscle proteins

    PubMed Central

    Meyer, Logan C.; Wright, Nathan T.

    2013-01-01

    Giant muscle proteins (e.g., titin, nebulin, and obscurin) play a seminal role in muscle elasticity, stretch response, and sarcomeric organization. Each giant protein consists of multiple tandem structural domains, usually arranged in a modular fashion spanning 500 kDa to 4 MDa. Although many of the domains are similar in structure, subtle differences create a unique function of each domain. Recent high and low resolution structural and dynamic studies now suggest more nuanced overall protein structures than previously realized. These findings show that atomic structure, interactions between tandem domains, and intrasarcomeric environment all influence the shape, motion, and therefore function of giant proteins. In this article we will review the current understanding of titin, obscurin, and nebulin structure, from the atomic level through the molecular level. PMID:24376425

  4. Non-contact translation-rotation sensor using combined effects of magnetostriction and piezoelectricity.

    PubMed

    Yang, Bintang; Liu, Qingwei; Zhang, Ting; Cao, Yudong; Feng, Zhiqiang; Meng, Guang

    2012-10-15

    Precise displacement sensors are an important topic in precision engineering. At present, this type of sensors typically have a single feature of either translation or rotation measurement. They are also inconvenient to integrate with the host devices. In this report we propose a new kind of sensor that enables both translation and rotation measurement by using the combined effect of magnetostriction and piezoelectricity. As a proof of concept, we experimentally realized a prototype of non-contact translation-rotation precise sensor. In the current research stage, through both theoretical and experimental study, the non-contact displacement sensor is shown to be feasible for measuring both translation and rotation either in coarse or fine measurement. Moreover, owing to its compact, rigid structure and fewer components, it can be easily embedded in host equipment.

  5. Large magneto-chemical-elastic coupling in highly magnetostrictive Fe-Ga alloys

    SciTech Connect

    Narsu, B.; Wang, Gui-Sheng; Johansson, B.; Vitos, L.

    2013-12-02

    The strong softening of the tetragonal shear elastic constant (C{sup ′}) is the main reason for the second magnetostriction peak observed in Fe{sub 100–x}Ga{sub x} alloys. Here, we study the coupling between chemical order and magnetism with the aim to understand the origin of the elastic softening. We demonstrate that C{sup ′} strongly depends on the degree of order of Ga atoms in α-Fe. The B{sub 2} type ordering proves to have an important role on the elastic softening for x<19%, whereas the extreme shear lattice softening and the anomalous temperature dependence of C{sup ′} are found to be due to the strong magnetochemical coupling in the DO{sub 3} phase.

  6. Low temperature heat capacity of Fe1-xGax alloys with large magnetostriction

    SciTech Connect

    Hill, J.M.; McQueeney, R.J.; Wu, Ruqian; Dennis, K.; McCallum, R.W.; Huang, M.; Lograsso, T.A.

    2008-01-22

    The low temperature heat capacity C{sub p} of Fe{sub 1-x}Ga{sub x} alloys with large magnetostriction has been investigated. The data were analyzed in the standard way using electron ({gamma}T) and phonon ({beta}T{sup 3}) contributions. The Debye temperature {Theta}{sub D} decreases approximately linearly with increasing Ga concentration, consistent with previous resonant ultrasound measurements and measured phonon dispersion curves. Calculations of {Theta}{sub D} from lattice dynamical models and from measured elastic constants C{sub 11}, C{sub 12}, and C{sub 44} are in agreement with the measured data. The linear coefficient of electronic specific heat {gamma} remains relatively constant as the Ga concentration increases, despite the fact that the magnetoelastic coupling increases. Band structure calculations show that this is due to the compensation of majority and minority spin states at the Fermi level.

  7. Flexible Heteroepitaxy of CoFe2O4/Muscovite Bimorph with Large Magnetostriction.

    PubMed

    Liu, Heng-Jui; Wang, Chih-Kuo; Su, Dong; Amrillah, Tahta; Hsieh, Ying-Hui; Wu, Kun-Hong; Chen, Yi-Chun; Juang, Jenh-Yih; Eng, Lukas M; Jen, Shien-Uang; Chu, Ying-Hao

    2017-03-01

    A bimorph composed of ferrimagnetic cobalt ferrite (CoFe2O4, CFO) and flexible muscovite was fabricated via van der Waals epitaxy. The combination of X-ray diffraction and transmission electron microscopy was conducted to reveal the heteroepitaxy of the CFO/muscovite system. The robust magnetic behaviors against mechanical bending were characterized by hysteresis measurements and magnetic force microscopy, which maintain a saturation magnetization (Ms) of ∼120-150 emu/cm(3) under different bending states. The large magnetostrictive response of the CFO film was then determined by digital holographic microscopy, where the difference of magnetostrction coefficient (Δλ) is -104 ppm. The superior performance of this bimorph is attributed to the nature of weak interaction between film and substrate. Such a flexible CFO/muscovite bimorph provides a new platform to develop next-generation flexible magnetic devices.

  8. Synchrotron Diffraction Studies of Spontaneous Magnetostriction in Rare Earth Transition Metal Compounds

    SciTech Connect

    Yang, Ning

    2004-12-19

    Thermal expansion anomalies of R2Fe14B and R2Fe17Cx (x = 0,2) (R = Y, Nd, Gd, Tb, Er) stoichiometric compounds are studied with high-energy synchrotron X-ray powder diffraction using Debye-Schemer geometry in temperature range 10K to 1000K. Large spontaneous magnetostriction up to their Curie temperatures (Tc) is observed. The a-axes show relatively larger invar effects than c-axes in the R2Fe14B compounds whereas the R2Fe17Cx show the contrary anisotropies. The iron sub-lattice is shown to dominate the spontaneous magnetostriction of the compounds. The contribution of the rare earth sublattice is roughly proportional to the spin magnetic moment of the rare earth in the R2Fe14B compounds but in R2Fe17Cx, the rare earth sub-lattice contribution appears more likely to be dominated by the local bonding. The calculation of spontaneous magnetostrain of bonds shows that the bonds associated with Fe(j2) sites in R2Fe14B and the dumbbell sites in R2Fe17Cx have larger values, which is strongly related to their largest magnetic moment and Wigner-Seitz atomic cell volume. The roles of the carbon atoms in increasing the Curie temperatures of the R2Fe17 compounds are attributed to the increased separation of Fe hexagons. The R2Fe17 and R2Fe14B phases with magnetic rare earth ions also show anisotropies of thermal expansion above c. For R2Fe17 and R2Fe14B the a a/a c > 1 whereas the anisotropy is reversed with the interstitial carbon in R2Fe17. The average bond magnetostrain is shown to be a possible predictor of the magnetic moment of Fe sites in the compounds. Both of the theoretical and

  9. Flexible Heteroepitaxy of CoFe 2 O 4 /Muscovite Bimorph with Large Magnetostriction

    DOE PAGES

    Liu, Heng-Jui; Wang, Chih-Kuo; Su, Dong; ...

    2017-02-03

    Van der Waals epitaxy was used to fabricate a bimorph composed of ferrimagnetic cobalt ferrite (CoFe2O4, CFO) and flexible muscovite. The combination of X-ray diffraction and transmission electron microscopy was conducted to reveal the heteroepitaxy of the CFO/muscovite system. The robust magnetic behaviors against mechanical bending were characterized by hysteresis measurements and magnetic force microscopy, which maintain a saturation magnetization (Ms) of ~120–150 emu/cm3 under different bending states. The large magnetostrictive response of the CFO film was then determined by digital holographic microscopy, where the difference of magnetostrction coefficient (Δλ) is -104 ppm. We attribute the superior performance of thismore » bimorph to the nature of weak interaction between film and substrate. Such a flexible CFO/muscovite bimorph provides a new platform to develop next-generation flexible magnetic devices.« less

  10. Magnetostrictive iron gallium thin films grown onto antiferromagnetic manganese nitride: Structure and magnetism

    NASA Astrophysics Data System (ADS)

    Mandru, Andrada-Oana; Corbett, Joseph P.; Richard, Andrea L.; Gallagher, James; Meng, Keng-Yuan; Ingram, David C.; Yang, Fengyuan; Smith, Arthur R.

    2016-10-01

    We report structural and magnetic properties of magnetostrictive Fe100 -xGax (x ≈ 15) alloys when deposited onto antiferromagnetic manganese nitride and non-magnetic magnesium oxide substrates. From X-ray diffraction measurements, we find that the FeGa films are single crystalline. Scanning tunneling microscopy imaging reveals that the surface morphologies are dictated by the growth temperature, composition, and substrate. The magnetic properties can be tailored by the substrate, as found by magnetic force microscopy imaging and vibrating sample magnetometry measurements. In addition to pronounced tetragonal deformations, depositing FeGa onto manganese nitride leads to the formation of stripe-like magnetic domain patterns and to the appearance of perpendicular magnetic anisotropy.

  11. Damage Detection by the Mode-Selectable Magnetostrictive Transducer for Cylindrical Ferromagnetic Waveguides

    NASA Astrophysics Data System (ADS)

    Kim, Youngkyu; Kim, Ikkyu; Kim, Yoon Young

    2004-02-01

    In recent years, ultrasonic inspection techniques adopting magnetostrictive effects have received much attention, because they are non-destructive and require no direct physical contact with target systems. By selecting the desired wave mode and thus rejecting the unwanted modes amongst propagating waves in cylindrical ferromagnetic waveguides, we can effectively detect various types of flaws. However, a bending wave mode selecting technique, in particular, has not been fully developed yet. The purpose of this work is to present a technique to select either bending or longitudinal waves alone from compound waves propagating in ferromagnetic cylindrical waveguide. To achieve this goal, a new bias magnet configuration suitable for bending mode selection is suggested. The experimental results verify the effectiveness of the proposed method.

  12. A method based on SVD for detecting the defect using the magnetostrictive guided wave technique

    NASA Astrophysics Data System (ADS)

    Tang, Mingxi; Wu, Xinjun; Cong, Ming; Guo, Kai

    2016-03-01

    Magnetostrictive guided wave testing is a useful non-contact nondestructive testing method. However the signal to noise ratio (SNR) of its testing signal is low due to the lift-off. In this paper, a novel index called singular decreasing index (SDI) is proposed to distinguish the defect signal, which is based on a new matrix form improved from the Hankel matrix and the singular value decomposition (SVD). Further, an SDI spectrum is proposed to locate defects. Simulation signals with different SNR are employed to evaluate the performance of this method, and results show that the SDI spectrum can locate the defect at a very low SNR. Experimental results also show the excellent performance of the SDI spectrum in defect location. Hence, it is believed that this method can effectively detect defects at low SNR.

  13. A Nonlinear Physics-Based Optimal Control Method for Magnetostrictive Actuators

    NASA Technical Reports Server (NTRS)

    Smith, Ralph C.

    1998-01-01

    This paper addresses the development of a nonlinear optimal control methodology for magnetostrictive actuators. At moderate to high drive levels, the output from these actuators is highly nonlinear and contains significant magnetic and magnetomechanical hysteresis. These dynamics must be accommodated by models and control laws to utilize the full capabilities of the actuators. A characterization based upon ferromagnetic mean field theory provides a model which accurately quantifies both transient and steady state actuator dynamics under a variety of operating conditions. The control method consists of a linear perturbation feedback law used in combination with an optimal open loop nonlinear control. The nonlinear control incorporates the hysteresis and nonlinearities inherent to the transducer and can be computed offline. The feedback control is constructed through linearization of the perturbed system about the optimal system and is efficient for online implementation. As demonstrated through numerical examples, the combined hybrid control is robust and can be readily implemented in linear PDE-based structural models.

  14. Magnetostrictive hypersound generation by spiral magnets in the vicinity of magnetic field induced phase transition

    NASA Astrophysics Data System (ADS)

    Bychkov, Igor V.; Kuzmin, Dmitry A.; Kamantsev, Alexander P.; Koledov, Victor V.; Shavrov, Vladimir G.

    2016-11-01

    In present work we have investigated magnetostrictive ultrasound generation by spiral magnets in the vicinity of magnetic field induced phase transition from spiral to collinear state. We found that such magnets may generate transverse sound waves with the wavelength equal to the spiral period. We have examined two types of spiral magnetic structures: with inhomogeneous exchange and Dzyaloshinskii-Moriya interactions. Frequency of the waves from exchange-caused spiral magnetic structure may reach some THz, while in case of Dzyaloshinskii-Moriya interaction-caused spiral it may reach some GHz. These waves will be emitted like a sound pulses. Amplitude of the waves is strictly depends on the phase transition speed. Some aspects of microwaves to hypersound transformation by spiral magnets in the vicinity of phase transition have been investigated as well. Results of the work may be interesting for investigation of phase transition kinetics as well, as for various hypersound applications.

  15. Giant Negative Electrocaloric Effect in Antiferroelectric La-Doped Pb(ZrTi)O3 Thin Films Near Room Temperature.

    PubMed

    Geng, Wenping; Liu, Yang; Meng, Xiangjian; Bellaiche, Laurent; Scott, James F; Dkhil, Brahim; Jiang, Anquan

    2015-05-27

    Antiferroelectric thin films are demonstrated as a new class of giant electrocaloric materials that exhibit a negative electrocaloric response of about -5 K near room temperature. The giant negative electrocaloric effect may open up a new paradigm for light, compact, reliable, and high-efficiency refrigeration devices.

  16. Giant right atrial thrombi treated with thrombolysis.

    PubMed

    Ruiz-Bailén, Manuel; López-Caler, Carmen; Castillo-Rivera, Ana; Rucabado-Aguilar, Luis; Ramos Cuadra, José Angel; Lara Toral, Juan; Lozano Cabezas, Cristobal; Fernández Guerrero, Juan Carlos

    2008-04-01

    The present report describes giant atrial thrombi that were treated with thrombolysis in a community hospital. Two patients with giant atrial thrombi whose treatment involved complications are presented. Both patients developed cardiogenic shock and were treated unsuccessfully with thrombolysis. Because thrombolysis of giant thrombi may be ineffective, patients in this situation may require surgery.

  17. Giant right atrial thrombi treated with thrombolysis

    PubMed Central

    Ruiz-Bailén, Manuel; López-Caler, Carmen; Castillo-Rivera, Ana; Rucabado-Aguilar, Luis; Cuadra, José Ángel Ramos; Toral, Juan Lara; Cabezas, Cristobal Lozano; Guerrero, Juan Carlos Fernández

    2008-01-01

    The present report describes giant atrial thrombi that were treated with thrombolysis in a community hospital. Two patients with giant atrial thrombi whose treatment involved complications are presented. Both patients developed cardiogenic shock and were treated unsuccessfully with thrombolysis. Because thrombolysis of giant thrombi may be ineffective, patients in this situation may require surgery. PMID:18401474

  18. Cabergoline treatment in invasive giant prolactinoma.

    PubMed

    Alsubaie, Sadeem; Almalki, Mussa H

    2014-01-01

    Patients with invasive giant prolactinoma suffer from a constellation of symptoms including headache, blurred vision, lethargy, and sexual dysfunction. Cabergoline, a potent dopamine agonist, is a known medication prescribed for the treatment of invasive giant prolactinoma. Here, we report a case of invasive giant prolactinoma in a 52-year-old Saudi male with dramatic response to cabergoline treatment clinically, biochemically, and radiologically.

  19. Charting the Giants

    NASA Astrophysics Data System (ADS)

    2004-06-01

    zero expansion asymptotically after an infinite time and has a flat geometry). All three observational tests by means of supernovae (green), the cosmic microwave background (blue) and galaxy clusters converge at a Universe around Ωm ~ 0.3 and ΩΛ ~ 0.7. The dark red region for the galaxy cluster determination corresponds to 95% certainty (2-sigma statistical deviation) when assuming good knowledge of all other cosmological parameters, and the light red region assumes a minimum knowledge. For the supernovae and WMAP results, the inner and outer regions corespond to 68% (1-sigma) and 95% certainty, respectively. References: Schuecker et al. 2003, A&A, 398, 867 (REFLEX); Tonry et al. 2003, ApJ, 594, 1 (supernovae); Riess et al. 2004, ApJ, 607, 665 (supernovae) Galaxy clusters are far from being evenly distributed in the Universe. Instead, they tend to conglomerate into even larger structures, "super-clusters". Thus, from stars which gather in galaxies, galaxies which congregate in clusters and clusters tying together in super-clusters, the Universe shows structuring on all scales, from the smallest to the largest ones. This is a relict of the very early (formation) epoch of the Universe, the so-called "inflationary" period. At that time, only a minuscule fraction of one second after the Big Bang, the tiny density fluctuations were amplified and over the eons, they gave birth to the much larger structures. Because of the link between the first fluctuations and the giant structures now observed, the unique REFLEX catalogue - the largest of its kind - allows astronomers to put considerable constraints on the content of the Universe, and in particular on the amount of dark matter that is believed to pervade it. Rather interestingly, these constraints are totally independent from all other methods so far used to assert the existence of dark matter, such as the study of very distant supernovae (see e.g. ESO PR 21/98) or the analysis of the Cosmic Microwave background (e

  20. Giant Platelets in Platelet Donors – A Blessing in Disguise?

    PubMed Central

    Choudhury, Nabajyoti; Ray, Deepanjan

    2015-01-01

    Introduction Inherited thrombocytopenias, including inherited giant platelet disorders (IGPD) are relatively rare, but their prevalence is probably underestimated. Harris platelet syndrome, the most common IGPD reported from Indian subcontinent, mostly from eastern part, is characterised by a low platelet count, high mean platelet volume (MPV) and absence of bleeding. Aim A short study was conducted to assess the prevalence of giant platelets in voluntary donors of single donor platelets (SDP) and analyse the effect of transfusion of such SDPs in patients. Materials and Methods Voluntary donors of SDPs were screened as per standard guidelines prior to the procedure. A complete blood count (including MPV) along with a peripheral smear was done. A total of 45 donors were screened for plateletpheresis. Following plateletpheresis from these donors, a platelet count from the collection bag was done after one hour. The SDP was transfused as a single unit or divided into two and transfused to the same patient at two different occasions, as per clinical need. Platelet counts on pateints were done after one hour and the platelet recovery was noted. Results Out of the 45 donors who were screened, 30 (66.67%) were found to have giant platelets. It was observed that the pre procedure platelet counts in donors having giant platelets were relatively low (1.5 -1.7 lacs) and so also the platelet yield (2.7-3x1011) compared to donors who did not, but the post transfusion platelet recovery was greater. Conclusion Since presence of giant platelets has been seen to be common in the Eastern part of India, a peripheral smear examination should always be considered during screening of plateletpheresis donors to avoid rejecting donors with giant platelets whose platelet counts are given falsely low by autoanalysers. PMID:26266124

  1. Giant magnetoimpedance effect in Fe75.5Cu1Nb3Si13.5B7 ribbon/FeGa film composite

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Gan, Tao; Wang, Tao; Wang, Feifei; Shi, Wangzhou

    2016-11-01

    Optimized giant magnetoimpedance effect of Fe75.5Cu1Nb3Si13.5B7 amorphous ribbon/Fe80Ga20 film composites has been investigated. FeCuNbSiB amorphous ribbons as the substrates are commercially available, magnetostrictive FeGa films are deposited on one or both sides of the ribbons by ion-beam sputtering. Compared with the GMI curves without FeGa layer, the GMI effect of FeCuNbSiB amorphous ribbon has been obviously improved with FeGa film covered (from 4% to 16%). Moreover, the details exhibit an interesting phenomenon: at a certain frequency, when the FeGa film covered on one side of the ribbon, the GMI ratio decreases with the thickness of the FeGa film; however, when the FeGa films covered on both sides of the ribbon, the GMI ratio increases with the thickness of the FeGa film. We mainly attribute the reason to strain-induced anisotropy, which is induced by magnetostrictive effect under a longitudinal applied magnetic field.

  2. Giant magnetoresistance through a single molecule.

    PubMed

    Schmaus, Stefan; Bagrets, Alexei; Nahas, Yasmine; Yamada, Toyo K; Bork, Annika; Bowen, Martin; Beaurepaire, Eric; Evers, Ferdinand; Wulfhekel, Wulf

    2011-03-01

    Magnetoresistance is a change in the resistance of a material system caused by an applied magnetic field. Giant magnetoresistance occurs in structures containing ferromagnetic contacts separated by a metallic non-magnetic spacer, and is now the basis of read heads for hard drives and for new forms of random access memory. Using an insulator (for example, a molecular thin film) rather than a metal as the spacer gives rise to tunnelling magnetoresistance, which typically produces a larger change in resistance for a given magnetic field strength, but also yields higher resistances, which are a disadvantage for real device operation. Here, we demonstrate giant magnetoresistance across a single, non-magnetic hydrogen phthalocyanine molecule contacted by the ferromagnetic tip of a scanning tunnelling microscope. We measure the magnetoresistance to be 60% and the conductance to be 0.26G(0), where G(0) is the quantum of conductance. Theoretical analysis identifies spin-dependent hybridization of molecular and electrode orbitals as the cause of the large magnetoresistance.

  3. IL-4 induces the formation of multinucleated giant cells and expression of β5 integrin in central giant cell lesion

    PubMed Central

    Aghbali, Amirala; Rafieyan, Sona; Mohamed-Khosroshahi, Leila; Baradaran, Behzad; Shanehbandi, Dariush

    2017-01-01

    Background It is now well established that IL-4 has a central role in the development of monocytes to multinucleated giant cells (MGCs) by inducing the expression of integrins on the surface of monocytes. The aim of this study was to investigate the potential role of IL-4 in induction of β5 integrin expression in the peripheral blood samples of patients with giant cell granuloma. Material and Methods Monocytes were isolated from peripheral blood samples of patients with central giant cell granuloma (CGCG) and healthy controls using human Monocyte Isolation Kit II. Isolated monocytes were then cultured in the absence or presence of IL-4 (10 and 20 ng/mL), and following RNA extraction and cDNA synthesis, Real-time PCR was performed to determine the level of β5 integrin expression. The formation of CGCGs and morphological analyses were done under light microscopy. For confirmation of CGCGs, immunocytochemistry technique was also carried out by anti-RANK (receptor-activator of NF-κB ligand) antibody. Results In both patient and control groups, β5 levels were significantly enhanced by increasing the IL-4 dose from 10 to 20 ng/mL. In addition, these differences were significant between patient and control groups without IL-4 treatment. On the other hand, the number of cells which expressed RANK and therefore the number of giant cells were significantly higher in the patient group in comparison to controls, as assessed by immunohistochemistry evaluations. Conclusions In this study, we showed an elevation in the expression levels of β5 integrin when stimulated by IL-4. It is strongly indicated that this integrin acts as an important mediator during macrophage to macrophage fusion and development of giant cells. Key words:β5 integrin, giant cell, Il-4, monocyte, rank. PMID:27918730

  4. Anomalies of magnetostriction and thermal expansion in La 0.7Sr 0.3MnO 3 perovskite

    NASA Astrophysics Data System (ADS)

    Demin, R. V.; Koroleva, L. I.; Balbashov, A. M.

    1998-01-01

    It has been found that an anisotropic contribution to the magnetostriction λ t of a La 0.7Sr 0.3MnO 3 single crystal is essential at low temperatures ( λ t ˜ 10 -4 at 90 K). In the region of the Curie temperature T c the value of λ t decreases sharply with T. The bulk magnetostriction ω is negative in the T c region and the | ω|( T) curve has a maximum at T c. The temperature dependence of the thermal expansion Δ l/l at T > T c is stronger than linear. The anomalies of ω and Δ l/l are explained by magnetic phase separation.

  5. A study of the rhombohedral distortion of the magnetostrictive samarium-iron compounds with addition of molybdenum or vanadium

    NASA Astrophysics Data System (ADS)

    Liu, Zen-Bao; Tai, Li-Chi

    1981-03-01

    The mechanical hardness and magnetostriction of annealed pseudo-binary compounds, based on the binary Laves phase, SmFe2 compound with additions of small percentage of Cu, Ni, V or Mo, have been studied. It is found that the compounds containing Mo have optimum hardness and values of magnetostriction. The pseudo-binary compounds SmFe2-xMox and SmFe2-xVx (x = 0.05, 0.1 and 0.2) have been studied by using X-ray counter diffractometer. Owing to the broadening and the splitting of line profiles at higher Bragg angles, a precision determination of lattice parameters becomes difficult. From the data the angles of rhombohedral cells and the relative change in lattice spacings of cubic (400) reflections in these compounds have been calculated.

  6. Effect of magnetic field on the crystalline structure of magnetostrictive TbFe2 alloy solidified unidirectionally in microgravity.

    PubMed

    Okutani, Takeshi; Nakata, Yoshinori; Nagai, Hideaki

    2004-11-01

    We performed unidirectional solidification experiments on TbFe(2) alloy in a static magnetic field in microgravity of 10(-4) g for 10 sec obtained by a 490 m free fall of the Japan microgravity center (JAMIC). When the magnetic field strength was increased from zero to 4.5 x 10(-2) T during unidirectional solidification in microgravity, a [1 1 1] crystallographic alignment dominated, and the maximum magnetostriction constant increased from 1,000 ppm to 4,000 ppm. For unidirectional solidification in normal gravity, the maximum magnetostriction constant remained at 2,000 ppm with increasing magnetic field. The columnar structure grows and orients along the magnetic field. TbFe(2) crystals grow in microgravity predominantly in the same direction as the magnetic field.

  7. Giant Serpentine Aneurysms: Multidisciplinary Management

    PubMed Central

    Anshun, W.; Feng, L.; Daming, W.

    2000-01-01

    Summary Sixty-five cases of intracranial giant serpentine aneurysms (GSΛs), including 61 cases reported in the literature and four additional cases presented in this study were reviewed. The clinical presentation, possible causes, natural history, and especially management of GSAs are discussed with emphasis on the need for aggressive intervention and multidisciplinary management. PMID:20667180

  8. On the Shoulders of Giants...

    DTIC Science & Technology

    2013-01-01

    REFERENCES 1. Newton I. Turnbull HW, ed. Correspondence of Isaac Newton . Vol I: 1661Y1675. Cambridge, United Kingdom: Cambridge University Press; 1959:416...calendar), Sir Isaac Newtonopined to Robert Hooke, ‘‘If I have seen further [than you and Descartes], it is by standing on the shoulders of giants.’’1 That

  9. The giant panda gut microbiome.

    PubMed

    Wei, Fuwen; Wang, Xiao; Wu, Qi

    2015-08-01

    Giant pandas (Ailuropoda melanoleuca) are bamboo specialists that evolved from carnivores. Their gut microbiota probably aids in the digestion of cellulose and this is considered an example of gut microbiota adaptation to a bamboo diet. However, this issue remains unresolved and further functional and compositional studies are needed.

  10. Tuning of the magnetostrictive properties of cobalt ferrite by forced distribution of substituted divalent metal ions at different crystallographic sites

    NASA Astrophysics Data System (ADS)

    Anantharamaiah, P. N.; Joy, P. A.

    2017-03-01

    Comparative studies have been made to understand the role of different crystallographic site preferences of the substituted non-magnetic divalent metal ions in the magnetostrictive properties of cobalt ferrite, by substitution of Zn2+ and/or Mg2+ for Fe3+ in CoMgxFe2-xO4, CoZnxFe2-xO4, and CoMgx/2Znx/2Fe2-xO4 (0.0 ≤ x ≤ 0.2). Detailed Raman spectral and magnetic characterizations are made to extract the information on the tetrahedral/octahedral site preferences of Zn and Mg in the spinel lattice of cobalt ferrite. The structural, microstructural, magnetic, Raman spectral, and magnetostrictive parameters of the studied compositions show distinguishable variations for x < 0.1 and x ≥ 0.1. Co-substitution of a small amount of Mg and Zn for Fe in CoMgx/2Znx/2Fe2-xO4 (x < 0.1) showed relatively larger strain sensitivity, [dλ/dH]max (-2.6 × 10-9 mA-1 for x = 0.05), higher than that for the Mg-substituted samples (-2.05 × 10-9 mA-1 for x = 0.05) and comparable to that for the Zn-substituted samples (-2.47 × 10-9 mA-1 for x = 0.05), without much drop in the maximum value of magnetostriction, λmax (-189 ppm for x = 0.05) compared to that for the unsubstituted counterpart (-221 ppm). The results show that it is possible to obtain high strain sensitivity (at fields <50 kA/m), along with high magnetostriction strain at low magnetic fields (˜250 kA/m), by tuning the distribution of the substituted cations in the tetrahedral and octahedral sites of the cobalt ferrite lattice.

  11. Atmospheric models for post- giant impact planets

    NASA Astrophysics Data System (ADS)

    Lupu, R.; Zahnle, K. J.; Marley, M. S.; Schaefer, L. K.; Fegley, B.; Morley, C.; Cahoy, K.; Freedman, R. S.; Fortney, J. J.

    2013-12-01

    The final assembly of terrestrial planets is now universally thought to have occurred through a series of giant impacts, such as Earth's own Moon-forming impact. These collisions take place over a time interval of about 100 million years, during which time it takes at least 10 collisions between planets to make a Venus or an Earth. In the aftermath of one of these collisions the surviving planet is hot, and can remain hot for millions of years. During this phase of accretion, the proto-terrestrial planet may have a dense steam atmosphere, that will affect both the cooling of the planet and our ability to detect it. Here we explore the atmospheric chemistry, photochemistry, and spectral signatures of post-giant-impact terrestrial planets enveloped by thick atmospheres consisting of vaporized rock material. The atmospheric chemistry is computed self-consistently for atmospheres in equilibrium with hot surfaces, with compositions reflecting either the bulk silicate Earth (BSE, which includes the crust, mantle, atmosphere and oceans) or Earth's continental crust (CC). These two cases allow us to examine differences in atmospheres formed by outgassing of silica-rich (felsic) rocks - like the Earth's continental crust - and MgO- and FeO-rich (mafic) rocks - like the BSE. Studies of detrital zircons from Jack Hills, Australia, show that the continental crust existed 164 million years after the formation of the solar system, in which case the material vaporized in a giant impact should likely reflect the CC composition. However, if at the time of impact the surface of the planet does not yet exhibit the formation of continents, then the BSE case becomes relevant. We compute atmospheric profiles for surface temperatures ranging from 1000 to 2200 K, surface pressures of 10 and 100 bar, and surface gravities of 10 and 30 m/s^2. We account for all major molecular and atomic opacity sources, including collision-induced absorption, to derive the atmospheric structure and compute

  12. Relation between Ga ordering and magnetostriction of Fe-Ga alloys studied by x-ray diffuse scattering

    SciTech Connect

    Du, Y.; Huang, M.; Chang, S.; Schlagel, D.L.; Lograsso, T.A.; McQueeney, R.J.

    2010-10-22

    Transmission synchrotron diffraction was employed to characterize the Ga ordering in magnetostrictive Fe{sub 100-x}Ga{sub x} alloys with Ga concentrations from 0 to 20.3 at.%. The experiments focused on the development of atomic short-range ordering (SRO) by analysis of the diffuse scattering appearing at superlattice positions of the D0{sub 3} ordered alloy structure. No SRO was found for Ga concentrations less than 4 at. %. Between 13 and 20.3 at. %, D0{sub 3}-type SRO clusters are observed whose size increases with Ga concentration for both slow-cooled and quenched samples. Thermal quenching of the samples suppresses the cluster sizes when compared to slow-cooled samples of the same concentration. For quenched samples with large Ga concentration, Ga pairing is evidenced by growing B2-type correlations. At low concentrations, the presence of SRO appears to have little (if any) effect on the enhanced magnetostriction. However, the dramatic suppression of magnetostriction near {approx} 20 at. % Ga can be linked rapid growth of SRO just before the onset of long-range chemical order.

  13. Analysis of internal wave reflection within a magnetostrictive patch transducer for high-frequency guided torsional waves.

    PubMed

    Kim, Hoe Woong; Cho, Seung Hyun; Kim, Yoon Young

    2011-08-01

    Recently, megahertz-range torsional waves have been successfully generated and measured by a magnetostrictive patch transducer employing a meander coil. But the waveform of a high-frequency torsional wave generated by magnetostrictive patch transducers becomes greatly distorted with multiple trailing pulses. The hypothesis explaining the cause of the waveform distortion is that the distortion results mainly from the internal wave reflection within the magnetostrictive patch, which is in turn caused by the impedance mismatch between the bare and patch-bonded parts of the pipe. Based on the hypothesis, we developed an analytic model for internal reflection simulation and conducted several experiments using a patch transducer to verify the hypothesis. The comparison of the analytical and experimental results showed that the internal reflection at the edge of the patch was responsible for the distortion of the measured waveform. The present study also confirmed that the standard acoustic impedance matching to avoid sudden discontinuities at the patch edges can effectively reduce the internal reflection and alleviate the waveform distortion problem.

  14. Effect of Mn substitution for Fe on magnetic and magnetostrictive properties of SmFe2 compound

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Ren, W. J.; Wang, Z. H.; Zhang, Y. Q.; Li, J.; Zhang, Z. D.

    2012-04-01

    The structural, magnetic, and magnetostrictive properties of Sm(Fe1-xMnx)2 (0 ≤ x ≤ 0.20) alloys have been investigated. The alloys are almost single phase cubic Laves Sm(Fe, Mn)2 when x ≤ 0.15. The lattice parameter increases and Curie temperature and the magnetization at 295 K decrease with increasing Mn content of the Sm(Fe1-xMnx)2 compounds. The spin-reorientation temperature for ⟨110⟩ to ⟨111⟩ of Sm(Fe1-xMnx)2 decreases from 200 K for x = 0 to 140 K for x = 0.15, indicating the increasing anisotropy of the Mn-substituted compounds. The magnetostriction coefficient λ111 of the Sm(Fe1-xMnx)2 compounds slightly decreases with Mn substitution and maintains a value larger than 1900 ppm for 0 ≤ x ≤ 0.15. The linear anisotropic magnetostriction λa = λ‖ - λ⊥ for the Sm(Fe1-xMnx)2 alloys decreases with increasing Mn content, which may be ascribed to the decrease of λ111 and the increased anisotropy.

  15. Exploring How Giant Planet Formation Affected the Asteroid Belt

    NASA Astrophysics Data System (ADS)

    Kretke, Katherine A.; Levison, Harold F.; Bottke, William

    2016-10-01

    The asteroid belt is observed to be a mixture of objects with different compositions, with volatile-poor asteroids (mostly S-complex) dominant in the inner asteroid belt while volatile-rich (mostly C-complex) asteroids dominate the outer asteroid belt. While this general compositional stratification was originally thought to be an indicator of the primordial temperature gradient in the protoplanetary disk, the very distinct properties of these populations suggest that they must represent two completely decoupled reservoirs, not a simple gradient (e.g., Warren 2011). It is possible to create this general stratification (as well as the observed mixing) as the implantation of outer Solar System material into the asteroid belt by the early migration of the giant planets (e.g. the Grand Tack, Walsh et al. 2011). However, this presupposes that the inner and outer Solar System materials were still sorted in their primordial locations prior to any migration of the planets. The lack of a fully dynamically self-consistent model of giant planet core formation has prevented the study of how the core formation process itself may result in dynamical mixing in the early Solar System's history. Recently, pebble accretion, the process by which planetesimals can grow to giant planet cores via the accretion of small, rapidly drifting sub-meter-sized bodies known as ``pebbles,'' (Lambrechts & Johansen 2012, Levison, Kretke & Duncan 2015) finally offers such a model. Here we show how the process of giant planet formation will impact the surrounding planetesimal population, possibly resulting in the observed compositional mixture of the asteroid belt, without requiring a dramatic migration of the giant planets. For example, preliminary runs suggest planetesimals from the Jupiter-formation zone can be implanted in the outer main belt via interactions with scattered Jupiter-zone protoplanets. This could potentially provide an alternative non-Grand Tack solution to the origin of many C

  16. Bio-assembled nanocomposites in conch shells exhibit giant electret hysteresis.

    PubMed

    Yao, Yingbang; Wang, QingXiao; Wang, Hongtao; Zhang, Bei; Zhao, Chao; Wang, Zhihong; Xu, Zhengkui; Wu, Ying; Huang, Wei; Qian, Pei-Yuan; Zhang, Xi Xiang

    2013-02-06

    Giant electric polarization (2000-4000 μC cm(-2)) is observed in natural conch shells. The nanolaminas and biopolymer layers of their unique hierarchical microstructures exhibit ferroelectret behavior and account for the observed polarization. Such huge polarization leads to extremely high pyroelectric coefficients, 2-3 orders of magnitude larger than those of conventional ferroelectric materials. The possibility of tailoring the giant polarization for various applications is considered.

  17. Multinucleate Giant Cells in FNAC of Benign Breast Lesions: Its Significance

    PubMed Central

    R, Kalyani; Murthy V, Srinivasa

    2014-01-01

    Background: Multinucleate giant cells are described in breast aspirates. However, due to its rarity very few cases have been described cytologically. Hence recognition and correct interpretation of their presence is difficult, yet crucial for accurate diagnosis. Materials and Methods: The prospective study of FNAC (fine needle aspirate cytology) of breast lumps was conducted for a period of six months. Direct smears were prepared from the material aspirated. In case of fluid aspirates, centrifuge done and cell sediment was used for making smears. Smears were alcohol fixed and stained with PAP/H&E or air dried smears were stained with Leishman stain. Further smears were subjected to immunocytochemistry using vimentin and CD34 markers to know the origin of multinucleate giant cells. Results: We have reported 11 cases of breast lesions, which showed multinucleate giant cells on FNAC. Out of the 11 cases, Cytologically six cases showed granuloma debris with relative proportion of epithelioid histiocytes, lymphocytes, neutrophils and multinucleate giant cells. Two cases were diagnosed as acute suppurative granulomatous mastitis. Two cases of fibroadenoma and one case of fat necrosis showed multinucleate giant cells. Immunocytochemistry showed vimentin positivity in both stromal and histiocytic type of multinucleate giant cells and in isolated histiocytes. CD34 was focally positive in histiocytic type of giant cells. Conclusion: An effort is made to distinguish between the stromal and histiocytic type giant cells in non-neoplastic breast lesions. Further molecular studies have to be done to know the exact histogenesis and role of these multinucleate giant cells in benign lesions. PMID:25653953

  18. An in-situ study of magnetic domain structures in undercooled Fe-29.5 at. %Pd magnetostrictive alloys by Lorentz microscopy and electron holography

    SciTech Connect

    Sun, Wen; Xu, Xianhui; Liu, Jian E-mail: xiawxing@nimte.ac.cn; Xia, Weixing E-mail: xiawxing@nimte.ac.cn; Yan, Aru

    2015-04-28

    Understanding of correlation between magnetic domain structure and functional properties is of importance for the magnetic field driven phase transition (e.g., martensitic transformation) or microstructure variation (e.g., twin boundary motion) materials. In this work, we report a Fe-29.5 at. %Pd shape memory alloy treated by undercooling processing upon a degree of 320 K below the liquid temperature. The effect of high undercooling on the solidified microstructure and martensitic transformation temperatures was investigated. By in-situ Lorentz transmission electron microscopy and electron holography, magnetic domain structure and the field-induced domain wall motion behavior in as-cast and undercooled samples have been schematically studied. The irregular domain structure can be observed in these alloys. On the application of a field up to 300 Oe, the domain walls for both samples are able to move along the direction of the external magnetic field, but structural transition and rearrangement of variants are not observed in the undercooled alloy. The large magnetostriction of Fe-29.5 at. %Pd undercooled alloy originates from the irregular domain walls motion instead of the rearrangement of martensitic twin variants.

  19. Enhancement of the Excitation Efficiency of the Non-Contact Magnetostrictive Sensor for Pipe Inspection by Adjusting the Alternating Magnetic Field Axial Length

    PubMed Central

    Sun, Pengfei; Wu, Xinjun; Xu, Jiang; Li, Jian

    2014-01-01

    The non-contact magnetostrictive sensor (MsS) has been widely used in the guided wave testing of pipes, cables, and so on. However, it has a disadvantage of low excitation efficiency. A new method for enhancing the excitation efficiency of the non-contact MsS for pipe inspection using guided waves, by adjusting the axial length of the excitation magnetic field, is proposed. A special transmitter structure, in which two copper rings are added beside the transmitter coil, is used to adjust the axial length at the expense of weakening the excitation magnetic field. An equivalent vibration model is presented to analyze the influence of the axial length variation. The final result is investigated by experiments. Results show that the excitation efficiency of the non-contact MsS is enhanced in the whole inspection frequency range of the L(0,2) mode if the axial length is adjusted to a certain value. Moreover that certain axial length is the same for pipes of different sizes but made of the same material. PMID:24441769

  20. Materials

    NASA Technical Reports Server (NTRS)

    Glaessgen, Edward H.; Schoeppner, Gregory A.

    2006-01-01

    NASA Langley Research Center has successfully developed an electron beam freeform fabrication (EBF3) process, a rapid metal deposition process that works efficiently with a variety of weldable alloys. The EBF3 process can be used to build a complex, unitized part in a layer-additive fashion, although the more immediate payoff is for use as a manufacturing process for adding details to components fabricated from simplified castings and forgings or plate products. The EBF3 process produces structural metallic parts with strengths comparable to that of wrought product forms and has been demonstrated on aluminum, titanium, and nickel-based alloys to date. The EBF3 process introduces metal wire feedstock into a molten pool that is created and sustained using a focused electron beam in a vacuum environment. Operation in a vacuum ensures a clean process environment and eliminates the need for a consumable shield gas. Advanced metal manufacturing methods such as EBF3 are being explored for fabrication and repair of aerospace structures, offering potential for improvements in cost, weight, and performance to enhance mission success for aircraft, launch vehicles, and spacecraft. Near-term applications of the EBF3 process are most likely to be implemented for cost reduction and lead time reduction through addition of details onto simplified preforms (casting or forging). This is particularly attractive for components with protruding details that would require a significantly large volume of material to be machined away from an oversized forging, offering significant reductions to the buy-to-fly ratio. Future far-term applications promise improved structural efficiency through reduced weight and improved performance by exploiting the layer-additive nature of the EBF3 process to fabricate tailored unitized structures with functionally graded microstructures and compositions.

  1. Giant piezoelectricity of monolayer group IV monochalcogenides

    NASA Astrophysics Data System (ADS)

    Fei, Ruixiang; Li, Wenbin; Li, Ju; Yang, Li

    We predict enormous, anisotropic piezoelectric effects in intrinsic monolayer group IV monochalcogenides (MX, M =Sn or Ge, X =Se or S), including SnSe, SnS, GeSe, and GeS. Using first-principle simulations based on the modern theory of polarization, we find that their piezoelectric coefficients are about one to two orders of magnitude larger than those of other 2D materials, such as MoS2 and GaSe, and bulk quartz and AlN which are widely used in industry. This enhancement is a result of the unique ``puckered'' C2v symmetry and electronic structure of monolayer group IV monochalcogenides. Given the achieved experimental advances in the fabrication of monolayers, their flexible character, and ability to withstand enormous strain, these 2D structures with giant piezoelectric effects may be promising for a broad range of applications such as nano-sized sensors, piezotronics, and energy harvesting in portable electronic devices.

  2. Giant piezoelectricity on Si for hyperactive MEMS.

    PubMed

    Baek, S H; Park, J; Kim, D M; Aksyuk, V A; Das, R R; Bu, S D; Felker, D A; Lettieri, J; Vaithyanathan, V; Bharadwaja, S S N; Bassiri-Gharb, N; Chen, Y B; Sun, H P; Folkman, C M; Jang, H W; Kreft, D J; Streiffer, S K; Ramesh, R; Pan, X Q; Trolier-McKinstry, S; Schlom, D G; Rzchowski, M S; Blick, R H; Eom, C B

    2011-11-18

    Microelectromechanical systems (MEMS) incorporating active piezoelectric layers offer integrated actuation, sensing, and transduction. The broad implementation of such active MEMS has long been constrained by the inability to integrate materials with giant piezoelectric response, such as Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PMN-PT). We synthesized high-quality PMN-PT epitaxial thin films on vicinal (001) Si wafers with the use of an epitaxial (001) SrTiO(3) template layer with superior piezoelectric coefficients (e(31,f) = -27 ± 3 coulombs per square meter) and figures of merit for piezoelectric energy-harvesting systems. We have incorporated these heterostructures into microcantilevers that are actuated with extremely low drive voltage due to thin-film piezoelectric properties that rival bulk PMN-PT single crystals. These epitaxial heterostructures exhibit very large electromechanical coupling for ultrasound medical imaging, microfluidic control, mechanical sensing, and energy harvesting.

  3. Giant impacts on a primitive Uranus

    NASA Technical Reports Server (NTRS)

    Slattery, Wayne L.; Benz, Willy; Cameron, A. G. W.

    1992-01-01

    Simulations of collisions are conducted between a model of the primitive Uranus and 1-3 earth-mass impactors, using smooth-particle hydrodynamics. A series of collisions was simulated for each impactor while varying the total angular momentum of the system. Most of the simulation runs left ices in orbit; a subset of the runs also left rock or iron (from the impactor). It is concluded on the basis of these results that there is a wide range of giant impacts which could have produced the current period and inclination of the spin axis relative to the plane of the ecliptic. A subset of these could have deposited the material in orbit from which the regular satellites of Uranus were assembled.

  4. Giant barocaloric effects at low pressure in ferrielectric ammonium sulphate

    PubMed Central

    Lloveras, P.; Stern-Taulats, E.; Barrio, M.; Tamarit, J.-Ll.; Crossley, S.; Li, W.; Pomjakushin, V.; Planes, A.; Mañosa, Ll.; Mathur, N. D.; Moya, X.

    2015-01-01

    Caloric effects are currently under intense study due to the prospect of environment-friendly cooling applications. Most of the research is centred on large magnetocaloric effects and large electrocaloric effects, but the former require large magnetic fields that are challenging to generate economically and the latter require large electric fields that can only be applied without breakdown in thin samples. Here we use small changes in hydrostatic pressure to drive giant inverse barocaloric effects near the ferrielectric phase transition in ammonium sulphate. We find barocaloric effects and strengths that exceed those previously observed near magnetostructural phase transitions in magnetic materials. Our findings should therefore inspire the discovery of giant barocaloric effects in a wide range of unexplored ferroelectric materials, ultimately leading to barocaloric cooling devices. PMID:26607989

  5. Giant barocaloric effects at low pressure in ferrielectric ammonium sulphate.

    PubMed

    Lloveras, P; Stern-Taulats, E; Barrio, M; Tamarit, J-Ll; Crossley, S; Li, W; Pomjakushin, V; Planes, A; Mañosa, Ll; Mathur, N D; Moya, X

    2015-11-26

    Caloric effects are currently under intense study due to the prospect of environment-friendly cooling applications. Most of the research is centred on large magnetocaloric effects and large electrocaloric effects, but the former require large magnetic fields that are challenging to generate economically and the latter require large electric fields that can only be applied without breakdown in thin samples. Here we use small changes in hydrostatic pressure to drive giant inverse barocaloric effects near the ferrielectric phase transition in ammonium sulphate. We find barocaloric effects and strengths that exceed those previously observed near magnetostructural phase transitions in magnetic materials. Our findings should therefore inspire the discovery of giant barocaloric effects in a wide range of unexplored ferroelectric materials, ultimately leading to barocaloric cooling devices.

  6. Giant barocaloric effects at low pressure in ferrielectric ammonium sulphate

    NASA Astrophysics Data System (ADS)

    Lloveras, P.; Stern-Taulats, E.; Barrio, M.; Tamarit, J.-Ll.; Crossley, S.; Li, W.; Pomjakushin, V.; Planes, A.; Mañosa, Ll.; Mathur, N. D.; Moya, X.

    2015-11-01

    Caloric effects are currently under intense study due to the prospect of environment-friendly cooling applications. Most of the research is centred on large magnetocaloric effects and large electrocaloric effects, but the former require large magnetic fields that are challenging to generate economically and the latter require large electric fields that can only be applied without breakdown in thin samples. Here we use small changes in hydrostatic pressure to drive giant inverse barocaloric effects near the ferrielectric phase transition in ammonium sulphate. We find barocaloric effects and strengths that exceed those previously observed near magnetostructural phase transitions in magnetic materials. Our findings should therefore inspire the discovery of giant barocaloric effects in a wide range of unexplored ferroelectric materials, ultimately leading to barocaloric cooling devices.

  7. Giant magnetoresistive sensor

    DOEpatents

    Stearns, Daniel G.; Vernon, Stephen P.; Ceglio, Natale M.; Hawryluk, Andrew M.

    1999-01-01

    A magnetoresistive sensor element with a three-dimensional micro-architecture is capable of significantly improved sensitivity and highly localized measurement of magnetic fields. The sensor is formed of a multilayer film of alternately magnetic and nonmagnetic materials. The sensor is optimally operated in a current perpendicular to plane mode. The sensor is useful in magnetic read/write heads, for high density magnetic information storage and retrieval.

  8. Giant magnetoimpedance modelling using Fourier analysis in soft magnetic amorphous wires

    NASA Astrophysics Data System (ADS)

    Gómez-Polo, C.; Knobel, M.; Pirota, K. R.; Vázquez, M.

    2001-06-01

    In this work, the Fourier analysis is employed to investigate the giant magnetoimpedance (GMI) effect in a FeCoSiB amorphous wire with vanishing magnetostriction. In order to modify the initial quenched-in anisotropy, pieces 8 cm in length were submitted to Joule heating treatments below the corresponding Curie point. The induced circumferential anisotropy determines the field evolution of the electrical impedance of the sample upon the application of an axial magnetic field. The experimental results are interpreted within the framework of the classical electrodynamical theory, where a simple rotational model is used to estimate the circular magnetization process of the sample. The mean value of the circumferential permeability is obtained through Fourier analysis of the time derivative of the estimated circular magnetization. Moreover, the existence of a second harmonic component of the GMI voltage is also experimentally detected. Its amplitude sensitively evolves with the axial DC magnetic field and its appearance is associated to an asymmetry in the circular magnetization process.

  9. Giant Herbig-Haro Flows

    NASA Astrophysics Data System (ADS)

    Reipurth, Bo; Bally, John; Devine, David

    1997-12-01

    We present the discovery of a number of Herbig-Haro flows which extend over parsec-scale distances. The largest of these is the well known HH 111 jet complex, which is shown, through CCD images and a proper motion study, to have an angular extent of almost one degree on the sky, corresponding to 7.7 pc, making it the largest known HH flow. In our imaging survey we also found that T Tauri is at the center of a huge bipolar HH flow, HH 355, with a total extent of 38 arcmin, corresponding to 1.55 pc, and aligned with the axis of the tiny HH 255 flow surrounding the infrared companion T Tau S. We additionally have found a number of other giant HH flow candidates, including HH 315 at PV Cep, HH 41/295 at Haro 5a/6a, HH 300 in Bl8w, HH 354 in Li 165, HH 376 in Li 152, and HH 114/115 and HH 243/244/245/179 in the X Orionis molecular ring. It thus appears that it is common for HH flows to attain parsec-scale dimensions. The ubiquity of parsec-scale HH flows profoundly alters our view of the impact of young stars on their environment. Giant flows have dynamical ages comparable to the duration of the accretion phase of the sources, and provide a fossil record of their mass loss and accretion history. Multiple internal working surfaces and their S-shaped point symmetry provide evidence for variability of ejection velocity and orientation of the source jets. Giant HH flows are either longer or comparable in length to associated CO outflows, providing evidence for unified models in which HH flows power CO flows. Many giant flows have burst out of their source cloud cores and are dissociating molecules and injecting momentum and kinetic energy into the interclump medium of the host clouds. They contribute to the UV radiation field, and may produce C I and C ii in cloud interiors. Giant flows may contribute to the chemical rejuvenation of clouds, the generation of turbulent motions, and the self-regulation of star formation. The terminal working surfaces of giant flows may be

  10. Digestive physiology of captive giant anteaters (Myrmecophaga tridactyla): determinants of faecal dry matter content.

    PubMed

    Gull, J M; Stahl, M; Osmann, C; Ortmann, S; Kreuzer, M; Hatt, J-M; Clauss, M

    2015-06-01

    Giant anteaters (Myrmecophaga tridactyla) are specialized insectivores and consume mainly ants and termites in the wild. In captivity, giant anteaters are either fed a complete diet, or a combination of a domestic carnivore diet with leaf eater pellets, or a traditional gruel-type diet. Soft faeces are a frequently encountered problem with this type of feeding. In the present study, we analysed diet and faeces composition, calculated digestibility and measured mean retention time on various diets in eight giant anteaters (total of n = 64 experiments). The results suggest that the digestive physiology of giant anteaters is similar to that of domestic dogs and cats in terms of nutrient digestibility and digesta retention. When testing correlations between faecal dry matter content and other variables, no relationship with dietary crude fibre content or mean digesta retention time could be detected. However, acid insoluble ash intake was significantly and positively correlated with faecal dry matter content. The amount of acid insoluble ash excreted with the faeces was higher than that ingested with the diet offered, indicating that the giant anteaters ingested soil from their enclosure of up to 93 g per day. This finding is consistent with observation of faeces of wild giant anteaters that contain soil or sand most likely due to indiscriminate feeding. It also corresponds to reports that indigestible materials such as peat, soil, chitin or cellulose contribute to a firmer faecal consistency in various carnivore species. Therefore, offering giant anteaters the opportunity to voluntarily ingest soil from their enclosure might be beneficial.

  11. Establishment and cryopreservation of a giant panda skeletal muscle-derived cell line.

    PubMed

    Yu, Fang-Jian; Zeng, Chang-Jun; Zhang, Yan; Wang, Cheng-Dong; Xiong, Tie-Yi; Fang, Sheng-Guo; Zhang, He-Min

    2015-06-01

    The giant panda Ailuropoda melanoleuca is an endangered species and is a symbol for wildlife conservation. Although efforts have been made to protect this rare and endangered species through breeding and conservative biology, the long-term preservation of giant panda genome resources (gametes, tissues, organs, genomic libraries, etc.) is still a practical option. In this study, the giant panda skeletal muscle-derived cell line was successfully established via primary explants culture and cryopreservation techniques. The population doubling time of giant panda skeletal cells was approximately 33.8 h, and this population maintained a high cell viability before and after cryopreservation (95.6% and 90.7%, respectively). The two skeletal muscle-specific genes SMYD1 and MYF6 were expressed and detected by RT-PCR in the giant panda skeletal muscle-derived cell line. Karyotyping analysis revealed that the frequencies of giant panda skeletal muscle cells showing a chromosome number of 2n=42 ranged from 90.6∼94.2%. Thus, the giant panda skeletal muscle-derived cell line provides a vital resource and material platform for further studies and is likely to be useful for the protection of this rare and endangered species.

  12. CENTRAL GIANT CELL GRANULOMA OF THE JAWS AND GIANT CELL TUMOR OF LONG BONES - AN IMMUNOHISTOCHEMICAL COMPARATIVE STUDY

    PubMed Central

    Aragão, Maria do Socorro; Piva, Marta Rabello; Nonaka, Cassiano Francisco Weege; Freitas, Roseana de Almeida; de Souza, Lélia Batista; Pinto, Leão Pereira

    2007-01-01

    Objective: This study investigated whether some components of the extracellular matrix and CD68 expression may drive the differences between the central giant cell granuloma (CGCG) of the jaws and giant cell tumor (GCT) of long bones, which present distinct evolution and clinical behavior. Material and Methods: Eight cases of CGCG and 7 cases of GCT were selected and immunohistochemically analyzed to verify the pattern of expression of CD68, tenascin (Tn) and fibronectin (Fn). Results: A large number of the mononuclear cells and multinucleated giant cells CD68+ was observed in both of the studied lesions, indicating histiocyte/macrophage origin. Seven cases of CGCG of the jaws showed intense staining of Fn, with uniform distribution predominantly. In all 7 cases of GCT of long bones the Fn displayed intense expression, with distribution pattern varying from uniform to reticulate/fibrillar. Six cases of CGCG were intensively stained by Tn, presenting focal expression in half of specimens, and reticulate/fibrillar pattern of expression in 4 cases. All cases of GCT of the long bones presented intense expression of Tn, uniform distribution, and reticulate/fibrillar pattern of expression in four cases. Conclusions: The immunoexpression of CD68 in mononuclear cells and multinucleated giant cells and staining patterns of Fn and Tn were similar in both entities. These findings indicate that these proteins could not be used to explain the differences between the CGCG of the jaws and GCT of the long bones. PMID:19089150

  13. Giant faraday rotation in conjugated, rod-like molecules

    NASA Astrophysics Data System (ADS)

    Vleugels, Rick; Brullot, Ward; Verbiest, Thierry

    2016-09-01

    Faraday rotation is a magneto-optic phenomenon in which the polarization plane of light is rotated due to magnetically induced circular birefringence. It can be used in a variety of applications such as optical isolators, magnetic field sensors and current sensors. So far, most of the applications use inorganic, paramagnetic materials, which have Verdet constants up to millions of degrees per tesla per meter in the visible spectrum range. They are performant at telecommunication wavelengths, though with smaller Verdet constants, so thicker materials are used. Disadvantages of these materials are their magnetic saturation at low magnetic fields and their strong temperature dependency. Organic, diamagnetic materials on the contrary, saturate at much larger magnetic fields and are less temperature dependent. Furthermore, they also have the advantage of their flexibility and processability. Up to now, magneto-optical research on organic materials has mostly characterized materials with low magneto-optical activity in regions without absorption, but there are some exceptions. Some pi-conjugated polymers have been shown to have very large magneto-optic responses. Furthermore, a mesogenic, organic molecule has been reported with a very high Verdet constant. Conclusive explanations for these large Verdet constants are still lacking, but different possible hypotheses were proposed. In our ongoing search for organic materials with exceptional magneto-optical properties, we examined conjugated, rod-like molecules. Structural, these molecules show close resemblances with the earlier reported mesogenic, organic molecule. We measured giant Verdet constants for thin films of these molecules, reaching values almost as giant as the previous reported mesogenic molecule. These findings shed first preliminary light on a structure-activity relationship for giant Faraday rotation in diamagnetic organic materials.

  14. Effects of Ni addition on the magnetostriction and microstructures of Fe70-xPd30Nix high-temperature ferromagnetic shape memory alloys

    NASA Astrophysics Data System (ADS)

    Lin, Yin-Chih; Lin, Chien-Feng

    2012-04-01

    This study investigated the effects of adding a third alloying element, Ni, to create Fe70-xPd30Nix (x = 2, 4, 6, and 8 at. % Ni) ferromagnetic shape memory alloys. The Ni replaced a portion of the Fe. The magnetostriction and microstructures of Fe70-xPd30Nix high-temperature ferromagnetic shape memory alloys were studied in detail. Investigation of the magnetostriction and microstructures indicated that the greater Ni amount in the Fe70-xPd30Nix alloys caused the less saturation magnetostriction at room temperature (RT); it was also observed that it was more difficult to generate an annealed recrystallization. However, greater Ni addition into the Fe70-xPd30Nix (x = 6 and 8 at. % Ni) alloys, the L10 + L1m twin phase decomposition into stoichiometric L10 + L1m + αbct structures could be suppressed when the alloys were aged at 500 °C for 100 h. The result was that the Fe70-xPd30Nix (x = 6 and 8 at. % Ni) alloys maintained a high magnetostriction and magnetostrictive susceptibility (Δλ‖s/ΔH) after the 500 °C/100 h aged treatment. This magnetic property of the Fe70-xPd30Nix (x = 6 and 8 at. % Ni) alloys is suitable for application in a high temperature (T > 500 °C) and high frequency environment.

  15. Magnetic properties and magnetostriction of PrxNd1-xFe1.9 (0 <= x <= 1.0) alloys at low temperature

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Tang, Shao-Long; Li, Yu-Long; Xie, Ren; Du, You-Wei

    2013-03-01

    The crystal structure, magnetic and magnetostrictive properties of high-pressure synthesized PrxNd1-xFe1.9 (0 <= x <= 1.0) alloys were studied. The alloys exhibit single cubic Laves phase with MgCu2-type structure. The initial magnetization curve reveals that Pr0.2Nd0.8Fe1.9 has a minimum magnetocrystalline anisotropy at 5 K. The magnetostriction curve at 5 K shows that Pr0.2Nd0.8Fe1.9 has a very good low-field magnetostrictive property, and the magnetostriction of the PrxNd1-xFe1.9 alloy in high magnetic field is attributable mainly to Pr. The temperature dependence of the magnetostriction (λ‖) at the field of 5 kOe shows that the substitution of Nd reduces the K1 remarkably, and the values of λ‖ of Pr0.2Nd0.8Fe1.9 and Pr0.8Nd0.2Fe1.9 alloys are nearly five times larger than that of the PrFe1.9 alloy below 50 K; the λ‖ of Pr0.8Nd0.2Fe1.9 reaches up to 1082 ppm at 100 K, which makes it a potential candidate for application in this temperature range.

  16. A structural, magnetostrictive and Mössbauer study of Tb0.3Dy0.7(Fe0.9 T 0.1)1.95 alloys

    NASA Astrophysics Data System (ADS)

    Zheng, Xiaoping; Zhang, Peifeng; Fan, Duowang; Li, Fashen; Hao, Yuan

    2005-11-01

    The effect of IIIA metal and transition metal T substitution for Fe on crystal structure, magnetostriction and spontaneous magnetostriction, anisotropy and spin reorientation of a series of polycrystalline Tb0.3 Dy0.7 (Fe0.9 T 0.1)1.95 ( T=Mn, Fe, Co, B, Al, Ga) alloys at room temperature were investigated systematically. It was found that the primary phase of the Tb0.3 Dy0.7 (Fe0.9 T 0.1)1.95 alloys is the MgCu2-type cubic Laves phase structure for different substitution. The magnetostriction λ s decrases greatly for the substitution of IIIA metal, B, Al and Ga, but is saturated more easily for Al and Ga substitution, showing that the Al and Ga substitution is beneficial to a decrease in the magnetocrystalline anisotropy of Tb0.3 Dy0.7 (Fe0.9 T 0.1)1.95 alloys. However, the substitution of transition metal Mn and Co decreases slightly the magnetostriction λ s . It was also found that the effect of different substitutions on the spontaneous magnetostriction λ 111 is distinct. The analysis of the Mössbauer spectra indicates that the easy magnetization direction in the {110} plane deviates slightly from the main axis of symmetry for Al and Ga substitution, namely spin reorientation, but it does not change evidently for B, Mn and Co substitution.

  17. Proteorhodopsin genes in giant viruses.

    PubMed

    Yutin, Natalya; Koonin, Eugene V

    2012-10-04

    Viruses with large genomes encode numerous proteins that do not directly participate in virus biogenesis but rather modify key functional systems of infected cells. We report that a distinct group of giant viruses infecting unicellular eukaryotes that includes Organic Lake Phycodnaviruses and Phaeocystis globosa virus encode predicted proteorhodopsins that have not been previously detected in viruses. Search of metagenomic sequence data shows that putative viral proteorhodopsins are extremely abundant in marine environments. Phylogenetic analysis suggests that giant viruses acquired proteorhodopsins via horizontal gene transfer from proteorhodopsin-encoding protists although the actual donor(s) could not be presently identified. The pattern of conservation of the predicted functionally important amino acid residues suggests that viral proteorhodopsin homologs function as sensory rhodopsins. We hypothesize that viral rhodopsins modulate light-dependent signaling, in particular phototaxis, in infected protists.

  18. Giant viruses come of age.

    PubMed

    Fischer, Matthias G

    2016-06-01

    Viruses with genomes up to a few megabases in length are a common occurrence in nature, even though they have escaped our notice until recently. These giant viruses infect mainly single-celled eukaryotes and isolation efforts concentrating on amoebal hosts alone have spawned hundreds of viral isolates, featuring viruses with previously unseen virion morphologies and the largest known viral genomes and particles. One of the challenges that lie ahead is to analyze and categorize the available data and to establish an approved classification system that reflects the evolutionary relationships and biological properties of these viruses. Extensive sampling of Acanthamoeba-infecting mimiviruses and initial characterization of their virophage parasites have provided a first blueprint of the genetic diversity and composition of a giant virus clade that will facilitate the taxonomic grouping of these fascinating microorganisms.

  19. Recurrent multilocular mandibular giant cell granuloma in neurofibromatosis type 1: Evidence for second hit mutation of NF1 gene in the jaw lesion and treatment with curettage and bone substitute materials.

    PubMed

    Friedrich, Reinhard E; Grob, Tobias J; Hollants, Silke; Zustin, Jozef; Spaepen, Marijke; Mautner, Victor F; Luebke, Andreas M; Hagel, Christian; Legius, Eric; Brems, Hilde

    2016-08-01

    Giant cell granuloma (GCG) of the jaw is a rare, well-known feature of neurofibromatosis type 1 (NF1), an inborn multisystem disorder. Recently, the development of GCG in NF1 was attributed to second hit mutations in the NF1 gene. The treatment of GCG is pragmatic with a preference for local curettage of lytic osseous areas. This report describes the surgical therapy of an NF1-affected female with multilocular mandibular GCG and hypodontia who additionally suffered from a brain tumour and Hashimoto's thyroiditis. Although local recurrence of GCG was noted, augmentation of the curetted cavities with a bone substitute in successive interventions successfully restored the extensive periradicular local defects and stabilised the teeth. A meticulous in vitro study of the GCG specimen revealed a second hit mutation in the NF1 gene in the GCG spindle-cells. This study contributes to the increasing knowledge of the molecular basis for GCG in the jaw of NF1 patients, indicating that it is a neoplasm.

  20. Giant thermoelectric effect in graphene

    NASA Astrophysics Data System (ADS)

    Dragoman, D.; Dragoman, M.

    2007-11-01

    The paper predicts a giant thermoelectric coefficient in a nanostructure consisting of metallic electrodes periodically patterned over graphene, which is deposited on a silicon dioxide substrate. The Seebeck coefficient in this device attains 30mV/K, this value being among the largest reported ever. The calculations are based on a transfer matrix approach that takes a particular form for graphene-based devices. The results are important for future nanogenerators with applications in the area of sensors, energy harvesting, and scavenging.