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Sample records for film bulk acoustic

  1. Recent developments of film bulk acoustic resonators

    NASA Astrophysics Data System (ADS)

    Gao, Junning; Liu, Guorong; Li, Jie; Li, Guoqiang

    2016-06-01

    Film bulk acoustic wave resonator (FBAR) experienced skyrocketing development in the past 15 years, owing to the explosive development of mobile communication. It stands out in acoustic filters mainly because of high quality factor, which enables low insertion loss and sharp roll off. Except for the massive application in wireless communication, FBARs are also promising sensors because of the high sensitivity and readily integration ability to miniaturize circuits. On the ground of summarizing FBAR’s application in wireless communication as filters and in sensors including electronic nose, bio field, and pressure sensing, this paper review the main challenges of each application faced. The number of filters installed in the mobile phone has being grown explosively, which leads to overcrowded bands and put harsh requirements on component size and power consumption control for each unit. Data flow and rate are becoming increasingly demanding as well. This paper discusses three promising technical strategies addressing these issues. Among which coupled resonator filter is given intense attention because it is able to vigorously reduce the filter size by stacking two or more resonators together, and it is a great technique to increase data flow and rate. Temperature compensation methods are discussed considering their vital influence on frequency stability. Finally, materials improvement and novel materials exploration for band width modulation, tunable band acquisition, and quality factor improvement are discussed. The authors appeal attention of the academic society to bring AlN epitaxial thin film into the FBAR fabrication and have proposed a configuration to implement this idea.

  2. Simulation and fabrication of thin film bulk acoustic wave resonator

    NASA Astrophysics Data System (ADS)

    Xixi, Han; Yi, Ou; Zhigang, Li; Wen, Ou; Dapeng, Chen; Tianchun, Ye

    2016-07-01

    In this paper, we present the simulation and fabrication of a thin film bulk acoustic resonator (FBAR). In order to improve the accuracy of simulation, an improved Mason model was introduced to design the resonator by taking the coupling effect between electrode and substrate into consideration. The resonators were fabricated by the eight inch CMOS process, and the measurements show that the improved Mason model is more accurate than a simple Mason model. The Q s (Q at series resonance), Q p (Q at parallel resonance), Q max and k t 2 of the FBAR were measured to be 695, 814, 1049, and 7.01% respectively, showing better performance than previous reports. Project supported by the National Natural Science Foundation of China (Nos. 61274119, 61306141, 61335008) and the Natural Science Foundation of Jiangsu Province (No. BK20131099).

  3. A new model for film bulk acoustic wave resonators

    NASA Astrophysics Data System (ADS)

    Li, Yu-Jin; Yuan, Xiu-Hua

    2014-11-01

    Based on cavity resonance and sandwich composite plate theory, this paper presents a universal three-dimensional (3D) theoretical model for frequency dispersion characterization and displacement profile shapes of the film bulk acoustic resonator (FBARs). This model provides results of FBAR excited thickness-extensional and flexure modes, and the result of frequency dispersion is proposed in which the thicknesses and impedance of the electrodes and the piezoelectric material are taken into consideration; its further simplification shows good agreement with the modified Butterworth—Van-Dyke (MBVD) model. The displacement profile reflects the vibration stress distribution of electrode shapes and the lateral resonance effect, which depends on the axis ratio of the electrode shapes a/b. The results are consistent with the 3D finite element method modeling and laser interferometry measurement in general.

  4. Quantitative Determination of Lateral Mode Dispersion in Film Bulk Acoustic Resonators through Laser Acoustic Imaging

    SciTech Connect

    Ken Telschow; John D. Larson III

    2006-10-01

    Film Bulk Acoustic Resonators are useful for many signal processing applications. Detailed knowledge of their operation properties are needed to optimize their design for specific applications. The finite size of these resonators precludes their use in single acoustic modes; rather, multiple wave modes, such as, lateral wave modes are always excited concurrently. In order to determine the contributions of these modes, we have been using a newly developed full-field laser acoustic imaging approach to directly measure their amplitude and phase throughout the resonator. This paper describes new results comparing modeling of both elastic and piezoelectric effects in the active material with imaging measurement of all excited modes. Fourier transformation of the acoustic amplitude and phase displacement images provides a quantitative determination of excited mode amplitude and wavenumber at any frequency. Images combined at several frequencies form a direct visualization of lateral mode excitation and dispersion for the device under test allowing mode identification and comparison with predicted operational properties. Discussion and analysis are presented for modes near the first longitudinal thickness resonance (~900 MHz) in an AlN thin film resonator. Plate wave modeling, taking account of material crystalline orientation, elastic and piezoelectric properties and overlayer metallic films, will be discussed in relation to direct image measurements.

  5. Laser Acoustic Imaging of Film Bulk Acoustic Resonator (FBAR) Lateral Mode Dispersion

    SciTech Connect

    Ken L. Telschow

    2004-07-01

    A laser acoustic imaging microscope has been developed that measures acoustic motion with high spatial resolution without scanning. Images are recorded at normal video frame rates and heterodyne principles are used to allow operation at any frequency from Hz to GHz. Fourier transformation of the acoustic amplitude and phase displacement images provides a direct quantitative determination of excited mode wavenumbers at any frequency. Results are presented at frequencies near the first longitudinal thickness mode (~ 900 MHz) demonstrating simultaneous excitation of lateral modes with nonzero wavenumbers in an electrically driven AlN thin film acoustic resonator. Images combined at several frequencies form a direct visualization of lateral mode dispersion relations for the device under test allowing mode identification and a direct measure of specific lateral mode properties. Discussion and analysis of the results are presented in comparison with plate wave modeling of these devices taking account for material anisotropy and multilayer films.

  6. Protein-modified shear mode film bulk acoustic resonator for bio-sensing applications

    NASA Astrophysics Data System (ADS)

    Wang, Jingjing; Liu, Weihui; Xu, Yan; Chen, Da; Li, Dehua; Zhang, Luyin

    2014-09-01

    In this paper, we present a shear mode film bulk acoustic biosensor based on micro-electromechanical technology. The film bulk acoustic biosensor is a diaphragmatic structure consisting of a lateral field excited ZnO piezoelectric film piezoelectric stack built on an Si3N4 membrane. The device works at near 1.6 GHz with Q factors of 579 in water and 428 in glycerol. A frequency shift of 5.4 MHz and a small decline in the amplitude are found for the measurements in glycerol compared with those in water because of the viscous damping derived from the adjacent glycerol. For bio-sensing demonstration, the resonator was modified with biotin molecule to detect protein-ligand interactions in real-time and in situ. The resonant frequency of the biotin-modified device drops rapidly and gradually reaches equilibrium when exposed to the streptavidin solution due to the biotin-streptavidin interaction. The proposed film bulk acoustic biosensor shows promising applications for disease diagnostics, prognosis, and drug discovery.

  7. Streptavidin Modified ZnO Film Bulk Acoustic Resonator for Detection of Tumor Marker Mucin 1.

    PubMed

    Zheng, Dan; Guo, Peng; Xiong, Juan; Wang, Shengfu

    2016-12-01

    A ZnO-based film bulk acoustic resonator has been fabricated using a magnetron sputtering technology, which was employed as a biosensor for detection of mucin 1. The resonant frequency of the thin-film bulk acoustic resonator was located near at 1503.3 MHz. The average electromechanical coupling factor [Formula: see text] and quality factor Q were 2.39 % and 224, respectively. Using the specific binding system of avidin-biotin, the streptavidin was self-assembled on the top gold electrode as the sensitive layer to indirectly test the MUC1 molecules. The resonant frequency of the biosensor decreases in response to the mass loading in range of 20-500 nM. The sensor modified with the streptavidin exhibits a high sensitivity of 4642.6 Hz/nM and a good selectivity. PMID:27624339

  8. 2-D modeling of laterally acoustically coupled thin film bulk acoustic wave resonator filters.

    PubMed

    Pensala, Tuomas; Meltaus, Johanna; Kokkonen, Kimmo; Ylilammi, Markku

    2010-11-01

    A 2-D model is developed for calculating lateral acoustical coupling between adjacent thin film BAW resonators forming an electrical N-port. The model is based on solution and superposition of lateral eigenmodes and eigenfrequencies in a structure consisting of adjacent regions with known plate wave dispersion properties. Mechanical and electrical response of the device are calculated as a superposition of eigenmodes according to voltage drive at one electrical port at a time while extracting current induced in the other ports, leading to a full Y-parameter description of the device. Exemplary cases are simulated to show the usefulness of the model in the study of the basic design rules of laterally coupled thin film BAW resonator filters. Model predictions are compared to an experimental 1.9-GHz band-pass filter based on aluminum nitride thin film technology and lateral acoustical coupling. Good agreement is obtained in prediction of passband behavior. The eigenmode-based model forms a useful tool for fast simulation of laterally coupled acoustic devices. It allows one to gain insight into basic device physics in a very intuitive fashion compared with more detailed but heavier finite element method. Shortcomings of this model and possible improvements are discussed. PMID:21041141

  9. Intrinsically tunable bulk acoustic wave resonators based on sol-gel grown PMN-PT films

    NASA Astrophysics Data System (ADS)

    Vorobiev, A.; Spreitzer, M.; Veber, A.; Suvorov, D.; Gevorgian, S.

    2014-08-01

    Intrinsically tunable bulk acoustic wave resonators, based on sol-gel 0.70Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 (PMN-PT) thin films, with high effective electromechanical coupling coefficient of 13% and tunability of the series resonance frequency up to 4.0% are fabricated and characterized. The enhanced electroacoustic properties of the PMN-PT resonators are attributed to the mechanism of polarization rotation occurring in the region of the morphotropic phase boundary. Electroacoustic performance of the PMN-PT resonators is analyzed using the theory of dc field-induced piezoelectric effect in ferroelectrics. Extrinsic acoustic loss in the PMN-PT resonators is analyzed using the model of the wave scattering at reflections from rough interfaces. Mechanical Q-factor of the resonators is up to 70 at 4.1 GHz and limited mainly by losses in the PMN-PT film.

  10. Film bulk acoustic resonators integrated on arbitrary substrates using a polymer support layer

    NASA Astrophysics Data System (ADS)

    Chen, Guohao; Zhao, Xinru; Wang, Xiaozhi; Jin, Hao; Li, Shijian; Dong, Shurong; Flewitt, A. J.; Milne, W. I.; Luo, J. K.

    2015-03-01

    The film bulk acoustic resonator (FBAR) is a widely-used MEMS device which can be used as a filter, or as a gravimetric sensor for biochemical or physical sensing. Current device architectures require the use of an acoustic mirror or a freestanding membrane and are fabricated as discrete components. A new architecture is demonstrated which permits fabrication and integration of FBARs on arbitrary substrates. Wave confinement is achieved by fabricating the resonator on a polyimide support layer. Results show when the polymer thickness is greater than a critical value, d, the FBARs have similar performance to devices using alternative architectures. For ZnO FBARs operating at 1.3-2.2 GHz, d is ~9 μm, and the devices have a Q-factor of 470, comparable to 493 for the membrane architecture devices. The polymer support makes the resonators insensitive to the underlying substrate. Yields over 95% have been achieved on roughened silicon, copper and glass.

  11. 3.4 GHz composite thin film bulk acoustic wave resonator for miniaturized atomic clocks

    SciTech Connect

    Artieda, Alvaro; Muralt, Paul

    2011-06-27

    Triple layer SiO{sub 2}/AlN/SiO{sub 2} composite thin film bulk acoustic wave resonators (TFBARs) were studied for applications in atomic clocks. The TFBAR's were tuned to 3.4 GHz, corresponding to half the hyperfine splitting of the ground state of rubidium {sup 87}Rb atoms. The quality factor (Q) was equal to 2300 and the temperature coefficient of the resonance frequency f{sub r} amounted to 1.5 ppm/K. A figure of merit Qf{sub r} of {approx} 0.8 x 10{sup 13} Hz and a thickness mode coupling factor of 1% were reached. Such figures are ideal for frequency sources in an oscillator circuit that tracks the optical signal in atomic clocks.

  12. Vibration optimization of ZnO thin film bulk acoustic resonator with ring electrodes

    NASA Astrophysics Data System (ADS)

    Zhao, Zinan; Qian, Zhenghua; Wang, Bin

    2016-04-01

    A rectangular ZnO thin film bulk acoustic resonator with ring electrodes is presented in this paper to demonstrate the existence of a nearly uniform displacement distribution at the central part of this typical resonator. The variational formulation based on two-dimensional scalar differential equations provides a theoretical foundation for the Ritz method adopted in our analysis. The resonant frequencies and vibration distributions for the thickness-extensional modes of this ring electrode resonator are obtained. The structural parameters are optimized to achieve a more uniform displacement distribution and therefore a uniform mass sensitivity, which guarantee the high accuracy and repeatable measurement for sensor detection in an air or a liquid environment. These results provide a fundamental reference for the design and optimization of the high quality sensor.

  13. Wave propagation in piezoelectric layered structures of film bulk acoustic resonators.

    PubMed

    Zhu, Feng; Qian, Zheng-hua; Wang, Bin

    2016-04-01

    In this paper, we studied the wave propagation in a piezoelectric layered plate consisting of a piezoelectric thin film on an electroded elastic substrate with or without a driving electrode. Both plane-strain and anti-plane waves were taken into account for the sake of completeness. Numerical results on dispersion relations, cut-off frequencies and vibration distributions of selected modes were given. The effects of mass ratio of driving electrode layer to film layer on the dispersion curve patterns and cut-off frequencies of the plane-strain waves were discussed in detail. Results show that the mass ratio does not change the trend of dispersion curves but larger mass ratio lowers corresponding frequency at a fixed wave number and may extend the frequency range for energy trapping. Those results are of fundamental importance and can be used as a reference to develop effective two-dimensional plate equations for structural analysis and design of film bulk acoustic resonators. PMID:26812132

  14. Film bulk acoustic resonators integrated on arbitrary substrates using a polymer support layer.

    PubMed

    Chen, Guohao; Zhao, Xinru; Wang, Xiaozhi; Jin, Hao; Li, Shijian; Dong, Shurong; Flewitt, A J; Milne, W I; Luo, J K

    2015-01-01

    The film bulk acoustic resonator (FBAR) is a widely-used MEMS device which can be used as a filter, or as a gravimetric sensor for biochemical or physical sensing. Current device architectures require the use of an acoustic mirror or a freestanding membrane and are fabricated as discrete components. A new architecture is demonstrated which permits fabrication and integration of FBARs on arbitrary substrates. Wave confinement is achieved by fabricating the resonator on a polyimide support layer. Results show when the polymer thickness is greater than a critical value, d, the FBARs have similar performance to devices using alternative architectures. For ZnO FBARs operating at 1.3-2.2 GHz, d is ~9 μm, and the devices have a Q-factor of 470, comparable to 493 for the membrane architecture devices. The polymer support makes the resonators insensitive to the underlying substrate. Yields over 95% have been achieved on roughened silicon, copper and glass. PMID:25824706

  15. Film bulk acoustic resonators integrated on arbitrary substrates using a polymer support layer

    PubMed Central

    Chen, Guohao; Zhao, Xinru; Wang, Xiaozhi; Jin, Hao; Li, Shijian; Dong, Shurong; Flewitt, A. J.; Milne, W. I.; Luo, J. K.

    2015-01-01

    The film bulk acoustic resonator (FBAR) is a widely-used MEMS device which can be used as a filter, or as a gravimetric sensor for biochemical or physical sensing. Current device architectures require the use of an acoustic mirror or a freestanding membrane and are fabricated as discrete components. A new architecture is demonstrated which permits fabrication and integration of FBARs on arbitrary substrates. Wave confinement is achieved by fabricating the resonator on a polyimide support layer. Results show when the polymer thickness is greater than a critical value, d, the FBARs have similar performance to devices using alternative architectures. For ZnO FBARs operating at 1.3–2.2 GHz, d is ~9 μm, and the devices have a Q-factor of 470, comparable to 493 for the membrane architecture devices. The polymer support makes the resonators insensitive to the underlying substrate. Yields over 95% have been achieved on roughened silicon, copper and glass. PMID:25824706

  16. Energy trapping of thickness-extensional modes in thin film bulk acoustic wave filters

    NASA Astrophysics Data System (ADS)

    Zhao, Zinan; Qian, Zhenghua; Wang, Bin

    2016-01-01

    This paper presents the thickness-extensional vibration of a rectangular piezoelectric thin film bulk acoustic wave filter with two pairs of electrodes symmetrically deposited on the center of the zinc oxide film. The two-dimensional scalar differential equations which were first derived to describe in-plane vibration distribution by Tiersten and Stevens are employed. The Ritz method with trigonometric functions as basis functions is used based on a variational formulation developed in our previous paper. Free vibration resonant frequencies and corresponding modes are obtained. The modes may separate into symmetric and antisymmetric ones for such a structurally symmetric filter. Trapped modes with vibrations mainly under the driving electrodes are exhibited. The six corner-type regions of the filter neglected by Tiersten and Stevens for an approximation are taken into account in our analysis. Results show that their approximation can lead to an inaccuracy on the order of dozens of ppm for the fundamental mode, which is quite significant in filter operation and application.

  17. Conformational Changes of Calmodulin on Calcium and Peptide Binding Monitored by Film Bulk Acoustic Resonators

    PubMed Central

    Nirschl, Martin; Ottl, Johannes; Vörös, Janos

    2011-01-01

    Film bulk acoustic resonators (FBAR) are mass sensitive, label-free biosensors that allow monitoring of the interaction between biomolecules. In this paper we use the FBAR to measure the binding of calcium and the CaMKII peptide to calmodulin. Because the mass of the calcium is too small to be detected, the conformational change caused by the binding process is measured by monitoring the resonant frequency and the motional resistance of the FBAR. The resonant frequency is a measure for the amount of mass coupled to the sensor while the motional resistance is influenced by the viscoelastic properties of the adsorbent. The measured frequency shift during the calcium adsorptions was found to be strongly dependent on the surface concentration of the immobilized calmodulin, which indicates that the measured signal is significantly influenced by the amount of water inside the calmodulin layer. By plotting the measured motional resistance against the frequency shift, a mass adsorption can be distinguished from processes involving measurable conformational changes. With this method three serial processes were identified during the peptide binding. The results show that the FBAR is a promising technology for the label-free measurement of conformational changes. PMID:25585566

  18. Investigation of the scaling rules determining the performance of film bulk acoustic resonators operating as mass sensors.

    PubMed

    Weber, Jan; Link, Mathias; Primig, Robert; Pitzer, Dana; Wersing, Wolfram; Schreiter, Matthias

    2007-02-01

    Solidly mounted (SMR-type) thin film bulk acoustic resonators operating at 2.2, 4.1, and 8.0 GHz and with lateral extents from 30 to 500 microm were fabricated and their performance as mass sensors was evaluated theoretically as well as experimentally. It was found that increasing the frequency leads to a principally improved performance of these devices. Problems arising for the horizontal as well as the vertical dimension and structure are investigated. PMID:17328337

  19. Full-Field Imaging of GHz Film Bulk Acoustic Resonator Motion

    SciTech Connect

    Telschow, Kenneth Louis; Deason, Vance Albert; Cottle, David Lynn; Larson III, J. D.

    2003-10-01

    A full-field view laser ultrasonic imaging method has been developed that measures acoustic motion at a surface without scanning. Images are recorded at normal video frame rates by using dynamic holography with photorefractive interferometric detection. By extending the approach to ultra high frequencies, an acoustic microscope has been developed that is capable of operation at gigahertz frequency and micron length scales. Both acoustic amplitude and phase are recorded, allowing full calibration and determination of phases to within a single arbitrary constant. Results are presented of measurements at frequencies of 800-900 MHz, illustrating a multitude of normal mode behavior in electrically driven thin film acoustic resonators. Coupled with microwave electrical impedance measurements, this imaging mode provides an exceptionally fast method for evaluation of electric-to-acoustic coupling of these devices and their performance. Images of 256 /spl times/ 240 pixels are recorded at 18 fps rates synchronized to obtain both in-phase and quadrature detection of the acoustic motion. Simple averaging provides sensitivity to the subnanometer level at each pixel calibrated over the image using interferometry. Identification of specific acoustic modes and their relationship to electrical impedance characteristics show the advantages and overall high speed of the technique.

  20. Monolithic integrated system with an electrowetting-on-dielectric actuator and a film-bulk-acoustic-resonator sensor

    NASA Astrophysics Data System (ADS)

    Zhang, Menglun; Cui, Weiwei; Chen, Xuejiao; Wang, Chao; Pang, Wei; Duan, Xuexin; Zhang, Daihua; Zhang, Hao

    2015-02-01

    Although digital microfluidics has shown great potential in a wide range of applications, a lab-on-a-chip with integrated digital droplet actuators and powerful biochemical sensors is still lacking. To address the demand, a fully integrated chip with electrowetting-on-dielectric (EWOD) and a film bulk acoustic resonator (FBAR) sensor is introduced, where an EWOD actuator manipulates digital droplets and the FBAR sensor detects the presence of substances in the droplets, respectively. The piezoelectric layer of the FBAR sensor and the dielectric layer of the EWOD share the same aluminum nitride (AlN) thin film, which is a key factor to achieve the full integration of the two completely different devices. The liquid droplets are reliably managed by the EWOD actuator to sit on or move off the FBAR sensor precisely. Sessile drop experiments and limit of detection (LOD) experiments are carried out to characterize the EWOD actuator and the FBAR sensor, respectively. Taking advantage of the digital droplet operation, a ‘dry sensing mode’ of the FBAR sensor in the lab-on-a-chip microsystem is proposed, which has a much higher signal to noise ratio than the conventional ‘wet sensing mode’. Hg2+ droplets with various concentrations are transported and sensed to demonstrate the capability of the integrated system. The EWOD-FBAR chip is expected to play an important role in many complex lab-on-a-chip applications.

  1. Nano-structural Characteristics of N-doped ZnO Thin Films and Fabrication of Film Bulk Acoustic Resonator Devices

    SciTech Connect

    Lee, E. J.; Zhang, R. R.; Yoon, G. W.; Park, J. D.

    2011-12-23

    N-doped ZnO thin films (ZnO:N) with c-axis preferred orientation were prepared on p-Si(100) wafers, using an RF magnetron sputter deposition. For ZnO deposition, N{sub 2}O gas was employed as a dopant source and various deposition conditions such as N{sub 2}O gas fraction and RF power were applied. In addition, the film bulk acoustic resonator (FBAR) devices with three kinds of top electrodes patterns were fabricated by using the N-doped ZnO thin films as the piezoelectric layers. The depth profiles of the nitrogen [N] atoms incorporated into the ZnO thin films were investigated by an Auger Electron Spectroscopy (AES) and the nano-scale structural characteristics of the N-doped ZnO (ZnO:N) thin films were also investigated by a scanning electron microscope (SEM) technique. The fabricated resonators were evaluated by measuring the return loss (S{sub 11}) characteristics using a probe station and E8361A PNA Network Analyzer.

  2. UV sensing using film bulk acoustic resonators based on Au/n-ZnO/piezoelectric-ZnO/Al structure

    PubMed Central

    Bian, Xiaolei; Jin, Hao; Wang, Xiaozhi; Dong, Shurong; Chen, Guohao; Luo, J. K.; Deen, M. Jamal; Qi, Bensheng

    2015-01-01

    A new type of ultraviolet (UV) light sensor based on film bulk acoustic wave resonator (FBAR) is proposed. The new sensor uses gold and a thin n-type ZnO layer deposited on the top of piezoelectric layer of FBAR to form a Schottky barrier. The Schottky barrier's capacitance can be changed with UV light, resulting in an enhanced shift in the entire FBAR's resonant frequency. The fabricated UV sensor has a 50 nm thick n-ZnO semiconductor layer with a carrier concentration of ~ 1017 cm−3. A large frequency downshift is observed when UV light irradiates the FBAR. With 365 nm UV light of intensity 1.7 mW/cm2, the FBAR with n-ZnO/Au Schottky diode has 250 kHz frequency downshift, much larger than the 60 kHz frequency downshift in a conventional FBAR without the n-ZnO layer. The shift in the new FBAR's resonant frequency is due to the junction formed between Au and n-ZnO semiconductor and its properties changes with UV light. The experimental results are in agreement with the theoretical analysis using an equivalent circuit model of the new FBAR structure. PMID:25773146

  3. Longitudinal bulk acoustic mass sensor

    SciTech Connect

    Hales, J. H.; Teva, J.; Boisen, A.; Davis, Z. J.

    2009-07-20

    A polycrystalline silicon longitudinal bulk acoustic cantilever is fabricated and operated in air at 51 MHz. A mass sensitivity of 100 Hz/fg (1 fg=10{sup -15} g) is obtained from the preliminary experiments where a minute mass is deposited on the device by means of focused ion beam. The total noise in the currently applied measurement system allows for a minimum detectable mass of 0.5 fg in air.

  4. Switchable and tunable film bulk acoustic resonator fabricated using barium strontium titanate active layer and Ta2O5/SiO2 acoustic reflector

    NASA Astrophysics Data System (ADS)

    Sbrockey, N. M.; Kalkur, T. S.; Mansour, A.; Khassaf, H.; Yu, H.; Aindow, M.; Alpay, S. P.; Tompa, G. S.

    2016-08-01

    A solidly mounted acoustic resonator was fabricated using a Ba0.60Sr0.40TiO3 (BST) film deposited by metal organic chemical vapor deposition. The device was acoustically isolated from the substrate using a Bragg reflector consisting of three pairs of Ta2O5/SiO2 layers deposited by chemical solution deposition. Transmission electron microscopy verified that the Bragg reflector was not affected by the high temperatures and oxidizing conditions necessary to process high quality BST films. Electrical characterization of the resonator demonstrated a quality factor (Q) of 320 and an electromechanical coupling coefficient (Kt2) of 7.0% at 11 V.

  5. Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

    NASA Astrophysics Data System (ADS)

    Polzikova, N. I.; Alekseev, S. G.; Pyataikin, I. I.; Kotelyanskii, I. M.; Luzanov, V. A.; Orlov, A. P.

    2016-05-01

    We present the generation and detection of spin currents by using magnetoelastic resonance excitation in a magnetoelectric composite high overtone bulk acoustic wave (BAW) resonator (HBAR) formed by a Al-ZnO-Al-GGG-YIG-Pt structure. Transversal BAW drives magnetization oscillations in YIG film at a given resonant magnetic field, and the resonant magneto-elastic coupling establishes the spin-current generation at the Pt/YIG interface. Due to the inverse spin Hall effect (ISHE) this BAW-driven spin current is converted to a dc voltage in the Pt layer. The dependence of the measured voltage both on magnetic field and frequency has a resonant character. The voltage is determined by the acoustic power in HBAR and changes its sign upon magnetic field reversal. We compare the experimentally observed amplitudes of the ISHE electrical field achieved by our method and other approaches to spin current generation that use surface acoustic waves and microwave resonators for ferromagnetic resonance excitation, with the theoretically expected values.

  6. Microfabricated bulk wave acoustic bandgap device

    DOEpatents

    Olsson, Roy H.; El-Kady, Ihab F.; McCormick, Frederick; Fleming, James G.; Fleming, Carol

    2010-06-08

    A microfabricated bulk wave acoustic bandgap device comprises a periodic two-dimensional array of scatterers embedded within the matrix material membrane, wherein the scatterer material has a density and/or elastic constant that is different than the matrix material and wherein the periodicity of the array causes destructive interference of the acoustic wave within an acoustic bandgap. The membrane can be suspended above a substrate by an air or vacuum gap to provide acoustic isolation from the substrate. The device can be fabricated using microelectromechanical systems (MEMS) technologies. Such microfabricated bulk wave phononic bandgap devices are useful for acoustic isolation in the ultrasonic, VHF, or UHF regime (i.e., frequencies of order 1 MHz to 10 GHz and higher, and lattice constants of order 100 .mu.m or less).

  7. Microfabricated bulk wave acoustic bandgap device

    DOEpatents

    Olsson, Roy H.; El-Kady, Ihab F.; McCormick, Frederick; Fleming, James G.; Fleming, legal representative, Carol

    2010-11-23

    A microfabricated bulk wave acoustic bandgap device comprises a periodic two-dimensional array of scatterers embedded within the matrix material membrane, wherein the scatterer material has a density and/or elastic constant that is different than the matrix material and wherein the periodicity of the array causes destructive interference of the acoustic wave within an acoustic bandgap. The membrane can be suspended above a substrate by an air or vacuum gap to provide acoustic isolation from the substrate. The device can be fabricated using microelectromechanical systems (MEMS) technologies. Such microfabricated bulk wave phononic bandgap devices are useful for acoustic isolation in the ultrasonic, VHF, or UHF regime (i.e., frequencies of order 1 MHz to 10 GHz and higher, and lattice constants of order 100 .mu.m or less).

  8. Spurious resonance suppression in gigahertz-range ZnO thin-film bulk acoustic wave resonators by the boundary frame method: modeling and experiment.

    PubMed

    Pensala, Tuomas; Ylilammi, Markku

    2009-08-01

    Zinc-oxide-based thin-film bulk acoustic wave (BAW) resonators operating at 932 MHz are investigated with respect to variation of dimensions of a boundary frame spurious mode suppression structure. A plate wave dispersion-based semi-2-D model and a 2-D finite element method are used to predict the eigenmode spectrum of the resonators to explain the detailed behavior. The models show how the boundary frame method changes the eigenmodes and their coupling to the driving electrical field via the modification of the mechanical boundary condition and leads to emergence of a flat-amplitude piston mode and suppression of spurious modes. Narrow band suppression of a single mode with a nonoptimal boundary frame is observed. Reduction of the effective electromechanical coupling coefficient k2eff as a function of the boundary width is observed and predicted by both models. The simple semi-2-D plate model is shown to predict the device behavior very well, and the 2-D finite element method results are shown to coincide with them with some additional effects. Breaking the resonator behavior down to eigenmodes, which are not directly observable in measurements, by the models, yields insight into the physics of the device operation. PMID:19686989

  9. Ultrahigh Q Bulk Acoustic Wave Cavities at the Quantum Limit

    NASA Astrophysics Data System (ADS)

    Tobar, Michael; Goryachev, Maxim; Ivanov, Eugene; van Kann, Frank; Galliou, Serge

    2015-03-01

    A Fabry-Perot cavity is an optical resonator, which can store photons for milliseconds and enhance interaction between light and matter. The acoustics analogue (phonon trapping), is the Bulk Acoustic Wave device (in thin film or crystal lattice). Measurements provide the ultimate material loss regimes, minimizing clamping losses and achieving record high Q.f products, allowing observation of various loss mechanisms such as Landau-Rumer, phonon-phonon dissipation and Rayleigh phonon scattering, as well as previously non-observed non-linear effects. This presentation will summarize our recent work towards cooling such modes to the ground state and operating the device at the Quantum Limit. This includes the first measurements of the Nyquist noise near at 4K, as well as details on using such devices to test fundamental physics. Funded by ARC Grant No. CE110001013.

  10. Porous silicon bulk acoustic wave resonator with integrated transducer

    PubMed Central

    2012-01-01

    We report that porous silicon acoustic Bragg reflectors and AlN-based transducers can be successfully combined and processed in a commercial solidly mounted resonator production line. The resulting device takes advantage of the unique acoustic properties of porous silicon in order to form a monolithically integrated bulk acoustic wave resonator. PMID:22776697

  11. S-Band Shallow Bulk Acoustic Wave (SBAW) microwave source

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Techniques necessary to fabricate a high performance S-band microwave single source using state-of-the-art shallow bulk acoustic wave (SBAW) were explored. The bulk wave structures of the AlN/Al 2O3 were investigated for both the R plane and basal plane of sapphire. A 1.072 GHz SBAW delay line and oscillators were developed. A method of selecting and setting oscillator output frequency by selecting substrate orientation angle was also established.

  12. Characterization of energy trapping in a bulk acoustic wave resonator

    NASA Astrophysics Data System (ADS)

    Kokkonen, Kimmo; Meltaus, Johanna; Pensala, Tuomas; Kaivola, Matti

    2010-12-01

    Acoustic wave fields both within the active electrode area of a solidly mounted 1.8 GHz bulk acoustic wave resonator, and around it in the surrounding region, are measured using a heterodyne laser interferometer. Plate-wave dispersion diagrams for both regions are extracted from the measurement data. The experimental dispersion data reveal the cutoff frequencies of the acoustic vibration modes in the region surrounding the resonator, and, therefore, the energy trapping range of the resonator can readily be determined. The measured dispersion properties of the surrounding region, together with the abruptly diminishing amplitude of the dispersion curves in the resonator, signal the onset of acoustic leakage from the resonator. This information is important for verifying and further developing the simulation tools used for the design of the resonators. Experimental wave field images, dispersion diagrams for both regions, and the threshold for energy leakage are discussed.

  13. Self-heating study of bulk acoustic wave resonators under high RF power.

    PubMed

    Ivira, Brice; Fillit, René-Yves; Ndagijimana, Fabien; Benech, Philippe; Parat, Guy; Ancey, Pascal

    2008-01-01

    The present work first provides an experimental technique to study self-heating of bulk acoustic wave (BAW) resonators under high RF power in the gigahertz range. This study is specially focused on film bulk acoustic wave resonators and solidly mounted resonators processed onto silicon wafers and designed for wireless systems. Precisely, the reflection coefficient of a one-port device is measured while up to several watts are applied and power leads to electrical drifts of impedances. In the following, we describe how absorbed power can be determined from the incident one in real time. Therefore, an infrared camera held over the radio frequency micro electromechanical system (RF-MEMS) surface with an exceptional spatial resolution reaching up to 2 microm/pixels gives accurate temperature mapping of resonators after emissivity correction. From theoretical point of view, accurate three-dimensional (3-D) structures for finite-element modeling analyses are carried out to know the best materials and architectures to use for enhancing power handling. In both experimental and theoretical investigations, comparison is made between film bulk acoustic wave resonators and solidly mounted resonators. Thus, the trend in term of material, architecture, and size of device for power application such as in transmission path of a transceiver is clearly identified. PMID:18334320

  14. Bulk photoemission from metal films and nanoparticles

    SciTech Connect

    Ikhsanov, R Sh; Babicheva, V E; Protsenko, I E; Uskov, A V; Guzhva, M E

    2015-01-31

    Internal emission of photoelectrons from metal films and nanoparticles (nanowires and nanospheres) into a semiconductor matrix is studied theoretically by taking into account the jump of the effective electron mass at the metal – semiconductor interface and the cooling effect of hot electrons due to electron – electron collisions in the metal. The internal quantum efficiency of photoemission for the film and nanoparticles of two types (nanospheres and nanowires) is calculated. It is shown that the reduction of the effective mass of the electron during its transition from metal to semiconductor may lead to a significant (orders of magnitude and higher) decrease in the internal quantum efficiency of bulk photoemission. (nanostructures)

  15. Optical find of hypersonic surface acoustic waves in bulk transparent materials

    NASA Astrophysics Data System (ADS)

    Jiménez Riobóo, Rafael J.; Sánchez-Sánchez, Alberto; Prieto, Carlos

    2016-07-01

    It is shown that direct information from surface acoustic waves (SAWs) of bulk transparent materials can be obtained by using Brillouin light scattering (BLS). The study of surface phonons by means of an optical spectroscopy such as BLS has been historically constrained to nontransparent and highly reflecting bulk and film samples or even to very thin films deposited on reflecting substrates. Probably due to its low signal and to the narrow window in experimental conditions, it was assumed for years that bulk transparent samples were not suited for Brillouin spectroscopy in order to get information on SAWs, negating this optical technique in the search for SAW properties. The reported experiments on transparent glasses and single crystals (cubic MgO and trigonal sapphire) prove that there is no intrinsic physical reason not to collect SAW propagation velocity data from transparent bulk samples and opens a challenge to apply the Brillouin spectroscopy in a wider scenario to obtain direct information, in a nondestructive and contactless way, about SAWs in bulk materials.

  16. High undercooling of bulk water during acoustic levitation

    NASA Astrophysics Data System (ADS)

    Lü, Yongjun; Cao, Chongde; Wei, Bingbo

    2003-06-01

    The experiments on undercooling of acoustically levitated water drops with the radius of 5-8 mm are carried out, and the maximum undercooling of 24 K is obtained in such a containerless state. Various factors influencing the undercoolability of water under acoustic levitation are synthetically analyzed. The experimental results indicate that impurities tend to decrease the undercooling level, whereas the dominant factor is the effect of ultrasound. The stirring and cavitation effects of ultrasound tend to stimulate the nucleation of water and prevent further bulk undercooling in experiments. The stirring effect provides some extra energy fluctuation to overcome the thermodynamic barrier for nucleation. The local high pressure caused by cavitation effect increases the local undercooling in water and stimulates nucleation before the achievement of a large bulk undercooling. According to the cooling curves, the dendrite growth velocity of ice is estimated, which is in good agreement with the theoretical prediction at the lower undercooling. The theoretical calculation predicts a dendrite growth velocity of 0.23 m/s corresponding to the maximum undercooling of 24 K, at which the rapid solidification of ice occurs.

  17. Surface acoustic wave propagation in graphene film

    SciTech Connect

    Roshchupkin, Dmitry Plotitcyna, Olga; Matveev, Viktor; Kononenko, Oleg; Emelin, Evgenii; Irzhak, Dmitry; Ortega, Luc; Zizak, Ivo; Erko, Alexei; Tynyshtykbayev, Kurbangali; Insepov, Zinetula

    2015-09-14

    Surface acoustic wave (SAW) propagation in a graphene film on the surface of piezoelectric crystals was studied at the BESSY II synchrotron radiation source. Talbot effect enabled the visualization of the SAW propagation on the crystal surface with the graphene film in a real time mode, and high-resolution x-ray diffraction permitted the determination of the SAW amplitude in the graphene/piezoelectric crystal system. The influence of the SAW on the electrical properties of the graphene film was examined. It was shown that the changing of the SAW amplitude enables controlling the magnitude and direction of current in graphene film on the surface of piezoelectric crystals.

  18. Dispersion and mirror transmission characteristics of bulk acoustic wave resonators.

    PubMed

    Kokkonen, Kimmo; Pensala, Tuomas; Kaivola, Matti

    2011-01-01

    A heterodyne laser interferometer is used for a detailed study of the acoustic wave fields excited in a 932-MHz solidly mounted ZnO thin-film BAW resonator. The sample is manufactured on a glass substrate, which also allows direct measurement of the vibration fields from the bottom of the acoustic mirror. Vibration fields are measured both on top of the resonator and at the mirror-substrate interface in a frequency range of 350 to 1200 MHz. Plate wave dispersion diagrams are calculated from the experimental data in both cases and the transmission characteristics of the acoustic mirror are determined as a function of both frequency and lateral wave number. The experimental data are compared with 1-D and 2-D simulations to evaluate the validity of the modeling tools commonly used in mirror design. All the major features observed in the 1-D model are identified in the measured dispersion diagrams, and the mirror transmission characteristics predicted for the longitudinal waves, by both the 1-D and the 2-D models, match the measured values well. PMID:21244989

  19. Cryogenic resonant acoustic spectroscopy of bulk materials (CRA spectroscopy).

    PubMed

    Zimmer, Anja; Nawrodt, Ronny; Koettig, Torsten; Neubert, Ralf; Thürk, Matthias; Vodel, Wolfgang; Seidel, Paul; Tünnermann, Andreas

    2007-06-01

    The capability to measure Q factors at cryogenic temperatures enhances the ability to study relaxation processes in solids. Here we present a high-precision cryogenic setup with the ability to measure Q factors of at least 10(9). This level of sensitivity offers new potential for analyzing relaxation processes in solids and for correlating mode shape and relaxation strength. Our improved method of mechanical spectroscopy, cryogenic resonant acoustic spectroscopy of bulk materials, is verified by identifying relaxation processes in low-loss quartz crystals. For the first time, we observe additional damping peaks. The mechanical Q factors of different modes of cylindrical crystalline quartz substrates were measured from 300 down to 6 K. Resonant modes with frequencies between 10 and 325 kHz were excited without contact to the substrates and the ring down of the amplitudes was recorded using an interferometric vibration readout. PMID:17614624

  20. Microwave bulk-acoustic-wave reflection-grating resonators.

    PubMed

    Oates, D E; Pan, J Y

    1988-01-01

    A technique for fabrication of bulk-acoustic-wave (BAW) resonators operating at fundamental frequencies between 1 and 10 GHz is presented. The resonators utilize a reflection grating made by optical holographic methods in iron-doped lithium niobate. Q factors of 30000 at 1 GHz have been demonstrated. Extension to Q of 10000 at 10 GHz appears feasible. Projected limitations to performance are discussed. The high Q at the high fundamental frequency directly results in low-phase noise. Phase-noise measurements of BAW resonator-stabilized oscillators operating at 1.14 GHz are presented. The single-sideband noise floor of <-140 dBc/Hz is shown to be in agreement with an analytical model. Projected improvements in the devices and circuits promise performance of <-160 dBc/Hz. PMID:18290157

  1. One-dimensional rigid film acoustic metamaterials

    NASA Astrophysics Data System (ADS)

    Ma, Fuyin; Wu, Jiu Hui; Huang, Meng

    2015-11-01

    We have designed a 1D film-type acoustic metamaterial structure consisting of several polymer films directly stacked on each other. It is experimentally revealed that the mass density law can be broken by such structures in the low frequency range. By comparing the sound transmission loss (STL) curves of structures with different numbers of cycles, materials and incident sound directions, several physical properties of the 1D film-type acoustic metamaterial are revealed, which consist of cyclical effects, surface effects and orientation effects. It is suggested that the excellent low frequency sound insulation capacity is influenced by both the cycle number and the stiffness of the film surface. Meanwhile, the surface effect plays a dominant role among these physical properties. Due to the surface acoustic property, for structures with a particular combination form, the STL dominated by the cyclical effects may reach saturation with increasing number of construction periods. Moreover, in some cases, the sound insulation ability is diverse for different sound incidence directions. This kind of 1D film-type periodic structure with these special physical properties provides a new concept for the regulation of sound waves.

  2. Picosecond Acoustic Measurement of Anisotropic Properties of Thin Films

    SciTech Connect

    Perton, M.; Rossignol, C.; Chigarev, N.; Audoin, B.

    2007-03-21

    Properties of thin metallic films have been studied extensively by means of laser-picosecond ultrasonics. Generation of longitudinal and shear waves via thermoelastic mechanism and large source has been only demonstrated for waves vectors along the normal to the interface. However, such measurements cannot provide complete information about elastic properties of films. As it has been already shown for nanosecond ultrasonics, the knowledge of group or phase velocities in several directions for sources with small lateral size allows determining the stiffness tensor coefficients of a sample. The experimental set-up was prepared to obtain the thinnest size for the source to achieve acoustic diffraction. The identification of the stiffness tensor components, based on the inversion of the bulk waves phase velocities, is applied to signals simulated and experimentally recorded for a material with hexagonal properties. First estimation of stiffness tensor coefficients for thin metallic film 2.1 {mu}m has been performed.

  3. Mechanically robust microfluidics and bulk wave acoustics to sort microparticles

    NASA Astrophysics Data System (ADS)

    Dauson, Erin R.; Gregory, Kelvin B.; Greve, David W.; Healy, Gregory P.; Oppenheim, Irving J.

    2016-04-01

    Sorting microparticles (or cells, or bacteria) is significant for scientific, medical and industrial purposes. Research groups have used lithium niobate SAW devices to produce standing waves, and then to align microparticles at the node lines in polydimethylsiloxane (PDMS, silicone) microfluidic channels. The "tilted angle" (skewed) configuration is a recent breakthrough producing particle trajectories that cross multiple node lines, making it practical to sort particles. However, lithium niobate wafers and PDMS microfluidic channels are not mechanically robust. We demonstrate "tilted angle" microparticle sorting in novel devices that are robust, rapidly prototyped, and manufacturable. We form our microfluidic system in a rigid polymethyl methacrylate (PMMA, acrylic) prism, sandwiched by lead-zirconium-titanate (PZT) wafers, operating in through-thickness mode with inertial backing, that produce standing bulk waves. The overall configuration is compact and mechanically robust, and actuating PZT wafers in through-thickness mode is highly efficient. Moving to this novel configuration introduced new acoustics questions involving internal reflections, but we show experimental images confirming the intended nodal geometry. Microparticles in "tilted angle" devices display undulating trajectories, where deviation from the straight path increases with particle diameter and with excitation voltage to create the mechanism by which particles are sorted. We show a simplified analytical model by which a "phase space" is constructed to characterize effective particle sorting, and we compare our experimental data to the predictions from that simplified model; precise correlation is not expected and is not observed, but the important physical trends from the model are paralleled in the measured particle trajectories.

  4. Acoustic resonant spectroscopy for characterization of thin polymer films

    NASA Astrophysics Data System (ADS)

    Tohmyoh, Hironori; Imaizumi, Takuya; Saka, Masumi

    2006-10-01

    An acoustic resonant spectroscopy technique for measuring the acoustic impedance, ultrasonic velocity, and density of micron-scale polymer films is developed. The method, which is based on spectral analysis, observes the acoustic resonance between water, the film, and a tungsten plate with high acoustic impedance in the frequency range of 20-70MHz. The interface between the film being examined and the plate is vacuum sealed, enabling us to characterize the low-density polyethylene film with acoustic impedances as low as about 1.9MNm-3s and the poly(vinyl chloride) film as thin as about 8μm. The error in the film density measurements is found to be less than 1%, and the validity of the technique is verified.

  5. An intermode-coupled thin-film micro-acoustic resonator

    NASA Astrophysics Data System (ADS)

    Arapan, Lilia; Katardjiev, Ilia; Yantchev, Ventsislav

    2012-08-01

    A novel concept for the development of thin-film micro-acoustic resonators based on the coupling between different plate acoustic modes is demonstrated. The basic principles for the design and fabrication of intermode-coupled plate acoustic wave resonators on c-textured thin aluminum nitride films are presented. More specifically, the lowest order symmetric S0 Lamb wave is excited and then coupled to the fundamental thickness shear bulk resonance by means of a metal strip grating with specific periodicity. The experimental results demonstrate that the grating-assisted intermode coupling can be employed in high-frequency resonators inheriting the low dispersive nature of the S0 mode in combination with the energy localization in the plate bulk typical for the fundamental thickness shear resonance.

  6. Electro-acoustic sensors based on AlN thin film: possibilities and limitations

    NASA Astrophysics Data System (ADS)

    Wingqvist, Gunilla

    2011-06-01

    The non-ferroelectric polar wurtzite aluminium nitride (AlN) material has been shown to have potential for various sensor applications both utilizing the piezoelectric effect directly for pressure sensors or indirectly for acoustic sensing of various physical, chemical and biochemical sensor applications. Especially, sputter deposited AlN thin films have played a central role for successful development of the thin film electro-acoustic technology. The development has been primarily driven by one device - the thin film bulk acoustic resonator (FBAR or TFBAR), with its primary use for high frequency filter applications for the telecom industry. AlN has been the dominating choice for commercial application due to compatibility with the integrated circuit technology, low acoustic and dielectric losses, high acoustic velocity in combination with comparably high (but still for some applications limited) electromechanical coupling. Recently, increased piezoelectric properties (and also electromechanical coupling) in the AlN through the alloying with scandium nitride (ScN) have been identified both experimentally and theoretically. Inhere, the utilization of piezoelectricity in electro-acoustic sensing will be discussed together with expectation on acoustic FBAR sensor performance with variation in piezoelectric material properties in the parameter space around AlN due to alloying, in view of the ScxAl1-xN (0

  7. Bulk microstructure and local elastic properties of carbon nanocomposites studied by impulse acoustic microscopy technique

    NASA Astrophysics Data System (ADS)

    Levin, V.; Petronyuk, Yu.; Morokov, E.; Chernozatonskii, L.; Kuzhir, P.; Fierro, V.; Celzard, A.; Bellucci, S.; Bistarelli, S.; Mastrucci, M.; Tabacchioni, I.

    2016-05-01

    Bulk microstructure and elastic properties of epoxy-nanocarbon nanocomposites for diverse types and different content of carbon nanofiller has been studied by using impulse acoustic microscopy technique. It has been shown occurrence of various types of mesoscopic structure formed by nanoparticles inside the bulk of nanocomposite materials, including nanoparticle conglomerates and nanoparticle aerogel systems. In spite of the bulk microstructure, nanocarbon composites demonstrate elastic uniformity and negligible influence of nanofiller on elastic properties of carbon nanocomposite materials.

  8. Diffraction of picosecond bulk longitudinal and shear waves in micron thick films

    NASA Astrophysics Data System (ADS)

    Audoin, B.; Perton, M.; Chigarev, N.; Rossignol, C.

    2008-01-01

    Investigation of thin metallic film properties by means of picosecond ultrasonics [C. Thomsen et al., Phys. Rev. Lett. 53, 989 (1984)] has been under the scope of several studies. Generation of longitudinal and shear waves [T. Pézeril et al., Phys. Rev. B 73, 132301 (2006); O. Matsuda et al., Phys. Rev. Lett. 93, 095501 (2004)] with a wave vector normal to the film free surface has been demonstrated. Such measurements cannot provide complete information about properties of anisotropic films. Extreme focusing of a laser pump beam (≈0.5 μm) on the sample surface has recently allowed us to provide evidence of picosecond acoustic diffraction in thin metallic films (≈1 μm) [C. Rossignol et al., Phys. Rev. Lett. 94, 166106 (2005)]. The resulting longitudinal and shear wavefronts propagate at group velocity through the bulk of the film. To interpret the received signals, source directivity diagrams are calculated taking into account material anisotropy, optical penetration, and laser beam width on the sample surface. It is shown that acoustic diffraction increases with optical penetration, so competing with the increasing of directivity caused by beam width. Reflection with mode conversion at the film-substrate interface is discussed.

  9. Characterization of graphene grown on bulk and thin film nickel.

    PubMed

    Lu, Chun-Chieh; Jin, Chuanhong; Lin, Yung-Chang; Huang, Chi-Ruei; Suenaga, Kazu; Chiu, Po-Wen

    2011-11-15

    We report on graphene films grown by atmospheric pressure chemical vapor deposition on bulk and thin film nickel. Carbon precipitation on the polycrystalline grains is controlled by the methane concentration and substrate cooling rate. It is found that graphene grows over multiple grains, with edges terminating along the grain boundaries and with dimensions directly correlated to the size of the underlying grains. This greatly restricts the resulting graphene size (<10 μm) in the thin film growth, whereas monolayer graphene with linear dimensions of hundreds of micrometers takes up the great majority of the surface overlayers on the bulk nickel (>50%). In addition, the number of layers can be better controlled in the bulk growth. Characterizations of the graphene sheets using transmission electron microscopy, Raman spectroscopy, and transport measurements in the field-effect configuration are also discussed. PMID:21967558

  10. Effects on LDEF exposed copper film and bulk

    NASA Technical Reports Server (NTRS)

    Peters, Palmer N.; Gregory, John C.; Christl, Ligia C.; Raikar, Ganesh N.

    1991-01-01

    Two forms of copper were exposed to the Long Duration Exposure Facility (LDEF) Mission 1 environment: a copper film, initially 74.2 plus or minus 1.1 nm thick sputter coated on a fused silica flat and a bulk piece of oxygen-free, high conductivity (OFHC) copper. The optical density of the copper film changed from 1.33 to 0.70 where exposed, and the film thickness increased to 106.7 plus or minus 0.5 nm where exposed. The exposed area appears purple by reflection and green by transmission for the thin film and maroon color for the bulk copper piece. The exposed areas increased in thickness, but only increase in the thickness of the thin film sample could be readily measured. The increase in film thickness is consistent with the density changes occurring during conversion of copper to an oxide. However, we have not been able to confirm appreciable conversion to an oxide by x-ray diffraction studies. We have not yet subjected the sample to e-beams or more abusive investigations out of concern that the film might be modified.

  11. Bulk and Thin Film Contact Resistance with Dissimilar Materials

    NASA Astrophysics Data System (ADS)

    Lau, Y. Y.; Zhang, P.; Tang, W.; Gomez, M. R.; French, D. M.; Zier, J. C.; Gilgenbach, R. M.

    2011-10-01

    Contact resistance is important to integrated circuits, thin film devices, carbon nanotube based cathodes, MEMS relays and interconnectors, wire-array z-pinches, metal-insulator-vacuum junctions, and high power microwave sources, etc. This paper summarizes the recent modeling efforts at U of M, addressing the effect of dissimilar materials and of finite dimensions on the contact resistance of both bulk contacts and thin film contacts. Accurate analytical scaling laws are constructed for the contact resistance of both bulk and thin film contacts over a large range of resistivity ratios and aspect ratios in Cartesian and cylindrical geometries. They were validated against known limiting cases; and spot-checks with numerical simulations and experiments. Supported by AFOSR, AFRL, L-3, and Northrop-Grumman.

  12. Acoustic phonon dynamics in thin-films of the topological insulator Bi{sub 2}Se{sub 3}

    SciTech Connect

    Glinka, Yuri D.; Babakiray, Sercan; Johnson, Trent A.; Holcomb, Mikel B.; Lederman, David

    2015-04-28

    Transient reflectivity traces measured for nanometer-sized films (6–40 nm) of the topological insulator Bi{sub 2}Se{sub 3} revealed GHz-range oscillations driven within the relaxation of hot carriers photoexcited with ultrashort (∼100 fs) laser pulses of 1.51 eV photon energy. These oscillations have been suggested to result from acoustic phonon dynamics, including coherent longitudinal acoustic phonons in the form of standing acoustic waves. An increase of oscillation frequency from ∼35 to ∼70 GHz with decreasing film thickness from 40 to 15 nm was attributed to the interplay between two different regimes employing traveling-acoustic-waves for films thicker than 40 nm and the film bulk acoustic wave resonator (FBAWR) modes for films thinner than 40 nm. The amplitude of oscillations decays rapidly for films below 15 nm thick when the indirect intersurface coupling in Bi{sub 2}Se{sub 3} films switches the FBAWR regime to that of the Lamb wave excitation. The frequency range of coherent longitudinal acoustic phonons is in good agreement with elastic properties of Bi{sub 2}Se{sub 3}.

  13. Extremely high Q-factor mechanical modes in quartz bulk acoustic wave resonators at millikelvin temperature

    SciTech Connect

    Goryachev, M.; Creedon, D. L.; Ivanov, E. N.; Tobar, M. E.; Galliou, S.; Bourquin, R.

    2014-12-04

    We demonstrate that Bulk Acoustic Wave (BAW) quartz resonator cooled down to millikelvin temperatures are excellent building blocks for hybrid quantum systems with extremely long coherence times. Two overtones of the longitudinal mode at frequencies of 15.6 and 65.4 MHz demonstrate a maximum f.Q product of 7.8×10{sup 16} Hz. With this result, the Q-factor in such devices near the quantum ground state can be four orders of magnitude better than previously attained in other mechanical systems. Tested quartz resonators possess the ultra low acoustic losses crucial for electromagnetic cooling to the phonon ground state.

  14. Acoustic Experiment to Measure the Bulk Viscosity of Near-Critical Xenon in Microgravity

    NASA Technical Reports Server (NTRS)

    Gillis, K. A.; Shinder, I.; Moldover, M. R.; Zimmerli, G. A.

    2002-01-01

    We plan a rigorous test of the theory of dynamic scaling by accurately measuring the bulk viscosity of xenon in microgravity 50 times closer to the critical temperature T(sub c) than previous experiments. The bulk viscosity zeta (or "second viscosity" or "dilational viscosity") will be determined by measuring the attenuation length of sound alpha lambda and also measuring the frequency-dependence of the speed of sound. For these measurements, we developed a unique Helmholtz resonator and specialized electro-acoustic transducers. We describe the resonator, the transducers, their performance on Earth, and their expected performance in microgravity.

  15. Dynamic behavior of microscale particles controlled by standing bulk acoustic waves

    SciTech Connect

    Greenhall, J.; Raeymaekers, B.; Guevara Vasquez, F.

    2014-10-06

    We analyze the dynamic behavior of a spherical microparticle submerged in a fluid medium, driven to the node of a standing bulk acoustic wave created by two opposing transducers. We derive the dynamics of the fluid-particle system taking into account the acoustic radiation force and the time-dependent and time-independent drag force acting on the particle. Using this dynamic model, we characterize the transient and steady-state behavior of the fluid-particle system as a function of the particle and fluid properties and the transducer operating parameters. The results show that the settling time and percent overshoot of the particle trajectory are dependent on the ratio of the acoustic radiation force and time-independent damping force. In addition, we show that the particle oscillates around the node of the standing wave with an amplitude that depends on the ratio of the time-dependent drag forces and the particle inertia.

  16. Zinc oxide thin film acoustic sensor

    SciTech Connect

    Mohammed, Ali Jasim; Salih, Wafaa Mahdi; Hassan, Marwa Abdul Muhsien; Nusseif, Asmaa Deiaa; Kadhum, Haider Abdullah; Mansour, Hazim Louis

    2013-12-16

    This paper reports the implementation of (750 nm) thickness of Zinc Oxide (ZnO) thin film for the piezoelectric pressure sensors. The film was prepared and deposited employing the spray pyrolysis technique. XRD results show that the growth preferred orientation is the (002) plane. A polycrystalline thin film (close to mono crystallite like) was obtained. Depending on the Scanning Electron Microscopy photogram, the film homogeneity and thickness were shown. The resonance frequency measured (about 19 kHz) and the damping coefficient was calculated and its value was found to be about (2.5538), the thin film be haves as homogeneous for under and over damped. The thin film pressure sensing was approximately exponentially related with frequency, the thin film was observed to has a good response for mechanical stresses also it is a good material for the piezoelectric properties.

  17. Zinc oxide thin film acoustic sensor

    NASA Astrophysics Data System (ADS)

    Mohammed, Ali Jasim; Salih, Wafaa Mahdi; Hassan, Marwa Abdul Muhsien; Mansour, Hazim Louis; Nusseif, Asmaa Deiaa; Kadhum, Haider Abdullah

    2013-12-01

    This paper reports the implementation of (750 nm) thickness of Zinc Oxide (ZnO) thin film for the piezoelectric pressure sensors. The film was prepared and deposited employing the spray pyrolysis technique. XRD results show that the growth preferred orientation is the (002) plane. A polycrystalline thin film (close to mono crystallite like) was obtained. Depending on the Scanning Electron Microscopy photogram, the film homogeneity and thickness were shown. The resonance frequency measured (about 19 kHz) and the damping coefficient was calculated and its value was found to be about (2.5538), the thin film be haves as homogeneous for under and over damped. The thin film pressure sensing was approximately exponentially related with frequency, the thin film was observed to has a good response for mechanical stresses also it is a good material for the piezoelectric properties.

  18. Progress on Acoustic Measurements of the Bulk Viscosity of Near-Critical Xenon (BVX)

    NASA Technical Reports Server (NTRS)

    Gillis, Keith A.; Shinder, Iosif I.; Moldover, Michael R.; Zimmerli, Gregory A.

    2004-01-01

    We plan to determine the bulk viscosity of xenon 10 times closer [in reduced temperature tau = (T-Tc)/Tc] to its liquid-vapor critical point than ever before. (Tc is the critical temperature.) To do so, we must measure the dispersion and attenuation of sound at frequencies 1/100 of those used previously. In general, sound attenuation has contributions from the bulk viscosity acting throughout the volume of the xenon as well as contributions from the thermal conductivity and the shear viscosity acting within thin thermoacoustic boundary layers at the interface between the xenon and the solid walls of the resonator. Thus, we can determine the bulk viscosity only when the boundary layer attenuation is small and well understood. We present a comparison of calculations and measurements of sound attenuation in the acoustic boundary layer of xenon near its liquid-vapor critical point.

  19. Measurement of thin films using very long acoustic wavelengths

    NASA Astrophysics Data System (ADS)

    Clement, G. T.; Nomura, H.; Adachi, H.; Kamakura, T.

    2013-12-01

    A procedure for measuring material thickness by means of necessarily long acoustic wavelengths is examined. The approach utilizes a temporal phase lag caused by the impulse time of wave momentum transferred through a thin layer that is much denser than its surrounding medium. In air, it is predicted that solid or liquid layers below approximately 1/2000 of the acoustic wavelength will exhibit a phase shift with an arctangent functional dependence on thickness and layer density. The effect is verified for thin films on the scale of 10 μm using audible frequency sound (7 kHz). Soap films as thin as 100 nm are then measured using 40 kHz air ultrasound. The method's potential for imaging applications is demonstrated by combining the approach with near-field holography, resulting in reconstructions with sub-wavelength resolution in both the depth and lateral directions. Potential implications at very high and very low acoustic frequencies are discussed.

  20. Crystalline state and acoustic properties of zinc oxide films

    SciTech Connect

    Kal'naya, G.I.; Pryadko, I.F.; Yarovoi, Yu.A.

    1988-08-01

    We study the effect of the crystalline state of zinc oxide films, prepared by magnetron sputtering, on the efficiency of SAW transducers based on the layered system textured ZnO film-interdigital transducer (IDT)-fused quartz substrate. The crystalline perfection of the ZnO films was studied by the x-ray method using a DRON-2.0 diffractometer. The acoustic properties of the layered system fused quartz substrate-IDT-zinc oxide film were evaluated based on the squared electromechanical coupling constant K/sup 2/ for strip filters. It was found that K/sup 2/ depends on the magnitude of the mechanical stresses. When zinc oxide films are deposited by the method of magnetron deposition on fused quartz substrates, depending on the process conditions limitations can arise on the rate of deposition owing to mechanical stresses, which significantly degrade the efficiency of SAW transducers based on them, in the ZnO films.

  1. Acoustic Techniques for Thin Film Thickness Measurement in Semiconductor Processing

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Sanjay

    In modern semiconductor manufacturing, process monitoring and control are important issues limited at the present time by a lack of sensors and instrumentation capable of measuring process parameters like film thickness. In order to address this problem, two novel systems for thin film thickness measurement in semiconductor processing based upon contacting acoustic techniques have been developed. Both of these systems couple acoustic energy into the wafer via a nondestructive Hertzian contact and achieve high resolution by exciting and receiving ultrasonic signals from a ZnO transducer with microwave frequency electronics. The basic physical mechanism for film thickness determination is to analyze reflected waves due to acoustic impedance mismatches between various material layers on a silicon substrate. The first system requires frontside contacting of a sapphire buffer rod to an opaque film deposited on a silicon wafer and involves the use of broadband, high frequency pulse-echo electronics in the 0.5-5 GHz range. With this system, ex-situ measurements of aluminum and gold thin films on a silicon substrate have been done in the 0.25-2.5 mum. range with 3-6% accuracy as compared to surface profilometer measurements. Possible applications for this system include using it as a post -deposition process monitor, generating film thickness contour maps, or examining multilayer structures. The second system requires backside contacting of a sapphire buffer rod to a silicon wafer, which is in a vacuum station, and involves monitoring the changes in phase of CW 1-2 GHz acoustic waves as a function of frontside film growth. Using this technique, in-situ indium and aluminum film thickness monitoring has been done in both evaporator and sputtering environments with a resolution of 40 A. Temperature experiments in an oven have shown a resolution of 0.05 K for the sapphire buffer rod. Finally, multistep processing has been done and a multilayer film structure has been measured

  2. Focus Adjustment System of Laser Probe for Radio Frequency Surface and Bulk Acoustic Wave Devices

    NASA Astrophysics Data System (ADS)

    Wu, Nan; Kashiwa, Keisuke; Hashimoto, Ken-ya; Omori, Tatsuya; Yamaguchi, Masatsune; Kasai, Naoki

    2009-10-01

    In this paper, we describe a focus adjustment system designed especially for a fast-mechanical-scanning laser probe for radio-frequency surface and bulk acoustic wave devices. When high spatial resolution is necessary for the observation, one needs an objective lens of large magnifying power with extremely shallow focal depth. Then, a small inclination of a measurement device may cause severe defocus resulting in blurred images. We installed the focus adjustment system in the laser probe, and showed that even with inclination, high-quality information of the wave field can be acquired without reducing the scanning speed.

  3. Flute-model acoustic metamaterials with simultaneously negative bulk modulus and mass density

    NASA Astrophysics Data System (ADS)

    Zeng, Hong-Cheng; Luo, Chun-Rong; Chen, Huai-Jun; Zhai, Shi-Long; Ding, Chang-Lin; Zhao, Xiao-Peng

    2013-11-01

    We experimentally constructed a three-dimensional flute-model meta-molecule structure acoustic metamaterial (AM) from a periodic array of perforated hollow steel tubes (PHSTs) and investigated its transmission and reflection behaviors in an impedance tube system. The AM exhibited a peak and dip, and an inverse phase, thus exhibiting the local resonance of the PHSTs. Based on the homogeneous media theory, the effective bulk modulus and mass density of the AM were calculated to be simultaneously negative; the refractive index was also negative. PHST AM slab focusing experiments showed that the medium with a resonant structure exhibited a distinct metamaterial property.

  4. Jump chaotic behaviour of ultra low loss bulk acoustic wave cavities

    SciTech Connect

    Goryachev, Maxim Farr, Warrick G.; Tobar, Michael E.; Galliou, Serge

    2014-08-11

    We demonstrate a previously unobserved nonlinear phenomenon in an ultra-low loss quartz bulk acoustic wave cavity (Q>3>10{sup 9}), which only occurs below 20 mK in temperature and under relatively weak pumping. The phenomenon reveals the emergence of several stable equilibria (at least two foci and two nodes) and jumps between these quasi states at random times. The degree of this randomness as well as separations between levels can be controlled by the frequency of the incident carrier signal. It is demonstrated that the nature of the effect lies beyond the standard Duffing model.

  5. Visualization of Surface Acoustic Waves in Thin Liquid Films

    PubMed Central

    Rambach, R. W.; Taiber, J.; Scheck, C. M. L.; Meyer, C.; Reboud, J.; Cooper, J. M.; Franke, T.

    2016-01-01

    We demonstrate that the propagation path of a surface acoustic wave (SAW), excited with an interdigitated transducer (IDT), can be visualized using a thin liquid film dispensed onto a lithium niobate (LiNbO3) substrate. The practical advantages of this visualization method are its rapid and simple implementation, with many potential applications including in characterising acoustic pumping within microfluidic channels. It also enables low-cost characterisation of IDT designs thereby allowing the determination of anisotropy and orientation of the piezoelectric substrate without the requirement for sophisticated and expensive equipment. Here, we show that the optical visibility of the sound path critically depends on the physical properties of the liquid film and identify heptane and methanol as most contrast rich solvents for visualization of SAW. We also provide a detailed theoretical description of this effect. PMID:26917490

  6. Visualization of Surface Acoustic Waves in Thin Liquid Films.

    PubMed

    Rambach, R W; Taiber, J; Scheck, C M L; Meyer, C; Reboud, J; Cooper, J M; Franke, T

    2016-01-01

    We demonstrate that the propagation path of a surface acoustic wave (SAW), excited with an interdigitated transducer (IDT), can be visualized using a thin liquid film dispensed onto a lithium niobate (LiNbO3) substrate. The practical advantages of this visualization method are its rapid and simple implementation, with many potential applications including in characterising acoustic pumping within microfluidic channels. It also enables low-cost characterisation of IDT designs thereby allowing the determination of anisotropy and orientation of the piezoelectric substrate without the requirement for sophisticated and expensive equipment. Here, we show that the optical visibility of the sound path critically depends on the physical properties of the liquid film and identify heptane and methanol as most contrast rich solvents for visualization of SAW. We also provide a detailed theoretical description of this effect. PMID:26917490

  7. Visualization of Surface Acoustic Waves in Thin Liquid Films

    NASA Astrophysics Data System (ADS)

    Rambach, R. W.; Taiber, J.; Scheck, C. M. L.; Meyer, C.; Reboud, J.; Cooper, J. M.; Franke, T.

    2016-02-01

    We demonstrate that the propagation path of a surface acoustic wave (SAW), excited with an interdigitated transducer (IDT), can be visualized using a thin liquid film dispensed onto a lithium niobate (LiNbO3) substrate. The practical advantages of this visualization method are its rapid and simple implementation, with many potential applications including in characterising acoustic pumping within microfluidic channels. It also enables low-cost characterisation of IDT designs thereby allowing the determination of anisotropy and orientation of the piezoelectric substrate without the requirement for sophisticated and expensive equipment. Here, we show that the optical visibility of the sound path critically depends on the physical properties of the liquid film and identify heptane and methanol as most contrast rich solvents for visualization of SAW. We also provide a detailed theoretical description of this effect.

  8. Soft resonator of omnidirectional resonance for acoustic metamaterials with a negative bulk modulus

    NASA Astrophysics Data System (ADS)

    Jing, Xiaodong; Meng, Yang; Sun, Xiaofeng

    2015-11-01

    Monopolar resonance is of fundamental importance in the acoustic field. Here, we present the realization of a monopolar resonance that goes beyond the concept of Helmholtz resonators. The balloon-like soft resonator (SR) oscillates omnidirectionally and radiates from all parts of its spherical surface, eliminating the need for a hard wall for the cavity and baffle effects. For airborne sound, such a low-modulus resonator can be made extremely lightweight. Deep subwavelength resonance is achieved when the SR is tuned by adjusting the shell thickness, benefiting from the large density contrast between the shell material and the encapsulated gas. The SR resonates with near-perfect monopole symmetry, as demonstrated by the theoretical and experimental results, which are in excellent agreement. For a lattice of SRs, a band gap occurs and blocks near-total transmission, and the effective bulk modulus exhibits a prominent negative band, while the effective mass density remains unchanged. Our study shows that the SR is suitable for building 3D acoustic metamaterials and provides a basis for constructing left-handed materials as a new means of creating a negative bulk modulus.

  9. Soft resonator of omnidirectional resonance for acoustic metamaterials with a negative bulk modulus.

    PubMed

    Jing, Xiaodong; Meng, Yang; Sun, Xiaofeng

    2015-01-01

    Monopolar resonance is of fundamental importance in the acoustic field. Here, we present the realization of a monopolar resonance that goes beyond the concept of Helmholtz resonators. The balloon-like soft resonator (SR) oscillates omnidirectionally and radiates from all parts of its spherical surface, eliminating the need for a hard wall for the cavity and baffle effects. For airborne sound, such a low-modulus resonator can be made extremely lightweight. Deep subwavelength resonance is achieved when the SR is tuned by adjusting the shell thickness, benefiting from the large density contrast between the shell material and the encapsulated gas. The SR resonates with near-perfect monopole symmetry, as demonstrated by the theoretical and experimental results, which are in excellent agreement. For a lattice of SRs, a band gap occurs and blocks near-total transmission, and the effective bulk modulus exhibits a prominent negative band, while the effective mass density remains unchanged. Our study shows that the SR is suitable for building 3D acoustic metamaterials and provides a basis for constructing left-handed materials as a new means of creating a negative bulk modulus. PMID:26538085

  10. Electrostatic Generation of Bulk Acoustic Waves and Electrical Parameters of Si-MEMS Resonators.

    PubMed

    Dulmet, Bernard; Ivan, Mihaela Eugenia; Ballandras, Sylvain

    2016-02-01

    This paper proposes an analytical approach to model the generation of bulk acoustic waves in an electrostatically excited silicon MEMS structure, as well as its electromechanical response in terms of static and dynamic displacements, electromechanical coupling, and motional current. The analysis pertains to the single-port electrostatic drive of trapped-energy thickness-extensional (TE) modes in thin plates. Both asymmetric single-side and symmetric double-side electrostatic gap configurations are modeled. Green's function is used to describe the characteristic of the static displacement of the driven surface of the structure versus the dc bias voltage, which allows us to determine the electrical response of the resonator. Optical and electrical characterizations have been performed on resonator samples operating at 10.3 MHz on the fundamental of TE mode under single-side electrostatic excitation. The various figures of merit depend on the dc bias voltage. Typical values of 9000 for the Q-factor, and of 10(-5) for the electromechanical coupling factor k(2) have been obtained with [Formula: see text] for [Formula: see text]-thick gaps. Here-considered modes have a typical temperature coefficients of frequency (TCF) close to -30 ppm/(°)C. We conclude that the practical usability of such electrostatically excited bulk acoustic waves (BAW) resonators essentially depends on the efficiency of the compensation of feed-through capacitance. PMID:26642450

  11. Soft resonator of omnidirectional resonance for acoustic metamaterials with a negative bulk modulus

    PubMed Central

    Jing, Xiaodong; Meng, Yang; Sun, Xiaofeng

    2015-01-01

    Monopolar resonance is of fundamental importance in the acoustic field. Here, we present the realization of a monopolar resonance that goes beyond the concept of Helmholtz resonators. The balloon-like soft resonator (SR) oscillates omnidirectionally and radiates from all parts of its spherical surface, eliminating the need for a hard wall for the cavity and baffle effects. For airborne sound, such a low-modulus resonator can be made extremely lightweight. Deep subwavelength resonance is achieved when the SR is tuned by adjusting the shell thickness, benefiting from the large density contrast between the shell material and the encapsulated gas. The SR resonates with near-perfect monopole symmetry, as demonstrated by the theoretical and experimental results, which are in excellent agreement. For a lattice of SRs, a band gap occurs and blocks near-total transmission, and the effective bulk modulus exhibits a prominent negative band, while the effective mass density remains unchanged. Our study shows that the SR is suitable for building 3D acoustic metamaterials and provides a basis for constructing left-handed materials as a new means of creating a negative bulk modulus. PMID:26538085

  12. Phonon-Electron Interactions in Piezoelectric Semiconductor Bulk Acoustic Wave Resonators

    PubMed Central

    Gokhale, Vikrant J.; Rais-Zadeh, Mina

    2014-01-01

    This work presents the first comprehensive investigation of phonon-electron interactions in bulk acoustic standing wave (BAW) resonators made from piezoelectric semiconductor (PS) materials. We show that these interactions constitute a significant energy loss mechanism and can set practical loss limits lower than anharmonic phonon scattering limits or thermoelastic damping limits. Secondly, we theoretically and experimentally demonstrate that phonon-electron interactions, under appropriate conditions, can result in a significant acoustic gain manifested as an improved quality factor (Q). Measurements on GaN resonators are consistent with the presented interaction model and demonstrate up to 35% dynamic improvement in Q. The strong dependencies of electron-mediated acoustic loss/gain on resonance frequency and material properties are investigated. Piezoelectric semiconductors are an extremely important class of electromechanical materials, and this work provides crucial insights for material choice, material properties, and device design to achieve low-loss PS-BAW resonators along with the unprecedented ability to dynamically tune resonator Q. PMID:25001100

  13. Bulk and thin films of FeTe: A Moessbauer study

    NASA Technical Reports Server (NTRS)

    Escue, W. T.; Aggarwal, K.; Mendiratta, R. G.

    1977-01-01

    Studies of bulk and thin films of FeTe using Moessbauer spectroscopy showed that FeTe has one noncubic Fe (+2) site which is 3d2 4s 4p3 hybridized. The presence of dangling bands was indicated in spectra of FeTe thin films. The films showed a tendency of texture formation. The substrate was observed to influence the film structure and nature of bonds in films.

  14. Absorption of surface acoustic waves by topological insulator thin films

    SciTech Connect

    Li, L. L.; Xu, W.

    2014-08-11

    We present a theoretical study on the absorption of the surface acoustic waves (SAWs) by Dirac electrons in topological insulator (TI) thin films (TITFs). We find that due to momentum and energy conservation laws, the absorption of the SAWs in TITFs can only be achieved via intra-band electronic transitions. The strong absorption can be observed up to sub-terahertz frequencies. With increasing temperature, the absorption intensity increases significantly and the cut-off frequency is blue-shifted. More interestingly, we find that the absorption of the SAWs by the TITFs can be markedly enhanced by the tunable subgap in the Dirac energy spectrum of the TI surface states. Such a subgap is absent in conventional two-dimensional electron gases (2DEGs) and in the gapless Dirac 2DEG such as graphene. This study is pertinent to the exploration of the acoustic properties of TIs and to potential application of TIs as tunable SAW devices working at hypersonic frequencies.

  15. Thin aerogel films for optical, thermal, acoustic, and electronic applications

    SciTech Connect

    Hrubesh, L.W.; Poco, J.F.

    1994-09-01

    Aerogels are a special class of continuously porous solid materials which are characterized by nanometer size particles and pores. Typically, aerogels are made using sol-gel chemistry to form a solvent filled, high porosity gel that is dried by removing the solvent without collapsing the tenuous solid phase. As bulk materials, aerogels are known to have many exceptional, and even some unique physical properties. Aerogels provide the highest thermal insulation and lowest dielectric constant of any other material known. However, some important applications require the aerogels in the form of thin films or sheets. For example, electronic applications require micrometer thin aerogel films bonded to a substrate, and others require thicker films, either on a substrate or as free standing sheets. Special methods are required to make aerogel thin films or sheets. In this paper, the authors discuss the special conditions needed to fabricate thin aerogel films and they describe methods to make films and thin sheets. They also give some specific applications for which aerogel films are being developed.

  16. Thermal conductivity in nanostructured films: from single cellulose nanocrystals to bulk films.

    PubMed

    Diaz, Jairo A; Ye, Zhijiang; Wu, Xiawa; Moore, Arden L; Moon, Robert J; Martini, Ashlie; Boday, Dylan J; Youngblood, Jeffrey P

    2014-11-10

    We achieved a multiscale description of the thermal conductivity of cellulose nanocrystals (CNCs) from single CNCs (∼0.72-5.7 W m(-1) K(-1)) to their organized nanostructured films (∼0.22-0.53 W m(-1) K(-1)) using experimental evidence and molecular dynamics (MD) simulation. The ratio of the approximate phonon mean free path (∼1.7-5.3 nm) to the lateral dimension of a single CNC (∼5-20 nm) suggested a contribution of crystal-crystal interfaces to polydisperse CNC film's heat transport. Based on this, we modeled the thermal conductivity of CNC films using MD-predicted single crystal and interface properties along with the degree of CNC alignment in the bulk films using Hermans order parameter. Film thermal conductivities were strongly correlated to the degree of CNC alignment and the direction of heat flow relative to the CNC chain axis. The low interfacial barrier to heat transport found for CNCs (∼9.4 to 12.6 m(2) K GW(-1)), and their versatile alignment capabilities offer unique opportunities in thermal conductivity control. PMID:25286405

  17. Density-velocity equations with bulk modulus for computational hydro-acoustics

    NASA Astrophysics Data System (ADS)

    Lin, Po-Hsien; Chen, Yung-Yu; John Yu, S.-T.

    2014-02-01

    This paper reports a new set of model equations for Computational Hydro Acoustics (CHA). The governing equations include the continuity and the momentum equations. The definition of bulk modulus is used to relate density with pressure. For 3D flow fields, there are four equations with density and velocity components as the unknowns. The inviscid equations are proved to be hyperbolic because an arbitrary linear combination of the three Jacobian matrices is diagonalizable and has a real spectrum. The left and right eigenvector matrices are explicitly derived. Moreover, an analytical form of the Riemann invariants are derived. The model equations are indeed suitable for modeling wave propagation in low-speed, nearly incompressible air and water flows. To demonstrate the capability of the new formulation, we use the CESE method to solve the 2D equations for aeolian tones generated by air flows passing a circular cylinder at Re = 89,000, 46,000, and 22,000. Numerical results compare well with previously published data. By simply changing the value of the bulk modulus, the same code is then used to calculate three cases of water flows passing a cylinder at Re = 89,000, 67,000, and 44,000.

  18. Titanium acoustic diaphragm coated with polycrystal diamond film

    SciTech Connect

    Zhiwei Zhang; Zhen Yan; Hesun Zhu

    1995-12-31

    The spherical titanium diaphragm, which is widely used in high frequency loudspeaker, coat with polycrystal diamond film (DF) was prepared for the first time in China by the method of DC arc plasma jet. Its acoustic performance was remarkably upgraded, as confirmed by Raman Shift Spectrum and frequency response curve. Its sensibility was improved by 3-6 dB and frequency widened by 5x10{sup 3}Hz. The frequency range extended from 2.2x10{sup 3}Hz to 25x10{sup 3}Hz. The preparation and process of DF is discussed.

  19. A lateral field excited (yxl)88° LiTaO3 bulk acoustic wave sensor with interdigital electrodes.

    PubMed

    Ma, Tingfeng; Wang, Ji; Du, Jianke; Yuan, Lili; Qian, Zhenghua; Zhang, Zhitian; Zhang, Chao

    2013-03-01

    In this work, to improve the sensitivity of lateral field excited (LFE) sensors to changes of liquid conductivity, LFE bulk acoustic wave sensors with interdigital electrodes are investigated. LFE bulk acoustic wave on thickness-shear mode is excited successfully by interdigital electrodes on (yxl)88° LiTaO(3) and applied in liquid-phase sensor. The electric field direction of LFE (yxl)88° LiTaO(3) plates is determined. Based on this, several LFE bulk acoustic wave sensors with interdigital electrodes are designed and fabricated to increase the sensitivity of LiTaO(3) LFE sensors. The results show that the (yxl)88° LiTaO(3) LFE sensor with interdigital electrodes is 10.9 times and 2.1 times more sensitive to changes in liquid conductivity compared to traditional LFE devices with single gap circular electrodes and Archimedes spiral electrodes, respectively. The results are important for investigating high-sensitivity LFE bulk acoustic wave sensors by using LiTaO(3) crystal. PMID:23339996

  20. Acoustic properties of alumina colloidal/polymer nano-composite film on silicon.

    PubMed

    Zhang, Rui; Cao, Wenwu; Zhou, Qifa; Cha, Jung Hyui; Shung, K Kirk; Huang, Yuhong

    2007-03-01

    Alumina colloidal/polymer composite films on silicon substrates have been successfully fabricated using the sol-gel method, in which the crystallite sizes of alumina are between 20 and 50 nm. The density and ultrasonic phase velocities in these films with different alumina ratios from 14% to 32% were measured at the desired operating frequency. We have proved that the density, acoustic phase velocities, and hence the acoustic impedance of the nano-composite films increase with the alumina content, which gives us another option of tailoring the acoustic impedance of the nano-composite film for making the matching layer of high-frequency medical ultrasonic transducers. PMID:17375816

  1. Fabrication and Operation of Acoustofluidic Devices Supporting Bulk Acoustic Standing Waves for Sheathless Focusing of Particles

    PubMed Central

    Shields, C. Wyatt; Cruz, Daniela F.; Ohiri, Korine A.; Yellen, Benjamin B.; Lopez, Gabriel P.

    2016-01-01

    Acoustophoresis refers to the displacement of suspended objects in response to directional forces from sound energy. Given that the suspended objects must be smaller than the incident wavelength of sound and the width of the fluidic channels are typically tens to hundreds of micrometers across, acoustofluidic devices typically use ultrasonic waves generated from a piezoelectric transducer pulsating at high frequencies (in the megahertz range). At characteristic frequencies that depend on the geometry of the device, it is possible to induce the formation of standing waves that can focus particles along desired fluidic streamlines within a bulk flow. Here, we describe a method for the fabrication of acoustophoretic devices from common materials and clean room equipment. We show representative results for the focusing of particles with positive or negative acoustic contrast factors, which move towards the pressure nodes or antinodes of the standing waves, respectively. These devices offer enormous practical utility for precisely positioning large numbers of microscopic entities (e.g., cells) in stationary or flowing fluids for applications ranging from cytometry to assembly. PMID:27022681

  2. Fabrication and Operation of Acoustofluidic Devices Supporting Bulk Acoustic Standing Waves for Sheathless Focusing of Particles.

    PubMed

    Shields, C Wyatt; Cruz, Daniela F; Ohiri, Korine A; Yellen, Benjamin B; Lopez, Gabriel P

    2016-01-01

    Acoustophoresis refers to the displacement of suspended objects in response to directional forces from sound energy. Given that the suspended objects must be smaller than the incident wavelength of sound and the width of the fluidic channels are typically tens to hundreds of micrometers across, acoustofluidic devices typically use ultrasonic waves generated from a piezoelectric transducer pulsating at high frequencies (in the megahertz range). At characteristic frequencies that depend on the geometry of the device, it is possible to induce the formation of standing waves that can focus particles along desired fluidic streamlines within a bulk flow. Here, we describe a method for the fabrication of acoustophoretic devices from common materials and clean room equipment. We show representative results for the focusing of particles with positive or negative acoustic contrast factors, which move towards the pressure nodes or antinodes of the standing waves, respectively. These devices offer enormous practical utility for precisely positioning large numbers of microscopic entities (e.g., cells) in stationary or flowing fluids for applications ranging from cytometry to assembly. PMID:27022681

  3. Surface Acoustic Wave (SAW) Resonators for Monitoring Conditioning Film Formation.

    PubMed

    Hohmann, Siegfried; Kögel, Svea; Brunner, Yvonne; Schmieg, Barbara; Ewald, Christina; Kirschhöfer, Frank; Brenner-Weiß, Gerald; Länge, Kerstin

    2015-01-01

    We propose surface acoustic wave (SAW) resonators as a complementary tool for conditioning film monitoring. Conditioning films are formed by adsorption of inorganic and organic substances on a substrate the moment this substrate comes into contact with a liquid phase. In the case of implant insertion, for instance, initial protein adsorption is required to start wound healing, but it will also trigger immune reactions leading to inflammatory responses. The control of the initial protein adsorption would allow to promote the healing process and to suppress adverse immune reactions. Methods to investigate these adsorption processes are available, but it remains difficult to translate measurement results into actual protein binding events. Biosensor transducers allow user-friendly investigation of protein adsorption on different surfaces. The combination of several transduction principles leads to complementary results, allowing a more comprehensive characterization of the adsorbing layer. We introduce SAW resonators as a novel complementary tool for time-resolved conditioning film monitoring. SAW resonators were coated with polymers. The adsorption of the plasma proteins human serum albumin (HSA) and fibrinogen onto the polymer-coated surfaces were monitored. Frequency results were compared with quartz crystal microbalance (QCM) sensor measurements, which confirmed the suitability of the SAW resonators for this application. PMID:26007735

  4. Surface Acoustic Wave (SAW) Resonators for Monitoring Conditioning Film Formation

    PubMed Central

    Hohmann, Siegfried; Kögel, Svea; Brunner, Yvonne; Schmieg, Barbara; Ewald, Christina; Kirschhöfer, Frank; Brenner-Weiß, Gerald; Länge, Kerstin

    2015-01-01

    We propose surface acoustic wave (SAW) resonators as a complementary tool for conditioning film monitoring. Conditioning films are formed by adsorption of inorganic and organic substances on a substrate the moment this substrate comes into contact with a liquid phase. In the case of implant insertion, for instance, initial protein adsorption is required to start wound healing, but it will also trigger immune reactions leading to inflammatory responses. The control of the initial protein adsorption would allow to promote the healing process and to suppress adverse immune reactions. Methods to investigate these adsorption processes are available, but it remains difficult to translate measurement results into actual protein binding events. Biosensor transducers allow user-friendly investigation of protein adsorption on different surfaces. The combination of several transduction principles leads to complementary results, allowing a more comprehensive characterization of the adsorbing layer. We introduce SAW resonators as a novel complementary tool for time-resolved conditioning film monitoring. SAW resonators were coated with polymers. The adsorption of the plasma proteins human serum albumin (HSA) and fibrinogen onto the polymer-coated surfaces were monitored. Frequency results were compared with quartz crystal microbalance (QCM) sensor measurements, which confirmed the suitability of the SAW resonators for this application. PMID:26007735

  5. (Ba,Sr)TiO{sub 3} dielectrics: Relationship between bulk and thin film properties

    SciTech Connect

    Kingon, A. I.; Streiffer, S. K.; Parker, C. B.; Stemmer, S.

    1999-12-22

    Thin films of complex perovskites have a number of potentially important applications. Of major scientific and practical concern is the scaling of properties as film dimensions are reduced. This paper describes a satisfactory relationship between bulk and thin film dielectric properties of (Ba,Sr)TiO{sub 3}. Relative contributions of strain, A:B cation stoichiometry, and interface are separated to explain temperature dependent dielectric behavior.

  6. Study of high-overtone bulk acoustic resonators based on the Me1/AlN/Me2/(100) diamond piezoelectric layered structure

    NASA Astrophysics Data System (ADS)

    Sorokin, B. P.; Kvashnin, G. M.; Telichko, A. V.; Gordeev, G. I.; Burkov, S. I.; Blank, V. D.

    2015-07-01

    The Me1/AlN/Me2/(100) diamond structure has been theoretically analyzed and experimentally investigated in the range 0.5-10 GHz using high-overtone bulk acoustic resonators with different electrodes topologies based on the Al/AlN/Mo/(100) diamond structure. The maximum quality parameter Q × f ≈ 1014 Hz was obtained at f = 9.5 GHz. The layered structure has been analyzed using the developed HBAR software v. 2.3. It is demonstrated that the features in the frequency dependences of the parameters of such resonators are related to the behavior of a loaded thin-film piezoelectric transducer. The calculation results are in good agreement with the experiment. The frequency dependences of the equivalent parameters of the resonators have been calculated. It is shown that the synthetic type IIa diamond single crystal in combination with aluminum nitride is promising for implementation of high-Q acoustoelectronic microwave devices.

  7. Thermoelectric and bulk mobility measurements in pentacene thin films

    SciTech Connect

    Kim, Gunho; Shtein, Max; Pipe, Kevin P.

    2011-03-02

    Low-noise thermoelectric and electrical measurements were used to derive the dependences of Seebeck coefficient and hole mobility on carrier concentration and grain size in the “bulk” regions of thermally evaporated pentacene thin films (in contrast to the channel field-effect mobility typically measured using thin-film transistor geometries). Distinct charge transport regimes were observed for larger (0.5 and 0.8 μm ) and smaller (0.2 μm) grain sizes, attributed to carrier-dopant scattering and percolation, respectively.

  8. Interaction of surface acoustic waves with moving vortex structures in superconducting films

    SciTech Connect

    Gutlyansky, E. D.

    2007-07-15

    A method is proposed for describing a moving film vortex structure and its interaction with surface acoustic waves. It is shown that the moving vortex structure can amplify (generate) surface acoustic waves. In contrast to a similar effect in semiconductor films, this effect can appear when the velocity of the vortex structure is much lower than the velocity of the surface acoustic waves. A unidirectional collective mode is shown to exist in the moving vortex structure. This mode gives rise to an acoustic analogue of the diode effect that is resonant in the velocity of the vortex structure. This acoustic effect is manifested as an anomalous attenuation of the surface acoustic waves in the direction of the vortex-structure motion and as the absence of this attenuation for the propagation in the opposite direction.

  9. Acoustic monitoring of carbon film formation by laser-induced chemical vapor deposition

    SciTech Connect

    Iida, Y.; Yeung, E.S. )

    1993-04-01

    Acoustic signals generated by the deposition of carbon thin films were monitored in situ by a microphone. Photolysis of benzene or adamantane vapor in the presence of helium buffer gas of 5 to 100 Torr by an ArF excimer laser formed several kinds of carbon films (e.g., polymeric, amorphous, and graphitic films), depending on the optical configuration, the ambient pressure, the laser fluence, and the reagent pressure. Analysis of the acoustic signal offers some insight into the mechanism of the deposition processes, which include the graphitization of the deposited films and the role of energetic particles, such as vibrationally excited benzene, in the deposition of amorphous hydrogenated carbon film. Also, the acoustic signal clearly showed the presence of surface-related processes in the course of film deposition. 26 refs., 6 figs., 1 tab.

  10. Structural comparison of Ag-Ge-S bulk glasses and thin films

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Jain, Mukul; Dunn, Porter; de Leo, Carter; Boolchand, Punit

    2007-03-01

    Ternary glasses of composition (GeS3)1-xAgx (x=0.1 and 0.2) are studied in form of bulk and thin films. Bulk glasses are synthesized and examined in Raman scattering and SEM. Raman scattering results of bulk glasses show that with increasing x, an increasing fraction of the Ag additive enters the base glass as Ag^+ with S^-anions serving to form thiogermanate species with one, two and three non-bridging S^- species. SEM measurements of the bulk glass show the material is intrinsically phase separated. White colored islands are observed distributed in a dark base. The EDS measurements show islands are Ag rich and the base is relatively Ag deficient. The Ag rich islands are expected to be mainly glassy phase Ag2S. Thin films of same compositions are fabricated using thermal evaporation. Films are evaporated following two different procedures to prevent the material from spitting. One method was preheating outgas and the other method was using tungsten mesh wrapped boats. The stoichiometry and molecular structure of films under each procedure are analyzed by Raman scattering and SEM to be compared with bulk glasses.

  11. Surface acoustic wave amplification by direct current-voltage supplied to graphene film

    SciTech Connect

    Insepov, Z.; Emelin, E.; Kononenko, O.; Roshchupkin, D. V.; Tnyshtykbayev, K. B.; Baigarin, K. A.

    2015-01-12

    Using a high-resolution X-Ray diffraction measurement method, the surface acoustic wave (SAW) propagation in a graphene film on the surface of a Ca{sub 3}TaGa{sub 3}Si{sub 2}O{sub 14} (CTGS) piezoelectric crystal was investigated, where an external current was driven across the graphene film. Here, we show that the application of the DC field leads to a significant enhancement of the SAW magnitude and, as a result, to amplification of the diffraction satellites. Amplification of 33.2 dB/cm for the satellite +1, and of 13.8 dB/cm for the satellite +2, at 471 MHz has been observed where the external DC voltage of +10 V was applied. Amplification of SAW occurs above a DC field much smaller than that of a system using bulk semiconductor. Theoretical estimates are in reasonable agreement with our measurements and analysis of experimental data for other materials.

  12. Bulk flow coupled to a viscous interfacial film sheared by a rotating knife edge

    NASA Astrophysics Data System (ADS)

    Raghunandan, Aditya; Rasheed, Fayaz; Hirsa, Amir; Lopez, Juan

    2015-11-01

    The measurement of the interfacial properties of highly viscous biofilms, such as DPPC (the primary component of lung surfactant), present on the surface of liquids (bulk phase) continues to attract significant attention. Most measurement techniques rely on shearing the interfacial film and quantifying its viscous response in terms of a surface (excess) viscosity at the air-liquid interface. The knife edge viscometer offers a significant advantage over other approaches used to study highly viscous films as the film is directly sheared by a rotating knife edge in direct contact with the film. However, accurately quantifying the viscous response is non-trivial and involves accounting for the coupled interfacial and bulk phase flows. Here, we examine the nature of the viscous response of water insoluble DPPC films sheared in a knife edge viscometer over a range of surface packing, and its influence on the strength of the coupled bulk flow. Experimental results, obtained via Particle Image Velocimetry in the bulk and at the surface (via Brewster Angle Microscopy), are compared with numerical flow predictions to quantify the coupling across hydrodynamic flow regimes, from the Stokes flow limit to regimes where flow inertia is significant. Supported by NNX13AQ22G, National Aeronautics and Space Administration.

  13. Materials Analysis of CED Nb Films Being Coated on Bulk Nb Single Cell SRF Cavities

    SciTech Connect

    Zhao, Xin; Reece, Charles; Palczewski, Ari; Ciovati, Gianluigi; Krishnan, Mahadevan; James, Colt; Irfan, Irfan

    2013-09-01

    This study is an on-going research on depositing a Nb film on the internal wall of bulk Nb single cell SRF cavities, via a cathodic arc Nb plasma ions source, an coaxial energetic condensation (CED) facility at AASC company. The motivation is to firstly create a homoepitaxy-like Nb/Nb film in a scale of a ~1.5GHz RF single cell cavity. Next, through SRF measurement and materials analysis, it might reveal the baseline properties of the CED-type homoepitaxy Nb films. Literally, a top-surface layer of Nb films which sustains SRF function, always grows up in homo-epitaxy mode, on top of a Nb nucleation layer. Homo-epitaxy growth of Nb must be the final stage (a crystal thickening process) of any coatings of Nb film on alternative cavity structure materials. Such knowledge of Nb-Nb homo-epitaxy is useful to create future realistic SRF cavity film coatings, such as hetero-epitaxy Nb/Cu Films, or template-layer-mitigated Nb films. One large-grain, and three fine grain bulk Nb cavities were coated. They went through cryogenic RF measurement. Preliminary results show that the Q0 of a Nb film could be as same as the pre-coated bulk Nb surface (which received a chemically-buffered polishing plus a light electro-polishing); but quality factor of two tested cavities dropped quickly. We are investigating if the severe Q-slope is caused by hydrogen incorporation before deposition, or is determined by some structural defects during Nb film growth.

  14. Bulk and thin film microstructures in untwinned martensites

    NASA Astrophysics Data System (ADS)

    Hane, Kevin F.

    1999-09-01

    The microstructure in alloys for which the martensite phase is either the 9R or 18R long-period stacking order structure is investigated. A choice of a new unit cell to describe the lattice of the product phase is made, and it is found to give an exact austenite-martensite interface. A comparison with experimental observations for several different material systems supports this choice of unit cell, and the predictions of the shape strain and habit plane normal vectors are the same as those given by a phenomenological calculation. The approach followed here de-emphasizes the role of the internal defects within the unit cell of the martensite lattice in providing the mechanism by which compatibility between the phases is achieved. It is this reason that the name untwinned martensites is proposed to replace the older name faulted martensites. In addition, microstructures in thin film specimens of the alloys exhibiting the untwinned martensite are studied. In particular, a tent microstructure is constructed in a specially oriented film, and such microstructures have potential applications in micro-devices to act as either a pump or an actuator.

  15. Microstructure and Magnetic Properties of PrMnO3 Bulk and Thin Film

    NASA Astrophysics Data System (ADS)

    Lim, K. P.; Halim, S. A.; Chen, S. K.; Ng, S. W.; Wong, J. K.; Gan, H. M. Albert; Woon, H. S.

    2011-03-01

    Perovskite PrMnO3 (PMO) had been prepared in bulk by solid state reaction and thin films on corning glass, fused silica and MgO (100) glass substrate by pulsed laser deposition technique. SEM micrographs show that grains with size 2˜3 μm is observed in bulk PMO while thin films PMO show strongly connected grain structure with particle size that not larger than 100 nm. X-ray diffraction analysis shows that all samples are in single phase with orthorhombic crystal structure. Bulk PMO sample had lattice strain of 0.134% which is the lowest value among others. However, larger lattice strain was observed in thin film samples due to lattice mismatch between film-substrate and caused the MnO6 to deform. All samples shown paramagnetic or antiferromagnetic behavior, enhancement in magnetization value occurred for all PMO grew as film. We believe that larger lattice strain favor the grain growth of PMO towards more order phase. In summary, formation of structure and microstructure of thin film PMO depends on type of substrate used and it affect the magnetic property.

  16. Microstructure and Magnetic Properties of PrMnO{sub 3} Bulk and Thin Film

    SciTech Connect

    Lim, K. P.; Halim, S. A.; Chen, S. K.; Ng, S. W.; Wong, J. K.; Gan, H. M. Albert; Woon, H. S.

    2011-03-30

    Perovskite PrMnO{sub 3}(PMO) had been prepared in bulk by solid state reaction and thin films on corning glass, fused silica and MgO (100) glass substrate by pulsed laser deposition technique. SEM micrographs show that grains with size 2{approx}3 {mu}m is observed in bulk PMO while thin films PMO show strongly connected grain structure with particle size that not larger than 100 nm. X-ray diffraction analysis shows that all samples are in single phase with orthorhombic crystal structure. Bulk PMO sample had lattice strain of 0.134% which is the lowest value among others. However, larger lattice strain was observed in thin film samples due to lattice mismatch between film-substrate and caused the MnO{sub 6} to deform. All samples shown paramagnetic or antiferromagnetic behavior, enhancement in magnetization value occurred for all PMO grew as film. We believe that larger lattice strain favor the grain growth of PMO towards more order phase. In summary, formation of structure and microstructure of thin film PMO depends on type of substrate used and it affect the magnetic property.

  17. Mechanical Characterization of Nanoporous Thin Films by Nanoindentation and Laser-induced Surface Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Chow, Gabriel

    Thin films represent a critical sector of modern engineering that strives to produce functional coatings at the smallest possible length scales. They appear most commonly in semiconductors where they form the foundation of all electronic circuits, but exist in many other areas to provide mechanical, electrical, chemical, and optical properties. The mechanical characterization of thin films has been a continued challenge due foremost to the length scales involved. However, emerging thin films focusing on materials with significant porosity, complex morphologies, and nanostructured surfaces produce additional difficulties towards mechanical analysis. Nanoindentation has been the dominant thin film mechanical characterization technique for the last decade because of the quick results, wide range of sample applicability, and ease of sample preparation. However, the traditional nanoindentation technique encounters difficulties for thin porous films. For such materials, alternative means of analysis are desirable and the lesser known laser-induced surface acoustic wave technique (LiSAW) shows great potential in this area. This dissertation focuses on studying thin, porous, and nanostructured films by nanoindentation and LiSAW techniques in an effort to directly correlate the two methodologies and to test the limits and applicabilities of each technique on challenging media. The LiSAW technique is particularly useful for thin porous films because unlike indentation, the substrate is properly accounted for in the wave motion analysis and no plastic deformation is necessary. Additionally, the use of lasers for surface acoustic wave generation and detection allows the technique to be fully non-contact. This is desirable in the measurement of thin, delicate, and porous films where physical sample probing may not be feasible. The LiSAW technique is also valuable in overcoming nanoscale roughness, particularly for films that cannot be mechanically polished, since typical SAW

  18. Observation of the fundamental Nyquist noise limit in an ultra-high Q-factor cryogenic bulk acoustic wave cavity

    SciTech Connect

    Goryachev, Maxim Ivanov, Eugene N.; Tobar, Michael E.; Kann, Frank van; Galliou, Serge

    2014-10-13

    Thermal Nyquist noise fluctuations of high-Q bulk acoustic wave cavities have been observed at cryogenic temperatures with a DC superconducting quantum interference device amplifier. High Q modes with bandwidths of few tens of milliHz produce thermal fluctuations with a signal-to-noise ratio of up to 23 dB. The estimated effective temperature from the Nyquist noise is in good agreement with the physical temperature of the device, confirming the validity of the equivalent circuit model and the non-existence of any excess resonator self-noise. The measurements also confirm that the quality factor remains extremely high (Q > 10{sup 8} at low order overtones) for very weak (thermal) system motion at low temperatures, when compared to values measured with relatively strong external excitation. This result represents an enabling step towards operating such a high-Q acoustic device at the standard quantum limit.

  19. Terahertz acoustic wave on piezoelectric semiconductor film via large-scale molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Hikata, Ryo; Tsuruta, Kenji; Ishikawa, Atsushi; Fujimori, Kazuhiro

    2015-07-01

    By atomistic simulation, we investigate an acoustic wave at THz frequencies in nanoscale thin films of aluminum-nitride piezoelectric material. A mode analysis reveals that the thickness longitudinal mode along the [0001] direction exists stably at the atomic level. To control the acoustic wave, we introduce a phononic crystal (PC) structure in the films. We determine the band-gap frequency in the phonon dispersion of the PC structure and confirm via molecular dynamics simulation that the acoustic wave within the band-gap frequency can be confined by a waveguide structure with a PC. The possibility of designing and controlling a THz acoustic wave in a nanoscale thin film with a PC is thereby demonstrated.

  20. Closing remarks on Faraday Discussion 107: Interactions of acoustic waves with thin films and interfaces

    SciTech Connect

    Martin, S.J.

    1997-11-01

    The papers in this Faraday Discussion represent the state-of-the-art in using acoustic devices to measure the properties of thin films and interfaces. Sauerbrey first showed that the mass sensitivity of a quartz crystal could be used to measure the thickness of vacuum-deposited metals. Since then, significant progress has been made in understanding other interaction mechanisms between acoustic devices and contacting media. Bruckenstein and Shay and Kanazawa and Gordon showed that quartz resonators could be operated in a fluid to measure surface mass accumulation and fluid properties. The increased understanding of interactions between acoustic devices and contacting media has allowed new information to be obtained about thin films and interfaces. These closing remarks will summarize the current state of using acoustic techniques to probe thin films and interfaces, describe the progress reported in this Faraday Discussion, and outline some remaining problems. Progress includes new measurement techniques, novel devices, new applications, and improved modeling and data analysis.

  1. Diblock copolymers in bulk and in thin films: Morphology and kinetics

    NASA Astrophysics Data System (ADS)

    Podariu, Iulia Anca

    In this thesis I numerically study the phase diagram and kinetics of a diblock copolymers melt in both bulk and thin films in the strong segregation limit. I probe various values of the volume fraction, f, of the shorter block of the copolymer chains, spanning the bulk phase diagram for the diblock copolymers from a spherical body-centered cubic (BCC) phase to a hexagonally packed cylindrical (HCP) phase, to a bicontinuous gyroid phase (G), to finally a lamellar phase(L). Finite size and wetting properties of the substrate modify the film morphology by shifting the effective value of the composition in the film. For neutral substrates, the film morphology is shifted toward a smaller relative composition f, while for substrates which prefer the longer blocks of the copolymers, the film morphology is shifted toward a large value of f. A dramatic change in thin film morphology takes place for a small change in external parameters if one chooses the composition f to be at the borderline between two different bulk phases. The next question addressed is that of the control over the thin film structure in the case of a symmetric diblock copolymer films with a thickness smaller than the bulk equilibrium period. These films are cast on either flat or corrugated substrates. The results show that the formation of uniformly sized lateral domains that appear randomly on a flat surface can be controlled by using topographically patterned substrates. Control of lateral pattern fails if the distance between steps is smaller than the lamellar wavelength or the lateral size of the corrugation is larger than the bulk lamellar wavelength. For thin block copolymer (BCP) films on a homogeneous substrate, a fast domain growth exponent has recently been observed in experiments. I have carried out numerical simulations of ordering and domain growth in a two-dimensional system of BCP melts. The model calculations explicitly include viscous, hydrodynamic flow and provide a scaling

  2. Considerations on nonlinearity measurement with high signal-to-noise ratio for RF surface and bulk acoustic wave devices

    NASA Astrophysics Data System (ADS)

    Kodaira, Ryosuke; Omori, Tatsuya; Hashimoto, Ken-ya; Kyoya, Haruki; Nakagawa, Ryo

    2015-07-01

    This paper discusses the measurement setup of non-linearity caused in radio frequency (RF) surface and bulk acoustic wave (SAW/BAW) devices with high signal-to-noise ratio (SNR). It is shown that when some important points are considered, the background level can be suppressed better than -135 dBm, and the non-linearity signals can be measured in high SNR. Finally, measured results are compared with those measured independently by Murata Manufacturing, and validity of the measurement is cross-checked.

  3. Near infrared to ultraviolet optical properties of bulk single crystal and nanocrystal thin film iron pyrite

    NASA Astrophysics Data System (ADS)

    Subedi, Indra; Bhandari, Khagendra P.; Ellingson, Randall J.; Podraza, Nikolas J.

    2016-07-01

    We report optical properties of iron pyrite (FeS2) determined from ex situ spectroscopic ellipsometry measurements made on both a commercially available bulk single crystal and nanocrystalline thin film over a spectral range of 0.735–5.887 eV. The complex dielectric function, ε (E) = ε 1 (E) + iε 2 (E), spectra have been determined by fitting a layered parametric model to the ellipsometric measurements. Spectra in ε are modeled using a Kramers–Kronig consistent critical point parabolic band model involving seven critical points for the bulk single crystal and four critical points for the nanocrystalline film. Absorption coefficient spectra for both types of samples are also determined from ε. Critical point features in the nanocrystalline films are broader, have lower amplitude and lower energy critical points detected having a small blue shift when compared to the single crystal sample.

  4. Approaching Bulk Carrier Dynamics in Organo-Halide Perovskite Nanocrystalline Films by Surface Passivation.

    PubMed

    Stewart, Robert J; Grieco, Christopher; Larsen, Alec V; Maier, Joshua J; Asbury, John B

    2016-04-01

    The electronic properties of organo-halide perovskite absorbers described in the literature have been closely associated with their morphologies and processing conditions. However, the underlying origins of this dependence remain unclear. A combination of inorganic synthesis, surface chemistry, and time-resolved photoluminescence spectroscopy was used to show that charge recombination centers in organo-halide perovskites are almost exclusively localized on the surfaces of the crystals rather than in the bulk. Passivation of these surface defects causes average charge carrier lifetimes in nanocrystalline thin films to approach the bulk limit reported for single-crystal organo-halide perovskites. These findings indicate that the charge carrier lifetimes of perovskites are correlated with their thin-film processing conditions and morphologies through the influence these have on the surface chemistry of the nanocrystals. Therefore, surface passivation may provide a means to decouple the electronic properties of organo-halide perovskites from their thin-film processing conditions and corresponding morphologies. PMID:26966792

  5. Near infrared to ultraviolet optical properties of bulk single crystal and nanocrystal thin film iron pyrite.

    PubMed

    Subedi, Indra; Bhandari, Khagendra P; Ellingson, Randall J; Podraza, Nikolas J

    2016-07-22

    We report optical properties of iron pyrite (FeS2) determined from ex situ spectroscopic ellipsometry measurements made on both a commercially available bulk single crystal and nanocrystalline thin film over a spectral range of 0.735-5.887 eV. The complex dielectric function, ε (E) = ε 1 (E) + iε 2 (E), spectra have been determined by fitting a layered parametric model to the ellipsometric measurements. Spectra in ε are modeled using a Kramers-Kronig consistent critical point parabolic band model involving seven critical points for the bulk single crystal and four critical points for the nanocrystalline film. Absorption coefficient spectra for both types of samples are also determined from ε. Critical point features in the nanocrystalline films are broader, have lower amplitude and lower energy critical points detected having a small blue shift when compared to the single crystal sample. PMID:27285310

  6. Surface Acoustic Wave Monitor for Deposition and Analysis of Ultra-Thin Films

    NASA Technical Reports Server (NTRS)

    Hines, Jacqueline H. (Inventor)

    2015-01-01

    A surface acoustic wave (SAW) based thin film deposition monitor device and system for monitoring the deposition of ultra-thin films and nanomaterials and the analysis thereof is characterized by acoustic wave device embodiments that include differential delay line device designs, and which can optionally have integral reference devices fabricated on the same substrate as the sensing device, or on a separate device in thermal contact with the film monitoring/analysis device, in order to provide inherently temperature compensated measurements. These deposition monitor and analysis devices can include inherent temperature compensation, higher sensitivity to surface interactions than quartz crystal microbalance (QCM) devices, and the ability to operate at extreme temperatures.

  7. Method and apparatus for detecting internal structures of bulk objects using acoustic imaging

    DOEpatents

    Deason, Vance A.; Telschow, Kenneth L.

    2002-01-01

    Apparatus for producing an acoustic image of an object according to the present invention may comprise an excitation source for vibrating the object to produce at least one acoustic wave therein. The acoustic wave results in the formation of at least one surface displacement on the surface of the object. A light source produces an optical object wavefront and an optical reference wavefront and directs the optical object wavefront toward the surface of the object to produce a modulated optical object wavefront. A modulator operatively associated with the optical reference wavefront modulates the optical reference wavefront in synchronization with the acoustic wave to produce a modulated optical reference wavefront. A sensing medium positioned to receive the modulated optical object wavefront and the modulated optical reference wavefront combines the modulated optical object and reference wavefronts to produce an image related to the surface displacement on the surface of the object. A detector detects the image related to the surface displacement produced by the sensing medium. A processing system operatively associated with the detector constructs an acoustic image of interior features of the object based on the phase and amplitude of the surface displacement on the surface of the object.

  8. Full-scale engine tests of bulk absorber acoustic inlet treatment

    NASA Technical Reports Server (NTRS)

    Heidelberg, L. J.; Homyak, L.

    1979-01-01

    Three different densities of Keviar bulk absorber fan inlet treatment were tested on a YF 102 turbofan engine. This bulk absorber material may have potential for flight application. Farfield noise measurements were made and the attenuation properties of the three treatment densities were compared. In addition, the best bulk treatment was compared to the best single degree of freedom, SDOF (honeycomb and perforated cover sheet) treatment from another investigation. Although the density was varied over a large range, (3 to 1) the effect on attenuation was small. The highest density treatment, 11.8 lb/cubic ft., had a somewhat broader attenuation bandwidth. The comparison of the best bulk and SDOF treatments showed the bulk to have a much greater attenuation bandwidth. At the design frequency both types of treatment had almost equal performance.

  9. Full-scale engine tests of bulk absorber acoustic inlet treatment

    NASA Technical Reports Server (NTRS)

    Heidelberg, L. J.; Homyak, L.

    1979-01-01

    Three different densities of Kevlar bulk absorber fan inlet treatment were tested on a YF 102 turbofan engine. This bulk absorber material may have potential for flight application. Far-field noise measurements were made and the attenuation properties of the three treatment densities were compared. In addition the best bulk treatment was compared to the best single degree of freedom, SDOF (honeycomb and perforated cover sheet) treatment from another investigation. Although the density was varied over a large range, (3 to 1) the effect on attenuation was small. The highest density treatment, 11.8 lb/cu ft, had a somewhat broader attenuation bandwidth. The comparison of the best bulk and SDOF treatments showed the bulk to have a greater attenuation bandwidth. At the design frequency both types of treatment had almost equal performance.

  10. Interaction of surface and bulk acoustic waves with a two-dimensional semimetal

    SciTech Connect

    Kovalev, V. M. Chaplik, A. V.

    2015-02-15

    The interaction of a surface elastic Rayleigh wave with an electron-hole plasma in a two-dimensional semimetal has been theoretically studied as determined by the deformation potential and piezoelectric mechanisms. Dispersion equations describing the coupled plasmon-acoustic modes for both types of interaction are derived, and damping of the Rayleigh wave is calculated. The damping of the acoustic and optical plasmon modes, which is related to the sound emission by plasma oscillations into the substrate volume, is calculated and it is shown that this sound emission is predominantly determined by the acoustic plasmon mode in the case of a deformation potential mechanism and by the optical mode in the case of a piezoelectric mechanism.

  11. Native oxidation of ultra high purity Cu bulk and thin films

    NASA Astrophysics Data System (ADS)

    Iijima, J.; Lim, J.-W.; Hong, S.-H.; Suzuki, S.; Mimura, K.; Isshiki, M.

    2006-12-01

    The effect of microstructure and purity on the native oxidation of Cu was studied by using angle-resolved X-ray photoelectron spectroscopy (AR-XPS) and spectroscopic ellipsometry (SE). A high quality copper film prepared by ion beam deposition under a substrate bias voltage of -50 V (IBD Cu film at Vs = -50 V) showed an oxidation resistance as high as an ultra high purity copper (UHP Cu) bulk, whereas a Cu film deposited without substrate bias voltage (IBD Cu film at Vs = 0 V) showed lower oxidation resistance. The growth of Cu 2O layer on the UHP Cu bulk and both types of the films obeyed in principle a logarithmic rate law. However, the growth of oxide layer on the IBD Cu films at Vs = 0 and -50 V deviated upward from the logarithmic rate law after the exposure time of 320 and 800 h, respectively. The deviation from the logarithmic law is due to the formation of CuO on the Cu 2O layer after a critical time.

  12. Bulk organisation and alignment in Langmuir and Langmuir-Blodgett films of tetrachloroperylene tetracarboxylic acid esters

    NASA Astrophysics Data System (ADS)

    Modlińska, Anna; Filipowicz, Marek; Martyński, Tomasz

    2016-12-01

    Perylene derivatives with chlorine atoms attached at the bay position to the dye core are expected to affect organisation and tendency to aggregation in Langmuir and Langmuir-Blodgett (LB) films. Therefore, newly synthesized core-twisted homologous series of tetrachloroperylene tetracarboxylic acid esters with n = 1,4,5,6,9 carbon atoms in terminal alkyl chains were studied. Phase transitions and crystalline structures were specified by differential scanning calorimetry (DSC) and single crystal X-ray diffraction (XRD), respectively. Intermolecular interactions and organisation of the dyes in monomolecular films were investigated by means of Brewster angle microscope (BAM), UV-Vis absorption and emission spectroscopy, fluorescence microscopy and atomic force microscopy (AFM). The dyes investigated do not form thermotropic mesogenic phases in bulk. The crystalline triclinic elementary cell with P-1 symmetry is revealed from X-ray experiments. In Langmuir and Langmuir-Blodgett films molecular tilted head-on alignment is postulated. Spectroscopic research confirmed by AFM texture images of the LB films show that in the Langmuir and LB films the dyes, depending on length of terminal chains, have a tendency to create H or I molecular aggregates. The impact of the twisted core on the molecular behavior in a bulk and thin films is discussed.

  13. Surface and bulk crystallization of amorphous solid water films: Confirmation of “top-down” crystallization

    DOE PAGESBeta

    Yuan, Chunqing; Smith, R. Scott; Kay, Bruce D.

    2016-01-11

    Here, the crystallization kinetics of nanoscale amorphous solid water (ASW) films are investigated using temperature-programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS). TPD measurements are used to probe surface crystallization and RAIRS measurements are used to probe bulk crystallization. Isothermal TPD results show that surface crystallization is independent of the film thickness (from 100 to 1000 ML). Conversely, the RAIRS measurements show that the bulk crystallization time increases linearly with increasing film thickness. These results suggest that nucleation and crystallization begin at the ASW/vacuum interface and then the crystallization growth front propagates linearly into the bulk. This mechanism wasmore » confirmed by selective placement of an isotopic layer (5% D2O in H2O) at various positions in an ASW (H2O) film. In this case, the closer the isotopic layer was to the vacuum interface, the earlier the isotopic layer crystallized. These experiments provide direct evidence to confirm that ASW crystallization in vacuum proceeds by a “top-down” crystallization mechanism.« less

  14. Bulk diffusion induced structural modifications of carbon-transition metal nanocomposite films

    SciTech Connect

    Berndt, M.; Abrasonis, G.; Kovacs, Gy. J.; Krause, M.; Munnik, F.; Heller, R.; Kolitsch, A.; Moeller, W.

    2011-03-15

    The influence of transition metal (TM = V,Co,Cu) type on the bulk diffusion induced structural changes in carbon:TM nanocomposite films is investigated. The TMs have been incorporated into the carbon matrix via ion beam co-sputtering, and subsequently the films have been vacuum annealed in the temperature range of 300 - 700 deg. C. The structure of both the dispersed metal rich and the carbon matrix phases has been determined by a combination of elastic recoil detection analysis, x-ray diffraction, transmission electron microscopy, and Raman spectroscopy. The as-grown films consist of carbidic (V and Co) and metallic (Cu) nanoparticles dispersed in the carbon matrix. Thermal annealing induces surface segregation of Co and Cu starting at {>=} 500 deg. C, preceded by the carbide-metal transformation of Co-carbide nanoparticles at {approx} 300 deg. C. No considerable morphological changes occur in C:V films. In contrast to the surface diffusion dominated regime where all the metals enhance the six-fold ring clustering of C, in the bulk diffusion controlled regime only Co acts as a catalyst for the carbon graphitization. These results are consistent with the metal-induced crystallization mechanism in the C:Co films. The results are discussed on the basis of the metal-carbide phase stability, carbon solubility in metals or their carbides, and interface species.

  15. Giant bulk photovoltaic effect in thin ferroelectric BaTiO3 films

    NASA Astrophysics Data System (ADS)

    Zenkevich, A.; Matveyev, Yu.; Maksimova, K.; Gaynutdinov, R.; Tolstikhina, A.; Fridkin, V.

    2014-10-01

    The voltage generated in a noncentrosymmetric crystal due to the bulk photovoltaic effect (BPE) can greatly exceed the energy gap, however, the light energy conversion efficiency is extremely low. Here we show that the BPE is remarkably enhanced in the case of thin films. The measurements of the BPE in heteroepitaxial single domain ferroelectric BaTiO3 thin films reveal the enhancement of both photoinduced electric field and conversion efficiencies of the BPE by more than 4 orders of magnitude. Besides the fundamental aspect, our results indicate the potential for the use of the BPE in photovoltaic applications.

  16. Bulk-wave and guided-wave photoacoustic evaluation of the mechanical properties of aluminum/silicon nitride double-layer thin films.

    PubMed

    Zhang, Feifei; Krishnaswamy, Sridhar; Lilley, Carmen M

    2006-12-01

    The development of devices made of micro- and nano-structured thin film materials has resulted in the need for advanced measurement techniques to characterize their mechanical properties. Photoacoustic techniques, which use pulsed laser irradiation to nondestructively induce very high frequency ultrasound in a test object via rapid thermal expansion, are suitable for nondestructive and non-contact evaluation of thin films. In this paper, we compare two photoacoustic techniques to characterize the mechanical parameters of edge-supported aluminum and silicon nitride double-layer thin films. The elastic properties and residual stresses in such films affect their mechanical performance. In a first set of experiments, a femtosecond transient pump-probe technique is used to investigate the Young's moduli of the aluminum and silicon nitride layers by launching ultra-high frequency bulk acoustic waves in the films. The measured transient signals are compared with simulated transient thermoelastic signals in multi-layer structures, and the elastic moduli are determined. Independent pump-probe tests on silicon substrate-supported region and unsupported region are in good agreement. In a second set of experiments, dispersion curves of the A(0) mode of the Lamb waves that propagate along the unsupported films are measured using a broadband photoacoustic guided-wave method. The residual stresses and flexural rigidities for the same set of double-layer membranes are determined from these dispersion curves. Comparisons of the results obtained by the two photoacoustic techniques are made and discussed. PMID:16899268

  17. Optical investigation of bulk electron mobility in 3C-SiC films on Si substrates

    NASA Astrophysics Data System (ADS)

    Piluso, N.; Severino, A.; Camarda, M.; Canino, A.; La Magna, A.; La Via, F.

    2010-10-01

    The dependence between the carrier concentration and electrical mobility has been studied by micro-Raman spectroscopy in n-doped 3C-SiC films grown on (111) and (100) Silicon oriented substrates. Bulk mobility varies between 10 and 510 cm2 V-1 s-1 for a carrier concentration ranging between 1.6×1016 and 5.4×1018 cm-3. Local stacking variations observed on the (111) 3C-SiC surface lead to a worse crystal morphology compared to (100) 3C-SiC films resulting in a decrease in the average bulk mobility. Defects are thus accountable for the dependence between mobility and carrier concentration for different 3C-SiC orientations.

  18. Bulk-like pentacene epitaxial films on hydrogen-terminated Si(111)

    SciTech Connect

    Shimada, Toshihiro; Nogawa, Hiroyuki; Hasegawa, Tetsuya; Okada, Ryusuke; Ichikawa, Hisashi; Ueno, Keiji; Saiki, Koichiro

    2005-08-08

    The epitaxial growth of pentacene on hydrogen-terminated Si(111) is reported. Reflection high energy electron diffraction (RHEED) revealed that the crystal packing resembles that in the bulk crystal even at a monolayer thickness, which was maintained in multilayers. A ripening effect was clearly observed by atomic force microscopy (AFM). These results are important to obtain oriented crystalline films of pentacene combined with silicon microdevices with reduced defect densities.

  19. Lower critical field measurements in NbN bulk and thin films.

    NASA Technical Reports Server (NTRS)

    Mathur, M. P.; Deis, D. W.; Gavaler, J. R.

    1972-01-01

    Low-field magnetization measurements were made at 4.2 K on thin-film and bulk NbN samples by using a vibrating-sample Foner magnetometer with a 50-kG superconducting solenoid. Values of the lower and upper critical fields are calculated, using magnetization curves as the basis. The significance of the Pauli spin paramagnetism and spin-orbit scattering in these materials is discussed.

  20. Effect of crystalline quality of diamond film to the propagation loss of surface acoustic wave devices.

    PubMed

    Fujii, Satoshi; Shikata, Shinichi; Uemura, Tomoki; Nakahata, Hideaki; Harima, Hiroshi

    2005-10-01

    Diamond films with various crystal qualities were grown by chemical vapor deposition on silicon wafers. Their crystallinity was characterized by Raman scattering and electron backscattering diffraction. By fabricating a device structure for surface acoustic wave (SAW) using these diamond films, the propagation loss was measured at 1.8 GHz and compared with the crystallinity. It was found that the propagation loss was lowered in relatively degraded films having small crystallites, a narrow distribution in the diamond crystallite size, and preferential grain orientation. This experiment clarifies diamond film characteristics required for high-frequency applications in SAW filters. PMID:16382634

  1. Surface acoustic wave properties of (100) AlN films on diamond with different IDT positions.

    PubMed

    Lin, Zhi-Xun; Wu, Sean; Ro, Ruyen; Lee, Maw-Shung

    2009-06-01

    (100) AlN films have better surface acoustic wave (SAW) properties than (002) AlN films. In this research, (100) AlN films were combined with diamonds as a new composite SAW substrate. The SAW properties of (100) AlN films on diamonds were analyzed with 4 composite structures: interdigital transducer (IDT)/(100) AlN/diamond, (100) AlN/IDT/diamond, IDT/(100) AlN/metal/diamond, and metal/IDT/(100) AlN/diamond, and they exhibited some excellent SAW properties. Our research results provide a predictable and theoretical basis for further application on high-velocity SAW devices. PMID:19574132

  2. Capillary and anchoring effects in thin hybrid nematic films and connection with bulk behavior.

    PubMed

    de las Heras, D; Mederos, Luis; Velasco, Enrique

    2009-01-01

    By means of a molecular model, we examine hybrid nematic films with antagonistic anchoring angles where one of the surfaces is in the strong anchoring regime. If anchoring at the other surface is weak, and in the absence of wetting by the isotropic phase, the anchoring transition may interact with the capillary isotropic-nematic transition. For general anchoring conditions on this surface we confirm the existence of the steplike biaxial phase and the associated transition to the linear constant-tilt-rotation, configuration. The steplike phase is connected with the bulk isotropic phase for increasing film thickness so that the latter transition is to be interpreted as the capillary isotropic-nematic transition in a hybrid film. PMID:19257057

  3. Nano-structured TiO2 film fabricated at room temperature and its acoustic properties

    PubMed Central

    Zhu, Jie; Cao, Wenwu; Jiang, Bei; Zhang, D S; Zheng, H; Zhou, Q; Shung, K K

    2009-01-01

    Nano-structured TiO2 thin film has been successfully fabricated at room temperature. Using a quarter wavelength characterization method, we have measured the acoustic impedance of this porous film, which can be adjusted from 5.3 to 7.19 Mrayl by curing it at different temperatures. The uniform microstructure and easy fabrication at room temperature make this material an excellent candidate for matching layers of ultra-high frequency ultrasonic imaging transducers. PMID:19672322

  4. High acoustic strains in Si through ultrafast laser excitation of Ti thin-film transducers.

    PubMed

    Tzianaki, Eirini; Bakarezos, Makis; Tsibidis, George D; Orphanos, Yannis; Loukakos, Panagiotis A; Kosmidis, Constantine; Patsalas, Panos; Tatarakis, Michael; Papadogiannis, Nektarios A

    2015-06-29

    The role of thin-film metal transducers in ultrafast laser-generated longitudinal acoustic phonons in Si (100) monocrystal substrates is investigated. For this purpose degenerate femtosecond pump-probe transient reflectivity measurements are performed probing the Brillouin scattering of laser photons from phonons. The influence of the metallic electron-phonon coupling factor, acoustical impedance and film thickness is examined. An optical transfer matrix method for thin films is applied to extract the net acoustic strain relative strength for the various transducer cases, taking into account the experimental probing efficiency. In addition, a theoretical thermo-mechanical approach based on the combination of a revised two-temperature model and elasticity theory is applied and supports the experimental findings. The results show highly efficient generation of acoustic phonons in Si when Ti transducers are used. This demonstrates the crucial role of the transducer's high electron-phonon coupling constant and high compressive yield strength, as well as strong acoustical impedance matching with the semiconductor substrate. PMID:26191728

  5. Bulk and surface acoustic waves in solid-fluid Fibonacci layered materials.

    PubMed

    Quotane, I; El Boudouti, E H; Djafari-Rouhani, B; El Hassouani, Y; Velasco, V R

    2015-08-01

    We study theoretically the propagation and localization of acoustic waves in quasi-periodic structures made of solid and fluid layers arranged according to a Fibonacci sequence. We consider two types of structures: either a given Fibonacci sequence or a periodic repetition of a given sequence called Fibonacci superlattice. Various properties of these systems such as: the scaling law and the self-similarity of the transmission spectra or the power law behavior of the measure of the energy spectrum have been highlighted for waves of sagittal polarization in normal and oblique incidence. In addition to the allowed modes which propagate along the system, we study surface modes induced by the surface of the Fibonacci superlattice. In comparison with solid-solid layered structures, the solid-fluid systems exhibit transmission zeros which can break the self-similarity behavior in the transmission spectra for a given sequence or induce additional gaps other than Bragg gaps in a periodic structure. PMID:25819878

  6. AlScN thin film based surface acoustic wave devices with enhanced microfluidic performance

    NASA Astrophysics Data System (ADS)

    Wang, W. B.; Fu, Y. Q.; Chen, J. J.; Xuan, W. P.; Chen, J. K.; Wang, X. Z.; Mayrhofer, P.; Duan, P. F.; Bittner, A.; Schmid, U.; Luo, J. K.

    2016-07-01

    This paper reports the characterization of scandium aluminum nitride (Al1‑x Sc x N, x  =  27%) films and discusses surface acoustic wave (SAW) devices based on them. Both AlScN and AlN films were deposited on silicon by sputtering and possessed columnar microstructures with (0 0 0 2) crystal orientation. The AlScN/Si SAW devices showed improved electromechanical coupling coefficients (K 2, ~2%) compared with pure AlN films (<0.5%). The performance of the two types of devices was also investigated and compared, using acoustofluidics as an example. The AlScN/Si SAW devices achieved much lower threshold powers for the acoustic streaming and pumping of liquid droplets, and the acoustic streaming and pumping velocities were 2  ×  and 3  ×  those of the AlN/Si SAW devices, respectively. Mechanical characterization showed that the Young’s modulus and hardness of the AlN film decreased significantly when Sc was doped, and this was responsible for the decreased acoustic velocity and resonant frequency, and the increased temperature coefficient of frequency, of the AlScN SAW devices.

  7. Advanced numerical technique for analysis of surface and bulk acoustic waves in resonators using periodic metal gratings

    NASA Astrophysics Data System (ADS)

    Naumenko, Natalya F.

    2014-09-01

    A numerical technique characterized by a unified approach for the analysis of different types of acoustic waves utilized in resonators in which a periodic metal grating is used for excitation and reflection of such waves is described. The combination of the Finite Element Method analysis of the electrode domain with the Spectral Domain Analysis (SDA) applied to the adjacent upper and lower semi-infinite regions, which may be multilayered and include air as a special case of a dielectric material, enables rigorous simulation of the admittance in resonators using surface acoustic waves, Love waves, plate modes including Lamb waves, Stonely waves, and other waves propagating along the interface between two media, and waves with transient structure between the mentioned types. The matrix formalism with improved convergence incorporated into SDA provides fast and robust simulation for multilayered structures with arbitrary thickness of each layer. The described technique is illustrated by a few examples of its application to various combinations of LiNbO3, isotropic silicon dioxide and silicon with a periodic array of Cu electrodes. The wave characteristics extracted from the admittance functions change continuously with the variation of the film and plate thicknesses over wide ranges, even when the wave nature changes. The transformation of the wave nature with the variation of the layer thicknesses is illustrated by diagrams and contour plots of the displacements calculated at resonant frequencies.

  8. Multi-Stimuli-Responsive Polymer Materials: Particles, Films, and Bulk Gels.

    PubMed

    Cao, Zi-Quan; Wang, Guo-Jie

    2016-06-01

    Stimuli-responsive polymers have received tremendous attention from scientists and engineers for several decades due to the wide applications of these smart materials in biotechnology and nanotechnology. Driven by the complex functions of living systems, multi-stimuli-responsive polymer materials have been designed and developed in recent years. Compared with conventional single- or dual-stimuli-based polymer materials, multi-stimuli-responsive polymer materials would be more intriguing since more functions and finer modulations can be achieved through more parameters. This critical review highlights the recent advances in this area and focuses on three types of multi-stimuli-responsive polymer materials, namely, multi-stimuli-responsive particles (micelles, micro/nanogels, vesicles, and hybrid particles), multi-stimuli-responsive films (polymer brushes, layer-by-layer polymer films, and porous membranes), and multi-stimuli-responsive bulk gels (hydrogels, organogels, and metallogels) from recent publications. Various stimuli, such as light, temperature, pH, reduction/oxidation, enzymes, ions, glucose, ultrasound, magnetic fields, mechanical stress, solvent, voltage, and electrochemistry, have been combined to switch the functions of polymers. The polymer design, preparation, and function of multi-stimuli-responsive particles, films, and bulk gels are comprehensively discussed here. PMID:27153184

  9. First measurements of bulk and shear mechanical loss in optical thin film materials

    NASA Astrophysics Data System (ADS)

    Abernathy, Matthew; Harry, Gregory; Newport, Jonathan; Fair, Hanna; Hickey, Sam; Grettarsson, Andri; Penn, Steve; LIGO Collaboration

    As advanced gravitational wave detectors come online, and the possibility of the first gravitational wave detection nears, plans for the next generation of gravitational wave detectors are already in the works. These new detectors, and those already planned for the future, are expected to be limited in their most sensitive frequency bands by the Brownian thermal noise generated within the optical thin films used to produce the interferometer mirrors. In order to fully predict the level of this Brownian noise, it is necessary to know the two independent mechanical moduli (Young modulus and Poisson ratio, Bulk and Shear moduli, etc.) as well as their associated mechanical loss parameters. Traditional measurements of the mechanical loss of thin films has measured only one linear combination of these two loss parameters. Here, we present measurements of the bulk and shear mechanical loss of tantalum pentoxide (tantala) thin films made by taking advantage of the differing ratios of elastic deformation in the various resonant modes of a coated silica disc. These results may have immediate implications for the ultimate sensitivity of currently operated gravitational wave detectors.

  10. A lightweight push-pull acoustic transducer composed of a pair of dielectric elastomer films.

    PubMed

    Sugimoto, Takehiro; Ando, Akio; Ono, Kazuho; Morita, Yuichi; Hosoda, Kosuke; Ishii, Daisaku; Nakamura, Kentaro

    2013-11-01

    A lightweight push-pull acoustic transducer using dielectric elastomer films was proposed for use in advanced audio systems in homes. The push-pull structure consists of two dielectric elastomer films developed to serve as an electroactive polymer. The transducer utilizes the change in the surface area of the dielectric elastomer film, induced by an electric-field-induced change in the thickness, for sound generation. The resonance frequency of the transducer was derived from modeling the push-pull configuration to estimate the lower limit of the frequency range. Measurement results presented an advantage of push-pull driving in the suppression of harmonic distortion. PMID:24181987

  11. Nickel Alloy Primary Water Bulk Surface and SCC Corrosion Film Analytical Characterization and SCC Mechanistic Implications

    SciTech Connect

    Morton, D.; Lewis, N.; Hanson, M.; Rice, S.; Sanders, P.

    2007-04-18

    Alloy 600 corrosion coupon tests were performed: (1) to quantify the temperature dependency of general corrosion and (2) to characterize the composition and structure of bulk surface corrosion films for comparison with ongoing primary water SCC (PWSCC) crack tip corrosion film analyses. Results suggest that the thermal activation energy of Alloy 600 corrosion is consistent with the thermal activation energy of nickel alloy PWSCC. Analytical investigations of the structure and composition of Alloy 600 bulk surface corrosion oxides revealed a duplex (inner and outer) oxide layer structure. The outer layer is discontinuous and comprised of relatively large (1 to 3 {micro}m) nickel ferrite crystals and smaller ({approx}0.1 {micro}m) chromium containing nickel ferrite crystals. The inner layer consists of a relatively continuous chromite spinel (major phase) and chromia (Cr{sub 2}O{sub 3} minor phase) which formed through non-selective oxidation. Chromia and dealloyed Alloy 600 (highly Ni enriched metal) were only observed at 337 C (640 F) and only along the boundaries of deformation induced fine grains and subcells. Specimens having deformation free surfaces exhibited continuous uniform inner chromite spinel oxide layers. Specimens with machining induced surface deformation produced non-uniform inner layer oxides (chromite spinel, Cr{sub 2}O{sub 3} and unoxidized material). PWSCC crack tip oxides, in contrast, were fine grain (no duplex structure) and consisted of both chromium rich spinels and ''NiO'' structure oxides. Generally, nickel rich oxides were more abundant under more oxidized conditions (reduced coolant hydrogen) and spinel rich crack tip oxides were favored under more reducing conditions (increased coolant hydrogen). Bulk surface corrosion film thickness did not correlate with observed SCC growth rates. These results suggest that corrosion is not the rate controlling step of PWSCC but rather that PWSCC and corrosion have a common rate controlling sub

  12. Observation of coherent acoustic phonon in titanyl phthalocyanine thin solid films

    NASA Astrophysics Data System (ADS)

    Ahn, Hyeyoung; Su, Shiu-Ho

    2015-08-01

    Ultrafast exciton dynamics is investigated in titanyl phthalocyanine (TiOPc) micrograin films in this study. Exponential exciton relaxation and oscillatory responses are observed in transient reflectivity measurements of the films. Laser-induced coherent acoustic waves (LCAW) are proposed to be responsible for this oscillation. Despite their fast attenuation with the increase in temperature, LCAWs are successfully detected at room temperature through probing at a large oblique angle near the low-energy absorption edge of the Q-Band. From the oscillation period of the LCAW, the sound velocity is estimated to be ∼3.1 × 103 m/s, and an acoustic echo arising from the boundary between the films and substrate is also observed.

  13. Mass variation of a thin liquid film driven by an acoustic wave

    NASA Astrophysics Data System (ADS)

    Batson, W.; Agnon, Y.; Oron, A.

    2015-06-01

    In this work, we investigate the dynamics of a thin liquid film subjected to an acoustic field in its bounding vapor space. For large acoustic wavelengths, the field imposes a spatially uniform, temporally periodic temperature and pressure at the vapor side of the film interface, which leads to a periodic driving force for mass exchange with the vapor. Neglecting the dynamics of the vapor space, we adopt the "one-sided" model for evaporation/condensation of thin liquid films. In the interest of determining the effect of oscillatory mass exchange on film stability, we consider films in thermodynamic equilibrium with the mean vapor conditions. The effects of oscillatory phase change on both linear stability and nonlinear dynamics are investigated for slightly inclined ceiling films that are destabilized by gravity and subject to thermocapillary effects. At linear order, this mass exchange is not found to alter the band of unstable wave numbers and only marginally affects the growth rates. Additionally, the mass exchanged during evaporation is balanced by condensation so that the total mass of the liquid film is conserved. However, due to nonlinear effects, we find that traveling waves encouraged by the inclination are subject to net mass loss. It is then found that normal thermocapillary effects enhance this loss, and that anomalous thermocapillarity mitigates or even reverses the loss to a mass gain.

  14. Mass variation of a thin liquid film driven by an acoustic wave

    SciTech Connect

    Batson, W.; Agnon, Y.; Oron, A.

    2015-06-15

    In this work, we investigate the dynamics of a thin liquid film subjected to an acoustic field in its bounding vapor space. For large acoustic wavelengths, the field imposes a spatially uniform, temporally periodic temperature and pressure at the vapor side of the film interface, which leads to a periodic driving force for mass exchange with the vapor. Neglecting the dynamics of the vapor space, we adopt the “one-sided” model for evaporation/condensation of thin liquid films. In the interest of determining the effect of oscillatory mass exchange on film stability, we consider films in thermodynamic equilibrium with the mean vapor conditions. The effects of oscillatory phase change on both linear stability and nonlinear dynamics are investigated for slightly inclined ceiling films that are destabilized by gravity and subject to thermocapillary effects. At linear order, this mass exchange is not found to alter the band of unstable wave numbers and only marginally affects the growth rates. Additionally, the mass exchanged during evaporation is balanced by condensation so that the total mass of the liquid film is conserved. However, due to nonlinear effects, we find that traveling waves encouraged by the inclination are subject to net mass loss. It is then found that normal thermocapillary effects enhance this loss, and that anomalous thermocapillarity mitigates or even reverses the loss to a mass gain.

  15. Highly mass-sensitive thin film plate acoustic resonators (FPAR).

    PubMed

    Arapan, Lilia; Alexieva, Gergana; Avramov, Ivan D; Radeva, Ekaterina; Strashilov, Vesseline; Katardjiev, Ilia; Yantchev, Ventsislav

    2011-01-01

    The mass sensitivity of thin aluminum nitride (AlN) film S0 Lamb wave resonators is theoretically and experimentally studied. Theoretical predictions based on modal and finite elements method analysis are experimentally verified. Here, two-port 888 MHz synchronous FPARs are micromachined and subsequently coated with hexamethyl-disiloxane(HMDSO)-plasma-polymerized thin films of various thicknesses. Systematic data on frequency shift and insertion loss versus film thickness are presented. FPARs demonstrate high mass-loading sensitivity as well as good tolerance towards the HMDSO viscous losses. Initial measurements in gas phase environment are further presented. PMID:22163994

  16. Efficient, Ordered Bulk Heterojunction Nanocyrstalline Solar Cells by Annealing of Ultrathin Squaraine Thin Films

    SciTech Connect

    Wei, Guodan; Lunt, Richard R; Sun, Kai; Wang, Siyi; Thompson, Mark E.; Forrest, Stephen R.

    2010-09-08

    Spin-cast 2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl]squaraine (SQ) thin films only 62 Å thick are converted from amorphous to polycrystalline via postannealing at elevated temperatures. The surface roughness of the SQ films increases by a factor of 2, while selected area electron diffraction spectra indicate an increase in the extent of postannealed film crystallinity. Dichloromethane solvent annealing is also demonstrated to increase the exciton diffusion length of SQ by a factor of 3 over thermally annealed SQ films as a result of further enhancement in crystalline order. We find that the roughened surface features have a length scale on the order of the exciton diffusion length. Hence, coating the donor SQ with the acceptor, C{sub 60}, results in a nearly optimum controlled bulk heterojunction solar cell structure. Optimized SQ/C{sub 60} photovoltaic cells have a power conversion efficiency of η{sub p} = 4.6 ± 0.1% (correcting for solar mismatch) at 1 sun (AM1.5G) simulated solar intensity, and a corresponding peak external quantum efficiency of EQE = 43 ± 1% even for the very thin SQ layers employed.

  17. Surface acoustic wave devices fabricated on epitaxial AlN film

    NASA Astrophysics Data System (ADS)

    Gao, Junning; Hao, Zhibiao; Yanxiong E.; Niu, Lang; Wang, Lai; Sun, Changzheng; Xiong, Bin; Han, Yanjun; Wang, Jian; Li, Hongtao; Luo, Yi; Li, Guoqiang

    2016-04-01

    This paper reports surface acoustic wave (SAW) devices fabricated on AlN epitaxial film grown on sapphire, aiming to avoid the detrimental polarization axis inconsistency and refrained crystalline quality of the normally used polycrystalline AlN films. Devices with center frequency of 357 MHz and 714 MHz have been fabricated. The stop band rejection ratio of the as-obtained device reaches 24.5 dB and the pass band ripple is profoundly smaller compared to most of the reported AlN SAW devices with the similar configuration. Judging from the rather high edge dislocation level of the film used in this study, the properties of the SAW devices have great potential to be improved by further improving the crystalline quality of the film. It is then concluded that the AlN epitaxial film is favorable for high quality SAW devices to meet the high frequency and low power consumption challenges facing the signal processing components.

  18. Surface acoustic wave velocity of gold films deposited on silicon substrates at different temperatures

    SciTech Connect

    Salas, E.; Jimenez Rioboo, R. J.; Prieto, C.; Every, A. G.

    2011-07-15

    Au thin films have been deposited by DC magnetron sputtering on Si (001) substrates at different substrate temperatures, ranging from 200 K to 450 K. With increasing temperature, the expected crystallinity and morphology of the Au thin film are clearly improved, as shown by x ray diffraction, atomic force microscopy and scanning electron microscopy experiments. Parallel to this, the surface acoustic wave propagation velocity shows a clear enhancement toward the ideal values obtained from numerical simulations of a Au thin film on Si (001) substrate. Moreover, a very thin and slightly rough interlayer between the Si (001) substrate and the Au thin film is developed for temperatures above 350 K. The composition and nature of this interlayer is not known. This interlayer may be responsible for the steep change in the structural and elastic properties of the Au thin films at the higher temperatures and possibly also for an improvement of the adhesion properties of the Au on the Si (001) substrate.

  19. PEDOT as a Flexible Organic Electrode for a Thin Film Acoustic Energy Harvester.

    PubMed

    Kim, Younghoon; Na, Jongbeom; Park, Chihyun; Shin, Haijin; Kim, Eunkyoung

    2015-08-01

    An efficient thin film acoustic energy harvester was explored using flexible poly(3,4-ethylene dioxythiophene) (PEDOT) films as electrodes in an all-organic triboelectric generator (AO-TEG). A thin film AO-TEG structured as PEDOT/Kapton//PET/PEDOT was prepared by the solution casting polymerization(SCP) on the dielectric polymer films. As-prepared AO-TEG showed high flexibility and durability due to the strong adhesion between the electrodes and the dielectric polymer. The short-circuit current density (Jsc), open-circuit voltage (Voc), and maximum power density (Pw) reached 50 mA/m(2), 700 V, and 12.9 W/m(2) respectively. The output current density decreased with the increase in the electrode resistance (Re), but the energy loss in the organic electrodes was negligible. The AO-TEG could light up 180 LEDs instantaneously upon touching of the AO-TEG with a palm (∼120 N). With the flexible structure, the AO-TEG was worn as clothes and generated electricity to light LEDs upon regular human movement. Furthermore, the AO-TEG was applicable as a thin film acoustic energy harvester, which used music to generate electricity enough for powering of 5 LEDs. An AO-TEG with a PEDOT electrode (Re = 200 Ω) showed instantaneous peak-to-peak voltage generation of 11 V under a sound pressure level (SPL) of 90-100 dB. The harvested acoustic energy through the AO-TEG was 350 μJ from the 4 min playing of the same single song. This is the first demonstration of a flexible triboelectric generator (TEG) using an organic electrode for harvesting acoustic energy from ambient environment. PMID:26153798

  20. Synthesis and characterization of transparent conducting indium iron oxide bulk and thin film materials

    NASA Astrophysics Data System (ADS)

    Fahed, Charbel T.

    2009-12-01

    In this dissertation, solid solutions of indium-iron oxide (In2-xFexO3) with varying compositions were prepared and a new ultra-fast microwave method was used for deposition of thin films of this material. Non-destructive characterization methods were used for studying these transparent conducting oxide (TCO) materials. In this work, the linear thermal expansion coefficients of bulk In 2-xFexO3 have been determined using high resolution x-ray diffraction measurements. The addition of Fe2O3 to In2O3 resulted in the formation of solid solutions in body centered cubic phase. The thermal expansion coefficients for solid solutions of In2-xFexO3 showed increased values in comparison to that of pure In2O3 phase. The study of thermal properties of these TCO materials is crucial for their potential applications in photovoltaic and spintronic devices operating at various temperatures. In addition, the bulk samples of In2-xFexO 3 were studied for their structural, transport, and magnetic properties, as a function of composition. The lattice parameters of the solid solutions decrease with increasing Fe-content. The four-probe electrical measurements showed reduced conductivities for higher Fe compositions. The magnetic data displayed ferromagnetism in these solid solutions, and that can be attributed to the presence of trace amounts of Fe2O3 or Fe 3O4. These results might be important for the use of TCOs in spintronic applications as well as structural materials such as ceramic coatings intended to withstand harsh environments. Thin films of Indium-iron oxide compositions were deposited by using ultra-fast microwave heating. This is a new method of deposition of TCOs that has never been done before. The advantage of microwave heating deposition over other deposition techniques is that it is extremely fast and can be used for materials of high evaporation temperature. In this work, the deposition was done in 50-120 seconds at 1950-2000°C. Characteristics of these transparent

  1. Growth and characterization of zinc oxide and PZT films for micromachined acoustic wave devices

    NASA Astrophysics Data System (ADS)

    Yoon, Sang Hoon

    The ability to detect the presence of low concentrations of harmful substances, such as biomolecular agents, warfare agents, and pathogen cells, in our environment and food chain would greatly advance our safety, provide more sensitive tools for medical diagnostics, and protect against terrorism. Acoustic wave (AW) devices have been widely studied for such applications due to several attractive properties, such as rapid response, reliability, portability, ease of use, and low cost. The principle of these sensors is based on a fundamental feature of the acoustic wave that is generated and detected by a piezoelectric material. The performance of the device, therefore, greatly depends on the properties of piezoelectric thin film. The required properties include a high piezoelectric coefficient and high electromechanical coefficients. The surface roughness and the mechanical properties, such as Young's modulus and hardness, are also factors that can affect the wave propagation of the device. Since the film properties are influenced by the structure of the material, understanding thin film structure is very important for the design of high-performance piezoelectric MEMS devices for biosensor applications. In this research, two piezoelectric thin film materials were fabricated and investigated. ZnO films were fabricated by CSD (Chemical Solution Deposition) and sputtering, and PZT films were fabricated by CSD only. The process parameters for solution derived ZnO and PZT films, such as the substrate type, the effect of the chelating agent, and heat treatment, were studied to find the relationship between process parameters and thin film structure. In the case of the sputtered ZnO films, the process gas types and their ratio, heat treatment in situ, and post deposition were investigated. The key results of systematic experiments show that the combined influence of chemical modifiers and substrates in chemical solution deposition have an effect on the crystallographic

  2. Biotin-Streptavidin Binding Interactions of Dielectric Filled Silicon Bulk Acoustic Resonators for Smart Label-Free Biochemical Sensor Applications

    PubMed Central

    Heidari, Amir; Yoon, Yong-Jin; Park, Woo-Tae; Su, Pei-Chen; Miao, Jianmin; Lin, Julius Tsai Ming; Park, Mi Kyoung

    2014-01-01

    Sensor performance of a dielectric filled silicon bulk acoustic resonator type label-free biosensor is verified with biotin-streptavidin binding interactions as a model system. The mass sensor is a micromachined silicon square plate with a dielectric filled capacitive excitation mechanism. The resonance frequency of the biotin modified resonator decreased 315 ppm when exposed to streptavidin solution for 15 min with a concentration of 10−7 M, corresponding to an added mass of 3.43 ng on the resonator surface. An additional control is added by exposing a bovine serum albumin (BSA)-covered device to streptavidin in the absence of the attached biotin. No resonance frequency shift was observed in the control experiment, which confirms the specificity of the detection. The sensor-to-sensor variability is also measured to be 4.3%. Consequently, the developed sensor can be used to observe in biotin-streptavidin interaction without the use of labelling or molecular tags. In addition, biosensor can be used in a variety of different immunoassay tests. PMID:24608003

  3. Biotin-streptavidin binding interactions of dielectric filled silicon bulk acoustic resonators for smart label-free biochemical sensor applications.

    PubMed

    Heidari, Amir; Yoon, Yong-Jin; Park, Woo-Tae; Su, Pei-Chen; Miao, Jianmin; Lin, Julius Tsai Ming; Park, Mi Kyoung

    2014-01-01

    Sensor performance of a dielectric filled silicon bulk acoustic resonator type label-free biosensor is verified with biotin-streptavidin binding interactions as a model system. The mass sensor is a micromachined silicon square plate with a dielectric filled capacitive excitation mechanism. The resonance frequency of the biotin modified resonator decreased 315 ppm when exposed to streptavidin solution for 15 min with a concentration of 10(-7) M, corresponding to an added mass of 3.43 ng on the resonator surface. An additional control is added by exposing a bovine serum albumin (BSA)-covered device to streptavidin in the absence of the attached biotin. No resonance frequency shift was observed in the control experiment, which confirms the specificity of the detection. The sensor-to-sensor variability is also measured to be 4.3%. Consequently, the developed sensor can be used to observe in biotin-streptavidin interaction without the use of labelling or molecular tags. In addition, biosensor can be used in a variety of different immunoassay tests. PMID:24608003

  4. Acoustics

    NASA Astrophysics Data System (ADS)

    The acoustics research activities of the DLR fluid-mechanics department (Forschungsbereich Stroemungsmechanik) during 1988 are surveyed and illustrated with extensive diagrams, drawings, graphs, and photographs. Particular attention is given to studies of helicopter rotor noise (high-speed impulsive noise, blade/vortex interaction noise, and main/tail-rotor interaction noise), propeller noise (temperature, angle-of-attack, and nonuniform-flow effects), noise certification, and industrial acoustics (road-vehicle flow noise and airport noise-control installations).

  5. The effects of changing deposition conditions on the similarity of sputter-deposited fluorocarbon thin films to bulk PTFE

    NASA Astrophysics Data System (ADS)

    Zandona, Philip

    Solid lubrication of space-borne mechanical components is essential to their survival and the continued human exploration of space. Recent discoveries have shown that PTFE when blended with alumina nanofillers exhibits greatly improved physical performance properties, with wear rates being reduced by several orders of magnitude. The bulk processes used to produce the PTFE-alumina blends are limiting. Co-sputter deposition of PTFE and a filler material overcomes several of these limitations by enabling the reduction of particle size to the atomic level and also by allowing for the even coating of the solid lubricant on relatively large areas and components. The goal of this study was to establish a baseline performance of the sputtered PTFE films as compared to the bulk material, and to establish deposition conditions that would result in the most bulk-like film possible. In order to coax change in the structure of the sputtered films, sputtering power and deposition temperature were increased independently. Further, post-deposition annealing was applied to half of the deposited film in an attempt to affect change in the film structure. Complications in the characterization process due to increasing film thickness were also examined. Bulk-like metrics for characterization processes the included Fourier transform infrared spectroscopy (FTIR), X-ray spectroscopy (XPS), nanoindentation via atomic force microscopy, and contact angle of water on surface measurements were established. The results of the study revealed that increasing sputtering power and deposition temperature resulted in an increase in the similarity between the fluorocarbon films and the bulk PTFE, at a cost of affecting the potential of the film thicknesses, either by affecting the deposition process directly, or by decreasing the longevity of the sputtering targets.

  6. Surface-acoustic-wave device incorporating conducting Langmuir-Blodgett films

    NASA Astrophysics Data System (ADS)

    Holcroft, B.; Roberts, G. G.; Barraud, A.; Richard, J.

    1987-04-01

    Surface-acoustic-wave devices incorporating conducting Langmuir-Blodgett films are reported for the first time. Excellent characteristics have been obtained using a mixed valence charge transfer salt of a substituted pyridinium tetracyanoquinodimethane. The control afforded by the deposition technique has enabled the fractional change in surface wave velocity due to the electrical effects to be distinguished from those due to mass loading. The resistivity of the organic surface layer is measured to be 2 ohm-cm.

  7. Hybrid Surface Acoustic Wave- Electrohydrodynamic Atomization (SAW-EHDA) For the Development of Functional Thin Films

    PubMed Central

    Choi, Kyung Hyun; Kim, Hyun Bum; Ali, Kamran; Sajid, Memoon; Uddin Siddiqui, Ghayas; Chang, Dong Eui; Kim, Hyung Chan; Ko, Jeong Beom; Dang, Hyun Woo; Doh, Yang Hoi

    2015-01-01

    Conventional surface acoustic wave - electrostatic deposition (SAW-ED) technology is struggling to compete with other thin film fabrication technologies because of its limitation in atomizing high density solutions or solutions with strong inter-particle bonding that requires very high frequency (100 MHz) and power. In this study, a hybrid surface acoustic wave - electrohydrodynamic atomization (SAW-EHDA) system has been introduced to overcome this problem by integrating EHDA with SAW to achieve the deposition of different types of conductive inks at lower frequency (19.8 MHZ) and power. Three materials, Poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV), Zinc Oxide (ZnO), and Poly(3, 4-ethylenedioxythiophene):Polystyrene Sulfonate (PEDOT:PSS) have been successfully deposited as thin films through the hybrid SAW-EHDA. The films showed good morphological, chemical, electrical, and optical characteristics. To further evaluate the characteristics of deposited films, a humidity sensor was fabricated with active layer of PEDOT:PSS deposited using the SAW-EHDA system. The response of sensor was outstanding and much better when compared to similar sensors fabricated using other manufacturing techniques. The results of the device and the films’ characteristics suggest that the hybrid SAW-EHDA technology has high potential to efficiently produce wide variety of thin films and thus predict its promising future in certain areas of printed electronics. PMID:26478189

  8. Hybrid Surface Acoustic Wave- Electrohydrodynamic Atomization (SAW-EHDA) For the Development of Functional Thin Films

    NASA Astrophysics Data System (ADS)

    Choi, Kyung Hyun; Kim, Hyun Bum; Ali, Kamran; Sajid, Memoon; Uddin Siddiqui, Ghayas; Chang, Dong Eui; Kim, Hyung Chan; Ko, Jeong Beom; Dang, Hyun Woo; Doh, Yang Hoi

    2015-10-01

    Conventional surface acoustic wave - electrostatic deposition (SAW-ED) technology is struggling to compete with other thin film fabrication technologies because of its limitation in atomizing high density solutions or solutions with strong inter-particle bonding that requires very high frequency (100 MHz) and power. In this study, a hybrid surface acoustic wave - electrohydrodynamic atomization (SAW-EHDA) system has been introduced to overcome this problem by integrating EHDA with SAW to achieve the deposition of different types of conductive inks at lower frequency (19.8 MHZ) and power. Three materials, Poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV), Zinc Oxide (ZnO), and Poly(3, 4-ethylenedioxythiophene):Polystyrene Sulfonate (PEDOT:PSS) have been successfully deposited as thin films through the hybrid SAW-EHDA. The films showed good morphological, chemical, electrical, and optical characteristics. To further evaluate the characteristics of deposited films, a humidity sensor was fabricated with active layer of PEDOT:PSS deposited using the SAW-EHDA system. The response of sensor was outstanding and much better when compared to similar sensors fabricated using other manufacturing techniques. The results of the device and the films’ characteristics suggest that the hybrid SAW-EHDA technology has high potential to efficiently produce wide variety of thin films and thus predict its promising future in certain areas of printed electronics.

  9. Thin film interface stresses produced by high amplitude laser generated surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Sherman, Bradley; Liou, Hong-Cin; Balogun, Oluwaseyi

    2015-10-01

    Surface acoustic waves (SAWs) have been explored for nondestructive metrology of thin film elastic properties and thickness due to confinement of their energy within a shallow depth from a material surface. In this paper, we study the dynamic interfacial stresses produced by high amplitude SAWs generated by a strongly ablative source in a thin film-substrate system, with the goal of investigating the possibility of inducing thin film delamination at high loading rates. For modeling purposes, we represent the mechanical loading resulting from the pulsed laser-sample interaction in the ablative regime by an equivalent compressive surface load, and the resulting stresses and particle velocities induced by the generated SAWs are calculated using a linear finite element model. We explore the numerical model to study the dependence of the film-substrate interface tractions on the ratio of the film thickness and SAW wavelength for a soft film on a stiff substrate. Furthermore, by matching the numerical results obtained from the finite element model with experimental results, we are able to predict the dynamic interfacial stresses for a copper film on a fused silica substrate produced by SAWs excited by a high power pulsed laser line source. This study has implications for exploring SAWs in the characterization of interfacial failure in thin-film substrate systems.

  10. Whispering-gallery acoustic sensing: characterization of mesoscopic films and scanning probe microscopy applications.

    PubMed

    La Rosa, Andres H; Li, Nan; Fernandez, Rodolfo; Wang, Xiaohua; Nordstrom, Richard; Padigi, S K

    2011-09-01

    Full understanding of the physics underlying the striking changes in viscoelasticity, relaxation time, and phase transitions that mesoscopic fluid-like films undergo at solid-liquid interfaces, or under confinement between two sliding solid boundaries, constitutes one of the major challenges in condensed matter physics. Their role in the imaging process of solid substrates by scanning probe microscopy (SPM) is also currently controversial. Aiming at improving the reliability and versatility of instrumentation dedicated to characterize mesoscopic films, a noninvasive whispering-gallery acoustic sensing (WGAS) technique is introduced; its application as feedback control in SPM is also demonstrated. To illustrate its working principle and potential merits, WGAS has been integrated into a SPM that uses a sharp tip attached to an electrically driven 32-kHz piezoelectric tuning fork (TF), the latter also tighten to the operating microscope's frame. Such TF-based SPMs typically monitor the TF's state of motion by electrical means, hence subjected to the effects caused by the inherent capacitance of the device (i.e., electrical resonance differing from the probe's mechanical resonance). Instead, the novelty of WGAS resides in exploiting the already existent microscope's frame as an acoustic cavity (its few centimeter-sized perimeter closely matching the operating acoustic wavelength) where standing-waves (generated by the nanometer-sized oscillations of the TF's tines) are sensitively detected by an acoustic transducer (the latter judiciously placed around the microscope's frame perimeter for attaining maximum detection). This way, WGAS is able to remote monitoring, via acoustic means, the nanometer-sized amplitude motion of the TF's tines. (This remote-detection method resembles the ability to hear faint, but still clear, levels of sound at the galleries of a cathedral, despite the extraordinary distance location of the sound source.) In applications aiming at

  11. Whispering-gallery acoustic sensing: Characterization of mesoscopic films and scanning probe microscopy applications

    NASA Astrophysics Data System (ADS)

    La Rosa, Andres H.; Li, Nan; Fernandez, Rodolfo; Wang, Xiaohua; Nordstrom, Richard; Padigi, S. K.

    2011-09-01

    Full understanding of the physics underlying the striking changes in viscoelasticity, relaxation time, and phase transitions that mesoscopic fluid-like films undergo at solid-liquid interfaces, or under confinement between two sliding solid boundaries, constitutes one of the major challenges in condensed matter physics. Their role in the imaging process of solid substrates by scanning probe microscopy (SPM) is also currently controversial. Aiming at improving the reliability and versatility of instrumentation dedicated to characterize mesoscopic films, a noninvasive whispering-gallery acoustic sensing (WGAS) technique is introduced; its application as feedback control in SPM is also demonstrated. To illustrate its working principle and potential merits, WGAS has been integrated into a SPM that uses a sharp tip attached to an electrically driven 32-kHz piezoelectric tuning fork (TF), the latter also tighten to the operating microscope's frame. Such TF-based SPMs typically monitor the TF's state of motion by electrical means, hence subjected to the effects caused by the inherent capacitance of the device (i.e., electrical resonance differing from the probe's mechanical resonance). Instead, the novelty of WGAS resides in exploiting the already existent microscope's frame as an acoustic cavity (its few centimeter-sized perimeter closely matching the operating acoustic wavelength) where standing-waves (generated by the nanometer-sized oscillations of the TF's tines) are sensitively detected by an acoustic transducer (the latter judiciously placed around the microscope's frame perimeter for attaining maximum detection). This way, WGAS is able to remote monitoring, via acoustic means, the nanometer-sized amplitude motion of the TF's tines. (This remote-detection method resembles the ability to hear faint, but still clear, levels of sound at the galleries of a cathedral, despite the extraordinary distance location of the sound source.) In applications aiming at

  12. Determination of acoustic properties of thin polymer films utilizing the frequency dependence of the reflection coefficient of ultrasound

    NASA Astrophysics Data System (ADS)

    Tohmyoh, Hironori; Sakamoto, Yuhei

    2015-11-01

    This paper reports on a technique to measure the acoustic properties of a thin polymer film utilizing the frequency dependence of the reflection coefficient of ultrasound reflected back from a system comprising a reflection plate, the film, and a material that covers the film. The frequency components of the echo reflected from the back of the plate, where the film is attached, take their minimum values at the resonant frequency, and from these frequency characteristics, the acoustic impedance, sound velocity, and the density of the film can be determined. We applied this technique to characterize an ion exchange membrane, which has high water absorbability, and successfully determined the acoustic properties of the membrane without getting it wet.

  13. Scanning Seebeck Coefficient Measurement System for Homogeneity Characterization of Bulk and Thin-Film Thermoelectric Materials

    SciTech Connect

    Iwanaga, S; Snyder, GJ

    2012-04-03

    Larger-scale production of thermoelectric materials is necessary when mass-producing thermoelectric devices at industrial level. Certain fabrication techniques can create inhomogeneity in the material through composition and doping fluctuations throughout the sample, causing local variations in thermoelectric properties. Some variations are in the range of sub-millimeter scale or larger but may be difficult to detect by traditional materials characterization techniques such as x-ray diffraction or scanning electron microscopy when the chemical variation is small but the doping variation, which strongly affects thermoelectric performance, is large. In this paper, a scanning apparatus to directly detect local variations of Seebeck coefficient on both bulk and thin-film samples is used. Results have shown that this technique can be utilized for detection of defective regions, as well as phase separation in the 100-m range or larger.

  14. A perfectly stoichiometric and flat CeO2(111) surface on a bulk-like ceria film

    PubMed Central

    Barth, C.; Laffon, C.; Olbrich, R.; Ranguis, A.; Parent, Ph.; Reichling, M.

    2016-01-01

    In surface science and model catalysis, cerium oxide (ceria) is mostly grown as an ultra-thin film on a metal substrate in the ultra-high vacuum to understand fundamental mechanisms involved in diverse surface chemistry processes. However, such ultra-thin films do not have the contribution of a bulk ceria underneath, which is currently discussed to have a high impact on in particular surface redox processes. Here, we present a fully oxidized ceria thick film (180 nm) with a perfectly stoichiometric CeO2(111) surface exhibiting exceptionally large, atomically flat terraces. The film is well-suited for ceria model studies as well as a perfect substitute for CeO2 bulk material. PMID:26879800

  15. A perfectly stoichiometric and flat CeO2(111) surface on a bulk-like ceria film

    NASA Astrophysics Data System (ADS)

    Barth, C.; Laffon, C.; Olbrich, R.; Ranguis, A.; Parent, Ph.; Reichling, M.

    2016-02-01

    In surface science and model catalysis, cerium oxide (ceria) is mostly grown as an ultra-thin film on a metal substrate in the ultra-high vacuum to understand fundamental mechanisms involved in diverse surface chemistry processes. However, such ultra-thin films do not have the contribution of a bulk ceria underneath, which is currently discussed to have a high impact on in particular surface redox processes. Here, we present a fully oxidized ceria thick film (180 nm) with a perfectly stoichiometric CeO2(111) surface exhibiting exceptionally large, atomically flat terraces. The film is well-suited for ceria model studies as well as a perfect substitute for CeO2 bulk material.

  16. Theoretical investigation of acoustic wave devices based on different piezoelectric films deposited on silicon carbide

    NASA Astrophysics Data System (ADS)

    Fan, Li; Zhang, Shu-yi; Ge, Huan; Zhang, Hui

    2013-07-01

    Performances of acoustic wave (AW) devices based on silicon carbide (SiC) substrates are theoretically studied, in which two types of piezoelectric films of ZnO and AlN deposited on 4H-SiC and 3C-SiC substrates are adopted. The phase velocities (PV), electromechanical coupling coefficients (ECC), and temperature coefficients of frequency (TCF) for three AW modes (Rayleigh wave, A0 and S0 modes of Lamb wave) often used in AW devices are calculated based on four types of configurations of interdigital transducers (IDTs). It is found that that the ZnO piezoelectric film is proper for the AW device operating in the low-frequency range because a high ECC can be realized using a thin ZnO film. The AlN piezoelectric film is proper for the device operating in the high-frequency range in virtue of the high PV of AlN, which can increase the finger width of the IDT. Generally, in the low-frequency Lamb wave devices using ZnO piezoelectric films with small normalized thicknesses of films to wavelengths hf/λ, thin SiC substrates can increase ECCs but induce high TCFs simultaneously. In the high-frequency device with a large hf/λ, the S0 mode of Lamb wave based on the AlN piezoelectric film deposited on a thick SiC substrate exhibits high performances by simultaneously considering the PV, ECC, and TCF.

  17. Crystal structure and electronic properties of bulk and thin film brownmillerite oxides.

    SciTech Connect

    Young, Joshua; Rondinelli, James M.

    2015-11-17

    The equilibrium structure and functional properties exhibited by brownmillerite oxides, a family of perovskitederived structures with alternating layers of BO6 octahedra and BO4 tetrahedra, viz., ordered arrangements of oxygen vacancies, is dependent on a variety of competing crystal-chemistry factors. We use electronic structure calculations to disentangle the complex interactions in two ferrates, Sr2Fe2O5 and Ca2Fe2O5, relating the stability of the equilibrium (strain-free) and thin film structures to both previously identified and herein newly proposed descriptors.We show that cation size and intralayer separation of the tetrahedral chains provide key contributions to the preferred ground state. We show the bulk ground-state structure is retained in the ferrates over a range of strain values; however, a change in the orientation of the tetrahedral chains, i.e., a perpendicular orientation of the vacancies relative to the substrate, is stabilized in the compressive region. The structure stability under strain is largely governed by maximizing the intraplane separation of the dipoles generated from rotations of the FeO4 tetrahedra. Lastly, we find that the electronic band gap is strongly influenced by strain, manifesting as an unanticipated asymmetric-vacancy alignment dependent response. This atomistic understanding establishes a practical route for the design of functional electronic materials in thin film geometries.

  18. Understanding of DNA directed nanoparticle superlattices in bulk and thin film

    NASA Astrophysics Data System (ADS)

    Lee, Byeongdu

    Over the years, there have been significant advances in assembling nanoparticles with DNA into superlattices. Since the first reports on DNA directed FCC and BCC superlattices consisting of single type of spherical nanoparticles, building blocks for the DNA-nanoparticle superlattices have been extended from a spherical gold nanoparticle to various types of other particles including quantum dots, magnetic, hollow, or polyhedral particles. Not only single component, but superlattices of binary and ternary components have also been synthesized. Although still many details are unclear, now there is a general consensus about thermodynamics of this type of assembly, which led us to fabricate thin films of DNA directed nanoparticle superlattices on substrate for applications such as optical materials. Since the structures are formed in aqueous condition, small angle x-ray scattering (SAXS) that does not disturb the system has been a critical tool to determine structural and thermodynamic characteristics of the assemblies. Thus, we have also been improving SAXS instrumentations and computational methods to calculate scattering profiles for the nanoparticle superlattices. In this talk, we will summarize our works with a focus on some structural details of these superlattices and DNA and understanding about the role of DNA in the crystallization processes in bulk and thin film.

  19. Crystal structure and electronic properties of bulk and thin film brownmillerite oxides

    NASA Astrophysics Data System (ADS)

    Young, Joshua; Rondinelli, James M.

    2015-11-01

    The equilibrium structure and functional properties exhibited by brownmillerite oxides, a family of perovskite-derived structures with alternating layers of B O6 octahedra and B O4 tetrahedra, viz., ordered arrangements of oxygen vacancies, is dependent on a variety of competing crystal-chemistry factors. We use electronic structure calculations to disentangle the complex interactions in two ferrates, Sr2Fe2O5 and Ca2Fe2O5 , relating the stability of the equilibrium (strain-free) and thin film structures to both previously identified and herein newly proposed descriptors. We show that cation size and intralayer separation of the tetrahedral chains provide key contributions to the preferred ground state. We show the bulk ground-state structure is retained in the ferrates over a range of strain values; however, a change in the orientation of the tetrahedral chains, i.e., a perpendicular orientation of the vacancies relative to the substrate, is stabilized in the compressive region. The structure stability under strain is largely governed by maximizing the intraplane separation of the dipoles generated from rotations of the FeO4 tetrahedra. Lastly, we find that the electronic band gap is strongly influenced by strain, manifesting as an unanticipated asymmetric-vacancy alignment dependent response. This atomistic understanding establishes a practical route for the design of functional electronic materials in thin film geometries.

  20. Fabrication of multiple Si nanohole thin films from bulk wafer by controlling metal-assisted etching direction

    NASA Astrophysics Data System (ADS)

    Shiu, Shu-Chia; Lin, Tzu-Ching; Pun, Keng-Lam; Syu, Hong-Jhang; Hung, Shih-Che; Lin, Ching-Fuh

    2011-10-01

    Crystalline Si photovoltaic modules still have high production cost due to significant consumption of the Si wafer. Reducing the large amount of Si material consumption is thus a critical issue. Here we develop a two-step metal-assisted etching technique for forming vertically-aligned Si nanohole thin films from bulk Si wafers. The formation of Si nanohole thin films includes a series of solution processes: deposition of Ag nanoparticles in an AgNO3/ HF aqueous solution, formation of Si nanohole arrays at the first-step metal-assisted etching, and side etching of the roots of the nanohole structure at the second-step metal-assisted etching. All the processes can proceed at around room temperature. A Si nanohole thin film with an average hole-size of 100 nm and a thickness of 5ìm-20ìm was hence formed at the top of the wafer. Afterwards, the Si nanohole thin film was transferred onto alien substrates. The Si nanohole thin film has the crystal quality similar to the bulk Si wafer. The above bulk Si substrate can be reused. With similar processes, other Si nanohole thin films can be formed from the above recycled Si wafer. The hole size and thickness are similar. The Si wafers recycled will significantly reduce the material consumption of Si. Thus, such technique is promising for lowering the cost of Si solar cells.m.

  1. Quantitative and high spatial resolution d{sub 33} measurement of piezoelectric bulk and thin films

    SciTech Connect

    Shetty, Smitha Yang, Jung In; Trolier-McKinstry, Susan; Stitt, Joe

    2015-11-07

    A single beam laser interferometer based on a modified Mirau detection scheme with a vertical resolution of ∼5 pm was developed for localized d{sub 33} measurements on patterned piezoelectric films. The tool provides high spatial resolution (∼2 μm), essential for understanding scaling and processing effects in piezoelectric materials. This approach enables quantitative information on d{sub 33}, currently difficult in local measurement techniques such as piezoresponse force microscopy. The interferometer is built in a custom microscope and employs a phase lock-in technique in order to detect sub-Angstrom displacements. d{sub 33} measurements on single crystal 0.67PbMg{sub 0.33}Nb{sub 0.67}O{sub 3}-0.33PbTiO{sub 3} and bulk PbZrTiO{sub 3}-5A ceramics demonstrated agreement within <3% with measurements using a double beam laser interferometer. Substrate bending contributions to out-of-plane strain, observed in thin continuous PbZr{sub 0.52}Ti{sub 0.48}O{sub 3} films grown on Si substrates is reduced for electrode diameters smaller than 100 μm. Direct scanning across room temperature and 150 °C poled 5 μm and 10 μm features etched in 0.5 μm thick PbZr{sub 0.52}Ti{sub 0.48}O{sub 3} films doped with 1% Nb confirmed minimal substrate contributions to the effective d{sub 33,f}. Furthermore, enhanced d{sub 33,f} values were observed along the feature edges due to partial declamping from the substrate, thus validating the application of single beam interferometry on finely patterned electrodes.

  2. Quantitative and high spatial resolution d33 measurement of piezoelectric bulk and thin films

    NASA Astrophysics Data System (ADS)

    Shetty, Smitha; Yang, Jung In; Stitt, Joe; Trolier-McKinstry, Susan

    2015-11-01

    A single beam laser interferometer based on a modified Mirau detection scheme with a vertical resolution of ˜5 pm was developed for localized d33 measurements on patterned piezoelectric films. The tool provides high spatial resolution (˜2 μm), essential for understanding scaling and processing effects in piezoelectric materials. This approach enables quantitative information on d33, currently difficult in local measurement techniques such as piezoresponse force microscopy. The interferometer is built in a custom microscope and employs a phase lock-in technique in order to detect sub-Angstrom displacements. d33 measurements on single crystal 0.67PbMg0.33Nb0.67O3-0.33PbTiO3 and bulk PbZrTiO3-5A ceramics demonstrated agreement within <3% with measurements using a double beam laser interferometer. Substrate bending contributions to out-of-plane strain, observed in thin continuous PbZr0.52Ti0.48O3 films grown on Si substrates is reduced for electrode diameters smaller than 100 μm. Direct scanning across room temperature and 150 °C poled 5 μm and 10 μm features etched in 0.5 μm thick PbZr0.52Ti0.48O3 films doped with 1% Nb confirmed minimal substrate contributions to the effective d33,f. Furthermore, enhanced d33,f values were observed along the feature edges due to partial declamping from the substrate, thus validating the application of single beam interferometry on finely patterned electrodes.

  3. Acoustics

    NASA Technical Reports Server (NTRS)

    Goodman, Jerry R.; Grosveld, Ferdinand

    2007-01-01

    The acoustics environment in space operations is important to maintain at manageable levels so that the crewperson can remain safe, functional, effective, and reasonably comfortable. High acoustic levels can produce temporary or permanent hearing loss, or cause other physiological symptoms such as auditory pain, headaches, discomfort, strain in the vocal cords, or fatigue. Noise is defined as undesirable sound. Excessive noise may result in psychological effects such as irritability, inability to concentrate, decrease in productivity, annoyance, errors in judgment, and distraction. A noisy environment can also result in the inability to sleep, or sleep well. Elevated noise levels can affect the ability to communicate, understand what is being said, hear what is going on in the environment, degrade crew performance and operations, and create habitability concerns. Superfluous noise emissions can also create the inability to hear alarms or other important auditory cues such as an equipment malfunctioning. Recent space flight experience, evaluations of the requirements in crew habitable areas, and lessons learned (Goodman 2003; Allen and Goodman 2003; Pilkinton 2003; Grosveld et al. 2003) show the importance of maintaining an acceptable acoustics environment. This is best accomplished by having a high-quality set of limits/requirements early in the program, the "designing in" of acoustics in the development of hardware and systems, and by monitoring, testing and verifying the levels to ensure that they are acceptable.

  4. Intensity demodulation-based acoustic sensor using dual fiber Bragg gratings and a titanium film

    NASA Astrophysics Data System (ADS)

    Wang, Shun; Lu, Ping; Zhang, Liang; Liu, Deming; Zhang, Jiangshan

    2014-07-01

    We report on recent experimental results obtained with fiber Bragg grating (FBG) microphone for acoustic measurement. The sensing element is formed by longitudinally sticking ends of two FBGs onto a titanium film, and then being packaged in an aluminum cylinder. Due to wavelength shift of the FBGs induced by the external acoustic disturbance, the corresponding periodic fluctuation in power can be observed on the optical oscilloscope. Theoretical analysis verifies that the optical power variation, result of the titanium film vibration caused by the acoustic disturbance, possesses a linear relationship with the sound pressure in a specific range. A relatively flat frequency response in the range from 100 Hz to 1 kHz with the average signal-to-noise ratio (SNR) above 22 dB is experimentally demonstrated. The maximum sound pressure sensitivity of the proposed sensor is found to be 90 μW/Pa within a sound pressure range 100.3-118.5 dB. The sensing system presents good stability and reliability, and has the advantage of direct self-demodulation.

  5. Loss reduction of leaky surface acoustic wave by loading with high-velocity thin film

    NASA Astrophysics Data System (ADS)

    Kakio, Shoji; Hosaka, Keiko

    2016-07-01

    The propagation properties of a leaky surface acoustic wave (LSAW) on rotated Y-cut X-propagating lithium niobate (YX-LN) substrates loaded with an aluminum nitride (AlN) thin film with a higher phase velocity than that of the substrate were investigated theoretically and experimentally. From the theoretical calculation, it was found that the minimum attenuation can be obtained at a certain thickness of the AlN thin film for a cut angle ranging from 0 to 60° because the cut angle giving the minimum attenuation shifts toward a smaller cut angle as the film thickness is increased. The propagation properties of an LSAW on several rotated YX-LN substrates were measured by using an interdigital transducer (IDT) pair with a wavelength λ of 8 µm, and the predicted shifts of the minimum attenuation toward a smaller cut angle were demonstrated experimentally. For 0° and 10°YX-LN samples, the measured insertion loss and propagation loss were markedly reduced by loading with the AlN thin film. A larger electromechanical coupling factor (16.9%) than that at the cut angle giving zero attenuation without a film and a propagation loss less of 0.02 dB/λ were obtained simultaneously at a film thickness of 0.125 λ for the 10°YX-LN sample.

  6. Role of Quantum and Surface-State Effects in the Bulk Fermi-Level Position of Ultrathin Bi Films.

    PubMed

    Hirahara, T; Shirai, T; Hajiri, T; Matsunami, M; Tanaka, K; Kimura, S; Hasegawa, S; Kobayashi, K

    2015-09-01

    We performed high-resolution photon-energy and polarization-dependent ARPES measurements on ultrathin Bi(111) films [6-180 bilayers (BL), 2.5-70 nm thick] formed on Si(111). In addition to the extensively studied surface states (SSs), the edge of the bulk valence band was clearly measured by using S-polarized light. We found direct evidence that this valence band edge, which forms a hole pocket in the bulk Bi crystal, does not cross the Fermi level for the 180 BL thick film. This is consistent with the predicted semimetal-to-semiconductor transition due to the quantum-size effect [V.B. Sandomirskii, Sov. Phys. JETP 25, 101 (1967)]. However, it became metallic again when the film thickness was decreased (below 30 BL). A plausible explanation for this phenomenon is the modification of the charge neutrality condition due to the size effect of the SSs. PMID:26382694

  7. [XPS and UPS characterization for Cr and Mn in high-temperature oxide films of bulk nanocrystalline 304 stainless steel].

    PubMed

    Xu, Song-Ning; Wang, Sheng-Gang; Han, Hai-Bao; Sun, Nai-Kun

    2013-03-01

    The authors studied the binding energies of valence electrons of two oxide scales, the atomic percentages of Cr and Mn elements in two oxide films, the work function of two oxide films on bulk nanocrystalline 304 stainless steel (BN-SS304) and conventional polycrystalline 304 stainless steel (CP-SS304). BN-SS304 was prepared by severe rolling technique, and the two oxide films were formed in atmosphere at 900 degrees C for 24 hours oxidation on BN-SS304 and CP-SS304 surfaces. In the two oxide films, Cr and Mn elements exist in the forms of Cr3+, Cr0, Mn4+ and Mn0. The atomic percentage ratios of Cr+ / (Cr3+ + Cr0) and Mn4+ / (Mn4+ + Mn0) in the oxide film on BN-SS304 are lower than those in the oxide film on CP-SS304. The interactions of the two oxides and the valence electrons of elements are Mn-O, Cr-O,3d and 4s of Mn0 and Cr0. The binding energies of the valence electrons in the oxide film on BN-SS304 are larger than those in the oxide film on CP-SS304, the work function of the oxide film on BN-SS304 is 0.07 eV larger than that on CP-SS304. PMID:23705465

  8. Mechanical characterization of porous nano-thin films by use of atomic force acoustic microscopy.

    PubMed

    Kopycinska-Müller, M; Clausner, A; Yeap, K-B; Köhler, B; Kuzeyeva, N; Mahajan, S; Savage, T; Zschech, E; Wolter, K-J

    2016-03-01

    The indentation modulus of thin films of porous organosilicate glass with a nominal porosity content of 30% and thicknesses of 350nm, 200nm, and 46nm is determined with help of atomic force acoustic microscopy (AFAM). This scanning probe microscopy based technique provides the highest possible depth resolution. The values of the indentation modulus obtained for the 350nm and 200nm thin films were respectively 6.3GPa±0.2GPa and 7.2GPa±0.2GPa and free of the substrate influence. The sample with the thickness of 46nm was tested in four independent measurement sets. Cantilevers with two different tip radii of about 150nm and less than 50nm were applied in different force ranges to obtain a result for the indentation modulus that was free of the substrate influence. A detailed data analysis yielded value of 8.3GPa±0.4GPa for the thinnest film. The values of the indentation modulus obtained for the thin films of porous organosilicate glasses increased with the decreasing film thickness. The stiffening observed for the porous films could be explained by evolution of the pore topology as a function of the film thickness. To ensure that our results were free of the substrate influence, we analyzed the ratio of the sample deformation as well as the tip radius to the film thickness. The results obtained for the substrate parameter were compared for all the measurement series and showed, which ones could be declared as free of the substrate influence. PMID:26799327

  9. Sodium potassium niobate-based lead-free piezoelectric ceramics: Bulk and freestanding thick films

    NASA Astrophysics Data System (ADS)

    Li, Huidong

    2008-10-01

    Due to the toxicity of lead, there is an urgent need to develop lead-free alternatives to replace the currently dominant lead-based piezoelectrics such as lead zirconate titanate (PZT). (Na0.5K0.5)NbO 3 (NKN)-based piezoelectrics are promising because of their relatively high Curie temperatures and piezoelectric coefficients among the non-lead piezoelectrics. However, it is difficult to sinter. In this thesis study, a colloidal coating method was developed to improve the sintering of NKN. With this coating method, NKN with good piezoelectric properties can be produced without cold isostatic pressing. To improve the piezoelectric performance of NKN, we performed antimony (Sb) doping studies for a NKN-LN solid solution using the coating approach. It was found that Sb doping greatly improved the density and the piezoelectric properties of the NKN-LiNbO3 solid solution and optimized performance was found at 4%Sb. The reasons for the improved piezoelectric properties and density were discussed. Recently, a large enhancement in the piezoelectric performance under electric fields was discovered in polycrystalline lead magnesium niobate-lead titanate (PMN-PT) when the material was made into freestanding film geometry. Here, for the first time, we show a similar effect was also observed in a lead-free system, (Na0.5K0.5)0.945Li0.055Nb 0.96Sb0.04O3. At 6-8 kV/cm, a giant --d 31 value of 1700 pm/V was achieved, 20 times higher than the value of bulk counterpart. The enhancement was found to result from the ease of domain motion imparted by the freestanding film geometry, and the magnitude of the enhancement can be affected by the electrode layer (a non-piezoelectric) thickness. The freestanding geometry provides a new approach to greatly improve the piezoelectric performance of the current lead-free systems.

  10. Influence of the side chain and substrate on polythiophene thin film surface, bulk, and buried interfacial structures.

    PubMed

    Xiao, Minyu; Jasensky, Joshua; Zhang, Xiaoxian; Li, Yaoxin; Pichan, Cayla; Lu, Xiaolin; Chen, Zhan

    2016-08-10

    The molecular structures of organic semiconducting thin films mediate the performance of various devices composed of such materials. To fully understand how the structures of organic semiconductors alter on substrates due to different polymer side chains and different interfacial interactions, thin films of two kinds of polythiophene derivatives with different side-chains, poly(3-hexylthiophene) (P3HT) and poly(3-potassium-6-hexanoate thiophene) (P3KHT), were deposited and compared on various surfaces. A combination of analytical tools was applied in this research: contact angle goniometry and X-ray photoelectron spectroscopy (XPS) were used to characterize substrate dielectric surfaces with varied hydrophobicity for polymer film deposition; X-ray diffraction and UV-vis spectroscopy were used to examine the polythiophene film bulk structure; sum frequency generation (SFG) vibrational spectroscopy was utilized to probe the molecular structures of polymer film surfaces in air and buried solid/solid interfaces. Both side-chain hydrophobicity and substrate hydrophobicity were found to mediate the crystallinity of the polythiophene film, as well as the orientation of the thiophene ring within the polymer backbone at the buried polymer/substrate interface and the polymer thin film surface in air. For the same type of polythiophene film deposited on different substrates, a more hydrophobic substrate surface induced thiophene ring alignment with the surface normal at both the buried interface and on the surface in air. For different films (P3HT vs. P3KHT) deposited on the same dielectric substrate, a more hydrophobic polythiophene side chain caused the thiophene ring to align more towards the surface at the buried polymer/substrate interface and on the surface in air. We believe that the polythiophene surface, bulk, and buried interfacial molecular structures all influence the hole mobility within the polythiophene film. Successful characterization of an organic conducting

  11. Pulsed laser deposition of epitaxial yttrium iron garnet films with low Gilbert damping and bulk-like magnetization

    SciTech Connect

    Onbasli, M. C. Kim, D. H.; Ross, C. A.; Kehlberger, A.; Jakob, G.; Kläui, M.; Chumak, A. V.; Hillebrands, B.

    2014-10-01

    Yttrium iron garnet (YIG, Y {sub 3}Fe{sub 5}O{sub 12}) films have been epitaxially grown on Gadolinium Gallium Garnet (GGG, Gd{sub 3}Ga{sub 5}O{sub 12}) substrates with (100) orientation using pulsed laser deposition. The films were single-phase, epitaxial with the GGG substrate, and the root-mean-square surface roughness varied between 0.14 nm and 0.2 nm. Films with thicknesses ranging from 17 to 200 nm exhibited low coercivity (<2 Oe), near-bulk room temperature saturation moments (∼135 emu cm{sup −3}), in-plane easy axis, and damping parameters as low as 2.2 × 10{sup −4}. These high quality YIG thin films are useful in the investigation of the origins of novel magnetic phenomena and magnetization dynamics.

  12. Effects of bulk flow pulsations on film cooling from different length injection holes at different blowing ratios

    SciTech Connect

    Seo, H.J.; Lee, J.S.; Ligrani, P.M.

    1999-07-01

    Bulk flow pulsations in the form of sinusoidal variations of velocity and static pressure at injectant Strouhal numbers from 0.8 to 10.0 are investigated as they affect film cooling from a single row of simple angle holes. Similar flow variations are produced by potential flow interactions and passing shock waves near turbine surfaces in gas turbine engines. Time-averaged temperature distributions, phase-averaged temperature distributions, adiabatic film cooling effectiveness values, and iso-energetic Stranton numbers show that important alterations to film cooling protection occur as pulsation frequency, coolant Strouhal number, blowing ratio, and nondimensional injection hole length are changed. Overall, the pulsations affect film performance and behavior more significantly both as L/D decreases, and as blowing ratio decreases.

  13. Manipulating block copolymer self-assemblies in bulk and thin films by thermal and solvent annealing

    NASA Astrophysics Data System (ADS)

    Gu, Weiyin

    The self--assembly of block copolymers (BCPs) into well--ordered nanoscopic arrays holds promise for new technological breakthroughs as templates and scaffolds for the fabrication of nanostructured materials. It is essential to establish convenient approaches to control the morphology of BCPs, since some applications require addressability, the BCP microdomains must be perfectly aligned and oriented. The theme of this thesis is the use of external forces, specifically thermal and solvent annealing, to guide the self--assembly of BCPs to obtain microphase separated morphologies for different applications. Three representative BCP systems, having lamellar, cylindrical and spherical microdomains are discussed. First, the self--assembly of lamella--forming brush block copolymers (BrBCPs) having polylactide (PLA) and polystyrene (PS) side chains were studied in the bulk and in thin films. The domain size increased approximately linearly with the molecular weight of the backbone, which indicated that the backbone was in an extended conformation that was confirmed theoretically. In situ small angle x--ray scattering (SAXS) measurements indicated that the self--assembly of the BrBCPs was quite rapid, due to the rigid nature of the backbone chain, Second, the directed self--assembly of cylinder--forming polystyrene--block--poly(ethylene oxide)s (PS--b--PEOs) in thin films were investigated. The polymer--surface interactions were tuned by hydroxyl end--functionalized polymers, so that the orientation of the PS--b--PEO microdomains was controlled during thermal annealing. Cylindrical PEO microdomains embedded in a PS matrix orientated normal to the silicon substrates were observed over a wide processing window when the substrates were modified by PS-- b--PEO BCPs. PS--b--PEOs with an o--nitrobenzyl ester junction point (PS--hnu --PEOs) were used to fabricate nanoscopic dot and line patterns having long--range lateral order. The cylindrical BCP microdomains were oriented

  14. Phase transition in bulk single crystals and thin films of VO2 by nanoscale infrared spectroscopy and imaging

    DOE PAGESBeta

    Liu, Mengkun; Sternbach, Aaron J.; Wagner, Martin; Slusar, Tetiana V.; Kong, Tai; Bud'ko, Sergey L.; Kittiwatanakul, Salinporn; Qazilbash, M. M.; McLeod, Alexander; Fei, Zhe; et al

    2015-06-29

    We have systematically studied a variety of vanadium dioxide (VO2) crystalline forms, including bulk single crystals and oriented thin films, using infrared (IR) near-field spectroscopic imaging techniques. By measuring the IR spectroscopic responses of electrons and phonons in VO2 with sub-grain-size spatial resolution (~20nm), we show that epitaxial strain in VO2 thin films not only triggers spontaneous local phase separations, but leads to intermediate electronic and lattice states that are intrinsically different from those found in bulk. Generalized rules of strain- and symmetry-dependent mesoscopic phase inhomogeneity are also discussed. Furthermore, these results set the stage for a comprehensive understanding ofmore » complex energy landscapes that may not be readily determined by macroscopic approaches.« less

  15. Structural defects and electronic structure of N-ion implanted TiO2: Bulk versus thin film

    NASA Astrophysics Data System (ADS)

    Zatsepin, D. A.; Boukhvalov, D. W.; Kurmaev, E. Z.; Zhidkov, I. S.; Gavrilov, N. V.; Korotin, M. A.; Kim, S. S.

    2015-11-01

    Systematic investigation of atomic structure of N-ion implanted TiO2 (thin films and bulk ceramics) was performed by XPS measurements (core levels and valence bands) and first-principles density functional theory (DFT) calculations. In bulk samples experiment and theory demonstrate anion N → O substitution. For the thin films case experiments evidence valuable contributions from N2 and NO molecule-like structures and theoretical modeling reveals a possibility of formation of these species as result of the appearance of interstitial nitrogen defects on the various surfaces of TiO2. Energetics of formation of oxygen vacancies and its key role for band gap reduction is also discussed.

  16. Phase transition in bulk single crystals and thin films of V O2 by nanoscale infrared spectroscopy and imaging

    NASA Astrophysics Data System (ADS)

    Liu, Mengkun; Sternbach, Aaron J.; Wagner, Martin; Slusar, Tetiana V.; Kong, Tai; Bud'ko, Sergey L.; Kittiwatanakul, Salinporn; Qazilbash, M. M.; McLeod, Alexander; Fei, Zhe; Abreu, Elsa; Zhang, Jingdi; Goldflam, Michael; Dai, Siyuan; Ni, Guang-Xin; Lu, Jiwei; Bechtel, Hans A.; Martin, Michael C.; Raschke, Markus B.; Averitt, Richard D.; Wolf, Stuart A.; Kim, Hyun-Tak; Canfield, Paul C.; Basov, D. N.

    2015-06-01

    We have systematically studied a variety of vanadium dioxide (V O2 ) crystalline forms, including bulk single crystals and oriented thin films, using infrared (IR) near-field spectroscopic imaging techniques. By measuring the IR spectroscopic responses of electrons and phonons in V O2 with sub-grain-size spatial resolution (˜20 nm ) , we show that epitaxial strain in V O2 thin films not only triggers spontaneous local phase separations, but also leads to intermediate electronic and lattice states that are intrinsically different from those found in bulk. Generalized rules of strain- and symmetry-dependent mesoscopic phase inhomogeneity are also discussed. These results set the stage for a comprehensive understanding of complex energy landscapes that may not be readily determined by macroscopic approaches.

  17. Crossover between Weak Antilocalization and Weak Localization of Bulk States in Ultrathin Bi2Se3 Films

    PubMed Central

    Wang, Huichao; Liu, Haiwen; Chang, Cui-Zu; Zuo, Huakun; Zhao, Yanfei; Sun, Yi; Xia, Zhengcai; He, Ke; Ma, Xucun; Xie, X. C.; Xue, Qi-Kun; Wang, Jian

    2014-01-01

    We report transport studies on the 5 nm thick Bi2Se3 topological insulator films which are grown via molecular beam epitaxy technique. The angle-resolved photoemission spectroscopy data show that the Fermi level of the system lies in the bulk conduction band above the Dirac point, suggesting important contribution of bulk states to the transport results. In particular, the crossover from weak antilocalization to weak localization in the bulk states is observed in the parallel magnetic field measurements up to 50 Tesla. The measured magneto-resistance exhibits interesting anisotropy with respect to the orientation of parallel magnetic field B// and the current I, signifying intrinsic spin-orbit coupling in the Bi2Se3 films. Our work directly shows the crossover of quantum interference effect in the bulk states from weak antilocalization to weak localization. It presents an important step toward a better understanding of the existing three-dimensional topological insulators and the potential applications of nano-scale topological insulator devices. PMID:25056600

  18. Analysis of Bulk and Thin Film Model Samples Intended for Investigating the Strain Sensitivity of Niobium-Tin

    SciTech Connect

    Mentink, M. G. T.; Anders, A.; Dhalle, M. M. J.; Dietderich, D. R.; Godeke, A.; Goldacker, W.; Hellman, F.; Kate, H. H. J. ten; Putnam, D.; Slack, J. L.; Sumption, M. D.; Susner, M. A.

    2010-08-01

    Bulk samples and thin films were fabricated and characterized to determine their suitability for studying the effect of composition and morphology on strain sensitivity. Heat capacity and resistivity data are used to determine the critical temperature distribution. It is found that all bulk samples contain stoichiometric Nb{sub 3}Sn regardless of their nominal Nb to Sn ratio. Furthermore, in bulk samples with Cu additions, a bi-modal distribution of stoichiometric and off-stoichiometric Nb-Sn is found. Thus the nominally off-stoichiometric bulk samples require additional homogenization steps to yield homogeneous off-stoichiometric samples. A binary magnetron-sputtered thin film has the intended off-stoichiometric Nb-Sn phase with a mid-point critical temperature of 16.3 K. This type of sample is a suitable candidate for investigating the strain sensitivity of A15 Nb{sub 1-{beta}}Sn{sub {beta}}, with 0.18 < {beta} < 0.25. The strain sensitivity of Nb-Sn as a function of composition and morphology is important for an in-depth understanding of the strain sensitivity of composite Nb{sub 3}Sn wires.

  19. Prospects for Adapting Current ASTM Wear and Erosion Tests for Bulk Materials to Thin Films, Coatings, and Surface Treatments

    SciTech Connect

    Blau, Peter Julian

    2007-01-01

    Most of ASTM Committee G2's erosion, wear, and friction test standards were developed for use with bulk materials, yet there is a growing need to evaluate the tribological behavior of films, coatings, and surface treatments (FCSTs), some that affect layers only tens of nanometers to a few micrometers thick. Tribotesting standards for bulk materials can sometimes be modified for use on FCSTs, but the conditions and methods developed for bulk materials may sometimes be too severe or inapplicable. An internet search and literature review indicated that a number of G2 Committee standards are currently being used for FCSTs. Of these, ASTM G99 and G65 seem to be the most popular. When attempting to apply an existing wear standard for bulk materials to FCSTs, two key issues must be addressed: (1) whether changes are needed in the magnitudes of the applied conditions, and (2) whether more precise methods are needed to measure the magnitude of surface damage. Straightforward calculations underscore the limitations for wear measurement of thin layers when evaluated using block-on-ring and pin-on-disk tests. Finally, suggestions are given for modifying selected ASTM G2 standards to enable their use on films, coatings, and surface treatments.

  20. Acoustic signal associated with the bursting of a soap film which initially closes an overpressurized cavity . Experiment and theory

    NASA Astrophysics Data System (ADS)

    Vidal, V.; Géminard, J.-C.; Divoux, T.; Melo, F.

    2006-12-01

    We report an experimental study of the sound produced by the bursting of a thin liquid film, which initially closes an overpressurized cylindrical cavity. There is a need for a deep understanding of the phenomenon, which can be very useful in numerous practical cases. For instance, in the nature, the volcanologists observe the bursting of large, elongated, gas-bubbles at the surface of lava lakes and record the associated sound emission. One can wonder which pieces of information they can get from such acoustic measurements. For a didactic purpose, we provide also the reader with all the theoretical background necessary for the understanding of the physical processes that govern the various characteristics of the acoustic signals: the cavity geometry governs the frequency; the viscous dissipation and the radiation are responsible for the damping; the acoustic energy informs about the characteristic time associated with the film-rupture more than about the energy initially loaded in the cavity.

  1. TiO2 films with rich bulk oxygen vacancies prepared by electrospinning for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Li, Xiaodong; Gao, Caitian; Wang, Jiangtao; Lu, Bingan; Chen, Wanjun; Song, Jie; Zhang, Shanshan; Zhang, Zhenxing; Pan, Xiaojun; Xie, Erqing

    2012-09-01

    Highly transparent nanocrystalline TiO2 films have been fabricated by electrospinning (ES) technique based on a transmutation process from as-spun nanofibers with an appropriate amount of tri-ethanolamine (TEOA) added to the precursor. A possible evolution mechanism of the transparent nanocrystalline TiO2 films is proposed. It is found that the films prepared via transmutation from electrospun nanofibers possess rich bulk oxygen vacancies (BOVs, PL band at 621-640 nm) by using photoluminescence (PL) spectroscopy. Contrastively, the dominant peak in PL spectrum of the spin-coated film is the emission from surface oxygen vacancies (SOVs, PL band at 537-555 nm). The electrospun TiO2 films with rich BOVs induce large open-circuit voltage (Voc) and fill factor (FF) improvements in dye-sensitized solar cells (DSCs), and thus a large improvement of energy conversion efficiency (η). In addition, these performance advantages are maintained for a double-layer cell with a doctor-bladed ˜7 μm top layer (P25 nanometer TiO2, Degussa) and an electrospun ˜3 μm bottom layer. The double-layer cell yields a high η of 6.01%, which has increased by 14% as compared with that obtained from a 10 μm thick P25 film.

  2. Pressure probe and hot-film probe rsponses to acoustic excitation in mean flow

    NASA Technical Reports Server (NTRS)

    Parrott, T. L.; Jones, M. G.

    1986-01-01

    An experiment was conducted to compare the relative responses of a hot-film probe and a pressure probe positioned in a flow duct carrying mean flow and progressive acoustic waves. The response of each probe was compared with that of a condenser-type microphone flush mounted in the duct wall for flow Mach numbers up to about 0.5. The response of the pressure probe was less than that of the flush-mounted microphone by not more than about 2.1 dB at the highest centerline Mach number. This decreased response of the probe can likely be attributed to flow-induced impedance changes at the probe sensor orifices. The response of the hot-film probe, expressed in terms of fluctuating pressure, was greater than that of the flush-mounted microphone by as much as 6.0 dB at the two higher centerline Mach numbers. Removal of the contribution from fluctuating temperature in the hot-film analytical model greatly improved the agreement between the two transducer responses.

  3. Micro-particle manipulation by single beam acoustic tweezers based on hydrothermal PZT thick film

    NASA Astrophysics Data System (ADS)

    Zhu, Benpeng; Xu, Jiong; Li, Ying; Wang, Tian; Xiong, Ke; Lee, Changyang; Yang, Xiaofei; Shiiba, Michihisa; Takeuchi, Shinichi; Zhou, Qifa; Shung, K. Kirk

    2016-03-01

    Single-beam acoustic tweezers (SBAT), used in laboratory-on-a-chip (LOC) device has promising implications for an individual micro-particle contactless manipulation. In this study, a freestanding hydrothermal PZT thick film with excellent piezoelectric property (d33 = 270pC/N and kt = 0.51) was employed for SBAT applications and a press-focusing technology was introduced. The obtained SBAT, acting at an operational frequency of 50MHz, a low f-number (˜0.9), demonstrated the capability to trap and manipulate a micro-particle sized 10μm in the distilled water. These results suggest that such a device has great potential as a manipulator for a wide range of biomedical and chemical science applications.

  4. Micro-particle manipulation by single beam acoustic tweezers based on hydrothermal PZT thick film

    PubMed Central

    Zhu, Benpeng; Xu, Jiong; Li, Ying; Wang, Tian; Xiong, Ke; Lee, Changyang; Yang, Xiaofei; Shiiba, Michihisa; Takeuchi, Shinichi; Zhou, Qifa; Shung, K. Kirk

    2016-01-01

    Single-beam acoustic tweezers (SBAT), used in laboratory-on-a-chip (LOC) device has promising implications for an individual micro-particle contactless manipulation. In this study, a freestanding hydrothermal PZT thick film with excellent piezoelectric property (d33 = 270pC/N and kt = 0.51) was employed for SBAT applications and a press-focusing technology was introduced. The obtained SBAT, acting at an operational frequency of 50MHz, a low f-number (∼0.9), demonstrated the capability to trap and manipulate a micro-particle sized 10μm in the distilled water. These results suggest that such a device has great potential as a manipulator for a wide range of biomedical and chemical science applications. PMID:27014504

  5. Bendable ZnO thin film surface acoustic wave devices on polyethylene terephthalate substrate

    SciTech Connect

    He, Xingli; Guo, Hongwei; Chen, Jinkai; Wang, Wenbo; Xuan, Weipeng; Xu, Yang E-mail: jl2@bolton.ac.uk; Luo, Jikui E-mail: jl2@bolton.ac.uk

    2014-05-26

    Bendable surface acoustic wave (SAW) devices were fabricated using high quality c-axis orientation ZnO films deposited on flexible polyethylene terephthalate substrates at 120 °C. Dual resonance modes, namely, the zero order pseudo asymmetric (A{sub 0}) and symmetric (S{sub 0}) Lamb wave modes, have been obtained from the SAW devices. The SAW devices perform well even after repeated flexion up to 2500 με for 100 times, demonstrating its suitability for flexible electronics application. The SAW devices are also highly sensitive to compressive and tensile strains, exhibiting excellent anti-strain deterioration property, thus, they are particularly suitable for sensing large strains.

  6. Microfluidic pumps employing surface acoustic waves generated in ZnO thin films

    SciTech Connect

    Du, X. Y.; Flewitt, A. J.; Milne, W. I.; Fu, Y. Q.; Luo, J. K.

    2009-01-15

    ZnO thin film based surface acoustic wave (SAW) devices have been utilized to fabricate microfluidic pumps. The SAW devices were fabricated on nanocrystalline ZnO piezoelectric thin films deposited on Si substrates using rf magnetron sputtering and use a Sezawa wave mode for effective droplet motion. The as-deposited ZnO surface is hydrophilic, with a water contact angle of {approx}75 deg., which prevents droplet pumping. Therefore, the ZnO surface was coated using a self-assembled monolayer of octadecyltrichlorosilane which forms a hydrophobic surface with a water contact angle of {approx}110 deg. Liquid droplets between 0.5 and 1 {mu}l in volume were successfully pumped on the hydrophobic ZnO surface at velocities up to 1 cm s{sup -1}. Under acoustic pressure, the water droplet on an hydrophilic surface becomes deformed, and the asymmetry in the contact angle at the trailing and leading edges allow the force acting upon the droplet to be calculated. These forces, which increase with input voltage above a threshold level, are found to be in the range of {approx}100 {mu}N. A pulsed rf signal has also been used to demonstrate precision manipulation of the liquid droplets. Furthermore, a SAW device structure is demonstrated in which the ZnO piezoelectric only exists under the input and output transducers. This structure still permits pumping, while avoiding direct contact between the piezoelectric material and the fluid. This is of particular importance for biological laboratory-on-a-chip applications.

  7. Surface acoustic wave technique for the characterization of porous properties of microporous silicate thin films

    NASA Astrophysics Data System (ADS)

    Hietala, Susan Leslie

    1997-12-01

    Features of gas adsorption onto sol-gel derived microporous silicate thin films, for characterization of porous properties, are detailed using a surface acoustic wave (SAW) technique. Mass uptake and film effective modulus changes calculated from the SAW data are investigated in detail. The effects of stress and surface tension on the SAW sensor are calculated and found to be negligible in these experiments. Transient behavior recorded during nitrogen adsorption at 77 K is discussed in the context of mass uptake and effective modulus contributions. The time constant associated with the effective modulus calculation is consistent with that of diffusivity of nitrogen into a 5A zeolite. Further calculations indicate that the transient behavior is not due to thermal effects. A unique dual sensor SAW experiment to decouple the mass and effective modulus contributions to the frequency response was performed in conjunction with a Silicon beam-bending experiment. The beam-bending experiment results in a calculation of stress induced during adsorption of methanol on a microporous silicate thin film. The decoupled mass and effective modulus calculated from the SAW data have similar shaped isotherms, and are quite different from that of the stress developed in the Silicon beam. The total effective modulus change calculated from the SAW data is consistent with that calculated using Gassmann's equation. The SAW system developed for this work included unique electronics and customized hardware which is suitable for work under vacuum and at temperatures from 77K to 473K. This unique setup is suitable for running thin film samples on a Micromeritics ASAP 2000 Gas Adsorption unit in automatic mode. This setup is also general enough to be compatible with a custom gas adsorption unit and the beam bending apparatus, both using standard vacuum assemblies.

  8. Deviation from bulk behaviour in the cold crystallization kinetics of ultrathin films of poly(3-hydroxybutyrate)

    NASA Astrophysics Data System (ADS)

    Napolitano, S.; Wübbenhorst, M.

    2007-05-01

    The cold crystallization kinetics of ultrathin films of poly(3-hydroxybutyrate) (PHB) have been investigated by dielectric spectroscopy. Upon reduction of the film thickness, a lowering of the Avrami exponent accompanied by an increase of the crystallization time was observed. The experimental results are analysed in terms of reduction of the total number of nuclei involved in the crystallization process.

  9. Epitaxial growth of hexagonal tungsten bronze Cs x WO3 films in superconducting phase region exceeding bulk limit

    NASA Astrophysics Data System (ADS)

    Soma, Takuto; Yoshimatsu, Kohei; Ohtomo, Akira

    2016-07-01

    We report epitaxial synthesis of superconducting Cs x WO3 (x = 0.11, 0.20, and 0.31) films on Y-stabilized ZrO2 (111) substrates. The hexagonal crystal structure was verified not only for the composition within the stable region of the bulk (x = 0.20 and 0.31), but also for the out-of-range composition (x = 0.11). The onset of the superconducting transition was recorded at 5.8 K for x = 0.11. We found a strong correlation between the superconducting transition temperature (T C) and the c-axis length, irrespective of the Cs content. These results indicated that the hidden superconducting phase region of hexagonal tungsten bronze is accessible using epitaxial synthesis of lightly doped films.

  10. Influence of molecular structure peculiarities of phthalocyanine derivatives on their supramolecular organization and properties in the bulk and thin films

    NASA Astrophysics Data System (ADS)

    Usol'tseva, Nadezhda V.; Kazak, Alexandr V.; Luk'yanov, Ivan Yu.; Sotsky, Valentin V.; Smirnova, Antonina I.; Yudin, Sergey G.; Shaposhnikov, Gennadiy P.; Galanin, Nikolay E.

    2014-08-01

    In order to study the influence of molecular structure peculiarities on supramolecular organization and properties in the bulk and thin films of discotic mesogens six new mix-substituted phthalocyanine derivatives with 3,6-dioctyloxyphthalonitrile and 3,4,5,6-tetrachlorophthalonitrile fragments were synthesized. Temperatures of phase transitions, types of mesophase and their dependence on molecule structure, chemical nature, position and ratio of different substituents as well as presence of holmium in the metal complexes were analyzed. The behavior of the studied molecules on the boundary between water and air was investigated and the peculiarity of supramolecular organization in floating layers as well as in thin films was determined. Quenching of luminescence in solutions of the studied compounds in the presence of fullerene C60 was determined, thus giving prospects for application of these compounds as sensors for fullerene microquantities.

  11. Wurtzite ZnO (001) films grown on cubic MgO (001) with bulk-like opto-electronic properties

    SciTech Connect

    Zhou Hua; Wang Huiqiong; Chen Xiaohang; Zhan Huahan; Kang Junyong; Wu Lijun; Zhu Yimei; Zhang Lihua; Kisslinger, Kim

    2011-10-03

    We report the growth of ZnO (001) wurtzite thin films with bulk-like opto-electronic properties on MgO (001) cubic substrates using plasma-assisted molecular beam epitaxy. In situ reflection high-energy electron diffraction patterns and ex situ high resolution transmission electron microscopy images indicate that the structure transition from the cubic MgO substrates to the hexagonal films involves 6 ZnO variants that have the same structure but different orientations. This work demonstrates the possibility of integrating wurtzite ZnO films and functional cubic substrates while maintaining their bulk-like properties.

  12. Location of Trapped Electron Centers in the Bulk of Epitaxial MgO(001) Films Grown on Mo(001) Using in situ W -band Electron Paramagnetic Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Cornu, Damien; Rocker, Jan; Gonchar, Anastasia; Risse, Thomas; Freund, Hans-Joachim

    2016-07-01

    We present the first in situ W -band (94-GHz) electron paramagnetic resonance (EPR) study of a trapped electron center in thin MgO(001) films. The improved resolution of the high-field EPR experiments proves that the signal originate from a well-defined species present in the bulk of the films, whose projection of the principal g -tensor components onto the (001) plane are oriented along the [110] direction of the MgO lattice. Based on a comparison between the structural properties of the films, knowledge of the ability of bulk defects to trap electrons, and the properties of the EPR signal, it is possible to propose that the paramagnetic species are located at the origin of a screw dislocation in the bulk of the film.

  13. Difference in chemical reactions in bulk plasma and sheath regions during surface modification of graphene oxide film using capacitively coupled NH{sub 3} plasma

    SciTech Connect

    Lee, Sung-Youp; Kim, Chan; Kim, Hong Tak

    2015-09-14

    Reduced graphene oxide (r-GO) films were obtained from capacitively coupled NH{sub 3} plasma treatment of spin-coated graphene oxide (GO) films at room temperature. Variations were evaluated according to the two plasma treatment regions: the bulk plasma region (R{sub bulk}) and the sheath region (R{sub sheath}). Reduction and nitridation of the GO films began as soon as the NH{sub 3} plasma was exposed to both regions. However, with the increase in treatment time, the reduction and nitridation reactions differed in each region. In the R{sub bulk}, NH{sub 3} plasma ions reacted chemically with oxygen functional groups on the GO films, which was highly effective for reduction and nitridation. While in the R{sub sheath}, physical reactions by ion bombardment were dominant because plasma ions were accelerated by the strong electrical field. The accelerated plasma ions reacted not only with the oxygen functional groups but also with the broken carbon chains, which caused the removal of the GO films by the formation of hydrocarbon gas species. These results showed that reduction and nitridation in the R{sub bulk} using capacitively coupled NH{sub 3} plasma were very effective for modifying the properties of r-GO films for application as transparent conductive films.

  14. ZnO films on /001/-cut (110)-propagating GaAs substrates for surface acoustic wave device applications

    NASA Technical Reports Server (NTRS)

    Hickernell, Frederick S.; Higgins, Robert J.; Jen, Cheng-Kuei; Kim, Yoonkee; Hunt, William D.

    1995-01-01

    A potential application for piezoelectric films substrates is the monolithic integration of surface acoustic wave (SAW) devices with GaAs electronics. Knowledge of the SAW properties of the layered structure is critical for the optimum and accurate design of such devices. The acoustic properties of ZnO films sputtered on /001/-cut group of (110) zone axes-propagating GaAs substrates are investigated in this article, including SAW velocity, effective piezoelectric coupling constant, propagation loss, diffraction, velocity surface, and reflectivity of shorted and open metallic gratings. The measurements of these essential SAW properties for the frequency range between 180 and 360 MHz have been performed using a knife-edge laser probe for film thicknesses over the range of 1.6-4 micron and with films of different grain sizes. The high quality of dc triode sputtered films was observed as evidenced by high K(sup 2) and low attenuation. The measurements of the velocity surface, which directly affects the SAW diffraction, on the bare and metalized ZnO on SiO2 or Si3N4 on /001/-cut GaAs samples are reported using two different techniques: (1) knife-edge laser probe, (2) line-focus-beam scanning acoustic microscope. It was found that near the group of (110) zone axes propagation direction, the focusing SAW property of the bare GaAs changes into a nonfocusing one for the layered structure, but a reversed phenomenon exists near the (100) direction. Furthermore, to some extent the diffraction of the substrate can be controlled with the film thickness. The reflectivity of shorted and open gratings are also analyzed and measured. Zero reflectivity is observed for a shorted grating. There is good agreement between the measured data and theoretical values.

  15. ZnO Films on {001}-Cut <110>-Propagating GaAs Substrates for Surface Acoustic Wave Device Applications

    NASA Technical Reports Server (NTRS)

    Kim, Yoonkee; Hunt, William D.; Hickernell, Frederick S.; Higgins, Robert J.; Jen, Cheng-Kuei

    1995-01-01

    A potential application for piezoelectric films on GaAs substrates is the monolithic integration of surface acoustic wave (SAW) devices with GaAs electronics. Knowledge of the SAW properties of the layered structure is critical for the optimum and accurate design of such devices. The acoustic properties of ZnO films sputtered on {001}-cut <110> -propagating GaAs substrates are investigated in this article, including SAW Velocity effective piezoelectric coupling constant, propagation loss. diffraction, velocity surface, and reflectivity of shorted and open metallic gratings. The measurements of these essential SAW properties for the frequency range between 180 and 360 MHz have been performed using a knife-edge laser probe for film thicknesses over the range of 1.6-4 micron and with films or different grain sizes. The high quality of dc triode sputtered films was observed as evidenced by high K(exp 2) and low attenuation. The measurements of the velocity surface, which directly affects the SAW diffraction, on the bare and metalized ZnO on SiO2, or Si3N4 on {001}-cut GaAs samples are reported using two different techniques: 1) knife-edge laser probe, 2) line-focus-beam scanning acoustic microscope. It was found that near the <110> propagation direction, the focusing SAW property of the bare GaAs changes into a nonfocusing one for the layered structure, but a reversed phenomenon exists near the <100> direction. Furthermore, to some extent the diffraction of the substrate can be controlled with the film thickness. The reflectivity of shorted and open gratings are also analyzed and measured. Zero reflectivity is observed for a shorted grating. There is good agreement between the measured data and theoretical values.

  16. Polarity-inverted ScAlN film growth by ion beam irradiation and application to overtone acoustic wave (000-1)/(0001) film resonators

    SciTech Connect

    Suzuki, Masashi; Yanagitani, Takahiko; Odagawa, Hiroyuki

    2014-04-28

    Polarity inversion in wurtzite film is generally achieved by the epitaxial growth on a specific under-layer. We demonstrate polarity inversion of c-axis oriented ScAlN films by substrate ion beam irradiation without using buffer layer. Substrate ion beam irradiation was induced by either sputtering a small amount of oxide (as a negative ion source) onto the cathode or by applying a RF bias to the substrate. Polarity of the films was determined by a press test and nonlinear dielectric measurement. Second overtone thickness extensional mode acoustic resonance and suppression of fundamental mode resonance, indicating complete polarity inversion, were clearly observed in bilayer highly oriented (000-1)/(0001) ScAlN film.

  17. Theoretical analysis of surface acoustic wave propagating properties of Y-cut nano lithium niobate film on silicon dioxide

    NASA Astrophysics Data System (ADS)

    Chen, Jing; Zhang, Qiaozhen; Han, Tao; Zhou, Liu; Tang, Gongbin; Liu, Boquan; Ji, Xiaojun

    2015-08-01

    The surface acoustic wave (SAW) propagating characteristics of Y-cut nano LiNbO3 (LN) film on SiO2/LN substrate have been theoretically calculated. The simulated results showed a shear horizontal (SH) SAW with enhanced electromechanical coupling factor K2 owing to a dimensional effect of the nanoscale LN film. However, a Rayleigh SAW and two other resonances related to thickness vibrations caused spurious responses for wideband SAW devices. These spurious waves could be fully suppressed by properly controlling structural parameters including the electrode layer height, thickness, and the Euler angle (θ) of the LN thin film. Finally, a pure SH SAW was obtained with a wide θ range, from 0° to 5° and 165° to 180°. The largest K2 achieved for the pure SH SAW was about 35.1%. The calculated results demonstrate the promising application of nano LN film to the realization of ultra-wideband SAW devices.

  18. Simulations of acoustic waves bandgaps in a surface of silicon with a periodic hole structure in a thin nickel film

    NASA Astrophysics Data System (ADS)

    Graczyk, Piotr; Mroz, Boguslaw

    2014-07-01

    We have performed simulations of dispersion relations for surface acoustic waves in two-dimensional phononic crystal by the finite elements method (FEM) and by the plane wave method (PWM). Considered medium is a thin nickel layer on a silicon single crystal (001) surface. The nickel film is decorated with cylindrical holes of the depth equal to the nickel film thickness arranged in a square lattice. We have obtained full bandgaps for the surface waves propagating in the medium of particular range of filling factor and layer thickness. The width of the bandgap had reached over 500[MHz] for the sample of the lattice constant 500[nm] and is sufficient for experimental design.

  19. Surface and related bulk properties of titania nanoparticles recovered from aramid–titania hybrid films: A novel attempt

    SciTech Connect

    Al-Omani, Sara J.; Bumajdad, Ali; Al Sagheer, Fakhreia A.; Zaki, Mohamed I.

    2012-11-15

    Highlights: ► Aramid–titania hybrid films (5 and 10 wt%-TiO{sub 2}) were prepared via sol–gel processing. ► 450 °C calcination of the films yield anatase-TiO{sub 2} nanoparticles of rod-like morphology. ► The titania nanoparticle, crystal structure, high surface area are stable up to 800 °C. ► The novel approach has the advantage of nearly 100% recovery of titania. ► Increasing calcination temperature up to 1100 °C triggers anatase → rutile transition. -- Abstract: 5 and 10 wt%-TiO{sub 2}-containing aramid–titania hybrid films were prepared using sol–gel processing improved by the inclusion of 3-isocyanato-propyltriethoxysilane (ICTOS) to strengthen bonding of the titania species to the polymer backbone and, hence, lessen its agglomeration. The films were thermally degraded by heating at 450 °C in a dynamic atmosphere of air. The solid residues were found by thermogravimetry, X-ray diffractometry and electron microscopy to consist dominantly of uniformly agglomerated rod-like anatase-TiO{sub 2} nanoparticles, irrespective of the titania content of the film. The recovered titania particle morphology and surface microstructure were examined by field emission scanning and high-resolution transmission electron microscopy, respectively. Whereas, the particle surface chemistry and texture were assessed, respectively, by means of X-ray photoelectron spectroscopy and N{sub 2} sorptiometry. The recovered titanias were found, irrespective of the film content of titania, to enjoy not only a high temperature (up to 800 °C) stable nanoscopic anatase bulk structure, but also a high-temperature stable surface chemical composition (lattice Ti{sup 4+} and O{sup 2−}, and adsorbed OH/CH{sub x} species), (101)-faceted microstructure and highly accessible (145–112 m{sup 2}/g), uniform mesoporous texture with average pore diameter in the narrow range of 3.9–6.3 nm. Increasing the calcination temperature up to 1100 °C enhances an anatase → rutile

  20. Fabrication and Characterization of PZT Thin-Film on Bulk Micromachined Si Motion Detectors

    SciTech Connect

    Clem, P.; Garino, T.J.; Laguna, G.; Tuttle, B.A.

    1999-01-07

    Motion detectors consisting of Pb(Zr{sub x}Ti{sub (1{minus}x)})O{sub 3} (PZT) thin films, between platinum electrodes, on micromachined silicon compound clamped-clamped or cantilever beam structures were fabricated using either hot KOH or High Aspect Ratio Silicon Etching (HARSE) to micromachine the silicon. The beams were designed such that a thicker region served as a test mass that produced stress at the top of the membrane springs that supported it when the object to which the detector was mounted moved. The PZT film devices were placed on these membranes to generate a charge or a voltage in response to the stress through the piezoelectric effect. Issues of integration of the PZT device fabrication process with the two etching processes are discussed. The effects of PZT composition and device geometry on the response of the detectors to motion is reported and discussed.

  1. Luminescent microstructures in bulk and thin films of PMMA, PDMS, PVA, and PS fabricated using femtosecond direct writing technique

    NASA Astrophysics Data System (ADS)

    Deepak, K. L. N.; Kuladeep, R.; Venugopal Rao, S.; Narayana Rao, D.

    2011-02-01

    We present here the luminescent properties of microstructures obtained through femtosecond (fs) laser direct writing (LDW) in bulk, and thin films of polymers such as poly methyl methacrylate (PMMA), poly dimethyl siloxane (PDMS), polystyrene (PS), and poly vinyl alcohol (PVA). We report the transmission, emission, excitation, laser confocal and ESR data from the modified regions acquired with the intention of understanding the fs irradiation effects in these polymers. Formation of different optical centers in the laser irradiated regions has been identified as the reason for emission characteristics which are dependent on the excitation source. Such emitting microstructures demonstrate their utility in memory based devices. ESR studies reveal the existence of peroxide type free radicals in PMMA, PDMS and PS after fs laser irradiation.

  2. Local elastic modulus of RF sputtered HfO{sub 2} thin film by atomic force acoustic microscopy

    SciTech Connect

    Jena, S. Tokas, R. B. Sarkar, P. Thakur, S.; Sahoo, N. K.; Misal, J. S.; Rao, K. D.

    2014-04-24

    Atomic force acoustic microscopy (AFAM) is a useful nondestructive technique for measurement of local elastic modulus of materials at nano-scale spatial resolution by measuring the contact resonance spectra for higher order modes of the AFM cantilever. The elastic modulus of RF sputtered HfO{sub 2} thin film has been measured quantitatively, using reference approach in which measurements are performed on the test and reference samples. Using AFAM, the measured elastic modulus of the HfO{sub 2} thin film is 223±27 GPa, which is in agreement with the literature value of 220±40 GPa for atomic layer deposited HfO{sub 2} thin film using nanoindentation technique.

  3. SEMICONDUCTOR PHYSICS: Young's modulus characterization of low-k films of nanoporous Black Diamond™ by surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Xingmeng, Shan; Xia, Xiao; Yaliang, Liu

    2010-08-01

    The laser-generated surface acoustic wave (SAW) technique is an accurate, fast and nondestructive solution to determine the mechanical properties of ultra thin films. SAWs are dispersive during the wave propagation on the layered structure. The Young's moduli of thin films can be obtained by matching the experimentally and theoretically calculated dispersive SAW curves. A short ultraviolet laser pulse is employed to generate the broad spectral range of the dispersive SAWs. The frequency range of dispersive SAWs in this study reaches 180 MHz, which is adequate for the SAW technique applied for the investigated samples. In this work, the Young's moduli of a series of nanoporous Black Diamond™1 low dielectric constant (low-k) films deposited on a Si (100) substrate are characterized successfully by the SAW technique.

  4. Effect of Doping on beta-Tricalcium Phosphate Bioresorbable Bulk Material and Thin Film Coatings

    NASA Astrophysics Data System (ADS)

    Abdalla, Suhaila

    Magnesium has emerged as a revolutionary biodegradable metal for use as an orthopedic material, it has several advantages over the current metallic materials in use, including eliminating the effects of stress shielding, improving biocompatibility and inhibiting degradation rates, thus removing the requirement of a second surgery for implant removal. Due to the rapid degradation of magnesium, it is necessary to control the corrosion rates of the materials to match the rates of bone healing. This dissertation reports on the effect of doping on the properties of beta-tricalcium phosphate (beta-TCP). It also reports on its application as a thin film coating on magnesium alloys for implant applications. Adding various dopants to beta-TCP significantly influences critical properties. In this study, discs were fabricated in two compositions: (i) undoped beta-TCP, (ii) beta-TCP doped with 1.0 wt % MgO, 0.5 wt % ZnO, and 1.0 wt % TiO2. Films were fabricated from these compositions using the pulsed laser deposition (PLD) technique. These coatings were then characterized for corrosive, hardness, and cytocompatibility. The XRD patterns of the coating confirm the amorphous nature of the films. The presence of the metal oxides in beta-TCP improved ceramic densification. The application of these doped coatings was also found to increase the hardness by 88 %, the modulus of elasticity by 66 %, and improve corrosion resistance of the magnesium alloy substrate; with a 2.4 % improvement in Ecorr and 95 % decrease in icorr. Cell viability was studied using an osteoblast precursor cell line MC3T3-E1 to assure that the biocompatibility of these ceramics was not altered due to the dopants. Long-term biodegradation studies were conducted by measuring weight change and surface microstructure as a function of time in simulated body fluid. The results suggest that these coatings could be used for bioresorbable implants with improved corrosion resistance and increased hardness.

  5. Tungsten Oxide Layers of High Acoustic Impedance for Fully Insulating Acoustic Reflectors.

    PubMed

    DeMiguel-Ramos, M; Diaz-Duran, Barbara; Munir, Junaid; Clement, Marta; Mirea, Teona; Olivares, Jimena; Iborra, Enrique

    2016-07-01

    Gravimetric sensors based on solidly mounted resonators require fully insulating acoustic reflectors to avoid parasitics when operating in liquid media. In this work, we propose a new high-acoustic impedance material, tungsten oxide ([Formula: see text]), for acoustic reflectors. We have optimized the sputtering conditions of [Formula: see text] to obtain nonconductive layers with mass density around [Formula: see text] and acoustic velocities for the shear and the longitudinal modes up to 2700 and 4500 m/s, respectively. Compared to other conventionally used high impedance layers, [Formula: see text] films display several manufacture advantages, such as high deposition rates, great reproducibility, and good adhesion to underlying substrates. We have demonstrated the applicability of [Formula: see text] in practical shear mode bulk acoustic wave resonators that display good performance in liquid environments. PMID:26571521

  6. Relation between surface and bulk electronic properties of Al doped ZnO films deposited at varying substrate temperature by radio frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Singh, C. C.; Patel, T. A.; Panda, E.

    2015-06-01

    In this study, a qualitative relationship between the surface and bulk electronic states for Al-doped ZnO (AZO) thin films (thickness < 260 nm) is established. To this end, AZO films were deposited on soda lime glass substrates by varying substrate temperature (Ts) from 303 K to 673 K in RF magnetron sputtering. All these AZO films are found to have grown in ZnO hexagonal wurtzite structure with strong (002) orientation of the crystallites and with an average transmittance of 84%-91% in the visible range. Room temperature scanning tunneling spectroscopy measurements reveal semiconducting behavior for the films deposited at Ts ≤ 373 K and semi-metallic behavior for those deposited at Ts > 373 K. Further, these films show two modes of electron tunneling, (a) direct tunneling at lower bias voltage and (b) FN tunneling at higher bias voltage, with transition voltage ( Vtrans ) shifting towards lower bias voltage (and thereby reducing the barrier height ( Φ)) with increasing Ts. This is attributed to additional (local) density of states near the Fermi level of these AZO films because of higher carrier concentration ( ne ) at increased Ts. Thus, qualitatively, the behavior in both the local surface electronic states and bulk state electronic properties for these deposited AZO films are found to follow similar trends with increasing Ts. The variation in local barrier heights (indicative of the local surface electronic structures) across the AZO film surface is found to be smaller for the films deposited at Ts ≤ 373 K, where semiconducting behavior is observed and wider for the semi-metallic AZO films deposited at higher Ts > 373 K, indicating a larger inhomogeneity of local surface electronic properties at higher bulk carrier concentration.

  7. Growth and Characterization of Polyimide-Supported AlN Films for Flexible Surface Acoustic Wave Devices

    NASA Astrophysics Data System (ADS)

    Li, Qi; Liu, Hongyan; Li, Gen; Zeng, Fei; Pan, Feng; Luo, Jingting; Qian, Lirong

    2016-06-01

    Highly c-axis oriented aluminum nitride (AlN) films, which can be used in flexible surface acoustic wave (SAW) devices, were successfully deposited on polyimide (PI) substrates by direct current reactive magnetron sputtering without heating. The sputtering power, film thickness, and deposition pressure were optimized. The characterization studies show that at the optimized conditions, the deposited AlN films are composed of columnar grains, which penetrate through the entire film thickness (~2 μm) and exhibit an excellent (0002) texture with a full width at half maximum value of the rocking curve equal to 2.96°. The film surface is smooth with a root mean square value of roughness of 3.79 nm. SAW prototype devices with a center frequency of about 520 MHz and a phase velocity of Rayleigh wave of about 4160 m/s were successfully fabricated using the AlN/PI composite structure. The obtained results demonstrate that the highly c-axis oriented AlN films with a smooth surface and low stress can be produced on relatively rough, flexible substrates, and this composite structure can be possibly used in flexible SAW devices.

  8. Substituted Septithiophenes with End Groups of Different Size: Packing and Frustration in Bulk and Thin Films.

    PubMed

    de Jeu, Wim H; Rahimi, Khosrow; Ziener, Ulrich; Vill, Roman; Herzig, Eva M; Müller-Buschbaum, Peter; Möller, Martin; Mourran, Ahmed

    2016-02-16

    We report on three different liquid crystalline compounds with a central septithiophene core and alkylated end groups of strongly increasing bulkiness. In principle, the thiophene cores prefer to pack parallel to optimize their π-π interactions, which becomes sterically impossible for the bulkier end groups. Using X-ray diffraction, we find that the way out of this packing dilemma is toward liquid-crystal phases of higher dimensionality in the order smectic → columnar ↔ bicontinuous cubic. For the smectic phase, packing in a monolayer is no problem; for the other ones packing considerations become more stringent in films due to the boundaries. Surface X-ray techniques and atomic force microscopy indicate an appreciable difference between monolayer and three-layer films, in which the monolayers appear to escape from packing frustration by generating superstructures. We propose a basic structure of columns parallel to the substrate that provides a compromise between preserving some π-π interactions and packing the bulky alkyl groups. PMID:26807677

  9. Experimental study of ultra-thin films mechanical integrity by combined nanoindentation and nano-acoustic emission

    NASA Astrophysics Data System (ADS)

    Zhang, Zihou

    Advancement of interconnect technology has imposed significant challenge on interface characterization and reliability for blurred interfaces between layers. There is a need for material properties and these miniaturized length scales and assessment of reliability; including the intrinsic film fracture toughness and the interfacial fracture toughness. The nano-meter range of film thicknesses currently employed, impose significant challenges on evaluating these physical quantities and thereby impose significant challenge on the design cycle. In this study we attempted to use a combined nano-indentation and nano-acoustic emission to qualitatively and quantitatively characterize the failure modes in ultra-thin blanket films on Si substrates or stakes of different characteristics. We have performed and analyzed an exhaustive group of testes that cove many diverge combination of film-substrate combination, provided by both Intel and IBM. When the force-indentation depth curve shows excursion, a direct measure of the total energy release rate is estimated. The collected acoustic emission signal is then used to partition the total energy into two segments, one associated with the cohesive fracture toughness of the film and the other is for the adhesive fracture toughness of the interface. The acoustic emission signal is analyzed in both the time and frequency domain to achieve such energy division. In particular, the signal time domain analysis for signal skewness, time of arrival and total energy content are employed with the proper signal to noise ratio. In the frequency domain, an expansive group of acoustic emission signals are utilized to construct the details of the power spectral density. A bank of band-pass filters are designed to sort the individual signals to those associated with adhesive interlayer cracking, cohesive channel cracking, or other system induced noise. The attenuation time and the energy content within each spectral frequency were the key elements

  10. Interaction of atomic oxygen with thin film and bulk copper: An XPS, AES, XRD, and profilometer study

    NASA Technical Reports Server (NTRS)

    Raikar, Genesh N.; Gregory, John C.; Christl, Ligia C.; Peters, Palmer N.

    1992-01-01

    The University of Alabama in Huntsville (UAH) experiment A-0114 was designed primarily to study degradation of material surfaces due to low earth orbital (LEO) atmospheric oxygen. The experiment contained 128 one inch circular samples: metals, polymers, carbons, and semiconductors. Among metal samples, copper has shown some interesting new results. Two types of copper samples, a film sputter coated on fused silica and a bulk piece of OFHC copper, were characterized employing a variety of techniques such as X-ray and Auger electron spectroscopies, X-ray diffraction, and high resolution profilometry. Cu 2p core level spectra were used to characterize the presence of Cu2O and CuO in addition to Cu Auger LMM lines. These results are supported by our recent X-ray diffraction studies which clearly establish the presence of Cu oxides which we were unable to prove in our earlier work. Profilometry showed an increase in thickness of the film sample where exposed to 106.7 +/- 0.5 nm from an initial thickness of 74.2 +/- 1.1 nm. Further studies with SEM and ellipsometry are underway.

  11. Measurement of surface acoustic wave velocity using phase shift mask and application on thin film of thermoelectric material

    NASA Astrophysics Data System (ADS)

    Li, Dongyao; Zhao, Peng; Gunning, Noel; Johnson, David; Zhao, Ji-Cheng; Cahill, David

    2014-03-01

    We describe a convenient approach for measuring the velocity vSAW of surface acoustic waves (SAWs) of the near-surface layer of a material through optical pump-probe measurements and apply this method, in combination with conventional picosecond acoustics, to determine a subset of the elastic constants of thin films of semiconducting misfit layered compounds. SAWs with a wavelength of 700 nm are generated and detected using an elastomeric polydimethylsiloxane (PDMS) phase-shift mask which is fabricated using a commercially-available Si grating as a mold. The velocity of SAWs of [(SnSe)1.04]m[MoSe2]n synthesized by elemental reactants show subtle variations in their elastic constants as a function of m and n. Precise measurements of elastic constants will enable a better understanding of interfacial stiffness in nanoscale multilayers and the effects of phonon focusing on thermal conductivity.

  12. Deposition of LiF onto Films of Fullerene Derivatives Leads to Bulk Doping.

    PubMed

    Torabi, Solmaz; Liu, Jian; Gordiichuk, Pavlo; Herrmann, Andreas; Qiu, Li; Jahani, Fatemeh; Hummelen, Jan C; Koster, L Jan Anton

    2016-08-31

    One of the most commonly used cathode interlayers for increasing the efficiency of electron injection/extraction in organic electronic devices is an ultrathin layer of LiF. Our capacitance measurements and electrical conductivity analysis show that thin films of fullerene derivatives and their mixtures with polymers are unintentionally doped upon deposition of LiF. The level of doping depends on the chemical structure of the fullerene derivatives. The doping effect on polymer/fullerene mixtures is significant only for blends in which the fullerene content is greater than the polymer content by weight. Our finding has profound implications for the development and characterization of organic photovoltaic devices, including a negative impact of doping on the stability of the device and erroneous estimations of properties such as charge carrier mobility and the dielectric constant. PMID:27526262

  13. Raman study on a bulk-heterojunction film of pentacene and C60

    NASA Astrophysics Data System (ADS)

    Iwasawa, Yasuhiro; Furukawa, Yukio

    2015-09-01

    We measured the 785-nm excited Raman spectrum of a pentacene:C60 blend film. The 1462-, 492-, and 268-cm-1 bands of C60 showed broadening in bandwidth and downward shifts in peak wavenumbers, whereas such broadening and downward shifts were not observed for pentacene. These results indicate that there are pentacene crystallites among the amorphous C60. The intensity ratio of the 1598-cm-1 (B3g) and the 1534-cm-1 (Ag) bands indicates that pentacene molecules have standing orientations. The appearance of a 514-cm-1 band (F1u) and the splitting of the Hg bands of C60 indicate symmetry lowering induced by the interaction between pentacene and C60 molecules.

  14. Mechanical back-action of a spin-wave resonance in a magnetoelastic thin film on a surface acoustic wave

    NASA Astrophysics Data System (ADS)

    Gowtham, P. G.; Labanowski, D.; Salahuddin, S.

    2016-07-01

    Surface acoustic waves (SAWs) traveling on the surface of a piezoelectric crystal can, through the magnetoelastic interaction, excite traveling spin-wave resonance in a magnetic film deposited on the substrate. This spin-wave resonance in the magnetic film creates a time-ynamic surface stress of magnetoelastic origin that acts back on the surface of the piezoelectric and modifies the SAW propagation. Unlike previous analyses that treat the excitation as a magnon-phonon polariton, here the magnetoelastic film is treated as a perturbation modifying boundary conditions on the SAW. We use acoustical perturbation theory to find closed-form expressions for the back-action surface stress and strain fields and the resultant SAW velocity shifts and attenuation. We demonstrate that the shear stres fields associated with this spin-wave back-action also generate effective surface currents on the piezoelectric both in phase and out of phase with the driving SAW potential. Characterization of these surface currents and their applications in determination of the magnetoelastic coupling are discussed. The perturbative calculation is carried out explicitly to first order (a regime corresponding to many experimental situations of current interest) and we provide a sketch of the implications of the theory at higher order.

  15. Study of a ternary blend system for bulk heterojunction thin film solar cells

    NASA Astrophysics Data System (ADS)

    Ahmad, Zubair; Touati, Farid; Shakoor, R. A.; Al-Thani, N. J.

    2016-08-01

    In this research, we report a bulk heterojunction (BHJ) solar cell consisting of a ternary blend system. Poly(3-hexylthiophene) P3HT is used as a donor and [6,6]-phenyl C61-butyric acid methylester (PCBM) plays the role of acceptor whereas vanadyl 2,9,16,23-tetraphenoxy-29H, 31H-phthalocyanine (VOPcPhO) is selected as an ambipolar transport material. The materials are selected and assembled in such a fashion that the generated charge carriers could efficiently be transported rightwards within the blend. The organic BHJ solar cells consist of ITO/PEDOT:PSS/ternary BHJ blend/Al structure. The power conversion efficiencies of the ITO/ PEDOT:PSS/P3HT:PCBM/Al and ITO/PEDOT:PSS/ P3HT:PCBM:VOPcPhO/Al solar cells are found to be 2.3% and 3.4%, respectively. This publication was made possible by PDRA (Grant No. PDRA1-0117-14109) from the Qatar National Research Fund (a member of Qatar Foundation). The findings achieved herein are solely the responsibility of the authors.

  16. Evaluating the adhesion of SU-8 thin films using an AlN/Si surface acoustic wave sensor

    NASA Astrophysics Data System (ADS)

    El Gowini, Mohamed M.; Moussa, Walied A.

    2015-03-01

    A new approach is developed for evaluating the adhesion of SU-8 thin films using a surface acoustic wave (SAW) sensor. The SAW sensor consists of a silicon (Si) substrate coated with a thin aluminum nitride (AlN) film and two sets of inter-digital electrodes (IDT) patterned on the AlN surface. Two sensor configurations are developed in order to evaluate the adhesion of SU-8. In the first configuration the SU-8 layer is patterned on top of a gold film that is deposited on the AlN surface. In the second configuration the gold film is coated with an omnicoat layer prior to patterning the SU-8 film. Omnicoat is an adhesion promoter for SU-8, which is used to increase its adhesion to gold. The frequency responses from both configurations are measured and the shift in the center frequency value is evaluated. The results illustrate that without omnicoat the center frequency shifts to a higher value indicating an increase in the wave velocity. This is because the poor adhesion of the SU-8 layer without omnicoat causes the wave to be more concentrated in the AlN/Si structure and AlN has a higher acoustic wave velocity in comparison to the SU-8 layer. In addition, four SAW sensors operating at four different center frequencies are developed to investigate the change in sensor sensitivity with the increase in center frequency. The results indicate that the sensor sensitivity increases proportionally to the increase in operating frequency. Finally, a theoretical model is developed to calculate the wave dispersion profile for the SU-8/AlN/Si configuration. The interface of the SU-8/AlN layers is modeled as a layer of mass-less springs with stiffness K(N m-3). The shifts in the wave dispersion profile at different levels of interface spring stiffness are compared to the experimental values to evaluate the adhesion of the SU-8 layer.

  17. Free films of a partially wetting liquid under the influence of a propagating MHz surface acoustic wave

    NASA Astrophysics Data System (ADS)

    Altshuler, Gennady; Manor, Ofer

    2016-07-01

    We use both theory and experiment to study the response of thin and free films of a partially wetting liquid to a MHz vibration, propagating in the solid substrate in the form of a Rayleigh surface acoustic wave (SAW). We generalise the previous theory for the response of a thin fully wetting liquid film to a SAW by including the presence of a small but finite three phase contact angle between the liquid and the solid. The SAW in the solid invokes a convective drift of mass in the liquid and leaks sound waves. The dynamics of a film that is too thin to support the accumulation of the sound wave leakage is governed by a balance between the drift and capillary stress alone. We use theory to demonstrate that a partially wetting liquid film, supporting a weak capillary stress, will spread along the path of the SAW. A partially wetting film, supporting an appreciable capillary stress, will however undergo a concurrent dynamic wetting and dewetting at the front and the rear, respectively, such that the film will displace, rather than spread, along the path of the SAW. The result of the theory for a weak capillary stress is in agreement with the previous experimental and theoretical studies on the response of thin silicon oil films to a propagating SAW. No corresponding previous results exist for the case of an appreciable capillary stress. We thus complement the large capillary limit of our theory by undertaking an experimental procedure where we explore the response of films of water and a surfactant solutions to a MHz SAW, which is found to be in qualitative agreement with the theory at this limit.

  18. First-principles study of dielectric properties of bulk NaCl and ultrathin NaCl films under a finite external electric field

    NASA Astrophysics Data System (ADS)

    Ono, Tomoya; Hirose, Kikuji

    2005-08-01

    We present a first-principles study of the dielectric properties of a NaCl crystal and ultrathin NaCl films under a finite external electric field. Our results show that the high-frequency dielectric constant of the films is less affected by the finite-size effect from crystal surfaces and is close to that of the crystal, whereas the static one is sensitive to the thickness of the film because of the thick buffer region where ionic displacements due to the electric field are not as homogeneous as those in the bulk.

  19. Component Dynamics and the Corresponding Compositional Heterogeneity in Bulk and Thin Film Miscible Polymer Blends

    NASA Astrophysics Data System (ADS)

    Yang, Hengxi; Green, Peter

    2014-03-01

    Miscible polymer blends are known to be compositional heterogeneous, due to self-concentration and thermally driven compositional fluctuation. In this work we investigate the segmental dynamics of poly(vinyl methyl ether) (PVME) in miscible polymer blends of polystyrene (PS) and PVME, using broadband dielectric spectroscopy, and manifest the correspondence between the component dynamics and the compositional heterogeneity in miscible blends. A single α-relaxation is observed at high temperatures, T, obeying Vogel-Fulcher relation, whereas two separate relaxations exist at low T. One relaxation, slower and exhibiting a strong T-dependence, is associated with an average local composition with smaller PVME fraction. The other relaxation, known as α'-relaxation, is weakly T-dependent and Arrhenius-like at low T; it reflects the PVME-rich domains within the confines of glassy PS-rich domains. In PVME/PS thin films confined between aluminum (Al) substrates, an additional relaxation process, due to PVME chains that preferentially segregated to Al interfaces, emerges.

  20. Preparation of Y-Ba-Cu oxide superconductor thin films using pulsed laser evaporation from high T/sub c/ bulk material

    SciTech Connect

    Dijkkamp, D.; Venkatesan, T.; Wu, X.D.; Shaheen, S.A.; Jisrawi, N.; Min-Lee, Y.H.; McLean, W.L.; Croft, M.

    1987-08-24

    We report the first successful preparation of thin films of Y-Ba-Cu-O superconductors using pulsed excimer laser evaporation of a single bulk material target in vacuum. Rutherford backscattering spectrometry showed the composition of these films to be close to that of the bulk material. Growth rates were typically 0.1 nm per laser shot. After an annealing treatment in oxygen the films exhibited superconductivity with an onset at 95 K and zero resistance at 85 and 75 K on SrTiO/sub 3/ and Al/sub 2/O/sub 3/ substrates, respectively. This new deposition method is relatively simple, very versatile, and does not require the use of ultrahigh vacuum techniques.

  1. A high-overtone bulk acoustic wave resonator-oscillator-based 4.596 GHz frequency source: Application to a coherent population trapping Cs vapor cell atomic clock

    SciTech Connect

    Daugey, Thomas; Friedt, Jean-Michel; Martin, Gilles; Boudot, Rodolphe

    2015-11-15

    This article reports on the design and characterization of a high-overtone bulk acoustic wave resonator (HBAR)-oscillator-based 4.596 GHz frequency source. A 2.298 GHz signal, generated by an oscillator constructed around a thermally controlled two-port aluminum nitride-sapphire HBAR resonator with a Q-factor of 24 000 at 68 °C, is frequency multiplied by 2–4.596 GHz, half of the Cs atom clock frequency. The temperature coefficient of frequency of the HBAR is measured to be −23 ppm/ °C at 2.298 GHz. The measured phase noise of the 4.596 GHz source is −105 dB rad{sup 2}/Hz at 1 kHz offset and −150 dB rad{sup 2}/Hz at 100 kHz offset. The 4.596 GHz output signal is used as a local oscillator in a laboratory-prototype Cs microcell-based coherent population trapping atomic clock. The signal is stabilized onto the atomic transition frequency by tuning finely a voltage-controlled phase shifter implemented in the 2.298 GHz HBAR-oscillator loop, preventing the need for a high-power-consuming direct digital synthesis. The short-term fractional frequency stability of the free-running oscillator is 1.8 × 10{sup −9} at one second integration time. In locked regime, the latter is improved in a preliminary proof-of-concept experiment at the level of 6.6 × 10{sup −11} τ{sup −1/2} up to a few seconds and found to be limited by the signal-to-noise ratio of the detected CPT resonance.

  2. Temperature and pressure dependences of acoustic anomalies of PET films studied by using Brillouin spectroscopy

    NASA Astrophysics Data System (ADS)

    Ko, Young Ho; Kim, Kwang Joo; Lee, Byoung Wan; Jeong, Min-Seok; Ko, Jae-Hyeon

    2015-04-01

    The acoustic properties of biaxially-oriented polyethylene terephthalate (PET) were investigated as a function of either temperature or pressure by using Brillouin spectroscopy. The Brillouin frequency shift of the longitudinal acoustic mode of both biaxially-oriented and amorphous PET materials showed a change in the slope near 80 °C, which was the approximate glass transition temperature. The acoustic damping of amorphous PET exhibited large values near the melting temperature compared to that of semicrystalline PET. This indicated stronger coupling between the acoustic waves and the structural relaxation process in the amorphous state. The pressure dependences of the sound velocities were investigated at pressures up to 8.5 GPa by using a diamond anvil cell. The pressure-density relationship could be obtained based on the Birch-Murnaghan equation of state.

  3. An overview of micro-optical components and system technology: bulk, planar, and thin-film for laser initiated devices

    NASA Astrophysics Data System (ADS)

    Lizotte, Todd

    2010-08-01

    There are a number of attractive micro optical elements or combinations of elements that are currently used or could be employed in optically initiated ordnance systems. When taking a broad-spectrum examination of optically initiated devices, the required key parameters become obviously straightforward for micro optics. Plainly stated, micro optics need to be simple, inexpensive, reliable, robust and compatible within their operational environment. This presentation focuses on the variety of optical elements and components available in the market place today that could be used to realize micro-optical beam shaping and delivery systems for optically initiated devices. A number of micro optical elements will be presented with specific bulk, planar optical and thin film optical devices, such as diffractive optics, micro prisms, axicons, waveguides, micro lenses, beam splitters and gratings. Further descriptions will be presented on the subject of coupling light from a laser beam into a multimode optical fiber. The use of micro optics for collimation of the laser source and conditioning of the laser beam to achieve the highest efficiency and matching the optical fiber NA will be explained. An emphasis on making these optical assemblies compact and rugged will be highlighted.

  4. Influence of roughness on the detection of mechanical characteristics of low-k film by the surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Xiao, Xia; Tao, Ye; Sun, Yuan

    2014-10-01

    The surface acoustic wave (SAW) technique is a precise and nondestructive method to detect the mechanical characteristics of the thin low dielectric constant (low-k) film by matching the theoretical dispersion curve with the experimental dispersion curve. In this paper, the influence of sample roughness on the precision of SAW mechanical detection is investigated in detail. Random roughness values at the surface of low-k film and at the interface between this low-k film and the substrate are obtained by the Monte Carlo method. The dispersive characteristic of SAW on the layered structure with rough surface and rough interface is modeled by numerical simulation of finite element method. The Young's moduli of the Black Diamond™ samples with different roughness values are determined by SAWs in the experiment. The results show that the influence of sample roughness is very small when the root-mean-square (RMS) of roughness is smaller than 50 nm and correlation length is smaller than 20 μm. This study indicates that the SAW technique is reliable and precise in the nondestructive mechanical detection for low-k films.

  5. Theoretical analysis of surface acoustic wave propagating properties of Y-cut nano lithium niobate film on silicon dioxide

    SciTech Connect

    Chen, Jing Zhang, Qiaozhen; Han, Tao; Zhou, Liu; Tang, Gongbin; Liu, Boquan; Ji, Xiaojun

    2015-08-15

    The surface acoustic wave (SAW) propagating characteristics of Y-cut nano LiNbO{sub 3} (LN) film on SiO{sub 2}/LN substrate have been theoretically calculated. The simulated results showed a shear horizontal (SH) SAW with enhanced electromechanical coupling factor K{sup 2} owing to a dimensional effect of the nanoscale LN film. However, a Rayleigh SAW and two other resonances related to thickness vibrations caused spurious responses for wideband SAW devices. These spurious waves could be fully suppressed by properly controlling structural parameters including the electrode layer height, thickness, and the Euler angle (θ) of the LN thin film. Finally, a pure SH SAW was obtained with a wide θ range, from 0° to 5° and 165° to 180°. The largest K{sup 2} achieved for the pure SH SAW was about 35.1%. The calculated results demonstrate the promising application of nano LN film to the realization of ultra-wideband SAW devices.

  6. High Performance Flexible Actuator of Urchin-Like ZnO Nanostructure/Polyvinylenefluoride Hybrid Thin Film with Graphene Electrodes for Acoustic Generator and Analyzer.

    PubMed

    Cheong, Oug Jae; Lee, James S; Kim, Jae Hyun; Jang, Jyongsik

    2016-05-01

    A bass frequency response enhanced flexible polyvinylidene fluoride (PVDF) based thin film acoustic actuator is successfully fabricated. High concentrations of various zinc oxide (ZnO) is embedded in PVDF matrix, enhancing the β phase content and the dielectric property of the composite thin film. ZnO acts as a nucleation agent for the crystallization of PVDF. A chemical vapor deposition grown graphene is used as electrodes, enabling high electron mobility for the distortion free acoustic signals. The frequency response of the fabricated acoustic actuator is studied as a function of the film thickness and filler content. The optimized film has a thickness of 80 μm with 30 wt% filler content and shows 72% and 42% frequency response enhancement in bass and midrange compared to the commercial PVDF, respectively. Also, the total harmonic distortion decreases to 82% and 74% in the bass and midrange regions, respectively. Furthermore, the composite film shows a promising potential for microphone applications. Most of all, it is demonstrated that acoustic actuator performance is strongly influenced by degree of PVDF crystalline. PMID:27028524

  7. Ab-initio study of structural and electronic properties of thin film and bulk forms of Bi2Q3 (Q = Se, Te) as topological insulators

    NASA Astrophysics Data System (ADS)

    Ranjbardizaj, Ahmad; Mizuseki, Hiroshi; Kawazoe, Yoshiyuki

    2013-03-01

    Bi2Q3 (Q =Se, Te) are the best-known bulk thermoelectric materials, which have been demonstrated to be topological insulators (TI). TI's are insulators with conductive surface states consisting of a single Dirac cones. These materials have layered structures consisting of stacked quintuple layers (QL), with relatively weak coupling between the QL's. Therefore, it might be easy to prepare the Bi2Q3 in the form of thin films with particular thicknesses using the available experimental techniques. In this study, the electronic and structural properties of bulk Bi2Se3 are investigated using density functional theory. Our results show that the Bi2Se3 is an indirect semiconductor with energy gap of ~ 0.27 eV. Additionally, the electronic structure dependence of Bi2Se3to the thicknesses of thin films (n-QL's with n =1,2...9) is considered. It is observed that the electronic structure of this kind of thin films depends on the number of QL's. For n-QL's with n larger than three, the thin film has a bulk band gap and has protected conducting states on its surface. Moreover, the effect of number of layers (n) on band-gap energy is studied. Similar calculations and discussions are carried out for Bi2Te3 and the results are compared to the Bi2Se3 case and also the available theoretical and experimental results.

  8. Terahertz emission from YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} thin films via bulk electric quadrupole optical rectification

    SciTech Connect

    Siders, J.L.W.; Trugman, S.A.; Houlton, R.J.; Garzon, F.H.; Taylor, A.J.

    1998-03-01

    The authors describe here the first observation of terahertz emission from unbiased YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) thin films. These films are excited by 150 fs, 1.5 eV and 3.0 eV, optical pulses for a range of temperatures, T, 4 K < T < 300 K and for a range of oxygen doping from optimally-doped ({delta} = 0) to insulating ({delta} = 0.8). They demonstrate that this emission is generated by optical rectification due to the bulk electric quadrupole source term, comprising the first observation of such a source term in terahertz emission.

  9. Difference in chemical reactions in bulk plasma and sheath regions during surface modification of graphene oxide film using capacitively coupled NH3 plasma

    NASA Astrophysics Data System (ADS)

    Lee, Sung-Youp; Kim, Chan; Kim, Hong Tak

    2015-09-01

    Reduced graphene oxide (r-GO) films were obtained from capacitively coupled NH3 plasma treatment of spin-coated graphene oxide (GO) films at room temperature. Variations were evaluated according to the two plasma treatment regions: the bulk plasma region (Rbulk) and the sheath region (Rsheath). Reduction and nitridation of the GO films began as soon as the NH3 plasma was exposed to both regions. However, with the increase in treatment time, the reduction and nitridation reactions differed in each region. In the Rbulk, NH3 plasma ions reacted chemically with oxygen functional groups on the GO films, which was highly effective for reduction and nitridation. While in the Rsheath, physical reactions by ion bombardment were dominant because plasma ions were accelerated by the strong electrical field. The accelerated plasma ions reacted not only with the oxygen functional groups but also with the broken carbon chains, which caused the removal of the GO films by the formation of hydrocarbon gas species. These results showed that reduction and nitridation in the Rbulk using capacitively coupled NH3 plasma were very effective for modifying the properties of r-GO films for application as transparent conductive films.

  10. Molecularly imprinted polymer film interfaced with Surface Acoustic Wave technology as a sensing platform for label-free protein detection.

    PubMed

    Tretjakov, Aleksei; Syritski, Vitali; Reut, Jekaterina; Boroznjak, Roman; Öpik, Andres

    2016-01-01

    Molecularly imprinted polymer (MIP)-based synthetic receptors integrated with Surface Acoustic Wave (SAW) sensing platform were applied for the first time for label-free protein detection. The ultrathin polymeric films with surface imprints of immunoglobulin G (IgG-MIP) were fabricated onto the multiplexed SAW chips using an electrosynthesis approach. The films were characterized by analyzing the binding kinetics recorded by SAW system. It was revealed that the capability of IgG-MIP to specifically recognize the target protein was greatly influenced by the polymer film thickness that could be easily optimized by the amount of the electrical charge consumed during the electrodeposition. The thickness-optimized IgG-MIPs demonstrated imprinting factors towards IgG in the range of 2.8-4, while their recognition efficiencies were about 4 and 10 times lower toward the interfering proteins, IgA and HSA, respectively. Additionally, IgG-MIP preserved its capability to recognize selectively the template after up to four regeneration cycles. The presented approach of the facile integration of the protein-MIP sensing layer with SAW technology allowed observing the real-time binding events of the target protein at relevant sensitivity levels and can be potentially suitable for cost effective fabrication of a biosensor for analysis of biological samples in multiplexed manner. PMID:26703269

  11. Modification of dislocation behavior in GaN overgrown on engineered AlN film-on-bulk Si substrate

    NASA Astrophysics Data System (ADS)

    Tungare, Mihir; Weng, Xiaojun; Leathersich, Jeffrey M.; Suvarna, Puneet; Redwing, Joan M.; (Shadi) Shahedipour-Sandvik, F.

    2013-04-01

    The changes that the AlN buffer and Si substrate undergo at each stage of our substrate engineering process, previously shown to lead to a simultaneous and substantial reduction in film crack density and dislocation density in overgrown GaN, are presented. Evidence of ion-implantation assisted grain reorientation for AlN islands coupled with physical isolation from the bulk Si substrate prove to be the dominating driving forces. This is further emphasized with x-ray diffraction analysis that demonstrates a reduction in the in-plane lattice constant of AlN from 3.148 Å to 3.113 Å and a relative change in rotation of AlN islands by 0.135° with regard to the Si substrate after substrate engineering. Misfit dislocations at the AlN-Si interface and disorder that is normally associated with formation of amorphous SiNx at this interface are considered to be two of the major contributors to dislocation nucleation within overgrown GaN. Following our technique, the disappearance of disorder at the AlN-Si interface is observed. Extensive ellipsometry and transmission electron microscopy suggests that larger AlN islands with a smoother surface morphology could further reduce the dislocation density below that previously reported. A 1.2 μm GaN layer deposited on an AlN buffer with larger islands and smoother morphology exhibits a 14× reduction in surface pit density after undergoing the ion-implantation assisted substrate modification technique.

  12. Pleomorphic structural imperfections caused by pulsed Bi-implantation in the bulk and thin-film morphologies of TiO2

    NASA Astrophysics Data System (ADS)

    Zatsepin, D. A.; Boukhvalov, D. W.; Kurmaev, E. Z.; Gavrilov, N. V.; Kim, S. S.; Zhidkov, I. S.

    2016-08-01

    The results of combined experimental and theoretical study of pleomorphic substitutional and clustering effects in Bi-doped TiO2 hosts (bulk and thin-film morphologies) are presented. Bi-doping of the bulk and thin-film titanium dioxide was made with help of pulsed ion-implantation (EBi+ = 30 keV, D = 1 × 1017 cm-2) without posterior tempering. The X-ray photoelectron spectroscopy (XPS) qualification (core-levels and valence bands) and Density-Functional Theory (DFT) calculations were employed in order to study the electronic structure of Bi-ion implanted TiO2 samples. According to XPS data obtained and DFT calculations, the Bi → Ti cation substitution occurs in Bi-implanted bulk TiO2, whereas in the thin-film morphology of TiO2:Bi the Bi-atoms have metal-like clusters segregation tendency. Based on the combined XPS and DFT considerations the possible reasons and mechanism for the observed effects are discussed. It is believed that established peculiarities of bismuth embedding into employed TiO2 hosts are mostly the sequence of pleomorphic origin for the formed "bismuth-oxygen" chemical bonding.

  13. First-principles study of the superconductivity in MgB2 bulk and in its bilayer thin film based on electron-phonon coupling

    NASA Astrophysics Data System (ADS)

    Morshedloo, T.; Roknabadi, M. R.; Behdani, M.

    2015-02-01

    In this paper, phonon-mediated superconductivity has been investigated in MgB2 bulk structure and bilayer thin film by using first-principles calculations. The electronic band structure, total and partial density of states (DOS and PDOS), phonon dispersion, isotropic Eliashberg function α2F(ω), and electron-phonon coupling have been calculated within the framework of density functional theory (DFT). Our results indicate that holes at the top of boron σ bands mainly and holes in the boron π band partially contribute to formation of coupled holes in superconductivity state. The density of states at the Fermi energy level is increased for MgB2 bilayer with respect to its bulk structure. According to the phonon dispersion and Eliashberg function curves, coupling considerably occurs between holes at the top of the boron σ band by means of optical phonon mode for both structures. This phonon mode has the E2g symmetry at the Г point. We obtain electron-phonon coupling constants of 0.74 and 0.91 for bulk and bilayer structures, respectively. By using the Allen-Dynes formula, we estimate superconducting transition temperature TC of 40 K for bulk and 48 K for the thin film.

  14. Properties and durability of the passive films on a nickel-chromium-molybdenum alloy and an iron-based bulk metallic glass

    NASA Astrophysics Data System (ADS)

    Pharkya, Pallavi

    Alloy 22, a Ni-Cr-Mo-W alloy, and SAM1651, an Fe-Cr-Mo-B-Y-C bulk metallic glass are highly corrosion-resistant alloys. The high corrosion resistance of these alloys is due to the formation of tenacious oxide films on their surfaces. This study examines the reformation behavior of the passive films as a function of the corrosion resistance of the alloys and the corrosivity of the environment. The main tasks of this study were (i) to determine the chemical durability of passive films on these highly corrosion-resistant alloys in aggressive environments, (ii) to investigate the durability after mechanically damaging the passive films either locally or over the entire surface area and to study the reformation kinetics, (iii) to compare the durability of the passive films of the aforementioned highly corrosion resistant alloys with an alloy of intermediate corrosion resistance, AL6XN, and an alloy of less corrosion resistance, 316L SS, (iv) to examine the evolution of the electronic properties of the passive films on alloy 22 and SAM1651 under different environmental conditions such as concentrated chloride solution, acidic solution, temperature, potential and oxyanions, and (v) to develop an understanding of the relationship between the passive films' composition, electronic and electrochemical properties and the performance. A combination of techniques was utilized to meet the above mentioned objectives. Cyclic potentiodynamic polarization (CPP) was used to determine the electrochemical parameters such as freely corroding, breakdown and repassivation potentials. Electrochemical impedance spectroscopy (EIS) was used to determine the electronic properties such as impedance, thickness and capacitance of the passive films. Mott-Schottky (M-S) analysis was used to determine the type and the density of the defects in the passive films. The mechanical durability and reformation kinetics of the passive films was investigated using a scratch-repassivation method. The quality

  15. Flexible surface acoustic wave resonators built on disposable plastic film for electronics and lab-on-a-chip applications

    PubMed Central

    Jin, Hao; Zhou, Jian; He, Xingli; Wang, Wenbo; Guo, Hongwei; Dong, Shurong; Wang, Demiao; Xu, Yang; Geng, Junfeng; Luo, J. K.; Milne, W. I.

    2013-01-01

    Flexible electronics are a very promising technology for various applications. Several types of flexible devices have been developed, but there has been limited research on flexible electromechanical systems (MEMS). Surface acoustic wave (SAW) devices are not only an essential electronic device, but also are the building blocks for sensors and MEMS. Here we report a method of making flexible SAW devices using ZnO nanocrystals deposited on a cheap and bendable plastic film. The flexible SAW devices exhibit two wave modes - the Rayleigh and Lamb waves with resonant frequencies of 198.1 MHz and 447.0 MHz respectively, and signal amplitudes of 18 dB. The flexible devices have a high temperature coefficient of frequency, and are thus useful as sensitive temperature sensors. Moreover, strong acoustic streaming with a velocity of 3.4 cm/s and particle concentration using the SAW have been achieved, demonstrating the great potential for applications in electronics and MEMS. PMID:23828169

  16. The metal-insulator transition in vanadium dioxide: A view at bulk and surface contributions for thin films and the effect of annealing

    SciTech Connect

    Yin, W.; West, K. G.; Lu, J. W.; Pei, Y.; Wolf, S. A.; Reinke, P.; Sun, Y.

    2009-06-01

    Vanadium dioxide is investigated as potential oxide barrier in spin switches, and in order to incorporate VO{sub 2} layers in complex multilayer devices, it is necessary to understand the relation between bulk and surface/interface properties. Highly oriented VO{sub 2} thin films were grown on (0001) sapphire single crystal substrates with reactive bias target ion beam deposition. In the analysis of the VO{sub 2} films, bulk-sensitive methods [x-ray diffraction (XRD) and transport measurements] and surface sensitive techniques [photoelectron spectroscopy (PES) and scanning tunneling microscopy and spectroscopy] were employed. The samples were subjected to heating cycles with annealing temperatures of up to 425 and 525 K. Prior to annealing the VO{sub 2} films exhibit the transition from the monoclinic to the tetragonal phase with the concurrent change in conductivity by more than a factor of 10{sup 3} and their phase purity is confirmed by XRD. Annealing to 425 K and thus cycling across the metal-insulator transition (MIT) temperature has no impact on the bulk properties of the VO{sub 2} film but the surface undergoes irreversible electronic changes. The observation of the valence band with PES during the annealing illustrates that the surface adopts a partially metallic character, which is retained after cooling. Annealing to a higher temperature (525 K) triggers a modification of the bulk, which is evidenced by a considerable reduction in the MIT characteristics, and a degradation in crystallite morphology. The local measurement of the conductivity with scanning tunneling spectroscopy shows the transition of the surface from predominantly semiconducting surface prior to annealing to a surface with an overwhelming contribution from metallic sections afterward. The spatial distribution of metallic regions cannot be linked in a unique manner to the crystallite size or location within the crystallites. The onset of oxygen depletion at the surface is held responsible

  17. Physical properties of metal-doped zinc oxide films for surface acoustic wave application

    PubMed Central

    2012-01-01

    Metal-doped ZnO [MZO] thin films show changes of the following properties by a dopant. First, group III element (Al, In, Ga)-doped ZnO thin films have a high conductivity having an n-type semiconductor characteristic. Second, group I element (Li, Na, K)-doped ZnO thin films have high resistivity due to a dopant that accepts a carrier. The metal-doped ZnO (M = Li, Ag) films were prepared by radio frequency magnetron sputtering on glass substrates with the MZO targets. We investigated on the optical and electrical properties of the as-sputtered MZO films as dependences on the doping contents in the targets. All the MZO films had shown a preferred orientation in the [002] direction. As the quantity and the variety of metal dopants were changed, the crystallinity and the transmittance, as well as optical band gap were changed. The electrical resistivity was also changed with changing metal doping amounts and kinds of dopants. An epitaxial Li-doped ZnO film has a high resistivity and very smooth surface; it will have the most optimum conditions which can be used for the piezoelectric devices. PMID:22221881

  18. Physical properties of metal-doped zinc oxide films for surface acoustic wave application.

    PubMed

    Nam, Sang-Hun; Cho, Sang-Jin; Boo, Jin-Hyo

    2012-01-01

    Metal-doped ZnO [MZO] thin films show changes of the following properties by a dopant. First, group III element (Al, In, Ga)-doped ZnO thin films have a high conductivity having an n-type semiconductor characteristic. Second, group I element (Li, Na, K)-doped ZnO thin films have high resistivity due to a dopant that accepts a carrier. The metal-doped ZnO (M = Li, Ag) films were prepared by radio frequency magnetron sputtering on glass substrates with the MZO targets. We investigated on the optical and electrical properties of the as-sputtered MZO films as dependences on the doping contents in the targets. All the MZO films had shown a preferred orientation in the [002] direction. As the quantity and the variety of metal dopants were changed, the crystallinity and the transmittance, as well as optical band gap were changed. The electrical resistivity was also changed with changing metal doping amounts and kinds of dopants. An epitaxial Li-doped ZnO film has a high resistivity and very smooth surface; it will have the most optimum conditions which can be used for the piezoelectric devices. PMID:22221881

  19. Physical properties of metal-doped zinc oxide films for surface acoustic wave application

    NASA Astrophysics Data System (ADS)

    Nam, Sang-Hun; Cho, Sang-Jin; Boo, Jin-Hyo

    2012-01-01

    Metal-doped ZnO [MZO] thin films show changes of the following properties by a dopant. First, group III element (Al, In, Ga)-doped ZnO thin films have a high conductivity having an n-type semiconductor characteristic. Second, group I element (Li, Na, K)-doped ZnO thin films have high resistivity due to a dopant that accepts a carrier. The metal-doped ZnO (M = Li, Ag) films were prepared by radio frequency magnetron sputtering on glass substrates with the MZO targets. We investigated on the optical and electrical properties of the as-sputtered MZO films as dependences on the doping contents in the targets. All the MZO films had shown a preferred orientation in the [002] direction. As the quantity and the variety of metal dopants were changed, the crystallinity and the transmittance, as well as optical band gap were changed. The electrical resistivity was also changed with changing metal doping amounts and kinds of dopants. An epitaxial Li-doped ZnO film has a high resistivity and very smooth surface; it will have the most optimum conditions which can be used for the piezoelectric devices.

  20. Ultra-violet absorption induced modifications in bulk and nanoscale electrical transport properties of Al-doped ZnO thin films

    SciTech Connect

    Kumar, Mohit; Basu, Tanmoy; Som, Tapobrata

    2015-08-07

    Using conductive atomic force microscopy and Kelvin probe force microscopy, we study local electrical transport properties in aluminum-doped zinc oxide (ZnO:Al or AZO) thin films. Current mapping shows a spatial variation in conductivity which corroborates well with the local mapping of donor concentration (∼10{sup 20 }cm{sup −3}). In addition, a strong enhancement in the local current at grains is observed after exposing the film to ultra-violet (UV) light which is attributed to persistent photocurrent. Further, it is shown that UV absorption gives a smooth conduction in AZO film which in turn gives rise to an improvement in the bulk photoresponsivity of an n-AZO/p-Si heterojunction diode. This finding is in contrast to the belief that UV absorption in an AZO layer leads to an optical loss for the underneath absorbing layer of a heterojunction solar cell.

  1. Dynamics of coherent acoustic phonons in thin films of CoSb3 and partially filled YbxCo4Sb12 skutterudites

    NASA Astrophysics Data System (ADS)

    He, Chuan; Daniel, Marcus; Grossmann, Martin; Ristow, Oliver; Brick, Delia; Schubert, Martin; Albrecht, Manfred; Dekorsy, Thomas

    2014-05-01

    Skutterudites are considered as interesting material for thermoelectric applications. Filling foreign atoms into the cagelike structure of a CoSb3 skutterudite is beneficial to its thermoelectric properties by increasing phonon scattering while maintaining the electrical conductivity. In this paper we demonstrate the generation and detection of coherent acoustic phonons in thin films of CoSb3 and partially filled YbxCo4Sb12 skutterudites using femtosecond pump-probe spectroscopy. By using a pulse-echo method, the longitudinal sound velocity of amorphous and polycrystalline CoSb3 thin films is obtained. For partially filled YbxCo4Sb12 thin films, an obvious decrease of the longitudinal sound velocity is observed at high filling fraction. Concomitantly, the high frequency acoustic phonon modes are strongly damped as the Yb filling fraction increases, which gives direct evidence for acoustic phonon scattering processes. It is shown that the reduction of lattice thermal conductivity after Yb filling is mainly achieved by the strong scattering of acoustic phonons.

  2. An experimental investigation of lead zirconate titanate--epoxy-multi-walled carbon nanotube bulk and flexible thick film composites

    NASA Astrophysics Data System (ADS)

    Banerjee, Sankha

    . Conventional solid oxide mixing, spin coating and deposition techniques will be used to fabricate the bulk and thick films. The piezoelectric and dielectric performance will be determined from the measurement of the piezoelectric strain coefficients, d33 and d31, dielectric constant, impedance and dielectric spectrum, dielectric loss tangent, and capacitance. These measurements will be correlated with inclusion size, shape, distribution, and surface morphology observations obtained from the scanning electron microscope (SEM) and transmission electron microscope (TEM).

  3. Phenomenological thermodynamic potentials for bulk and thin-film Ba (Zr0.08 Ti 0.92 ) O 3 single crystals

    NASA Astrophysics Data System (ADS)

    Peng, J. L.; Li, Q.; Shan, D. L.; Pan, K.; Yu, G. S.; Liu, Y. Y.

    2016-05-01

    Phenomenological thermodynamic analysis is an important theoretical investigation method for ferroelectric materials, however, it cannot be implemented for Ba ( Zr x Ti 1 - x ) O 3 due to the lack of thermodynamic potential coefficients. In this paper, we have constructed a phenomenological thermodynamic potential for bulk Ba ( Zr 0.08 Ti 0.92 ) O 3 single crystals, which reproduces the three phase transition temperatures, dielectric and piezoelectric constants of bulk Ba ( Zr 0.08 Ti 0.92 ) O 3 single crystals well, suggesting that the constructed thermodynamic potential is reliable. Then the thermodynamic potential with appropriate modification is applied to predict misfit strain-temperature phase diagram and electromechanical properties of Ba ( Zr 0.08 Ti 0.92 ) O 3 thin films. It is found that compressive strain favors the tetragonal c phase with an out-of-plane polarization component, while tensile misfit strain favors orthorhombic aa phase with an in-plane polarization component. It also reveals that Ba ( Zr 0.08 Ti 0.92 ) O 3 thin films under appropriate compressive strain show higher piezoelectric coefficient d15 than that of their bulk counterpart. The constructed thermodynamic potential opens a new avenue to theoretical analysis on Ba ( Zr 0.08 Ti 0.92 ) O 3 .

  4. Undulate microarray fabrication on polymer film using standing surface acoustic waves and ultraviolet polymerization

    NASA Astrophysics Data System (ADS)

    Mei, Deqing; Xue, Dai; Wang, Yancheng; Chen, Shaochen

    2016-06-01

    By exciting standing surface acoustic waves (SAWs), a monomer solution can be shaped into a wavy structure. By applying ultraviolet (UV) polymerization, a linear undulate microarray can be fabricated on the polymer material using one-dimensional standing SAWs. When two-dimensional standing SAWs are applied, a latticed microarray, which presents periodically distributed bumps and wells, can be fabricated. The periodicity of the undulate microarray is dependent on the SAW wavelength. Also, the undulating amplitude of the microarray is tunable when applying different input voltages to generate SAWs. The integrated standing SAWs and UV polymerization process provide a rapid method for creating periodic surface patterns.

  5. Common electronic origin of superconductivity in (Li,Fe)OHFeSe bulk superconductor and single-layer FeSe/SrTiO3 films

    PubMed Central

    Zhao, Lin; Liang, Aiji; Yuan, Dongna; Hu, Yong; Liu, Defa; Huang, Jianwei; He, Shaolong; Shen, Bing; Xu, Yu; Liu, Xu; Yu, Li; Liu, Guodong; Zhou, Huaxue; Huang, Yulong; Dong, Xiaoli; Zhou, Fang; Liu, Kai; Lu, Zhongyi; Zhao, Zhongxian; Chen, Chuangtian; Xu, Zuyan; Zhou, X. J.

    2016-01-01

    The mechanism of high-temperature superconductivity in the iron-based superconductors remains an outstanding issue in condensed matter physics. The electronic structure plays an essential role in dictating superconductivity. Recent revelation of distinct electronic structure and high-temperature superconductivity in the single-layer FeSe/SrTiO3 films provides key information on the role of Fermi surface topology and interface in inducing or enhancing superconductivity. Here we report high-resolution angle-resolved photoemission measurements on the electronic structure and superconducting gap of an FeSe-based superconductor, (Li0.84Fe0.16)OHFe0.98Se, with a Tc at 41 K. We find that this single-phase bulk superconductor shows remarkably similar electronic behaviours to that of the superconducting single-layer FeSe/SrTiO3 films in terms of Fermi surface topology, band structure and the gap symmetry. These observations provide new insights in understanding high-temperature superconductivity in the single-layer FeSe/SrTiO3 films and the mechanism of superconductivity in the bulk iron-based superconductors. PMID:26853801

  6. Common electronic origin of superconductivity in (Li,Fe)OHFeSe bulk superconductor and single-layer FeSe/SrTiO3 films.

    PubMed

    Zhao, Lin; Liang, Aiji; Yuan, Dongna; Hu, Yong; Liu, Defa; Huang, Jianwei; He, Shaolong; Shen, Bing; Xu, Yu; Liu, Xu; Yu, Li; Liu, Guodong; Zhou, Huaxue; Huang, Yulong; Dong, Xiaoli; Zhou, Fang; Liu, Kai; Lu, Zhongyi; Zhao, Zhongxian; Chen, Chuangtian; Xu, Zuyan; Zhou, X J

    2016-01-01

    The mechanism of high-temperature superconductivity in the iron-based superconductors remains an outstanding issue in condensed matter physics. The electronic structure plays an essential role in dictating superconductivity. Recent revelation of distinct electronic structure and high-temperature superconductivity in the single-layer FeSe/SrTiO3 films provides key information on the role of Fermi surface topology and interface in inducing or enhancing superconductivity. Here we report high-resolution angle-resolved photoemission measurements on the electronic structure and superconducting gap of an FeSe-based superconductor, (Li0.84Fe0.16)OHFe0.98Se, with a Tc at 41 K. We find that this single-phase bulk superconductor shows remarkably similar electronic behaviours to that of the superconducting single-layer FeSe/SrTiO3 films in terms of Fermi surface topology, band structure and the gap symmetry. These observations provide new insights in understanding high-temperature superconductivity in the single-layer FeSe/SrTiO3 films and the mechanism of superconductivity in the bulk iron-based superconductors. PMID:26853801

  7. Microwave bandpass filters based on thin-film acoustic resonators: theory and experiment

    NASA Astrophysics Data System (ADS)

    Dvoesherstov, M. Yu.; Cherednik, V. I.

    2015-11-01

    We theoretically and experimentally analyze microwave thin-film acoustoelectronic bandpass ladder filters built on AlN-based thin-film acoustoelectronic microwave resonators operating in the frequency range 4.6-5 GHz and describe the technology of their fabrication. We demonstrate that the parameters of filters are mainly determined by the characteristics of resonators that make up the filter and show that the characteristics of a three-section ladder filter can be significantly improved by optimizing the areas of the upper electrodes of the series and parallel resonators contained in it.

  8. X-ray diffraction and surface acoustic wave analysis of BST/Pt/TiO{sub 2}/SiO{sub 2}/Si thin films

    SciTech Connect

    Mseddi, Souhir; Hedi Ben Ghozlen, Mohamed; Njeh, Anouar; Schneider, Dieter; Fuess, Hartmut

    2011-11-15

    High dielectric constant and electrostriction property of (Ba, Sr)Ti0{sub 3} (BST) thin films result in an increasing interest for dielectric devices and microwave acoustic resonator. Barium strontium titanate (Ba{sub 0.645}Sr{sub 0.355}TiO{sub 3}) films of about 300 nm thickness are grown on Pt(111)/TiO{sub 2}/SiO{sub 2}/Si(001) substrates by rf magnetron sputtering deposition techniques. X-ray diffraction is applied for the microstructural characterization. The BST films exhibit a cubic perovskite structure with a dense and smooth surface. A laser acoustic waves (LA-waves) technique is used to generate surface acoustic waves (SAW) propagating in the BST films. Young's modulus E and the Poisson ratio {nu} of TiO{sub 2,} Pt and BST films in different propagation directions are derived from the measured dispersion curves. Estimation of BST elastics constants are served in SAW studies. Impact of stratification process on SAW, propagating along [100] and [110] directions of silicon substrate, has been interpreted on the basis of ordinary differential equation (ODE) and stiffness matrix method (SMM). A good agreement is observed between experimental and calculated dispersion curves. The performed calculations are strongly related to the implemented crystallographic data of each layer. Dispersion curves are found to be sensitive to the SAW propagation direction and the stratification process for the explored frequency ranges 50-250 MHz, even though it corresponds to a wave length clearly higher than the whole films thickness.

  9. A New Commercializable Route for the Preparation of Single-Source Precursors for Bulk, Thin-Film, and Nanocrystallite I-III-IV Semiconductors

    NASA Technical Reports Server (NTRS)

    Banger, Kulbinder K.; Jin, Michael H. C.; Harris, Jerry D.; Fanwick, Philip E.; Hepp, Aloysius F.

    2004-01-01

    We report a new simplified synthetic procedure for commercial manufacture of ternary single source precursors (SSP). This new synthetic process has been successfully implemented to fabricate known SSPs on bulk scale and the first liquid SSPs to the semiconductors CuInSe2 and AgIn(x)S(y). Single crystal X-ray determination reveals the first unsolvated ternary AgInS SSP. SSPs prepared via this new route have successfully been used in a spray assisted chemical vapor deposition (CVD) process to deposit polycrystalline thin films, and for preparing ternary nanocrystallites.

  10. Acoustic biosensors

    PubMed Central

    Fogel, Ronen; Seshia, Ashwin A.

    2016-01-01

    Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of cost, size and scalability, as well as potential additional features including integration with microfluidics and electronics, scaled sensitivities associated with smaller dimensions and higher operational frequencies, the ability to multiplex detection across arrays of hundreds of devices embedded in a single chip, increased throughput and the ability to interrogate a wider range of modes including within the same device. Additionally, device fabrication is often compatible with semiconductor volume batch manufacturing techniques enabling cost scalability and a high degree of precision and reproducibility in the manufacturing process. Integration with microfluidics handling also enables suitable sample pre-processing/separation/purification/amplification steps that could improve selectivity and the overall signal-to-noise ratio. Three device types are reviewed here: (i) bulk acoustic wave sensors, (ii) surface acoustic wave sensors, and (iii) micro/nano-electromechanical system (MEMS/NEMS) sensors. PMID:27365040

  11. Acoustic biosensors.

    PubMed

    Fogel, Ronen; Limson, Janice; Seshia, Ashwin A

    2016-06-30

    Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of cost, size and scalability, as well as potential additional features including integration with microfluidics and electronics, scaled sensitivities associated with smaller dimensions and higher operational frequencies, the ability to multiplex detection across arrays of hundreds of devices embedded in a single chip, increased throughput and the ability to interrogate a wider range of modes including within the same device. Additionally, device fabrication is often compatible with semiconductor volume batch manufacturing techniques enabling cost scalability and a high degree of precision and reproducibility in the manufacturing process. Integration with microfluidics handling also enables suitable sample pre-processing/separation/purification/amplification steps that could improve selectivity and the overall signal-to-noise ratio. Three device types are reviewed here: (i) bulk acoustic wave sensors, (ii) surface acoustic wave sensors, and (iii) micro/nano-electromechanical system (MEMS/NEMS) sensors. PMID:27365040

  12. Influence of Rare Earth Ho3+ Doping on Structural, Microstructure and Magnetic Properties of ZnO Bulk and Thin Film Systems

    NASA Astrophysics Data System (ADS)

    Murtaza Rai, Ghulam; Azhar Iqbal, Muhammad; Xu, Yongbing; Will, Iain Gordon; Zhang, Wen

    2011-06-01

    We have investigated the doping behavior of rare earth element holmium (Ho3+) in ZnO semiconductor. The structural, microstructure, and magnetic properties of Zn1-xHoxO (x=0.0, 0.04, and 0.05) thin films deposited on Si(100) substrate by thermal evaporation technique were studied. The ceramic targets were prepared by conventional solid state ceramic technique. The pallets used as target were final sintered at 900 °C in the presence of N2 atmosphere. The experimental results of X-ray diffraction (XRD) spectra, surface morphology, and magnetic properties show that the Ho3+ doped ZnO thin films has a strong influence on the materials properties. The higher angle shift in peak position and most preferred (101) orientation were observed in XRD pattern. These spectra confirmed the substitution of Ho3+ in ZnO lattice. The surface morphology and stoichiometry for both bulk and thin films were analyzed by scanning electron microscopy and energy dispersive spectroscopy. It was observed that grain size decreases with the increase of Ho3+. Room temperature ferromagnetism was observed for Zn0.95Ho0.05O films. The ferromagnetism might be attributed to the substitution of Ho ions for Zn2+ in ZnO lattices.

  13. Intrinsic spin polarized electronic structure of CrO{sub 2} epitaxial film revealed by bulk-sensitive spin-resolved photoemission spectroscopy

    SciTech Connect

    Fujiwara, Hirokazu; Sunagawa, Masanori; Kittaka, Tomoko; Terashima, Kensei; Wakita, Takanori; Muraoka, Yuji; Yokoya, Takayoshi

    2015-05-18

    We have performed bulk-sensitive spin-resolved photoemission spectroscopy in order to clarify the intrinsic spin-resolved electronic states of half-metallic ferromagnet CrO{sub 2}. We used CrO{sub 2} epitaxial films on TiO{sub 2}(100), which shows a peak at 1 eV with a clear Fermi edge, consistent with the bulk-sensitive PES spectrum for CrO{sub 2}. In spin-resolved spectra at 40 K, while the Fermi edge was observed in the spin up (majority spin) state, no states at the Fermi level (E{sub F}) with an energy gap of 0.5 eV below E{sub F} were observed in the spin down (minority spin) state. At 300 K, the gap in the spin down state closes. These results are consistent with resistivity measurements and magnetic hysteresis curves of the fabricated CrO{sub 2} film, constituting spectroscopic evidence for the half-metallicity of CrO{sub 2} at low temperature and reducing the spin polarization at room temperature. We also discuss the electron correlation effects of Cr 3d.

  14. Intrinsic spin polarized electronic structure of CrO2 epitaxial film revealed by bulk-sensitive spin-resolved photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Fujiwara, Hirokazu; Sunagawa, Masanori; Terashima, Kensei; Kittaka, Tomoko; Wakita, Takanori; Muraoka, Yuji; Yokoya, Takayoshi

    2015-05-01

    We have performed bulk-sensitive spin-resolved photoemission spectroscopy in order to clarify the intrinsic spin-resolved electronic states of half-metallic ferromagnet CrO2. We used CrO2 epitaxial films on TiO2(100), which shows a peak at 1 eV with a clear Fermi edge, consistent with the bulk-sensitive PES spectrum for CrO2. In spin-resolved spectra at 40 K, while the Fermi edge was observed in the spin up (majority spin) state, no states at the Fermi level (EF) with an energy gap of 0.5 eV below EF were observed in the spin down (minority spin) state. At 300 K, the gap in the spin down state closes. These results are consistent with resistivity measurements and magnetic hysteresis curves of the fabricated CrO2 film, constituting spectroscopic evidence for the half-metallicity of CrO2 at low temperature and reducing the spin polarization at room temperature. We also discuss the electron correlation effects of Cr 3d.

  15. High performance AlScN thin film based surface acoustic wave devices with large electromechanical coupling coefficient

    SciTech Connect

    Wang, Wenbo; He, Xingli; Ye, Zhi E-mail: jl2@bolton.ac.uk; Wang, Xiaozhi; Mayrhofer, Patrick M.; Gillinger, Manuel; Bittner, Achim; Schmid, Ulrich

    2014-09-29

    AlN and AlScN thin films with 27% scandium (Sc) were synthesized by DC magnetron sputtering deposition and used to fabricate surface acoustic wave (SAW) devices. Compared with AlN-based devices, the AlScN SAW devices exhibit much better transmission properties. Scandium doping results in electromechanical coupling coefficient, K{sup 2}, in the range of 2.0% ∼ 2.2% for a wide normalized thickness range, more than a 300% increase compared to that of AlN-based SAW devices, thus demonstrating the potential applications of AlScN in high frequency resonators, sensors, and high efficiency energy harvesting devices. The coupling coefficients of the present AlScN based SAW devices are much higher than that of the theoretical calculation based on some assumptions for AlScN piezoelectric material properties, implying there is a need for in-depth investigations on the material properties of AlScN.

  16. Surface tension and disjoining pressure of free-standing smectic films above the bulk smectic-A-isotropic transition temperature

    SciTech Connect

    Zakharov, A. V.; Śliwa, Izabela

    2014-03-28

    We have carried out a numerical study of both the structural and thermodynamic properties of free-standing smectic films for the case of enhanced pair interaction in the bounding layers. Calculations, based upon the extended McMillan's mean-field theory with anisotropic forces, show that the layer-thinning transitions are characterized by abrupt drops to lower values, both for a disjoining pressure and a fluctuation-induced long-range interaction between the smectic film surfaces, and then continues to increase with a larger positive slope. Reasonable agreement between the theoretically predicted and the experimentally obtained data on the surface tension of the partially fluorinated 5-n-alkyl-2-(4-n-(perfluoroalkyl-metheleneoxy)phenyl) film has been obtained.

  17. High Resolution X-ray Diffraction Characterization of III-Nitride Semiconductors: Bulk Crystals and Thin Films

    NASA Astrophysics Data System (ADS)

    Bobea, Milena Rebeca

    As III-nitrides continue to evolve into a homoepitaxial growth scenario, the development of non-traditional metrologies for the proper study of III-nitride single crystals and homoepitaxial thin films becomes critical. To this purpose, the work presented in this dissertation has focused on the development and application of suitable high resolution X-ray diffraction (HRXRD) methods, desirable for their sensitivity, accuracy and non-destructive nature. HRXRD techniques were explored and developed for the identification of polishing-induced damage in processed III-nitride single crystals, the structural analysis of non-polar AlN homoepitaxial films grown on AlN single crystals and the assessment of alloy film characteristics of AlxGa1-xN epilayers deposited on AlN substrates. AlN and GaN substrates were treated to various degrees of mechanical polishing and chemical mechanical polishing (CMP). Gross damage created from aggressive polishing was readily quantified using X-ray rocking curve (XRC) peak broadening and diffuse scatter intensity. However, once the wafers were exposed to CMP treatment, it was found that the use of line scanning methods was unable to distinguish the effects of CMP time exposure on the crystal surface. Alternatively, the analysis of surface-related diffraction features recorded from on- and off-axis high-resolution reciprocal space maps (RSMs) allowed the classification of remnant damage in CMP-treated substrates as a function of CMP exposure time. By comparing the crystal truncation rod intensity and the pole diffuse scatter magnitude, differences at the near-surface regions of CMP-processed wafers were qualitatively and quantitatively measured. For AlN, the mapping of the (101¯3) reflection, observable under grazing incidence conditions, was introduced as an effective HRXRD method to analyze the crystal surface of AlN substrates using a laboratory source. HRXRD methods were employed on high-quality non-polar homoepitaxial AlN films grown on

  18. Acoustic microscopy with mixed-mode transducers

    SciTech Connect

    Chou, C.H.; Parent, P.; Khuri-Yakub, B.T.

    1988-12-31

    The new amplitude-phase acoustic microscope is versatile; it operates in a wide frequency range 1--200 MHz, with selection of longitudinal, shear, and mixed modes. This enables it to be used in many NDE applications for different kinds of materials. Besides the application examples presented in this paper (bulk defect imaging of lossy materials or at deep locations; leads of IC chip in epoxy package; amplitude images of surface crack on Si nitride ball bearing; thin Au film on quartz), this system can also be applied for residual stress and anisotropy mapping with high accuracy and good spatial resolution. 7 refs, 6 figs.

  19. The Effects of Damage on Hydrogen-Implant-Induced Thin-Film Separation from Bulk Silicon Carbide

    SciTech Connect

    Gregory, R.B.; Holland, O.W.; Thomas, D.K.; Wetteroth, T.A.; Wilson, S.R.

    1999-04-05

    Exfoliation of Sic by hydrogen implantation and subsequent annealing forms the basis for a thin-film separation process which, when combined with hydrophilic wafer bonding, can be exploited to produce silicon-carbide-on-insulator, SiCOI. Sic thin films produced by this process exhibit unacceptably high resistivity because defects generated by the implant neutralize electrical carriers. Separation occurs because of chemical interaction of hydrogen with dangling bonds within microvoids created by the implant, and physical stresses due to gas-pressure effects during post-implant anneal. Experimental results show that exfoliation of Sic is dependent upon the concentration of implanted hydrogen, but the damage generated by the implant approaches a point when exfoliation is, in fact, retarded. This is attributed to excessive damage at the projected range of the implant which inhibits physical processes of implant-induced cleaving. Damage is controlled independently of hydrogen dosage by elevating the temperature of the SiC during implant in order to promote dynamic annealing. The resulting decrease in damage is thought to promote growth of micro-cracks which form a continuous cleave. Channeled H{sup +} implantation enhances the cleaving process while simultaneously minimizing residual damage within the separated film. It is shown that high-temperature irradiation and channeling each reduces the hydrogen fluence required to affect separation of a thin film and results in a lower concentration of defects. This increases the potential for producing SiC01 which is sufficiently free of defects and, thus, more easily electrically activated.

  20. Physicochemical studies on the interaction of serum albumin with pulmonary surfactant extract in films and bulk bilayer phase.

    PubMed

    Nag, Kaushik; Vidyashankar, Sangeetha; Devraj, Ravi; Fritzen Garcia, Mauricia; Panda, Amiya K

    2010-12-15

    Functionality, structure and composition of the adsorbed films of bovine lipid extract surfactant (BLES), in the absence and presence of bovine serum albumin (BSA), at the air-buffer interface was characterized through surface tension, atomic force microscopy and time of flight secondary ion mass spectrometric methods. Gel and fluid domains of BLES films were found to be altered significantly in the presence of BSA. Differential scanning calorimetric studies on BLES dispersions in presence of BSA revealed that the perturbations of the lipid bilayer structures were significant only at higher amount of BSA. FTIR studies on the BLES dispersions in buffer solution revealed that BSA could affect the lipid head-group hydrations in bilayer as well as the methylene and methyl vibration modes of fatty acyl chains of the phospholipids present in BLES. Serum albumin could perturb the film structure at pathophysiological concentration while higher amount of BSA was required in perturbing the bilayer structures. The studies suggest a connected perturbed bilayer to monolayer transition model for surfactant inactivation at the alveolar-air interface in dysfunctional surfactants. PMID:20850129

  1. Surface Brillouin scattering of cubic boron nitride films

    NASA Astrophysics Data System (ADS)

    Zinin, P.; Manghnani, M. H.; Zhang, X.; Feldermann, H.; Ronning, C.; Hofsäss, H.

    2002-04-01

    Surface Brillouin scattering has been used to determine the elastic properties of thin hard submicron cubic boron nitride (cBN) films grown on silicon by mass selected ion beam deposition. The elastic properties of the films have been determined by fitting experimental data to theoretical dispersion curves. A Green's function method was used to predict Brillouin scattering spectra of the acoustic excitation at the free surface. Our results demonstrate that the effect of the thin hexagonal boron nitride interlayer located between cBN film and the Si substrate on the velocity of the surface acoustic wave does not exceed 2% for a thin (16 nm) film and is negligible for cBN films thicker than 100 nm. The elastic properties of the cBN films are not softer than those of bulk cBN.

  2. Spectra of optical parameters in bulk and film amorphous alloys of the Se{sub 95}As{sub 5} system containing samarium (Sm) impurities

    SciTech Connect

    Djalilov, N. Z.; Damirov, G. M.

    2011-09-15

    Reflectance spectra of bulk and film amorphous alloys of the Se{sub 95}As{sub 5} system containing samarium (Sm) impurities are studied in the energy range of 1-6 eV. Spectral dependences of optical constants and derivatives of optical dielectric functions are calculated by the Kramers-Kronig method. Changes in spectra of optical parameters depending on the content of impurities introduced into Se{sub 95}As{sub 5} and conditions of their preparation are explained based on the cluster model. According to the latter, changes in the electron density of states depends on changes in atomic configurations in clusters, i.e., short-range order changes.

  3. Combined optical and acoustical method for determination of thickness and porosity of transparent organic layers below the ultra-thin film limit

    NASA Astrophysics Data System (ADS)

    Rodenhausen, K. B.; Kasputis, T.; Pannier, A. K.; Gerasimov, J. Y.; Lai, R. Y.; Solinsky, M.; Tiwald, T. E.; Wang, H.; Sarkar, A.; Hofmann, T.; Ianno, N.; Schubert, M.

    2011-10-01

    Analysis techniques are needed to determine the quantity and structure of materials composing an organic layer that is below an ultra-thin film limit and in a liquid environment. Neither optical nor acoustical techniques can independently distinguish between thickness and porosity of ultra-thin films due to parameter correlation. A combined optical and acoustical approach yields sufficient information to determine both thickness and porosity. We describe application of the combinatorial approach to measure single or multiple organic layers when the total layer thickness is small compared to the wavelength of the probing light. The instrumental setup allows for simultaneous in situ spectroscopic ellipsometry and quartz crystal microbalance dynamic measurements, and it is combined with a multiple-inlet fluid control system for different liquid solutions to be introduced during experiments. A virtual separation approach is implemented into our analysis scheme, differentiated by whether or not the organic adsorbate and liquid ambient densities are equal. The analysis scheme requires that the film be assumed transparent and rigid (non-viscoelastic). We present and discuss applications of our approach to studies of organic surfactant adsorption, self-assembled monolayer chemisorption, and multiple-layer target DNA sensor preparation and performance testing.

  4. Combined optical and acoustical method for determination of thickness and porosity of transparent organic layers below the ultra-thin film limit.

    PubMed

    Rodenhausen, K B; Kasputis, T; Pannier, A K; Gerasimov, J Y; Lai, R Y; Solinsky, M; Tiwald, T E; Wang, H; Sarkar, A; Hofmann, T; Ianno, N; Schubert, M

    2011-10-01

    Analysis techniques are needed to determine the quantity and structure of materials composing an organic layer that is below an ultra-thin film limit and in a liquid environment. Neither optical nor acoustical techniques can independently distinguish between thickness and porosity of ultra-thin films due to parameter correlation. A combined optical and acoustical approach yields sufficient information to determine both thickness and porosity. We describe application of the combinatorial approach to measure single or multiple organic layers when the total layer thickness is small compared to the wavelength of the probing light. The instrumental setup allows for simultaneous in situ spectroscopic ellipsometry and quartz crystal microbalance dynamic measurements, and it is combined with a multiple-inlet fluid control system for different liquid solutions to be introduced during experiments. A virtual separation approach is implemented into our analysis scheme, differentiated by whether or not the organic adsorbate and liquid ambient densities are equal. The analysis scheme requires that the film be assumed transparent and rigid (non-viscoelastic). We present and discuss applications of our approach to studies of organic surfactant adsorption, self-assembled monolayer chemisorption, and multiple-layer target DNA sensor preparation and performance testing. PMID:22047284

  5. Thin film and bulk investigations of LiCoBO3 as a Li-ion battery cathode

    SciTech Connect

    Bo, Shou-Hang; Veith, Gabriel M; Saccomanno, Michael; Huang, Huafeng; Burmistrova, Polina; Malingowski, Andrew; Sacci, Robert L; Grey, Clare; Khalifah, P.

    2014-01-01

    The compound LiCoBO3 is an appealing candidate for next generation Li-ion batteries based on its high theoretical specific capacity of 215 mAh/g and high expected discharge voltage (more than 4 V vs. Li+/Li). However, this level of performance has not yet been realized in experimental cells, even with nanosized particles. Reactive magnetron sputtering was therefore used to prepare thin films of LiCoBO3, allowing the influence of particle thickness on electrochemical performance to be explicitly tested. Even when ultra-thin films (~15 nm) were prepared, there was a negligible electrochemical response from LiCoBO3. Impedance spectroscopy measurements suggest that the conductivity of LiCoBO3 is many orders of magnitude worse than that of LiFeBO3, and may be severely limiting performance. The band gap and unusual blue color of LiCoBO3 were investigated by spectroscopic techniques, which allowed the determination of an optical gap of 4.2 eV and the assignment of the visible light absorption to a symmetry-allowed e a transition that occurs within the context of a particularly simple electronic configuration.

  6. Thin-film and bulk investigations of LiCoBO₃ as a Li-ion battery cathode.

    PubMed

    Bo, Shou-Hang; Veith, Gabriel M; Saccomanno, Michael R; Huang, Huafeng; Burmistrova, Polina V; Malingowski, Andrew C; Sacci, Robert L; Kittilstved, Kevin R; Grey, Clare P; Khalifah, Peter G

    2014-07-23

    The compound LiCoBO3 is an appealing candidate for next-generation Li-ion batteries based on its high theoretical specific capacity of 215 mAh/g and high expected discharge voltage (more than 4 V vs Li(+)/Li). However, this level of performance has not yet been realized in experimental cells, even with nanosized particles. Reactive magnetron sputtering was therefore used to prepare thin films of LiCoBO3, allowing the influence of the particle thickness on the electrochemical performance to be explicitly tested. Even when ultrathin films (∼15 nm) were prepared, there was a negligible electrochemical response from LiCoBO3. Impedance spectroscopy measurements suggest that the conductivity of LiCoBO3 is many orders of magnitude worse than that of LiFeBO3 and may severely limit the performance. The unusual blue color of LiCoBO3 was investigated by spectroscopic techniques, which allowed the determination of a charge-transfer optical gap of 4.2 eV and the attribution of the visible light absorption peak at 2.2 eV to spin-allowed d → d transitions (assigned as overlapping (4)A2' to (4)A2″ and (4)E″ final states based on ligand-field modeling). PMID:24809458

  7. Measurement of the refractive index dispersion of As{sub 2}Se{sub 3} bulk glass and thin films prior to and after laser irradiation and annealing using prism coupling in the near- and mid-infrared spectral range

    SciTech Connect

    Carlie, N.; Petit, L.; Musgraves, J. D.; Richardson, K.

    2011-05-15

    The prism coupling technique has been utilized to measure the refractive index in the near- and mid-IR spectral region of chalcogenide glasses in bulk and thin film form. A commercial system (Metricon model 2010) has been modified with additional laser sources, detectors, and a new GaP prism to allow the measurement of refractive index dispersion over the 1.5-10.6 {mu}m range. The instrumental error was found to be {+-}0.001 refractive index units across the entire wavelength region examined. Measurements on thermally evaporated AMTIR2 thin films confirmed that (i) the film deposition process provides thin films with reduced index compared to that of the bulk glass used as a target, (ii) annealing of the films increases the refractive index of the film to the level of the bulk glass used as a target to create it, and (iii) it is possible to locally increase the refractive index of the chalcogenide glass using laser exposure at 632.8 nm.

  8. Measurement of the refractive index dispersion of As2Se3 bulk glass and thin films prior to and after laser irradiation and annealing using prism coupling in the near- and mid-infrared spectral range

    SciTech Connect

    Carlie, Nathan; Anheier, Norman C.; Qiao, Hong; Bernacki, Bruce E.; Phillips, Mark C.; Petit, Laticia; Musgraves, Jonathan D.; Richardson, Kathleen

    2011-05-01

    The prism coupling technique has been utilized to measure the refractive index in the near- and mid-IR spectral region of chalcogenide glasses in bulk and thin film form. A commercial system (Metricon model 2010) has been modified with additional laser sources, detectors, and a new GaP prism to allow the measurement of refractive index dispersion over the 1.5–10.6 μm range. The instrumental error was found to be ±0.001 refractive index units across the entire wavelength region examined. Measurements on thermally evaporated AMTIR2 thin films confirmed that (i) the film deposition process provides thin films with reduced index compared to that of the bulk glass used as a target, (ii) annealing of the films increases the refractive index of the film to the level of the bulk glass used as a target to create it, and (iii) it is possible to locally increase the refractive index of the chalcogenide glass using laser exposure at 632.8 nm.

  9. Acoustic neuroma

    MedlinePlus

    Vestibular schwannoma; Tumor - acoustic; Cerebellopontine angle tumor; Angle tumor ... Acoustic neuromas have been linked with the genetic disorder neurofibromatosis type 2 (NF2). Acoustic neuromas are uncommon.

  10. Single-ion magnetic anisotropy of transition metal impurities in Bi2Se3 bulk and thin film topological insulators

    NASA Astrophysics Data System (ADS)

    Islam, Fhokrul; Pertsova, Anna; Mahani, Reza; Canali, Carlo

    The breaking of time reversal symmetry in a topological insulator (TI) by magnetic doping is one of the most studied phenomena among the properties of Dirac materials. The robustness of the topological surface states (TSS) against magnetic impurities is of critical importance for spin-dependent transport in these systems. The interaction between TSS and magnetic impurities can open a gap, provided that the magnetic order is oriented normal to the surface of the TI. Such gap opening is crucial for realizing TI-based spintronic devices and for the observation of different fundamental phenomena, such as the anomalous quantum Hall effect. Using density functional theory as implemented in the WIEN2k ab-initio package, we have investigated the effect of the magnetization orientation on the gap opening at the Dirac point, for substitutional Mn and Fe impurities on the Bi2Se3 surface, and have calculated the associated single-ion anisotropy (SIA). We also have studied bulk SIA in order to compare the role played by TSS on the surface SIA.

  11. Towards p × n transverse thermoelectrics: extreme anisotropic conduction in bulk doped semiconductor thin films via proton implantation

    NASA Astrophysics Data System (ADS)

    Tang, Yang; Koblmüller, G.; Riedl, H.; Grayson, M.

    2016-03-01

    Transverse thermoelectrics promise entirely new strategies for integrated cooling elements for optoelectronics. The recently introduced p × n-type transverse thermoelectric paradigm indicates that the most important step to engineering artificial transverse thermoelectrics is to create alternate p- and n-doped layers with orthogonally oriented anisotropic conductivity. This paper studies an approach to creating extreme anisotropic conductivity in bulk-doped semiconductor thin films via ion implantation. This approach defines an array of parallel conduction channels with photolithographic patterning of an SiO2 mask layer, followed by proton implantation. With a 10 μm channel width and 20 μm pitch, both n-type and p-type Al0.42 Ga0.58As thin films demonstrate a conductivity anisotropy ratio σ /σ⊥ > 104 at room temperature, while the longitudinal resistivity along the channel direction after implantation only increased by a factor of 3.3 ˜ 3.6. This approach can be readily adapted to other semiconductor materials for artificial p × n-type transverse thermoelectrics as other applications.

  12. Semiconductor to metallic transition in bulk accumulated amorphous indium-gallium-zinc-oxide dual gate thin-film transistor

    SciTech Connect

    Chun, Minkyu; Chowdhury, Md Delwar Hossain; Jang, Jin

    2015-05-15

    We investigated the effects of top gate voltage (V{sub TG}) and temperature (in the range of 25 to 70 {sup o}C) on dual-gate (DG) back-channel-etched (BCE) amorphous-indium-gallium-zinc-oxide (a-IGZO) thin film transistors (TFTs) characteristics. The increment of V{sub TG} from -20V to +20V, decreases the threshold voltage (V{sub TH}) from 19.6V to 3.8V and increases the electron density to 8.8 x 10{sup 18}cm{sup −3}. Temperature dependent field-effect mobility in saturation regime, extracted from bottom gate sweep, show a critical dependency on V{sub TG}. At V{sub TG} of 20V, the mobility decreases from 19.1 to 15.4 cm{sup 2}/V ⋅ s with increasing temperature, showing a metallic conduction. On the other hand, at V{sub TG} of - 20V, the mobility increases from 6.4 to 7.5cm{sup 2}/V ⋅ s with increasing temperature. Since the top gate bias controls the position of Fermi level, the temperature dependent mobility shows metallic conduction when the Fermi level is above the conduction band edge, by applying high positive bias to the top gate.

  13. Depth profiling sulphur in bulk CdTe and {CdTe}/{CdS} thin film heterojunctions

    NASA Astrophysics Data System (ADS)

    Lane, D. W.; Conibeer, G. J.; Romani, S.; Healy, M. J. F.; Rogers, K. D.

    1998-03-01

    Polycrystalline CdTeCdS heterojunction solar cells are a possible candidate for the low cost, high efficiency conversion of solar energy. The formation of an intermediate CdS xTe 1- x layer during a high temperature annealing stage is believed to increase optical absorption and decrease cell efficiency. S diffusion in single crystal CdTe has been investigated by NRA using the 32S (d,p o) 33S nuclear reaction, at a deuteron energy of 2 MeV. Details of the NRA depth profiling procedure are given, which was found to be relatively straightforward and suitable for use on a small Van de Graaff accelerator. The resulting diffusion parameters are compared to those obtained by SIMS using a Cs + primary ion beam, examining negative secondary ions. The diffusion coefficients were found to be 1.1 × 10 -15cm 2 s -1 at 450°C and ˜8 × 10 -15cm -1 s at 550°C. S diffusion in thin films was also investigated by 2 MeV 4He + RBS on annealed polycrystalline CdSCdTe multilayers.

  14. Excitation of Love waves in a thin film layer by a line source.

    NASA Technical Reports Server (NTRS)

    Tuan, H.-S.; Ponamgi, S. R.

    1972-01-01

    The excitation of a Love surface wave guided by a thin film layer deposited on a semiinfinite substrate is studied in this paper. Both the thin film and the substrate are considered to be elastically isotropic. Amplitudes of the surface wave in the thin film region and the substrate are found in terms of the strength of a line source vibrating in a direction transverse to the propagating wave. In addition to the surface wave, the bulk shear wave excited by the source is also studied. Analytical expressions for the bulk wave amplitude as a function of the direction of propagation, the acoustic powers transported by the surface and bulk waves, and the efficiency of surface wave excitation are obtained. A numerical example is given to show how the bulk wave radiation pattern depends upon the source frequency, the film thickness and other important parameters of the problem. The efficiency of surface wave excitation is also calculated for various parameter values.

  15. Computational investigation of structure, dynamics and nucleation kinetics of a family of modified Stillinger-Weber model fluids in bulk and free-standing thin films.

    PubMed

    Gianetti, Melisa M; Haji-Akbari, Amir; Paula Longinotti, M; Debenedetti, Pablo G

    2016-02-01

    In recent years, computer simulations have found increasingly widespread use as powerful tools for studying phase transitions in wide variety of systems. In the particular and very important case of aqueous systems, the commonly used force-fields tend to offer quite different predictions with respect to a wide range of thermodynamic and kinetic properties, including the ease of ice nucleation, the propensity to freeze at a vapor-liquid interface, and the existence of a liquid-liquid phase transition. It is thus of fundamental and practical interest to understand how different features of a given water model affect its thermodynamic and kinetic properties. In this work, we use the forward-flux sampling technique to study the crystallization kinetics of a family of modified Stillinger-Weber (SW) potentials with energy (ε) and length (σ) scales taken from the monoatomic water (mW) model, but with different tetrahedrality parameters (λ). By increasing λ from 21 to 24, we observe the nucleation rate increases by 48 orders of magnitude at a supercooling of ζ = T/Tm = 0.845. Using classical nucleation theory, we are able to demonstrate that this change can largely be accounted for by the increase in |Δμ|, the thermodynamic driving force. We also perform rate calculations in freestanding thin films of the supercooled liquid, and observe a crossover from surface-enhanced crystallization at λ = 21 to bulk-dominated crystallization for λ ≥ 22. PMID:26778494

  16. Piezoelectric Pb(Zrx, Ti1-x)O3 thin film cantilever and bridge acoustic sensors for miniaturized photoacoustic gas detectors

    NASA Astrophysics Data System (ADS)

    Ledermann, Nicolas; Muralt, Paul; Baborowski, Jacek; Forster, Martin; Pellaux, Jean-Paul

    2004-12-01

    Novel, highly sensitive piezoelectric acoustic sensors based on partially unclamped Pb(Zrx, Ti1-x)O3 (PZT) coated cantilever and bridge have been fabricated by silicon micromachining. High sensitivity at low frequencies (5-100 Hz) has been achieved by patterning very narrow slits (3 to 5 µm) around the structures. A typical response of 100 mV Pa-1 and a noise equivalent pressure of 1.6 mPa Hz1/2 at 20 Hz have been measured using a 10 pF charge amplifier. Stress compensation, dry etching and integration of high performance piezoelectric thin films were the key issues. PZT/Pt/SiO2 stacks have been patterned by reactive ion etching and stress compensation has been achieved by compensating the PZT film's tensile stress by adjusting the thickness of a thermal SiO2 layer. The integration of sol-gel PZT films with a transverse piezoelectric coefficient e31,f of -12.8 C m-2 has been realized without any degradation of the properties. The microphones were successfully integrated into a miniature photoacoustic detector and tested for CO2 detection. Concentrations down to 330 ppm could be measured with significant signals.

  17. Effects of interface and bulk properties of gate-dielectric on the performance and stability of hydrogenated amorphous silicon thin-film transistors

    NASA Astrophysics Data System (ADS)

    Ando, M.; Wakagi, M.; Onisawa, K.

    2015-12-01

    In order to investigate the effects of interface and bulk properties of gate insulator on the threshold voltage (Vth) and the gate-bias induced instability of hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs), four kinds of TFT structures were fabricated with SiNx and SiOx insulators stacked to make different combinations of the bulk and interface in the gate-dielectric layers. It was found that the Vth and the stability are independently controlled by tuning stoichiometry and thickness of the SiOx insertion layer between a-Si:H and SiNx. In TFTs with SiOx insertion layer of 50 nm thickness, on increasing oxygen/silicon (O/Si = x) ratio from 1.7 to 1.9, Vth increased from 0 V to 9 V. In these TFTs with a relatively thick SiOx insertion layer, positive Vth shift with negative bias stress was observed, confirmed to be due to defect creation in a-Si:H with the thermalization barrier energy of 0.83 eV. On reducing the thickness of the SiOx insertion layer down to approximately 1 nm, thin enough for hole injection through SiOx by tunneling effect, stable operation was obtained while keeping the high Vth value under negative stress bias. These results are consistently explained as follows: (1) the high value for Vth is caused by the dipole generated at the interface between a-Si:H and SiOx; and (2) two causes for Vth shift, charge injection to the gate insulator and defect creation in a-Si:H, are mutually related to each other through the "effective bias stress," Vbseff = Vbs - ΔVfb (Vbs: applied bias stress and ΔVfb: flat band voltage shift due to the charge injection). It was experimentally confirmed that there should be an optimum thickness of SiOx insertion layer of approximately 1 nm with stable high Vth, where enhanced injection increases ΔVfb, reduces Vbseff to reduce defect creation, and totally minimizes Vth shift.

  18. Real-time measurement of protein adsorption on electrophoretically deposited hydroxyapatite coatings and magnetron sputtered metallic films using the surface acoustic wave technique.

    PubMed

    Meininger, M; Schmitz, T; Wagner, T; Ewald, A; Gbureck, U; Groll, J; Moseke, C

    2016-04-01

    Surface acoustic wave (SAW) biosensors are highly sensitive for mass binding and are therefore used to detect protein-protein and protein-antibody interactions. Whilst the standard surface of the chips is a thin gold film, measurements on implant- or bone-like surfaces could significantly enhance the range of possible applications for this technique. The aim of this study was to establish methods to coat biosensor chips with Ti, TiN, and silver-doped TiN using physical vapor deposition as well as with hydroxyapatite by electrophoresis. To demonstrate that protein adsorption can be detected on these surfaces, binding experiments with fibronectin and fibronectin-specific antibodies have been performed with the coatings, which successfully proved the applicability of PVD and EPD for SAW biosensor functionalization. PMID:26838860

  19. OSCEE fan exhaust bulk absorber treatment evaluation

    NASA Technical Reports Server (NTRS)

    Bloomer, H. E.; Samanich, N. E.

    1980-01-01

    The acoustic suppression capability of bulk absorber material designed for use in the fan exhaust duct walls of the quiet clean short haul experiment engine (OCSEE UTW) was evaluated. The acoustic suppression to the original design for the engine fan duct which consisted of phased single degree-of-freedom wall treatment was tested with a splitter and also with the splitter removed. Peak suppression was about as predicted with the bulk absorber configuration, however, the broadband characteristics were not attained. Post test inspection revealed surface oil contamination on the bulk material which could have caused the loss in bandwidth suppression.

  20. Phase transition in bulk single crystals and thin films of VO2 by nanoscale infrared spectroscopy and imaging

    SciTech Connect

    Liu, Mengkun; Sternbach, Aaron J.; Wagner, Martin; Slusar, Tetiana V.; Kong, Tai; Bud'ko, Sergey L.; Kittiwatanakul, Salinporn; Qazilbash, M. M.; McLeod, Alexander; Fei, Zhe; Abreu, Elsa; Zhang, Jingdi; Goldflam, Michael; Dai, Siyuan; Ni, Guang -Xin; Lu, Jiwei; Bechtel, Hans A.; Martin, Michael C.; Raschke, Markus B.; Averitt, Richard D.; Wolf, Stuart A.; Kim, Hyun -Tak; Canfield, Paul C.; Basov, D. N.

    2015-06-29

    We have systematically studied a variety of vanadium dioxide (VO2) crystalline forms, including bulk single crystals and oriented thin films, using infrared (IR) near-field spectroscopic imaging techniques. By measuring the IR spectroscopic responses of electrons and phonons in VO2 with sub-grain-size spatial resolution (~20nm), we show that epitaxial strain in VO2 thin films not only triggers spontaneous local phase separations, but leads to intermediate electronic and lattice states that are intrinsically different from those found in bulk. Generalized rules of strain- and symmetry-dependent mesoscopic phase inhomogeneity are also discussed. Furthermore, these results set the stage for a comprehensive understanding of complex energy landscapes that may not be readily determined by macroscopic approaches.

  1. Isomorphic surface acoustic waves on multilayer structures

    NASA Astrophysics Data System (ADS)

    Hunt, William D.

    2001-03-01

    There has been growing interest in recent years over the investigation of bulk acoustic waves (BAWs) which propagate along certain directions in anisotropic crystals with a minimum of diffraction. One application of these BAWs is for multichannel acousto-optic devices. The fact that the beams propagate with the minimum diffraction implies that the channels in such a device can be closely packed. Since surface acoustic waves (SAWs) are constrained to be within roughly one acoustic wavelength from the surface, the possibility exists to deposit thin films of isotropic or anisotropic material on the substrate and embue the aggregate multilayer structure with properties not present in the beginning substrate material. The characteristic investigated in this article is the velocity anisotropy which, as is known, predominates SAW diffraction. Specifically, we present a method whereby self-collimating SAWs can be generated on surfaces even though the substrate material itself does not exhibit this behavior. We discuss the particular case of a ZnO layer on (001)-cut <110>-propagating GaAs for which a fair amount of slowness surface data exists. Finally, using angular spectrum of plane waves diffraction theory, we present data which substantiate the claim that self-collimating can more accurately be viewed as isomorphic because the SAW beam profile can propagate without changing its shape.

  2. Bulk undercooling

    NASA Technical Reports Server (NTRS)

    Kattamis, T. Z.

    1984-01-01

    Bulk undercooling methods and procedures will first be reviewed. Measurement of various parameters which are necessary to understand the solidification mechanism during and after recalescence will be discussed. During recalescence of levitated, glass-encased large droplets (5 to 8 mm diam) high speed temperature sensing devices coupled with a rapid response oscilloscope are now being used at MIT to measure local thermal behavior in hypoeutectic and eutectic binary Ni-Sn alloys. Dendrite tip velocities were measured by various investigators using thermal sensors or high speed cinematography. The confirmation of the validity of solidification models of bulk-undercooled melts is made difficult by the fineness of the final microstructure, the ultra-rapid evolution of the solidifying system which makes measurements very awkward, and the continuous modification of the microstructure which formed during recalescence because of precipitation, remelting and rapid coarsening.

  3. Influence of SiO2/In2O3 film acoustical waveguide on the mode index of Ti:LiNbO3 optical waveguide in acousto-optical mode converter

    NASA Astrophysics Data System (ADS)

    Lin, Hang-you; Ning, Ji-ping; Geng, Fan

    2004-04-01

    TE/TM mode converter is a key element of integrated acoustooptical tunable filter (AOTF). Employing SiO2/In2O3 film as acoustical waveguide can suppress sidelobes effectively and simplify fabrication technique in integrated quasi-collinear AOTF. In this report, the eigenvalue equation and the field solution of such configuration has been obtained by using modified Wenzel-Kramers-Brillouin (WKB) method. The results are compared with those by using vector finite element method (VFEM). When the optical waveguides are covered by such oxide film, the difference of mode indices of both polarizations and the effective propagation velocity of surface acoustical wave (SAW) will decrease, and these decreases lead the shift of optical wavelength, which mainly results in the change of the former.

  4. Theoretical requirements for broadband perfect absorption of acoustic waves by ultra-thin elastic meta-films

    PubMed Central

    Duan, Yuetao; Luo, Jie; Wang, Guanghao; Hang, Zhi Hong; Hou, Bo; Li, Jensen; Sheng, Ping; Lai, Yun

    2015-01-01

    We derive and numerically demonstrate that perfect absorption of elastic waves can be achieved in two types of ultra-thin elastic meta-films: one requires a large value of almost pure imaginary effective mass density and a free space boundary, while the other requires a small value of almost pure imaginary effective modulus and a hard wall boundary. When the pure imaginary density or modulus exhibits certain frequency dispersions, the perfect absorption effect becomes broadband, even in the low frequency regime. Through a model analysis, we find that such almost pure imaginary effective mass density with required dispersion for perfect absorption can be achieved by elastic metamaterials with large damping. Our work provides a feasible approach to realize broadband perfect absorption of elastic waves in ultra-thin films. PMID:26184117

  5. Acoustic Neuroma

    MedlinePlus

    An acoustic neuroma is a benign tumor that develops on the nerve that connects the ear to the brain. ... can press against the brain, becoming life-threatening. Acoustic neuroma can be difficult to diagnose, because the ...

  6. Acoustic Seal

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M. (Inventor)

    2006-01-01

    The invention relates to a sealing device having an acoustic resonator. The acoustic resonator is adapted to create acoustic waveforms to generate a sealing pressure barrier blocking fluid flow from a high pressure area to a lower pressure area. The sealing device permits noncontacting sealing operation. The sealing device may include a resonant-macrosonic-synthesis (RMS) resonator.

  7. Acoustic seal

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M. (Inventor)

    2006-01-01

    The invention relates to a sealing device having an acoustic resonator. The acoustic resonator is adapted to create acoustic waveforms to generate a sealing pressure barrier blocking fluid flow from a high pressure area to a lower pressure area. The sealing device permits noncontacting sealing operation. The sealing device may include a resonant-macrosonic-synthesis (RMS) resonator.

  8. Large enhancement of bulk spin polarization by suppressing CoMn anti-sites in Co2Mn(Ge0.75Ga0.25) Heusler alloy thin film

    NASA Astrophysics Data System (ADS)

    Li, S.; Takahashi, Y. K.; Sakuraba, Y.; Tsuji, N.; Tajiri, H.; Miura, Y.; Chen, J.; Furubayashi, T.; Hono, K.

    2016-03-01

    We have investigated the structure and magneto-transport properties of Co2Mn(Ge0.75Ga0.25) (CMGG) Heusler alloy thin films with near-stoichiometric and Mn-rich compositions in order to understand the effect of Co-Mn anti-sites on bulk spin polarization. Anomalous x-ray diffraction measurements using synchrotron radiated x-rays confirmed that CoMn anti-sites easily form in the near-stoichiometric CMGG compound at annealing temperature higher than 400 °C, while it can be suppressed in Mn-rich CMGG films. Accordingly, large enhancement in negative anisotropic magnetoresistance of CMGG films and giant magnetoresistance (GMR) in current-perpendicular-to-plane (CPP) pseudo spin valves were observed in the Mn-rich composition. A large resistance-area product change (ΔRA) of 12.8 mΩ μm2 was demonstrated in the CPP-GMR pseudo spin valves using the Mn-rich CMGG layers after annealing at 600 °C. It is almost twice of the maximum output observed in the CPP-GMR pseudo spin valves using the near-stoichiometric CMGG. These indicate that the spin polarization of CMGG is enhanced in the Mn-rich composition through suppressing the formation of CoMn-antisites in CMGG films, being consistent with first-principle calculation results.

  9. Acoustic Absorption in Porous Materials

    NASA Technical Reports Server (NTRS)

    Kuczmarski, Maria A.; Johnston, James C.

    2011-01-01

    An understanding of both the areas of materials science and acoustics is necessary to successfully develop materials for acoustic absorption applications. This paper presents the basic knowledge and approaches for determining the acoustic performance of porous materials in a manner that will help materials researchers new to this area gain the understanding and skills necessary to make meaningful contributions to this field of study. Beginning with the basics and making as few assumptions as possible, this paper reviews relevant topics in the acoustic performance of porous materials, which are often used to make acoustic bulk absorbers, moving from the physics of sound wave interactions with porous materials to measurement techniques for flow resistivity, characteristic impedance, and wavenumber.

  10. Strain engineered barium strontium titanate for tunable thin film resonators

    SciTech Connect

    Khassaf, H.; Khakpash, N.; Sun, F.; Sbrockey, N. M.; Tompa, G. S.; Kalkur, T. S.; Alpay, S. P.

    2014-05-19

    Piezoelectric properties of epitaxial (001) barium strontium titanate (BST) films are computed as functions of composition, misfit strain, and temperature using a non-linear thermodynamic model. Results show that through adjusting in-plane strains, a highly adaptive rhombohedral ferroelectric phase can be stabilized at room temperature with outstanding piezoelectric response exceeding those of lead based piezoceramics. Furthermore, by adjusting the composition and the in-plane misfit, an electrically tunable piezoelectric response can be obtained in the paraelectric state. These findings indicate that strain engineered BST films can be utilized in the development of electrically tunable and switchable surface and bulk acoustic wave resonators.

  11. Surface Acoustic Wave Microfluidics

    NASA Astrophysics Data System (ADS)

    Yeo, Leslie Y.; Friend, James R.

    2014-01-01

    Fluid manipulations at the microscale and beyond are powerfully enabled through the use of 10-1,000-MHz acoustic waves. A superior alternative in many cases to other microfluidic actuation techniques, such high-frequency acoustics is almost universally produced by surface acoustic wave devices that employ electromechanical transduction in wafer-scale or thin-film piezoelectric media to generate the kinetic energy needed to transport and manipulate fluids placed in adjacent microfluidic structures. These waves are responsible for a diverse range of complex fluid transport phenomena - from interfacial fluid vibration and drop and confined fluid transport to jetting and atomization - underlying a flourishing research literature spanning fundamental fluid physics to chip-scale engineering applications. We highlight some of this literature to provide the reader with a historical basis, routes for more detailed study, and an impression of the field's future directions.

  12. Highly c-axis oriented growth of GaN film on sapphire (0001) by laser molecular beam epitaxy using HVPE grown GaN bulk target

    SciTech Connect

    Kushvaha, S. S.; Kumar, M. Senthil; Maurya, K. K.; Dalai, M. K.; Sharma, Nita D.

    2013-09-15

    Growth temperature dependant surface morphology and crystalline properties of the epitaxial GaN layers grown on pre-nitridated sapphire (0001) substrates by laser molecular beam epitaxy (LMBE) were investigated in the range of 500–750 °C. The grown GaN films were characterized using high resolution x-ray diffraction, atomic force microscopy (AFM), micro-Raman spectroscopy, and secondary ion mass spectroscopy (SIMS). The x-ray rocking curve full width at a half maximum (FWHM) value for (0002) reflection dramatically decreased from 1582 arc sec to 153 arc sec when the growth temperature was increased from 500 °C to 600 °C and the value further decreased with increase of growth temperature up to 720 °C. A highly c-axis oriented GaN epitaxial film was obtained at 720 °C with a (0002) plane rocking curve FWHM value as low as 102 arc sec. From AFM studies, it is observed that the GaN grain size also increased with increasing growth temperature and flat, large lateral grains of size 200-300 nm was obtained for the film grown at 720 °C. The micro-Raman spectroscopy studies also exhibited the high-quality wurtzite nature of GaN film grown on sapphire at 720 °C. The SIMS measurements revealed a non-traceable amount of background oxygen impurity in the grown GaN films. The results show that the growth temperature strongly influences the surface morphology and crystalline quality of the epitaxial GaN films on sapphire grown by LMBE.

  13. Effect of 100 MeV Ag+7 ion irradiation on the bulk and surface magnetic properties of Co-Fe-Si thin films

    NASA Astrophysics Data System (ADS)

    Hysen, T.; Geetha, P.; Al-Harthi, Salim; Al-Omari, I. A.; Lisha, R.; Ramanujan, R. V.; Sakthikumar, D.; Avasthi, D. K.; Anantharaman, M. R.

    2014-12-01

    Thin films of Co-Fe-Si were vacuum evaporated on pre-cleaned float glass substrates employing thermal evaporation. The films were subsequently irradiated with 100 MeV Ag+7 ions at fluences of 1×1011, 1×1012 and 1×1013 ions/cm2. The pristine and irradiated samples were subjected to surface analysis using Atomic Force Microscopy (AFM), Vibrating Sample Magnetometry (VSM) and Magneto Optic Kerr Effect (MOKE) measurements. The as deposited film has a root mean square roughness (Rq) of 8.9 nm and an average roughness of (Ra) 5.6 nm. Irradiation of the as deposited films with 100 MeV Ag7+ ions modifies the surface morphology. Irradiating with ions at fluences of 1×1011 ions/cm2 smoothens the mesoscopic hill-like structures, and then, at 1×1012 ions/cm2 new surface structures are created. When the fluence is further increased to 1×1013 ions/cm2 an increase in the surface roughness is observed. The MOKE loop of as prepared film indicated a squareness ratio of 0.62. As the film is irradiated with fluences of 1×1011 ions/cm2, 1×1012 ions/cm2 and 1×1013 ions/cm2 the squareness ratio changes to 0.76, 0.8 and 0.86 respectively. This enhancement in squareness ratio towards 1 is a typical feature when the exchange interaction starts to dominates the inherent anisotropies in the system. The variation in surface magnetisation is explained based on the variations in surface roughness with swift heavy ion (SHI) irradiation.

  14. Infrared study on the molecular orientation in bulk-heterojunction films based on perylene and 3,4,9,10-perylenetetracarboxylic dianhydride

    NASA Astrophysics Data System (ADS)

    Seto, Keisuke; Pham, John; Furukawa, Yukio

    2012-03-01

    Solid-state structures of thin blend films of perylene and 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) formed on the Au surface have been studied by a combination of infrared reflection-absorption spectroscopy and the RATIO method of Debe. In the blend films, PTCDA molecules take the face-on orientation in the whole range of PTCDA contents from 7.5 to 88 mol%. On the other hand, the molecular orientation of perylene molecules changes from edge-on toward random as the PTCDA content increases.

  15. Observation of the nonlinear meissner effect in YBCO thin films: evidence for a D-wave order parameter in the bulk of the cuprate superconductors.

    PubMed

    Oates, D E; Park, S-H; Koren, G

    2004-11-01

    We present experimental evidence for the observation of the nonlinear Meissner effect in high-quality epitaxial yttrium barium copper oxide thin films by measuring their intermodulation distortion at microwave frequencies versus temperature. Most of the films measured show a characteristic increase in nonlinearity at low temperatures as predicted by the nonlinear Meissner effect. We could measure the nonlinear Meissner effect because intermodulation distortion measurements are an extremely sensitive method that can detect changes in the penetration depth of the order of 1 part in 10(5). PMID:15600869

  16. Topological Acoustics

    NASA Astrophysics Data System (ADS)

    Yang, Zhaoju; Gao, Fei; Shi, Xihang; Lin, Xiao; Gao, Zhen; Chong, Yidong; Zhang, Baile

    2015-03-01

    The manipulation of acoustic wave propagation in fluids has numerous applications, including some in everyday life. Acoustic technologies frequently develop in tandem with optics, using shared concepts such as waveguiding and metamedia. It is thus noteworthy that an entirely novel class of electromagnetic waves, known as "topological edge states," has recently been demonstrated. These are inspired by the electronic edge states occurring in topological insulators, and possess a striking and technologically promising property: the ability to travel in a single direction along a surface without backscattering, regardless of the existence of defects or disorder. Here, we develop an analogous theory of topological fluid acoustics, and propose a scheme for realizing topological edge states in an acoustic structure containing circulating fluids. The phenomenon of disorder-free one-way sound propagation, which does not occur in ordinary acoustic devices, may have novel applications for acoustic isolators, modulators, and transducers.

  17. Topological acoustics.

    PubMed

    Yang, Zhaoju; Gao, Fei; Shi, Xihang; Lin, Xiao; Gao, Zhen; Chong, Yidong; Zhang, Baile

    2015-03-20

    The manipulation of acoustic wave propagation in fluids has numerous applications, including some in everyday life. Acoustic technologies frequently develop in tandem with optics, using shared concepts such as waveguiding and metamedia. It is thus noteworthy that an entirely novel class of electromagnetic waves, known as "topological edge states," has recently been demonstrated. These are inspired by the electronic edge states occurring in topological insulators, and possess a striking and technologically promising property: the ability to travel in a single direction along a surface without backscattering, regardless of the existence of defects or disorder. Here, we develop an analogous theory of topological fluid acoustics, and propose a scheme for realizing topological edge states in an acoustic structure containing circulating fluids. The phenomenon of disorder-free one-way sound propagation, which does not occur in ordinary acoustic devices, may have novel applications for acoustic isolators, modulators, and transducers. PMID:25839273

  18. Acoustic neuroma

    MedlinePlus

    Vestibular schwannoma; Tumor - acoustic; Cerebellopontine angle tumor; Angle tumor ... 177. Battista RA. Gamma knife radiosurgery for vestibular schwannoma. Otolaryngol Clin North Am . 2009;42:635-654. ...

  19. A Semi-Empirical Multi-Scale Dynamic Monte Carlo Model of Organic Photovoltaic Performance in RIR-MAPLE Bulk Heterojunction Films

    NASA Astrophysics Data System (ADS)

    Stiff-Roberts, Adrienne; Atewologun, Ayomide

    A semi-empirical method for investigating the performance of OPVs in resonant infrared, matrix-assisted pulsed laser evaporation (RIR-MAPLE) films is explored. Emulsion-based RIR-MAPLE offers a unique experimental backdrop for investigating trends through simulation and gaining a better understanding of how different thin film characteristics impact OPV device performance. A novel multi-scale formulation of the Dynamic Monte Carlo (DMC) model is developed based on observable morphology features. Specifically, using confocal microscopy, we observe the presence of micro-scale regimes of pure materials and nano-scale regions of the composite blend. This enables us to assign weighted percentages to DMC implementations on two different scales: the microscale and nanoscale regions. In addition to this, we use input simulation parameters acquired by characterization of as-deposited films. The semi-empirical multi-scale model presented serves as a unique simulation opportunity for exploring different properties of RIR-MAPLE deposited OPVs, their effects on OPV performance and potential design routes for improving device efficiencies. This work was supported, in part, by the Office of Naval Research under Grant N00014-10-1-0481 and the NSF Triangle MRSEC on Soft Matter.

  20. Bulk and interfacial glass transitions of water.

    PubMed

    Bhattacharya, Deepanjan; Payne, Candace N; Sadtchenko, Vlad

    2011-06-16

    Fast scanning calorimetry (FSC) was employed to investigate glass softening dynamics in bulk-like and ultrathin glassy water films. Bulk-like water samples were prepared by vapor-deposition on the surface of a tungsten filament near 140 K where vapor-deposition results in low enthalpy glassy water films. The vapor-deposition approach was also used to grow multiple nanoscale (approximately 50 nm thick) water films alternated with benzene and methanoic films of similar dimensions. When heated from cryogenic temperatures, the ultrathin water films underwent a well manifested glass softening transition at temperatures 20 K below the onset of crystallization. However, no such transition was observed in bulk-like samples prior to their crystallization. These results indicate that thin-film water demonstrates glass softening dynamics that are dramatically distinct from those of the bulk phase. We attribute these differences to water's interfacial glass transition, which occurs at temperatures tens of degrees lower than that in the bulk. Implications of these findings for past studies of glass softening dynamics in various glassy water samples are discussed. PMID:21401034

  1. Microfluidic device for acoustic cell lysis

    DOEpatents

    Branch, Darren W.; Cooley, Erika Jane; Smith, Gennifer Tanabe; James, Conrad D.; McClain, Jaime L.

    2015-08-04

    A microfluidic acoustic-based cell lysing device that can be integrated with on-chip nucleic acid extraction. Using a bulk acoustic wave (BAW) transducer array, acoustic waves can be coupled into microfluidic cartridges resulting in the lysis of cells contained therein by localized acoustic pressure. Cellular materials can then be extracted from the lysed cells. For example, nucleic acids can be extracted from the lysate using silica-based sol-gel filled microchannels, nucleic acid binding magnetic beads, or Nafion-coated electrodes. Integration of cell lysis and nucleic acid extraction on-chip enables a small, portable system that allows for rapid analysis in the field.

  2. Musical Acoustics

    NASA Astrophysics Data System (ADS)

    Gough, Colin

    This chapter provides an introduction to the physical and psycho-acoustic principles underlying the production and perception of the sounds of musical instruments. The first section introduces generic aspects of musical acoustics and the perception of musical sounds, followed by separate sections on string, wind and percussion instruments.

  3. Effects of electron irradiation on the ferroelectric 180 deg. in-plane nanostripe domain structure in a thin film prepared from a bulk single crystal of BaTiO{sub 3} by focused ion beam

    SciTech Connect

    Matsumoto, Takao; Okamoto, Masakuni

    2011-01-01

    Effects of electron irradiation on the ferroelectric 180 deg. in-plane nanostripe domain structure in a thin film prepared from a bulk single crystal of BaTiO{sub 3} by focused ion beam were studied. The domain structure transformed into a characteristic 90 deg. in-plane nanostripe domain structure under intense electron irradiation. In particular, an unconventional triangular 90 deg. in-plane nanostripe domain structure was observed. Polarization analysis suggests the existence of an incomplete or half tetradomain vortex at the boundary of the triangular domain structure. Together with the help of phase-field simulations using time-dependent Ginzburg-Landau equations, it is suggested that such a domain structure is created by an anisotropic in-plane electric field, which is plausibly induced by an anisotropic interaction of the incident electron beam with the ferroelectric material.

  4. QCSEE fan exhaust bulk absorber treatment evaluation

    NASA Technical Reports Server (NTRS)

    Bloomer, H. E.; Samanich, N. E.

    1980-01-01

    The purpose of the experimental program reported herein was to evaluate the acoustic suppression capability of bulk absorber material designed for use in the fan exhaust duct walls of the QCSEE UTW (under-the-wing) engine and to compare it with other means of acoustic suppression. The paper includes comparison of the acoustic suppression to the original design for the QCSEE UTW engine fan duct which consisted of phased SDOF (single-degree-of-freedom) wall treatment and a splitter and also with the splitter removed. The method of approach consisted of mounting the UTW engine on the test stand of the Lewis Engine Noise Facility with an appropriate array of far-field microphones in order to measure the acoustic levels of the various configurations. Peak suppression was about as predicted with the bulk absorber configuration; however, the broadband characteristics were not attained. Post-test inspection revealed surface oil contamination on the bulk material which could have caused the loss in bandwidth suppression.

  5. Property characterization of AlN thin films in composite resonator structure

    NASA Astrophysics Data System (ADS)

    Chen, Qingming; Qin, Lifen; Wang, Qing-Ming

    2007-04-01

    AlN thin films with c-axis orientation have been investigated for fabricating thin film bulk acoustic wave resonators in the past few years. Characterization of thin film material properties including density, elastic modulus, and piezoelectric coefficient is essential in processing study and for predicting the performance of the acoustic devices. In this paper, we present our results on the fabrication of highly c-axis oriented AlN thin films on Pt /Ti/Si (100) substrates by dc reactive magnetron sputtering method. The crystalline structure and the surface morphology of AlN films are characterized by x-ray diffraction and scanning electron microscopy. The effective piezoelectric coefficient d33eff of the AlN films was measured by a laser interferometer method and the piezoelectric coefficient d33 was estimated. A recently developed resonance spectrum method is applied to characterize the electromechanical properties of AlN thin films based on the input electrical impedance equation derived by one-dimensional transmission line theory for composite resonators. Using the experimental impedance spectrum data, the density and elastic constant of the piezoelectric AlN thin film in the four-layer composite resonator structure are evaluated. The calculated results reveal that the piezoelectric coefficient d33, density, and velocity of the c-axis oriented AlN thin film are 4.19pm/V, 3187.3kg/m3, and 10631m/s, respectively.

  6. Lattice dynamics in elemental modulated Sb 2 Te 3 films: Lattice dynamics in elemental modulated Sb 2 Te 3 films

    SciTech Connect

    Bessas, D.; Winkler, M.; Sergueev, I.; König, J. D.; Böttner, H.; Hermann, R. P.

    2015-09-03

    We investigate the crystallinity and the lattice dynamics in elemental modulated Sbinline imageTeinline image films microscopically using high energy synchrotron radiation diffraction combined with inline imageSb nuclear inelastic scattering. The correlation length is found to be finite but less than 100 . Moreover, the element specific density of phonon states is extracted. A comparison with the element specific density of phonon states in bulk Sbinline imageTeinline image confirms that the main features in the density of phonon states arise from the layered structure. The average speed of sound at inline image inline image, is almost the same compared to bulk Sbinline imageTeinline image at inline image, inline image. Similarly, the change in the acoustic cut-off energy is within the experimental detection limit. Therefore, we suggest that the lattice thermal conductivity in elemental modulated Sbinline imageTeinline image films should not be significantly changed from its bulk value.

  7. Controlled gelation of poly(3-alkylthiophene)s in bulk and in thin-films using low volatility solvent/poor-solvent mixtures.

    PubMed

    Newbloom, Gregory M; de la Iglesia, Pablo; Pozzo, Lilo D

    2014-11-28

    Low volatility solvent/non-solvent mixtures were utilized to engineer the structure of poly(3-alkylthiophene) (P3AT) organogels. The ratio of solvent to poor-solvent was manipulated to systematically control the kinetics of self-assembly. Specific solvent mixtures were utilized to produce similar gelation kinetics with polymers of differing alkyl chain length. Simultaneous small angle neutron scattering (SANS) and dielectric spectroscopy was used to probe the structure and the electronic properties of isothermally self-assembled P3ATs. It was determined that alkyl chain length has a dominant effect on the relationship between fiber development and conductivity. Furthermore, using transmission electron microscopy (TEM) and SANS we demonstrate that, for P3HT organogels, lower poor-solvent content leads to fewer fibers with larger nucleation centers while higher poor-solvent amounts results in more fibers and nucleation centers that are smaller and more abundant. This leads to opposing effects in terms of the contribution of the solvent quality to the electrical conductivity. An optimum in conductivity is found at different amounts of poor-solvent for each type of polymer. It is also shown that low volatility solvent mixtures allow for the formation of thermoreversible conjugated polymer organogels in thin-films at room temperature. This work highlights the potential to engineer the structure of conjugated polymer organogels while enabling the use of interconnected gel structures in thin-film organic electronic devices. PMID:25287514

  8. Acoustic Waves in Medical Imaging and Diagnostics

    PubMed Central

    Sarvazyan, Armen P.; Urban, Matthew W.; Greenleaf, James F.

    2013-01-01

    Up until about two decades ago acoustic imaging and ultrasound imaging were synonymous. The term “ultrasonography,” or its abbreviated version “sonography” meant an imaging modality based on the use of ultrasonic compressional bulk waves. Since the 1990s numerous acoustic imaging modalities started to emerge based on the use of a different mode of acoustic wave: shear waves. It was demonstrated that imaging with these waves can provide very useful and very different information about the biological tissue being examined. We will discuss physical basis for the differences between these two basic modes of acoustic waves used in medical imaging and analyze the advantages associated with shear acoustic imaging. A comprehensive analysis of the range of acoustic wavelengths, velocities, and frequencies that have been used in different imaging applications will be presented. We will discuss the potential for future shear wave imaging applications. PMID:23643056

  9. Determination of near-surface material properties by line-focus acoustic microscopy

    SciTech Connect

    Achenbach, J.D.; Li, W.

    1996-12-31

    A line-focus acoustic microscope is used in conjunction with a multiple wave-mode method to determine elastic constants from a single V(z) measurement. V(z) curves which include contributions from different wave modes, measured using the line-focus acoustic microscope at 225 MHz, have been compared with theoretical results predicted by a V(z) measurement model. The determination of elastic constants has been achieved numerically by seeking a set of elastic constants that leads to the best fit, in the least square sense, of the theoretical results to the experimental ones. The method has been applied to isotropic materials in bulk, and plate and thin-film configurations. Elastic constants for each of these cases have been determined. The consistency, convergence, sensitivity and accuracy of the procedure have been investigated.

  10. Room Acoustics

    NASA Astrophysics Data System (ADS)

    Kuttruff, Heinrich; Mommertz, Eckard

    The traditional task of room acoustics is to create or formulate conditions which ensure the best possible propagation of sound in a room from a sound source to a listener. Thus, objects of room acoustics are in particular assembly halls of all kinds, such as auditoria and lecture halls, conference rooms, theaters, concert halls or churches. Already at this point, it has to be pointed out that these conditions essentially depend on the question if speech or music should be transmitted; in the first case, the criterion for transmission quality is good speech intelligibility, in the other case, however, the success of room-acoustical efforts depends on other factors that cannot be quantified that easily, not least it also depends on the hearing habits of the listeners. In any case, absolutely "good acoustics" of a room do not exist.

  11. Acoustic Neuroma

    MedlinePlus

    ... slow growing tumor which arise primarily from the vestibular portion of the VIII cranial nerve and lie ... you have a "brain tumor" called acoustic neuroma (vestibular schwannoma). You think you are the only one ...

  12. Underwater Acoustics

    NASA Astrophysics Data System (ADS)

    Kuperman, William A.; Roux, Philippe

    It is well underwater established that sound waves, compared to electromagnetic waves, propagate long distances in the ocean. Hence, in the ocean as opposed to air or a vacuum, one uses sound navigation and ranging (SONAR) instead navigation and ranging (SONAR) of radar, acoustic communication instead of radio, and acoustic imaging and tomography instead of microwave or optical imaging or X-ray tomography. Underwater acoustics is the science of sound in water (most commonly in the ocean) and encompasses not only the study of sound propagation, but also the masking of sound signals by interfering phenomenon and signal processing for extracting these signals from interference. This chapter we will present the basics physics of ocean acoustics and then discuss applications.

  13. Bulk chlorine uptake by polyamide active layers of thin-film composite membranes upon exposure to free chlorine-kinetics, mechanisms, and modeling.

    PubMed

    Powell, Joshua; Luh, Jeanne; Coronell, Orlando

    2014-01-01

    We studied the volume-averaged chlorine (Cl) uptake into the bulk region of the aromatic polyamide active layer of a reverse osmosis membrane upon exposure to free chlorine. Volume-averaged measurements were obtained using Rutherford backscattering spectrometry with samples prepared at a range of free chlorine concentrations, exposure times, and mixing, rinsing, and pH conditions. Our volume-averaged measurements complement previous studies that have quantified Cl uptake at the active layer surface (top ≈ 7 nm) and advance the mechanistic understanding of Cl uptake by aromatic polyamide active layers. Our results show that surface Cl uptake is representative of and underestimates volume-averaged Cl uptake under acidic conditions and alkaline conditions, respectively. Our results also support that (i) under acidic conditions, N-chlorination followed by Orton rearrangement is the dominant Cl uptake mechanism with N-chlorination as the rate-limiting step; (ii) under alkaline conditions, N-chlorination and dechlorination of N-chlorinated amide links by hydroxyl ion are the two dominant processes; and (iii) under neutral pH conditions, the rates of N-chlorination and Orton rearrangement are comparable. We propose a kinetic model that satisfactorily describes Cl uptake under acidic and alkaline conditions, with the largest discrepancies between model and experiment occurring under alkaline conditions at relatively high chlorine exposures. PMID:24506252

  14. Piezoelectric thin films and their applications for electronics

    NASA Astrophysics Data System (ADS)

    Yoshino, Yukio

    2009-03-01

    ZnO and AlN piezoelectric thin films have been studied for applications in bulk acoustic wave (BAW) resonator. This article introduces methods of forming ZnO and AlN piezoelectric thin films by radio frequency sputtering and applications of BAW resonators considering the relationship between the crystallinity of piezoelectric thin films and the characteristics of the BAW resonators. Using ZnO thin films, BAW resonators were fabricated for a contour mode at 3.58 MHz and thickness modes from 200 MHz to 5 GHz. The ZnO thin films were combined with various materials, substrates, and thin films to minimize the temperature coefficient of frequency (TCF). The minimum TCF of BAW resonators was approximately 2 ppm/°C in the range -20 to 80 °C. The electromechanical coupling coefficient (k2) in a 1.9 GHz BAW resonator was 6.9%. Using AlN thin films, 5-20 GHz BAW resonators with an ultrathin membrane were realized. The membrane thickness of a 20 GHz BAW resonator was about 200 nm, k2 was 6.1%, and the quality factor (Q) was about 280. Q decreased with increasing resonant frequency. The value of k2 is almost the same for 5-20 GHz resonators. This result could be obtained by improving the thickness uniformity, by controlling internal stress of thin films, and by controlling the crystallinity of AlN piezoelectric thin film.

  15. Influences of Crystalline Anisotropy, Doping, Porosity, and Connectivity on the Critical Current Densities of Superconducting Magnesium Diboride Bulks, Wires, and Thin Films

    NASA Astrophysics Data System (ADS)

    Susner, Michael Adam

    Magnesium diboride (MgB2) is a material with a superconducting transition temperature of 39 K. Discovered in 2001, the relatively large coherence length (and associated lack of weak links) together with its simple binary composition (making phase pure formation relatively easy) have made it a material of substantial interest. However, it has been difficult to assess in detail the relative importance of the roles of flux pinning, crystalline anisotropy, porosity, connectivity, doping, and doping homogeneity on the observed transport limitations of this conductor. This work focused on deconvoluting the most dominant of these effects. First, the overall effects of electrical connectivity and crystalline anisotropy of critical current density (Jc) were investigated. In doing so the Jcs of dense, well-connected c-axis oriented films were compared with the relatively degraded Jcs of standard powder-in-tube MgB2 wires. With the aid of a percolation model it was deduced that at 4.2 K, 10 T. about 60% of the degradation was due to MgB2’s crystalline anisotropy and the remaining 40% to porosity. Second, chemical substitutions onto both the Mg and B sites were investigated in terms of effects on structure and superconducting properties. The homogeneity of C-substitution onto the B site was quantified in terms of the width of the superconducting specific heat transition. Analysis of the results led to optimization of methods for homogeneous doping of C into the B sublattice. Zr substituted onto the Mg sublattice was investigated using samples prepared by pulsed laser deposition (PLD). Changes in magnetic, resistive, superconductive, chemical, and structural properties were studied over a wide range of Zr composition.

  16. Drag Measurements of Porous Plate Acoustic Liners

    NASA Technical Reports Server (NTRS)

    Wolter, John D.

    2005-01-01

    This paper presents the results of direct drag measurements on a variety of porous plate acoustic liners. The existing literature describes numerous studies of drag on porous walls with injection or suction, but relatively few of drag on porous plates with neither injection nor suction. Furthermore, the porosity of the porous plate in existing studies is much lower than typically used in acoustic liners. In the present work, the acoustic liners consisted of a perforated face sheet covering a bulk acoustic absorber material. Factors that were varied in the experiment were hole diameter, hole pattern, face sheet thickness, bulk material type, and size of the gap (if any) between the face sheet and the absorber material.

  17. High Q Miniature Sapphire Acoustic Resonator

    NASA Technical Reports Server (NTRS)

    Wang, Rabi T.; Tjoelker, R. L.

    2010-01-01

    We have demonstrated high Q measurements in a room temperature Miniature Sapphire Acoustic Resonator (MSAR). Initial measurements of bulk acoustic modes in room temperature sapphire at 39 MHz have demonstrated a Q of 8.8 x 10(exp 6). The long term goal of this work is to integrate such a high Q resonator with small, low noise quartz oscillator electronics, providing a fractional frequency stability better than 1 x 10(exp -14) @ 1s.

  18. Gas sensing with acoustic devices

    SciTech Connect

    Martin, S.J.; Frye, G.C.; Spates, J.J.; Butler, M.A.

    1996-12-31

    A survey is made of acoustic devices that are suitable as gas and vapor sensors. This survey focuses on attributes such as operating frequency, mass sensitivity, quality factor (Q), and their ability to be fabricated on a semiconductor substrate to allow integration with electronic circuitry. The treatment of the device surface with chemically-sensitive films to detect species of interest is discussed. Strategies for improving discrimination are described, including sensor arrays and species concentration and separation schemes. The advantages and disadvantages of integrating sensors with microelectronics are considered, along with the effect on sensitivity of scaling acoustic gas sensors to smaller size.

  19. Holographic interpretation of acoustic black holes

    NASA Astrophysics Data System (ADS)

    Ge, Xian-Hui; Sun, Jia-Rui; Tian, Yu; Wu, Xiao-Ning; Zhang, Yun-Long

    2015-10-01

    With the attempt to find the holographic description of the usual acoustic black holes in fluid, we construct an acoustic black hole formed in the d -dimensional fluid located at the timelike cutoff surface of a neutral black brane in asymptotically AdSd +1 spacetime; the bulk gravitational dual of the acoustic black hole is presented at the first order of the hydrodynamic fluctuation. Moreover, the Hawking-like temperature of the acoustic black hole horizon is showed to be connected to the Hawking temperature of the real anti-de Sitter (AdS) black brane in the bulk, and the duality between the phonon scattering in the acoustic black hole and the sound channel quasinormal mode propagating in the bulk perturbed AdS black brane is extracted. We thus point out that the acoustic black hole appearing in fluid, which was originally proposed as an analogous model to simulate Hawking radiation of the real black hole, is not merely an analogy, it can indeed be used to describe specific properties of the real AdS black holes, in the spirit of the fluid/gravity duality.

  20. Acoustically enhanced heat transport.

    PubMed

    Ang, Kar M; Yeo, Leslie Y; Friend, James R; Hung, Yew Mun; Tan, Ming K

    2016-01-01

    We investigate the enhancement of heat transfer in the nucleate boiling regime by inducing high frequency acoustic waves (f ∼ 10(6) Hz) on the heated surface. In the experiments, liquid droplets (deionized water) are dispensed directly onto a heated, vibrating substrate. At lower vibration amplitudes (ξs ∼ 10(-9) m), the improved heat transfer is mainly due to the detachment of vapor bubbles from the heated surface and the induced thermal mixing. Upon increasing the vibration amplitude (ξs ∼ 10(-8) m), the heat transfer becomes more substantial due to the rapid bursting of vapor bubbles happening at the liquid-air interface as a consequence of capillary waves travelling in the thin liquid film between the vapor bubble and the air. Further increases then lead to rapid atomization that continues to enhance the heat transfer. An acoustic wave displacement amplitude on the order of 10(-8) m with 10(6) Hz order frequencies is observed to produce an improvement of up to 50% reduction in the surface temperature over the case without acoustic excitation. PMID:26827343

  1. Acoustically enhanced heat transport

    NASA Astrophysics Data System (ADS)

    Ang, Kar M.; Yeo, Leslie Y.; Friend, James R.; Hung, Yew Mun; Tan, Ming K.

    2016-01-01

    We investigate the enhancement of heat transfer in the nucleate boiling regime by inducing high frequency acoustic waves (f ˜ 106 Hz) on the heated surface. In the experiments, liquid droplets (deionized water) are dispensed directly onto a heated, vibrating substrate. At lower vibration amplitudes (ξs ˜ 10-9 m), the improved heat transfer is mainly due to the detachment of vapor bubbles from the heated surface and the induced thermal mixing. Upon increasing the vibration amplitude (ξs ˜ 10-8 m), the heat transfer becomes more substantial due to the rapid bursting of vapor bubbles happening at the liquid-air interface as a consequence of capillary waves travelling in the thin liquid film between the vapor bubble and the air. Further increases then lead to rapid atomization that continues to enhance the heat transfer. An acoustic wave displacement amplitude on the order of 10-8 m with 106 Hz order frequencies is observed to produce an improvement of up to 50% reduction in the surface temperature over the case without acoustic excitation.

  2. ROTARY BULK SOLIDS DIVIDER

    DOEpatents

    Maronde, Carl P.; Killmeyer JR., Richard P.

    1992-03-03

    An apparatus for the disbursement of a bulk solid sample comprising, a gravity hopper having a top open end and a bottom discharge end, a feeder positioned beneath the gravity hopper so as to receive a bulk solid sample flowing from the bottom discharge end, and a conveyor receiving the bulk solid sample from the feeder and rotating on an axis that allows the bulk solid sample to disperse the sample to a collection station.

  3. Rotary bulk solids divider

    DOEpatents

    Maronde, Carl P.; Killmeyer, Jr., Richard P.

    1992-01-01

    An apparatus for the disbursement of a bulk solid sample comprising, a gravity hopper having a top open end and a bottom discharge end, a feeder positioned beneath the gravity hopper so as to receive a bulk solid sample flowing from the bottom discharge end, and a conveyor receiving the bulk solid sample from the feeder and rotating on an axis that allows the bulk solid sample to disperse the sample to a collection station.

  4. Bulk Fuel Man.

    ERIC Educational Resources Information Center

    Marine Corps Inst., Washington, DC.

    This student guide, one of a series of correspondence training courses designed to improve the job performance of members of the Marine Corps, deals with the skills needed by bulk fuel workers. Addressed in the four individual units of the course are the following topics: bulk fuel equipment, bulk fuel systems, procedures for handling fuels, and…

  5. Growth of <1100> Epitaxial ZnO Film on Y-Plane LiNbO3 Substrate

    NASA Astrophysics Data System (ADS)

    Kadota, Michio; Ito, Yoshihiro; Kobayashi, Hideaki

    2008-05-01

    A <0001> oriented polycrystal ZnO film is deposited on many types of substrate. However, an epitaxial ZnO film is deposited on only specific substrates, because it depends greatly on the lattice constant of the substrate. An epitaxial ZnO film with the c-axis oriented horizontally on some types of substrate has been reported. In this study, a <1100> orientated epitaxial ZnO film has been deposited on a pre-heat-treated Y-plane (0110) LiNbO3 substrate for the first time. A <0001> oriented polycrystal ZnO film has also been deposited on this substrate without pre-heat-treatment. Thus, two orientation directions can be controlled by pre-heat-treatment for the first time. Moreover, their applications to shear bulk wave transducers and surface acoustic wave devices are discussed.

  6. 19 CFR 149.4 - Bulk and break bulk cargo.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...

  7. 19 CFR 149.4 - Bulk and break bulk cargo.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 19 Customs Duties 2 2012-04-01 2012-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...

  8. 19 CFR 149.4 - Bulk and break bulk cargo.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 2 2014-04-01 2014-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...

  9. 19 CFR 149.4 - Bulk and break bulk cargo.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 2 2011-04-01 2011-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...

  10. 19 CFR 149.4 - Bulk and break bulk cargo.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 2 2013-04-01 2013-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...

  11. Surface acoustic wave/silicon monolithic sensor/processor

    NASA Technical Reports Server (NTRS)

    Kowel, S. T.; Kornreich, P. G.; Nouhi, A.; Kilmer, R.; Fathimulla, M. A.; Mehter, E.

    1983-01-01

    A new technique for sputter deposition of piezoelectric zinc oxide (ZnO) is described. An argon-ion milling system was converted to sputter zinc oxide films in an oxygen atmosphere using a pure zinc oxide target. Piezoelectric films were grown on silicon dioxide and silicon dioxide overlayed with gold. The sputtered films were evaluated using surface acoustic wave measurements, X-ray diffraction, scanning electron microscopy, Auger electron spectroscopy, and resistivity measurements. The effect of the sputtering conditions on the film quality and the result of post-deposition annealing are discussed. The application of these films to the generation of surface acoustic waves is also discussed.

  12. Acoustic transducer for acoustic microscopy

    DOEpatents

    Khuri-Yakub, Butrus T.; Chou, Ching H.

    1990-01-01

    A shear acoustic transducer-lens system in which a shear polarized piezoelectric material excites shear polarized waves at one end of a buffer rod having a lens at the other end which excites longitudinal waves in a coupling medium by mode conversion at selected locations on the lens.

  13. Acoustic transducer for acoustic microscopy

    DOEpatents

    Khuri-Yakub, B.T.; Chou, C.H.

    1990-03-20

    A shear acoustic transducer-lens system is described in which a shear polarized piezoelectric material excites shear polarized waves at one end of a buffer rod having a lens at the other end which excites longitudinal waves in a coupling medium by mode conversion at selected locations on the lens. 9 figs.

  14. The acoustic spectrophonometer: a novel bioanalytical technique based on multifrequency acoustic devices.

    PubMed

    Stevenson, A C; Araya-Kleinsteuber, B; Sethi, R S; Mehta, H M; Lowe, C R

    2003-10-01

    A measurement technique similar to optical absorption spectroscopy but based on evanescent acoustic waves is described in this paper. This format employs a planar spiral coil to vibrate a single crystal of quartz from 6 to 400 MHz, in order to measure multifrequency acoustic spectra. Consistency with the defined Sauerbrey and Kanazawa terms K1 and K2 when applied to multiple frequencies was found for these specific operating conditions in terms of a significant fit between the measured and calculated values: For an IgG surface density of 13.5 ng mm(-2) the measured value of K1 is 22.5 x 10(-6) and the calculated value is 20.4 x 10(-6), whilst for glycerol viscous loadings of 5.131 cP the measured value of K2 is 0.47 and the calculated value is 0.54. Thus for these specific surface loadings the multifrequency data fits to the predictions of the Sauerbrey model to within 10% and to Kanazawa model within 13%. However collective frequency shifts for 5.131 cP solutions of sucrose, dextran and glucose were found to exhibit an unanticipated additional variability (R2 < 0.4) with frequency, but retained a square root of frequency dependency within a factor 2 of the interpolated K2 values. The response to the 5.131 cP dextran solution was found to be significantly below the other isoviscous solutions, with a substantially reduced frequency shift and K2 value than would be expected from its bulk viscosity. In comparison with these viscous solutions, IgG protein films consistently produced linear frequency shifts with little scatter (R2 > 0.96) that were proportional to the operating frequency, and fully consistent with the Sauerbrey model under these specific conditions. A t-test value of 14.52 was calculated from the variance and mean of the two groups, and demonstrates that the acoustic spectrophonometer can be used to distinguish between the acoustic impedance characteristics of two chemical systems that are not clearly differentiable at a single operating frequency. PMID

  15. Medical Acoustics

    NASA Astrophysics Data System (ADS)

    Beach, Kirk; Dunmire, Barbrina

    Medical acoustics can be subdivided into diagnostics and therapy. Diagnostics are further separated into auditory and ultrasonic methods, and both employ low amplitudes. Therapy (excluding medical advice) uses ultrasound for heating, cooking, permeablizing, activating and fracturing tissues and structures within the body, usually at much higher amplitudes than in diagnostics. Because ultrasound is a wave, linear wave physics are generally applicable, but recently nonlinear effects have become more important, even in low-intensity diagnostic applications.

  16. Acoustic chaos

    SciTech Connect

    Lauterborn, W.; Parlitz, U.; Holzfuss, J.; Billo, A.; Akhatov, I.

    1996-06-01

    Acoustic cavitation, a complex, spatio-temporal dynamical system, is investigated with respect to its chaotic properties. The sound output, the {open_quote}{open_quote}noise{close_quote}{close_quote}, is subjected to time series analysis. The spatial dynamics of the bubble filaments is captured by high speed holographic cinematography and subsequent digital picture processing from the holograms. Theoretical models are put forward for describing the pattern formation. {copyright} {ital 1996 American Institute of Physics.}

  17. Writing magnetic patterns with surface acoustic waves

    SciTech Connect

    Li, Weiyang; Buford, Benjamin; Jander, Albrecht; Dhagat, Pallavi

    2014-05-07

    A novel patterning technique that creates magnetization patterns in a continuous magnetostrictive film with surface acoustic waves is demonstrated. Patterns of 10 μm wide stripes of alternating magnetization and a 3 μm dot of reversed magnetization are written using standing and focusing acoustic waves, respectively. The magnetization pattern is size-tunable, erasable, and rewritable by changing the magnetic field and acoustic power. This versatility, along with its solid-state implementation (no moving parts) and electronic control, renders it as a promising technique for application in magnetic recording, magnonic signal processing, magnetic particle manipulation, and spatial magneto-optical modulation.

  18. Acoustically based fetal heart rate monitor

    NASA Technical Reports Server (NTRS)

    Baker, Donald A.; Zuckerwar, Allan J.

    1991-01-01

    The acoustically based fetal heart rate monitor permits an expectant mother to perform the fetal Non-Stress Test in her home. The potential market would include the one million U.S. pregnancies per year requiring this type of prenatal surveillance. The monitor uses polyvinylidene fluoride (PVF2) piezoelectric polymer film for the acoustic sensors, which are mounted in a seven-element array on a cummerbund. Evaluation of the sensor ouput signals utilizes a digital signal processor, which performs a linear prediction routine in real time. Clinical tests reveal that the acoustically based monitor provides Non-Stress Test records which are comparable to those obtained with a commercial ultrasonic transducer.

  19. Containerless processing of materials by acoustic levitation

    NASA Astrophysics Data System (ADS)

    Gao, J. R.; Cao, C. D.; Wei, B.

    1999-01-01

    A single-axis ultrasonic levitator which can be applied to containerless processing of materials was described. Analytical expressions of acoustic pressure, acoustic radiation potential and force were derived from the velocity potential function of the applied acoustic field. The levitation region and the levitation stability were then discussed. A sphere of liquid crystal, 4-pentylphenyl-4‧-methylbenzoate, was also selected for containerless melting and solidification using the levitator. The results showed that rapid heating of the sample is necessary so as to avoid its escape from the levitation region. However, the measured bulk undercooling of the melt is smaller than that obtained using a container. It was supposed that ultrasonic cavitation produce a local undercooling large enough to initiate solidification of the melt, thus leading to a limited bulk undercooling.

  20. Acoustic Tooth Cleaner

    NASA Technical Reports Server (NTRS)

    Heyman, J. S.

    1984-01-01

    Acoustically-energized water jet aids in plaque breakdown. Acoustic Wand includes acoustic transducer 1/4 wave plate, and tapered cone. Together elements energize solution of water containing mild abrasive injected into mouth to help prevent calculous buildup.

  1. What does See the Impulse Acoustic Microscopy inside Nanocomposites?

    NASA Astrophysics Data System (ADS)

    Levin, V. M.; Petronyuk, Y. S.; Morokov, E. S.; Celzard, A.; Bellucci, S.; Kuzhir, P. P.

    The paper presents results of studying bulk microstructure in carbon nanocomposites by impulse acoustic microscopy technique. Nanocomposite materials are in the focus of interest because of their outstanding properties in minimal nanofiller content. Large surface area and high superficial activity cause strong interaction between nanoparticles that can result in formation of fractal conglomerates. This paper involves results of the first direct observation of nanoparticle conglomerates inside the bulk of epoxy-carbon nanocomposites. Diverse types of carbon nanofiller have been under investigation. The impulse acoustic microscope SIAM-1 (Acoustic Microscopy Lab, IBCP RAS) has been employed for 3D imaging bulk microstructure and measuring elastic properties of the nanocomposite specimens. The range of 50-200 MHz allows observing microstructure inside the entire specimen bulk. Acoustic images are obtained in the ultramicroscopic regime; they are formed by the Rayleigh type scattered radiation. It has been found the high-resolution acoustic vision (impulse acoustic microscopy) is an efficient technique to observe mesostructure formed by fractal cluster inside nanocomposites. The clusterization takes its utmost form in nanocomposites with graphite nanoplatelets as nanofiller. The nanoparticles agglomerate into micron-sized conglomerates distributed randomly over the material. Mesostructure in nanocomposites filled with carbon nanotubes is alternation of regions with diverse density of nanotube packing. Regions with alternative density of CNT packing are clearly seen in acoustical images as neighboring pixels of various brightness.

  2. Analysis of spurious bulk waves in ball surface wave device.

    PubMed

    Ishikawa, Satoru; Cho, Hideo; Tsukahara, Yusuke; Nakaso, Noritaka; Yamanaka, Kazushi

    2003-01-01

    We analyzed the acoustic waves propagating in a sphere to establish a useful guideline for the design of NDE apparatus and ball surface acoustic wave (SAW) device exploiting the diffraction-free propagation of SAW on a sphere. First, we calculated the laser-generated acoustic displacements both under ablation condition and under thermoelastic condition and verified experimentally the validity of the calculation. Next, the acoustic waves excited by out-of-plane stress and those excited by in-plane stress were compared. The results showed that when the out-of-plane stress was applied, the relative amplitudes of the bulk waves to that of the SAW were larger and the number of bulk waves was larger than that when the in-plane stress was applied, while the SAW had similar waveforms in each case. The ratio of the relative amplitude of the bulk waves for the out-of-plane stress and the in-plane stress was 3.1:1 at phi(1)=90 degrees and 1.67:1 at phi(1)=0 degrees. The large amplitude for the out-of-plane stress can be explained by wide directivities of bulk waves. Consequently, we found that it is necessary for ball SAW device to select a piezoelectric material and form of interdigital transducer so that the in-plane stress becomes dominant. PMID:12464407

  3. c-axis inclined ZnO films for shear-wave transducers deposited by reactive sputtering using an additional blind

    SciTech Connect

    Link, M.; Schreiter, M.; Weber, J.; Gabl, R.; Pitzer, D.; Primig, R.; Wersing, W.; Assouar, M.B.; Elmazria, O.

    2006-03-15

    This article reports on the growth and characterization of polycrystalline ZnO films having c axis inclined up to 16 deg. with respect to the substrate normal. These films allow the excitation of shear and longitudinal waves with comparable electromechanical coupling constants and are of significant interest for thin film bulk acoustic resonators (FBARs). The films are deposited on silicon substrates covered by Al{sub 2}O{sub 3} and SiO{sub 2} buffer layers under low pressure using a modified reactive dc-pulsed magnetron sputtering system. A blind has been positioned between target and substrate, allowing oblique particle incidence without tilting the wafer. The study of structural properties of the deposited ZnO films by x-ray diffraction and scanning electron microscopy has permitted to show the presence of the inclined structure. Electromechanical coupling constants K up to 13% have been extracted for shear-mode excitation using highly overmoded FBARs.

  4. An acoustic emission study of plastic deformation in polycrystalline aluminium

    NASA Technical Reports Server (NTRS)

    Bill, R. C.; Frederick, J. R.; Felbeck, D. K.

    1979-01-01

    Acoustic emission experiments were performed on polycrystalline and single crystal 99.99% aluminum while undergoing tensile deformation. It was found that acoustic emission counts as a function of grain size showed a maximum value at a particular grain size. Furthermore, the slip area associated with this particular grain size corresponded to the threshold level of detectability of single dislocation slip events. The rate of decline in acoustic emission activity as grain size is increased beyond the peak value suggests that grain boundary associated dislocation sources are giving rise to the bulk of the detected acoustic emissions.

  5. Acoustic design of the QCSEE propulsion systems

    NASA Technical Reports Server (NTRS)

    Loeffler, I. J.; Smith, E. B.; Sowers, H. D.

    1976-01-01

    Acoustic design features and techniques employed in the Quiet Clean Short-Haul Experimental Engine (QCSEE) Program are described. The role of jet/flap noise in selecting the engine fan pressure ratio for powered lift propulsion systems is discussed. The QCSEE acoustic design features include a hybrid inlet (near-sonic throat velocity with acoustic treatment); low fan and core pressure ratios; low fan tip speeds; gear-driven fans; high and low frequency stacked core noise treatment; multiple-thickness treatment; bulk absorber treatment; and treatment on the stator vanes. The QCSEE designs represent and anticipated acoustic technology improvement of 12 to 16 PNdb relative to the noise levels of the low-noise engines used on current wide-body commercial jet transport aircraft.

  6. Anisotropic acoustic metafluid for underwater operation.

    PubMed

    Popa, Bogdan-Ioan; Wang, Wenqi; Konneker, Adam; Cummer, Steven A; Rohde, Charles A; Martin, Theodore P; Orris, Gregory J; Guild, Matthew D

    2016-06-01

    The paper presents a method to design and characterize mechanically robust solid acoustic metamaterials suitable for operation in dense fluids such as water. These structures, also called metafluids, behave acoustically as inertial fluids characterized by anisotropic mass densities and isotropic bulk modulus. The method is illustrated through the design and experimental characterization of a metafluid consisting of perforated steel plates held together by rubber coated magnetic spacers. The spacers are very effective at reducing the effective shear modulus of the structure, and therefore effective at minimizing the ensuing coupling between the shear and pressure waves inside the solid effective medium. Inertial anisotropy together with fluid-like acoustic behavior are key properties that bring transformation acoustics in dense fluids closer to reality. PMID:27369158

  7. Interfacial destabilization and atomization driven by surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Qi, Aisha; Yeo, Leslie Y.; Friend, James R.

    2008-07-01

    Surface acoustic wave atomization is a rapid means for generating micron and submicron aerosol droplets. Little, however, is understood about the mechanisms by which these droplets form due to the complex hydrodynamic processes that occur across widely varying length and time scales. Through experiments, scaling theory, and simple numerical modeling, we elucidate the interfacial destabilization mechanisms that lead to droplet formation. Using a millimeter-order fluid drop exposed to surface acoustic waves as it sits atop a single-crystal lithium niobate piezoelectric substrate, large aerosol droplets on the length scale of the parent drop dimension are ejected through a whipping and pinch-off phenomenon, which occurs at the asymmetrically formed crest of the drop due to leakage of acoustic radiation at the Rayleigh angle. Smaller micron order droplets, on the other hand, are formed due to the axisymmetric breakup of cylindrical liquid jets that are ejected as a consequence of interfacial destabilization. The 10μm droplet dimension correlates with the jet radius and the instability wavelength, both determined from a simple scaling argument involving a viscous-capillary dominant force balance. The results are further supported by numerical solution of the evolution equation governing the interfacial profile of a sessile drop along which an acoustic pressure wave is imposed. Viscous and capillary forces dominate in the bulk of the parent drop, but inertia is dominant in the ejected jets and within a thin boundary layer adjacent to the substrate where surface and interfacial accelerations are large. With the specific exception of parent drops that spread into thin films with thicknesses on the order of the boundary layer dimension prior to atomization, the free surface of the drop is always observed to vibrate at the capillary-viscous resonance frequency—even if the exciting frequency of the surface acoustic wave is several orders of magnitude larger—contrary to

  8. Acoustic Liner for Turbomachinery Applications

    NASA Technical Reports Server (NTRS)

    Huff, Dennis L.; Sutliff, Daniel L.; Jones, Michael G.; Hebsur, Mohan G.

    2010-01-01

    The purpose of this innovation is to reduce aircraft noise in the communities surrounding airports by significantly attenuating the noise generated by the turbomachinery, and enhancing safety by providing a containment barrier for a blade failure. Acoustic liners are used in today's turbofan engines to reduce noise. The amount of noise reduction from an acoustic liner is a function of the treatment area, the liner design, and the material properties, and limited by the constraints of the nacelle or casement design. It is desirable to increase the effective area of the acoustic treatment to increase noise suppression. Modern turbofan engines use wide-chord rotor blades, which means there is considerable treatment area available over the rotor tip. Turbofan engines require containment over the rotors for protection from blade failure. Traditional methods use a material wrap such as Kevlar integrated with rub strips and sometimes metal layers (sandwiches). It is possible to substitute the soft rub-strip material with an open-cell metallic foam that provides noise-reduction benefits and a sacrificial material in the first layer of the containment system. An open-cell foam was evaluated that behaves like a bulk acoustic liner, serves as a tip rub strip, and can be integrated with a rotor containment system. Foams can be integrated with the fan-containment system to provide sufficient safety margins and increased noise attenuation. The major innovation is the integration of the foam with the containment.

  9. Acoustic transducer

    DOEpatents

    Drumheller, D.S.

    1997-12-30

    An acoustic transducer is described comprising a one-piece hollow mandrel into the outer surface of which is formed a recess with sides perpendicular to the central axis of the mandrel and separated by a first distance and with a bottom parallel to the central axis and within which recess are a plurality of washer-shaped discs of a piezoelectric material and at least one disc of a temperature-compensating material with the discs being captured between the sides of the recess in a pre-stressed interference fit, typically at 2,000 psi of compressive stress. The transducer also includes a power supply and means to connect to a measurement device. The transducer is intended to be used for telemetry between a measurement device located downhole in an oil or gas well and the surface. The transducer is of an construction that is stronger with fewer joints that could leak fluids into the recess holding the piezoelectric elements than is found in previous acoustic transducers. 4 figs.

  10. Acoustic transducer

    DOEpatents

    Drumheller, Douglas S.

    1997-01-01

    An acoustic transducer comprising a one-piece hollow mandrel into the outer surface of which is formed a recess with sides perpendicular to the central axis of the mandrel and separated by a first distance and with a bottom parallel to the central axis and within which recess are a plurality of washer-shaped discs of a piezoelectric material and at least one disc of a temperature-compensating material with the discs being captured between the sides of the recess in a pre-stressed interference fit, typically at 2000 psi of compressive stress. The transducer also includes a power supply and means to connect to a measurement device. The transducer is intended to be used for telemetry between a measurement device located downhole in an oil or gas well and the surface. The transducer is of an construction that is stronger with fewer joints that could leak fluids into the recess holding the piezoelectric elements than is found in previous acoustic transducers.

  11. Material and Phonon Engineering for Next Generation Acoustic Devices

    NASA Astrophysics Data System (ADS)

    Kuo, Nai-Kuei

    This thesis presents the theoretical and experimental work related to micromachining of low intrinsic loss sapphire and phononic crystals for engineering new classes of electroacoustic devices for frequency control applications. For the first time, a low loss sapphire suspended membrane was fabricated and utilized to form the main body of a piezoelectric lateral overtone bulk acoustic resonator (LOBAR). Since the metalized piezoelectric transducer area in a LOBAR is only a small fraction of the overall resonant cavity (made out of sapphire), high quality factor (Q) overtones are attained. The experiment confirms the low intrinsic mechanical loss of the transferred sapphire thin film, and the resonators exhibit the highest Q of 5,440 at 2.8 GHz ( f·Q of 1.53.1013 Hz). This is also the highest f·Q demonstrated for aluminum-nitride-(AIN)-based Lamb wave devices to date. Beyond demonstrating a low loss device, this experimental work has laid the foundation for the future development of new micromechanical devices based on a high Q, high hardness and chemically resilient material. The search for alternative ways to more efficiently perform frequency control functionalities lead to the exploration of Phononic Crystal (PnC) structures in AIN thin films. Four unit cell designs were theoretically and experimentally investigated to explore the behavior of phononic bandgaps (PBGs) in the ultra high frequency (UHF) range: (i) the conventional square lattice with circular air scatterer, (ii) the inverse acoustic bandgap (IABG) structure, (iii) the fractal PnC, and (iv) the X-shaped PnC. Each unit cell has its unique frequency characteristic that was exploited to synthesize either cavity resonators or improve the performance of acoustic delay lines. The PBGs operate in the range of 770 MHz to 1 GHz and exhibit a maximum acoustic rejection of 40 dB. AIN Lamb wave transducers (LWTs) were employed for the experimental demonstration of the PBGs and cavity resonances. Ultra

  12. Mechanical properties of diamond films: A comparative study of polycrystalline and smooth fine-grained diamonds by Brillouin light scattering

    NASA Astrophysics Data System (ADS)

    Djemia, P.; Dugautier, C.; Chauveau, T.; Dogheche, E.; De Barros, M. I.; Vandenbulcke, L.

    2001-10-01

    Brillouin light scattering, Raman light scattering and x-ray diffraction were used to investigate the elastic and microstructural properties of polycrystalline and smooth fine-grained diamond films of varying diamond quality. They were deposited on a titanium alloy by a two-step microwave plasma-assisted chemical vapor deposition process at 600 °C. Their morphology and roughness were studied by scanning electron microscopy and atomic force microscopy. Their refractive indices were determined by the M-line spectroscopy technique. The diamond purity of all these coatings in terms of the sp3 bonding fraction was deduced from visible and UV Raman spectroscopy as a function of the deposition conditions. All the samples were found to be textured with a <011> crystallographic direction normal to the film plane, leading to essentially hexagonal symmetry of the elastic tensor. By taking advantage of the detection of a number of different acoustic modes, complete elastic characterization of the films was achieved. The elastic constants C11 and C66, respectively, were selectively determined from the frequency of the longitudinal and shear horizontal bulk modes traveling parallel to the film surface. The three remaining elastic constants, namely, C44, C33 and C13, were obtained from detection of the Rayleigh surface wave a bulk shear wave and the bulk longitudinal wave propagating at different angles from the normal to the surface. The values of the elastic constants depend on the deposition conditions and on the microstructural properties of the films, especially the diamond quality and the polycrystalline or smooth fine-grained nature of the diamond. For the polycrystalline diamond film with the best quality, the elastic constants are rather close to the Voigt or Reuss average estimate values using known bulk elastic constants of diamond, whereas those of the smooth fine-grained diamond films are reduced because of the poorer diamond quality leading to lower residual stress

  13. Material fabrication using acoustic radiation forces

    SciTech Connect

    Sinha, Naveen N.; Sinha, Dipen N.; Goddard, Gregory Russ

    2015-12-01

    Apparatus and methods for using acoustic radiation forces to order particles suspended in a host liquid are described. The particles may range in size from nanometers to millimeters, and may have any shape. The suspension is placed in an acoustic resonator cavity, and acoustical energy is supplied thereto using acoustic transducers. The resulting pattern may be fixed by using a solidifiable host liquid, forming thereby a solid material. Patterns may be quickly generated; typical times ranging from a few seconds to a few minutes. In a one-dimensional arrangement, parallel layers of particles are formed. With two and three dimensional transducer arrangements, more complex particle configurations are possible since different standing-wave patterns may be generated in the resonator. Fabrication of periodic structures, such as metamaterials, having periods tunable by varying the frequency of the acoustic waves, on surfaces or in bulk volume using acoustic radiation forces, provides great flexibility in the creation of new materials. Periodicities may range from millimeters to sub-micron distances, covering a large portion of the range for optical and acoustical metamaterials.

  14. Validation of a phase-mass characterization concept and interface for acoustic biosensors.

    PubMed

    Montagut, Yeison; García, José V; Jiménez, Yolanda; March, Carmen; Montoya, Angel; Arnau, Antonio

    2011-01-01

    Acoustic wave resonator techniques are widely used in in-liquid biochemical applications. The main challenges remaining are the improvement of sensitivity and limit of detection, as well as multianalysis capabilities and reliability. The sensitivity improvement issue has been addressed by increasing the sensor frequency, using different techniques such as high fundamental frequency quartz crystal microbalances (QCMs), surface generated acoustic waves (SGAWs) and film bulk acoustic resonators (FBARs). However, this sensitivity improvement has not been completely matched in terms of limit of detection. The decrease on frequency stability due to the increase of the phase noise, particularly in oscillators, has made it impossible to increase the resolution. A new concept of sensor characterization at constant frequency has been recently proposed based on the phase/mass sensitivity equation: Δφ/Δm ≈ -1/m(L), where m(L) is the liquid mass perturbed by the resonator. The validation of the new concept is presented in this article. An immunosensor application for the detection of a low molecular weight pollutant, the insecticide carbaryl, has been chosen as a validation model. PMID:22163871

  15. Electro-thermo-mechanical model for bulk acoustic wave resonators.

    PubMed

    Rocas, Eduard; Collado, Carlos; Mateu, Jordi; Orloff, Nathan D; Aigner, Robert; Booth, James C

    2013-11-01

    We present the electro-thermo-mechanical constitutive relations, expanded up to the third order, for a BAW resonator. The relations obtained are implemented into a circuit model, which is validated with extensive linear and nonlinear measurements. The mathematical analysis, along with the modeling, allows us to identify the dominant terms, which are the material temperature derivatives and two intrinsic nonlinear terms, and explain, for the first time, all observable effects in a BAW resonator by use of a unified physical description. Moreover, the terms that are responsible for the second-harmonic generation and the frequency shift with dc voltage are shown to be the same. PMID:24158294

  16. Acoustic cryocooler

    DOEpatents

    Swift, Gregory W.; Martin, Richard A.; Radenbaugh, Ray

    1990-01-01

    An acoustic cryocooler with no moving parts is formed from a thermoacoustic driver (TAD) driving a pulse tube refrigerator (PTR) through a standing wave tube. Thermoacoustic elements in the TAD are spaced apart a distance effective to accommodate the increased thermal penetration length arising from the relatively low TAD operating frequency in the range of 15-60 Hz. At these low operating frequencies, a long tube is required to support the standing wave. The tube may be coiled to reduce the overall length of the cryocooler. One or two PTR's are located on the standing wave tube adjacent antinodes in the standing wave to be driven by the standing wave pressure oscillations. It is predicted that a heat input of 1000 W at 1000 K will maintian a cooling load of 5 W at 80 K.

  17. Acoustic transducer

    DOEpatents

    Drumheller, Douglas S.

    2000-01-01

    An active acoustic transducer tool for use down-hole applications. The tool includes a single cylindrical mandrel including a shoulder defining the boundary of a narrowed portion over which is placed a sandwich-style piezoelectric tranducer assembly. The piezoelectric transducer assembly is prestressed by being placed in a thermal interference fit between the shoulder of the mandrel and the base of an anvil which is likewise positioned over the narrower portion of the mandrel. In the preferred embodiment, assembly of the tool is accomplished using a hydraulic jack to stretch the mandrel prior to emplacement of the cylindrical sandwich-style piezoelectric transducer assembly and anvil. After those elements are positioned and secured, the stretched mandrel is allowed to return substantially to its original (pre-stretch) dimensions with the result that the piezoelectric transducer elements are compressed between the anvil and the shoulder of the mandrel.

  18. Acoustic hemostasis

    NASA Astrophysics Data System (ADS)

    Crum, L.; Andrew, M.; Bailey, M.; Beach, K.; Brayman, A.; Curra, F.; Kaczkowski, P.; Kargl, S.; Martin, R.; Vaezy, S.

    2003-04-01

    Over the past several years, the Center for Industrial and Medical Ultrasound (CIMU) at the Applied Physics Laboratory in the University of Washington has undertaken a broad research program in the general area of High Intensity Focused Ultrasound (HIFU). Our principal emphasis has been on the use of HIFU to induce hemostasis; in particular, CIMU has sought to develop a small, lightweight, portable device that would use ultrasound for both imaging and therapy. Such a technology is needed because nearly 50% of combat casualty mortality results from exsanguinations, or uncontrolled bleeding. A similar percentage occurs for civilian death due to trauma. In this general review, a presentation of the general problem will be given, as well as our recent approaches to the development of an image-guided, transcutaneous, acoustic hemostasis device. [Work supported in part by the USAMRMC, ONR and the NIH.

  19. A comparison of partially specular radiosity and ray tracing for room acoustics modeling

    NASA Astrophysics Data System (ADS)

    Beamer, C. Walter; Muehleisen, Ralph T.

    2005-04-01

    Partially specular (PS) radiosity is an extended form of the general radiosity method. Acoustic radiosity is a form of bulk transfer of radiant acoustic energy. This bulk transfer is accomplished through a system of energy balance equations that relate the bulk energy transfer of each surface in the system to all other surfaces in the system. Until now acoustic radiosity has been limited to modeling only diffuse surface reflection. The new PS acoustic radiosity method can model all real surface types, diffuse, specular and everything in between. PS acoustic radiosity also models all real source types and distributions, not just point sources. The results of the PS acoustic radiosity method are compared to those of well known ray tracing programs. [Work supported by NSF.

  20. Acoustic telemetry.

    SciTech Connect

    Drumheller, Douglas Schaeffer; Kuszmaul, Scott S.

    2003-08-01

    Broadcasting messages through the earth is a daunting task. Indeed, broadcasting a normal telephone conversion through the earth by wireless means is impossible with todays technology. Most of us don't care, but some do. Industries that drill into the earth need wireless communication to broadcast navigation parameters. This allows them to steer their drill bits. They also need information about the natural formation that they are drilling. Measurements of parameters such as pressure, temperature, and gamma radiation levels can tell them if they have found a valuable resource such as a geothermal reservoir or a stratum bearing natural gas. Wireless communication methods are available to the drilling industry. Information is broadcast via either pressure waves in the drilling fluid or electromagnetic waves in the earth and well tubing. Data transmission can only travel one way at rates around a few baud. Given that normal Internet telephone modems operate near 20,000 baud, these data rates are truly very slow. Moreover, communication is often interrupted or permanently blocked by drilling conditions or natural formation properties. Here we describe a tool that communicates with stress waves traveling through the steel drill pipe and production tubing in the well. It's based on an old idea called Acoustic Telemetry. But what we present here is more than an idea. This tool exists, it's drilled several wells, and it works. Currently, it's the first and only acoustic telemetry tool that can withstand the drilling environment. It broadcasts one way over a limited range at much faster rates than existing methods, but we also know how build a system that can communicate both up and down wells of indefinite length.

  1. MTCI acoustic agglomeration particulate control

    SciTech Connect

    Chandran, R.R.; Mansour, M.N.; Scaroni, A.W.; Koopmann, G.H.; Loth, J.L.

    1994-10-01

    The overall objective of this project is to demonstrate pulse combination induced acoustic enhancement of coal ash agglomeration and sulfur capture at conditions typical of direct coal-fired turbines and PFBC hot gas cleanup. MTCI has developed an advanced compact pulse combustor island for direct coal-firing in combustion gas turbines. This combustor island comprises a coal-fired pulse combustor, a combined ash agglomeration and sulfur capture chamber (CAASCC), and a hot cyclone. In the MTCI proprietary approach, the pulse combustion-induced high intensity sound waves improve sulfur capture efficiency and ash agglomeration. The resulting agglomerates allow the use of commercial cyclones and achieve very high particulate collection efficiency. In the MTCI proprietary approach, sorbent particles are injected into a gas stream subjected to an intense acoustic field. The acoustic field serves to improve sulfur capture efficiency by enhancing both gas film and intra-particle mass transfer rates. In addition, the sorbent particles act as dynamic filter foci, providing a high density of stagnant agglomerating centers for trapping the finer entrained (in the oscillating flow field) fly ash fractions. A team has been formed with MTCI as the prime contractor and Penn State University and West Virginia University as subcontractors to MTCI. MTCI is focusing on hardware development and system demonstration, PSU is investigating and modeling acoustic agglomeration and sulfur capture, and WVU is studying aerovalve fluid dynamics. Results are presented from all three studies.

  2. Arabic Phonology: An Acoustical and Physiological Investigation.

    ERIC Educational Resources Information Center

    Al-Ani, Salman H.

    This book presents an acoustical and physiological Investigation of contemporary standard Arabic as spoken in Iraq. Spectrograms and X-ray sound films are used to perform the analysis for the study. With this equipment, the author considers the vowels, consonants, pharyngealized consonants, pharyngeals and glottals, duration, gemination, and…

  3. Micromachined lead zirconium titanate thin-film-cantilever-based acoustic emission sensor with poly(N-isopropylacrylamide) actuator for increasing contact pressure

    NASA Astrophysics Data System (ADS)

    Feng, Guo-Hua; Chen, Wei-Ming

    2016-05-01

    This paper presents an innovative acousticemission (AE) sensor with a cantilever sensing structure. A hydrothermal lead zirconium titanate (PZT) film was deposited on the cantilever for AE sensing, and an SU8 micropillar at the free end of the cantilever served as an AE wave coupler; in addition, a poly(N-isopropylacrylamide)-based thermoresponsive actuator was integrated with the cantilever to increase the contact pressure exerted on the target. The AE sensor showed higher performance compared with an existing commercial AE sensor. Micromachining technology was used to fabricate AE sensors, and an array of four sensors was fabricated on a 50 μm thick titanium substrate of dimensions 15 mm × 15 mm. The piezoelectric properties of the hydrothermal PZT film were verified by electrically driving the cantilever and measuring the displacement; the piezoelectric constant d 31 of the cantilever was 2.43 pC N‑1. The output force of the sensing cantilever generated by activating the thermoresponsive actuator was determined. For an electrical power input of 2.5 W, the maximum force output at the SU8 micropillar was 1 N. This force corresponded to the application of a pressure of 1.4 MPa on the target. Pencil lead break tests were conducted to determine and compare the performance of the proposed AE sensor with commercial sensors. Here, experimental and theoretical discussions on the effect of the activation of the thermoresponsive actuator of the proposed AE sensor on AE detection are presented.

  4. Selective inorganic thin films

    SciTech Connect

    Phillips, M.L.F.; Weisenbach, L.A.; Anderson, M.T.

    1995-05-01

    This project is developing inorganic thin films as membranes for gas separation applications, and as discriminating coatings for liquid-phase chemical sensors. Our goal is to synthesize these coatings with tailored porosity and surface chemistry on porous substrates and on acoustic and optical sensors. Molecular sieve films offer the possibility of performing separations involving hydrogen, air, and natural gas constituents at elevated temperatures with very high separation factors. We are focusing on improving permeability and molecular sieve properties of crystalline zeolitic membranes made by hydrothermally reacting layered multicomponent sol-gel films deposited on mesoporous substrates. We also used acoustic plate mode (APM) oscillator and surface plasmon resonance (SPR) sensor elements as substrates for sol-gel films, and have both used these modified sensors to determine physical properties of the films and have determined the sensitivity and selectivity of these sensors to aqueous chemical species.

  5. Photoacoustic Evaluation of the Mechanical Properties of Aluminum / Silicon Nitride Double-Layer Thin Films

    NASA Astrophysics Data System (ADS)

    Zhang, Feifei; Krishnaswamy, Sridhar; Lilley, Carmen M.

    2006-03-01

    In this paper, we compare two photoacoustic techniques to characterize the mechanical parameters of edge-supported aluminum and silicon nitride double-layer thin films. In a first set of experiments, a femtosecond transient pump-probe technique is used to investigate the Young's moduli of the aluminum and silicon nitride layers by launching ultra-high frequency bulk acoustic waves in the films. In a second set of experiments, dispersion curves of the A0 mode of the Lamb waves that propagate along the unsupported films are measured using a broadband photoacoustic guided-wave method. The residual stresses and flexural rigidities for the same set of double-layer membranes are determined from these dispersion curves. Comparisons of the results obtained by the two photoacoustic techniques are made.

  6. Consecutive plate acoustic suppressor apparatus and methods

    NASA Technical Reports Server (NTRS)

    Doychak, Joseph (Inventor); Parrott, Tony (Inventor)

    1992-01-01

    An apparatus and method for suppressing acoustic noise utilizes consecutive plates, closely spaced to each other so as to exploit dissipation associated with sound propagation in narrow channels to optimize the acoustic resistance at a liner surface. The closely spaced plates can be utilized as high temperature structural materials for jet engines by constructing the plates from composite materials. Geometries of the plates, such as plate depth, shape, thickness, inter-plate spacing, arrangement, etc., can be selected to achieve bulk material-like behavior.

  7. Consecutive Plate Acoustic Suppressor Apparatus and Methods

    NASA Technical Reports Server (NTRS)

    Doychak, Joseph (Inventor); Parrott, Tony L. (Inventor)

    1993-01-01

    An apparatus and method for suppressing acoustic noise utilizes consecutive plates, closely spaced to each other so as to exploit dissipation associated with sound propagation in narrow channels to optimize the acoustic resistance at a liner surface. The closely spaced plates can be utilized as high temperature structural materials for jet engines by constructing the plates from composite materials. Geometries of the plates, such as plate depth, shape, thickness, inter-plate spacing, arrangement, etc., can be selected to achieve bulk material-like behavior.

  8. Effects of annealing electrodeposited bismuth Telluride films

    NASA Technical Reports Server (NTRS)

    Snyder, J.; Stoltz, N. G.

    2002-01-01

    Thermoelectric thin films exhibit different qualities when compared with bulk materials. The goal however is to achieve thermoelectric properties of bulk materials from electrodeposited thin films. Thin films are produced by electrochemical deposition at room temperature. In order to optimize thermoelectric figure of merit proper carrierconcentration must be obtained.

  9. Acoustic hemostasis

    NASA Astrophysics Data System (ADS)

    Crum, Lawrence; Beach, Kirk; Carter, Stephen; Chandler, Wayne; Curra, Francesco; Kaczkowski, Peter; Keilman, George; Khokhlova, Vera; Martin, Roy; Mourad, Pierre; Vaezy, Shahram

    2000-07-01

    In cases of severe injury, physicians speak of a "golden hour"—a brief grace period in which quickly applied, proper therapy can save the life of the patient. Much of this mortality results from exsanguination, i.e., bleeding to death—often from internal hemorrhage. The inability of a paramedic to treat breaches in the vascular system deep within the body or to stem the loss of blood from internal organs is a major reason for the high level of mortality associated with blunt trauma. We have undertaken an extensive research program to treat the problem of internal bleeding. Our approach is as follows: (a) We use scanning ultrasound to identify internal bleeding and hemorrhage, (b) we use ultrasound imaging to locate specific breaches in the vascular system, both from damaged vessels and gross damage to the capillary bed, and (c) we use High Intensity Focused Ultrasound (HIFU) to treat the damaged region and to induce hemostasis. We present a general review of this research with some emphasis on the role of nonlinear acoustics.

  10. Generation and detection of gigahertz surface acoustic waves using an elastomeric phase-shift mask

    NASA Astrophysics Data System (ADS)

    Li, Dongyao; Zhao, Peng; Zhao, Ji-Cheng; Cahill, David G.

    2013-10-01

    We describe a convenient approach for measuring the velocity vSAW of surface acoustic waves (SAWs) of the near-surface layer of a material through optical pump-probe measurements. The method has a lateral spatial resolution of <10 μm and is sensitive to the elastic constants of the material within ≈300 nm of the surface. SAWs with a wavelength of 700 nm and 500 nm are generated and detected using an elastomeric polydimethylsiloxane phase-shift mask which is fabricated using a commercially available Si grating as a mold. Time-domain electromagnetics calculations show, in agreement with experiment, that the efficiency of the phase-shift mask for generating and detecting SAWs decreases rapidly as the periodicity of the mask decreases below the optical wavelength. We validate the experimental approach using bulk and thin film samples with known elastic constants.

  11. Magnetic resonance imaging of acoustic streaming: absorption coefficient and acoustic field shape estimation.

    PubMed

    Madelin, Guillaume; Grucker, Daniel; Franconi, Jean-Michel; Thiaudiere, Eric

    2006-07-01

    In this study, magnetic resonance imaging (MRI) is used to visualize acoustic streaming in liquids. A single-shot spin echo sequence (HASTE) with a saturation band perpendicular to the acoustic beam permits the acquisition of an instantaneous image of the flow due to the application of ultrasound. An average acoustic streaming velocity can be estimated from the MR images, from which the ultrasonic absorption coefficient and the bulk viscosity of different glycerol-water mixtures can be deduced. In the same way, this MRI method could be used to assess the acoustic field and time-average power of ultrasonic transducers in water (or other liquids with known physical properties), after calibration of a geometrical parameter that is dependent on the experimental setup. PMID:16650447

  12. Artificial Swimmers Propelled by Acoustically Activated Flagella.

    PubMed

    Ahmed, Daniel; Baasch, Thierry; Jang, Bumjin; Pane, Salvador; Dual, Jürg; Nelson, Bradley J

    2016-08-10

    Recent studies have garnered considerable interest in the field of propulsion to maneuver micro- and nanosized objects. Acoustics provide an alternate and attractive method to generate propulsion. To date, most acoustic-based swimmers do not use structural resonances, and their motion is determined by a combination of bulk acoustic streaming and a standing-wave field. The resultant field is intrinsically dependent on the boundaries of their resonating chambers. Though acoustic based propulsion is appealing in biological contexts, existing swimmers are less efficient, especially when operating in vivo, since no predictable standing-wave can be established in a human body. Here we describe a new class of nanoswimmer propelled by the small-amplitude oscillation of a flagellum-like flexible tail in standing and, more importantly, in traveling acoustic waves. The artificial nanoswimmer, fabricated by multistep electrodeposition techniques, compromises a rigid bimetallic head and a flexible tail. During acoustic excitation of the nanoswimmer the tail structure oscillates, which leads to a large amplitude propulsion in traveling waves. FEM simulation results show that the structural resonances lead to high propulsive forces. PMID:27459382

  13. Coherent acoustic phonon oscillation accompanied with backward acoustic pulse below exciton resonance in a ZnO epifilm on oxide-buffered Si(1 1 1)

    NASA Astrophysics Data System (ADS)

    Lin, Ja-Hon; Shen, Yu-Kai; Liu, Wei-Rein; Lu, Chia-Hui; Chen, Yao-Hui; Chang, Chun-peng; Lee, Wei-Chin; Hong, Minghwei; Kwo, Jueinai-Raynien; Hsu, Chia-Hung; Hsieh, Wen-Feng

    2016-08-01

    Unlike coherent acoustic phonons (CAPs) generated from heat induced thermal stress by the coated Au film, we demonstrated the oscillation from c-ZnO epitaxial film on oxide buffered Si through a degenerate pump–probe technique. As the excited photon energy was set below the exciton resonance, the electronic stress that resulted from defect resonance was used to induce acoustic wave. The damped oscillation revealed a superposition of a high frequency and long decay CAP signal with a backward propagating acoustic pulse which was generated by the absorption of the penetrated pump beam at the Si surface and selected by the ZnO layer as the acoustic resonator.

  14. Acoustic source for generating an acoustic beam

    DOEpatents

    Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian

    2016-05-31

    An acoustic source for generating an acoustic beam includes a housing; a plurality of spaced apart piezo-electric layers disposed within the housing; and a non-linear medium filling between the plurality of layers. Each of the plurality of piezoelectric layers is configured to generate an acoustic wave. The non-linear medium and the plurality of piezo-electric material layers have a matching impedance so as to enhance a transmission of the acoustic wave generated by each of plurality of layers through the remaining plurality of layers.

  15. Intelligent front-end sample preparation tool using acoustic streaming.

    SciTech Connect

    Cooley, Erika J.; McClain, Jaime L.; Murton, Jaclyn K.; Edwards, Thayne L.; Achyuthan, Komandoor E.; Branch, Darren W.; Clem, Paul Gilbert; Anderson, John Mueller; James, Conrad D.; Smith, Gennifer; Kotulski, Joseph Daniel

    2009-09-01

    We have successfully developed a nucleic acid extraction system based on a microacoustic lysis array coupled to an integrated nucleic acid extraction system all on a single cartridge. The microacoustic lysing array is based on 36{sup o} Y cut lithium niobate, which couples bulk acoustic waves (BAW) into the microchannels. The microchannels were fabricated using Mylar laminates and fused silica to form acoustic-fluidic interface cartridges. The transducer array consists of four active elements directed for cell lysis and one optional BAW element for mixing on the cartridge. The lysis system was modeled using one dimensional (1D) transmission line and two dimensional (2D) FEM models. For input powers required to lyse cells, the flow rate dictated the temperature change across the lysing region. From the computational models, a flow rate of 10 {micro}L/min produced a temperature rise of 23.2 C and only 6.7 C when flowing at 60 {micro}L/min. The measured temperature changes were 5 C less than the model. The computational models also permitted optimization of the acoustic coupling to the microchannel region and revealed the potential impact of thermal effects if not controlled. Using E. coli, we achieved a lysing efficacy of 49.9 {+-} 29.92 % based on a cell viability assay with a 757.2 % increase in ATP release within 20 seconds of acoustic exposure. A bench-top lysing system required 15-20 minutes operating up to 58 Watts to achieve the same level of cell lysis. We demonstrate that active mixing on the cartridge was critical to maximize binding and release of nucleic acid to the magnetic beads. Using a sol-gel silica bead matrix filled microchannel the extraction efficacy was 40%. The cartridge based magnetic bead system had an extraction efficiency of 19.2%. For an electric field based method that used Nafion films, a nucleic acid extraction efficiency of 66.3 % was achieved at 6 volts DC. For the flow rates we tested (10-50 {micro}L/min), the nucleic acid extraction

  16. Ultrasonic array of thick film transducers for biological tissue characterization.

    PubMed

    Gwirc, Sergio N; Negreira, Carlos A; Marino, Nestor R

    2010-01-01

    The initial motivation for this work was to accomplish an easy way to manufacture different geometries of ultrasonic transducers and arrays using a PZT powder, combined with a standard process to have repetitive series of them. The piezoelectric thick film was obtained using a PZT paste and applying it by screen printing on an alumina substrate. Then, the film was drying and sintered with a temperature-time profile determined by the paste characteristics. Each transducer is composed by three layers, one by PZT and two acting as electrodes. The active element of the paste is a PZT powder which is dispersed in a commercial vehicle to obtain rheological properties suitable for use the screen printing process. The connection between PZT particles is improved by adding a lead borosilicate frit glass that also helps to attach the film to the substrate due to the relatively low temperature of sintered that has been used in this process. The PZT film has low density that is generated by internal porosity, so its acoustic impedance is lower than for a bulk ceramic transducer and so is well adapted to testing human tissues. At the same time the thick film technology is well suited to make medium size transducers and also arrays performed with tiny ultrasonic transducers. PMID:21097177

  17. Acoustic Holography

    NASA Astrophysics Data System (ADS)

    Kim, Yang-Hann

    One of the subtle problems that make noise control difficult for engineers is the invisibility of noise or sound. A visual image of noise often helps to determine an appropriate means for noise control. There have been many attempts to fulfill this rather challenging objective. Theoretical (or numerical) means for visualizing the sound field have been attempted, and as a result, a great deal of progress has been made. However, most of these numerical methods are not quite ready for practical applications to noise control problems. In the meantime, rapid progress with instrumentation has made it possible to use multiple microphones and fast signal-processing systems. Although these systems are not perfect, they are useful. A state-of-the-art system has recently become available, but it still has many problematic issues; for example, how can one implement the visualized noise field. The constructed noise or sound picture always consists of bias and random errors, and consequently, it is often difficult to determine the origin of the noise and the spatial distribution of the noise field. Section 26.2 of this chapter introduces a brief history, which is associated with sound visualization, acoustic source identification methods and what has been accomplished with a line or surface array. Section 26.2.3 introduces difficulties and recent studies, including de-Dopplerization and de-re verberation methods, both essential for visualizing a moving noise source, such as occurs for cars or trains. This section also addresses what produces ambiguity in realizing real sound sources in a room or closed space. Another major issue associated with sound/noise visualization is whether or not we can distinguish between mutual dependencies of noise in space (Sect. 26.2.4); for example, we are asked to answer the question, Can we see two birds singing or one bird with two beaks?

  18. Acoustic Holography

    NASA Astrophysics Data System (ADS)

    Kim, Yang-Hann

    One of the subtle problems that make noise control difficult for engineers is the invisibility of noise or sound. A visual image of noise often helps to determine an appropriate means for noise control. There have been many attempts to fulfill this rather challenging objective. Theoretical (or numerical) means for visualizing the sound field have been attempted, and as a result, a great deal of progress has been made. However, most of these numerical methods are not quite ready for practical applications to noise control problems. In the meantime, rapid progress with instrumentation has made it possible to use multiple microphones and fast signal-processing systems. Although these systems are not perfect, they are useful. A state-of-the-art system has recently become available, but it still has many problematic issues; for example, how can one implement the visualized noise field. The constructed noise or sound picture always consists of bias and random errors, and consequently, it is often difficult to determine the origin of the noise and the spatial distribution of the noise field. Section 26.2 of this chapter introduces a brief history, which is associated with "sound visualization," acoustic source identification methods and what has been accomplished with a line or surface array. Section 26.2.3 introduces difficulties and recent studies, including de-Dopplerization and de-reverberation methods, both essentialfor visualizing a moving noise source, such as occurs for cars or trains. This section also addresses what produces ambiguity in realizing real sound sources in a room or closed space. Another major issue associated with sound/noise visualization is whether or not we can distinguish between mutual dependencies of noise in space (Sect. 26.2.4); for example, we are asked to answer the question, "Can we see two birds singing or one bird with two beaks?"

  19. Post Test Evaluation of HSCT Nozzle Acoustic Liner Subcomponents Subjected to a Hot Acoustic Durability Test

    NASA Technical Reports Server (NTRS)

    Verrilli, Michael J.; Lee, Kuan

    2008-01-01

    The acoustic liner system designed for use in the High Speed Civil Transport (HSCT) was tested in a thermal-acoustic environment. Five ceramic matrix composite (CMC) acoustic tile configurations, five bulk acoustic absorbers, and one thermal protection system design were tested. The CMC acoustic tiles were subjected to two 2 3/4 hr ambient temperature acoustic exposures to measure their dynamic response. One exposure was conducted on the tiles alone and the second exposure included the tiles and the T-foam bulk absorber. The measured tile RMS strains were small. With or without the T-foam absorber, the dynamic strains were below strain levels that would cause damage during fatigue loading. After the ambient exposure, a 75-hr durability test of the entire acoustic liner system was conducted using a thermal-acoustic cycle that approximated the anticipated service cycle. Acoustic loads up to 139 dB/Hz and temperatures up to 1670 F (910 C) were employed during this 60 cycle test. During the durability test, the CMC tiles were exposed to temperatures up to 1780 F and a transient through thickness gradient up to 490 F. The TPS peak temperatures on the hot side of the panels ranged from 750 to 1000 F during the 60 cycles. The through thickness delta T ranged from 450 to 650 F, varying with TPS location and cycle number. No damage, such as cracks or chipping, was observed in the CMC tiles after completion of the testing. However, on tile warped during the durability test and was replaced after 43 or 60 cycles. No externally observed damage was found in this tile. No failure of the CMC fasteners occurred, but damage was observed. Cracks and missing material occurred, only in the fastener head region. No indication of damage was observed in the T-foam acoustic absorbers. The SiC foam acoustic absorber experienced damage after about 43 cycles. Cracking in the TPS occurred around the attachment holes and under a vent. In spite of the development of damage, the TPS maintained

  20. Hydrogels: DNA bulks up

    NASA Astrophysics Data System (ADS)

    Labean, Thom

    2006-10-01

    Since the 1940s DNA has been known as the genetic material connected to heredity, and from the early 1980s it has also been considered as a potential structural material for nanoscale construction. Now, a hydrogel made entirely of DNA brings this molecule into the realm of bulk materials.

  1. What Is an Acoustic Neuroma

    MedlinePlus

    ... Acoustic Neuroma An acoustic neuroma, also called a vestibular schwannoma, is a rare benign tumor of the ... Acoustic Neuroma? An acoustic neuroma, known as a vestibular schwannoma, is a benign (non-cancerous) growth that ...

  2. Canonical Acoustics and Its Application to Surface Acoustic Wave on Acoustic Metamaterials

    NASA Astrophysics Data System (ADS)

    Shen, Jian Qi

    2016-08-01

    In a conventional formalism of acoustics, acoustic pressure p and velocity field u are used for characterizing acoustic waves propagating inside elastic/acoustic materials. We shall treat some fundamental problems relevant to acoustic wave propagation alternatively by using canonical acoustics (a more concise and compact formalism of acoustic dynamics), in which an acoustic scalar potential and an acoustic vector potential (Φ ,V), instead of the conventional acoustic field quantities such as acoustic pressure and velocity field (p,u) for characterizing acoustic waves, have been defined as the fundamental variables. The canonical formalism of the acoustic energy-momentum tensor is derived in terms of the acoustic potentials. Both the acoustic Hamiltonian density and the acoustic Lagrangian density have been defined, and based on this formulation, the acoustic wave quantization in a fluid is also developed. Such a formalism of acoustic potentials is employed to the problem of negative-mass-density assisted surface acoustic wave that is a highly localized surface bound state (an eigenstate of the acoustic wave equations). Since such a surface acoustic wave can be strongly confined to an interface between an acoustic metamaterial (e.g., fluid-solid composite structures with a negative dynamical mass density) and an ordinary material (with a positive mass density), it will give rise to an effect of acoustic field enhancement on the acoustic interface, and would have potential applications in acoustic device design for acoustic wave control.

  3. Acoustic energy-driven fluid pump and method

    SciTech Connect

    Janus, Michael C.; Richards, George A.; Robey, Edward H.

    1997-12-01

    Bulk fluid motion is promoted in a gaseous fluid contained within a conduit system provided with a diffuser without the need for a mean pressure differential across the conduit system. The contacting of the gaseous fluid with unsteady energy at a selected frequency and pressure amplitude induces fluid flow through the conical diffuser. The unsteady energy can be provided by pulse combustors, thermoacoustic engines, or acoustic energy generators such as acoustic speakers.

  4. Acoustical properties of highly porous fibrous materials

    NASA Technical Reports Server (NTRS)

    Lambert, R. F.

    1979-01-01

    Highly porous, fibrous bulk sound absorbing materials are studied with a view toward understanding their acoustical properties and performance in a wide variety of applications including liners of flow ducts. The basis and criteria for decoupling of acoustic waves in the pores of the frame and compressional waves in the frame structure are established. The equations of motion are recast in a form that elucidates the coupling mechanisms. The normal incidence surface impedance and absorption coefficient of two types of Kevlar 29 and an open celled foam material are studied. Experimental values and theoretical results are brought into agreement when the structure factor is selected to provide a fit to the experimental data. A parametric procedure for achieving that fit is established. Both a bulk material quality factor and a high frequency impedance level are required to characterize the real and imaginary part of the surface impedance and absorption coefficient. A derivation of the concepts of equivalent density and dynamic resistance is presented.

  5. Soap film vibration: origin of the dissipation.

    PubMed

    Acharige, Sébastien Kosgodagan; Elias, Florence; Derec, Caroline

    2014-11-01

    We investigate the complex dispersion relationship of a transverse antisymmetric wave on a horizontal soap film. Experimentally, the complex wave number k at a fixed forcing frequency is determined by measuring the vibrating amplitude of the soap film: the wavelength (linked to the real part of k) is determined by the spatial variation of the amplitude; the decay length (linked to the imaginary part of k) is determined by analyzing the resonance curves of the vibrating wave as a function of frequency. Theoretically, we compute the complex dispersion relationship taking into account the physical properties of the bulk liquid and gas phase, and of the gas-liquid interfaces. The comparison between the computation (developed to the leading order under our experimental conditions) and the experimental results confirms that the phase velocity is fixed by the interplay between surface tension, and liquid and air inertia, as reported in previous studies. Moreover, we show that the attenuation of the transverse antisymmetric wave originates from the viscous dissipation in the gas phase surrounding the liquid film. This result is an important step in understanding the propagation of an acoustic wave in liquid foam, using a bottom-up approach. PMID:25197982

  6. A superior process for forming titanium hydrogen isotopic films

    NASA Technical Reports Server (NTRS)

    Steinberg, R.; Alger, D. L.; Cooper, D. W.

    1975-01-01

    Process forms stoichiometric, continuous, strongly bonded titanium hydrogen isotopic films. Films have thermal and electrical conductivities approximately the same as bulk pure titanium, ten times greater than those of usual thin films.

  7. Inverse Doppler Effects in Broadband Acoustic Metamaterials.

    PubMed

    Zhai, S L; Zhao, X P; Liu, S; Shen, F L; Li, L L; Luo, C R

    2016-01-01

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with 'flute-like' acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe. PMID:27578317

  8. Symptoms of Acoustic Neuroma

    MedlinePlus

    ... Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your Physician Questions to Ask Yourself ... Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your Physician Questions to Ask Yourself ...

  9. Ultrafast magnetoelastic probing of surface acoustic transients

    NASA Astrophysics Data System (ADS)

    Janušonis, J.; Chang, C. L.; Jansma, T.; Gatilova, A.; Vlasov, V. S.; Lomonosov, A. M.; Temnov, V. V.; Tobey, R. I.

    2016-07-01

    We generate in-plane magnetoelastic waves in nickel films using the all-optical transient grating technique. When performed on amorphous glass substrates, two dominant magnetoelastic excitations can be resonantly driven by the underlying elastic distortions, the Rayleigh surface acoustic wave and the surface skimming longitudinal wave. An applied field, oriented in the sample plane, selectively tunes the coupling between magnetic precession and one of the elastic waves, thus demonstrating selective excitation of coexisting, large-amplitude magnetoelastic waves. Analytical calculations based on the Green's function approach corroborate the generation of multiple surface acoustic transients with disparate decay dynamics.

  10. Acoustic emission frequency discrimination

    NASA Technical Reports Server (NTRS)

    Sugg, Frank E. (Inventor); Graham, Lloyd J. (Inventor)

    1988-01-01

    In acoustic emission nondestructive testing, broadband frequency noise is distinguished from narrow banded acoustic emission signals, since the latter are valid events indicative of structural flaws in the material being examined. This is accomplished by separating out those signals which contain frequency components both within and beyond (either above or below) the range of valid acoustic emission events. Application to acoustic emission monitoring during nondestructive bond verification and proof loading of undensified tiles on the Space Shuttle Orbiter is considered.

  11. Tutorial on architectural acoustics

    NASA Astrophysics Data System (ADS)

    Shaw, Neil; Talaske, Rick; Bistafa, Sylvio

    2002-11-01

    This tutorial is intended to provide an overview of current knowledge and practice in architectural acoustics. Topics covered will include basic concepts and history, acoustics of small rooms (small rooms for speech such as classrooms and meeting rooms, music studios, small critical listening spaces such as home theatres) and the acoustics of large rooms (larger assembly halls, auditoria, and performance halls).

  12. Numerical analysis of acoustic impedance microscope utilizing acoustic lens transducer to examine cultured cells.

    PubMed

    Gunawan, Agus Indra; Hozumi, Naohiro; Takahashi, Kenta; Yoshida, Sachiko; Saijo, Yoshifumi; Kobayashi, Kazuto; Yamamoto, Seiji

    2015-12-01

    A new technique is proposed for non-contact quantitative cell observation using focused ultrasonic waves. This technique interprets acoustic reflection intensity into the characteristic acoustic impedance of the biological cell. The cells are cultured on a plastic film substrate. A focused acoustic beam is transmitted through the substrate to its interface with the cell. A two-dimensional (2-D) reflection intensity profile is obtained by scanning the focal point along the interface. A reference substance is observed under the same conditions. These two reflections are compared and interpreted into the characteristic acoustic impedance of the cell based on a calibration curve that was created prior to the observation. To create the calibration curve, a numerical analysis of the sound field is performed using Fourier Transforms and is verified using several saline solutions. Because the cells are suspended by two plastic films, no contamination is introduced during the observation. In a practical observation, a sapphire lens transducer with a center frequency of 300 MHz was employed using ZnO thin film. The objects studied were co-cultured rat-derived glial (astrocyte) cells and glioma cells. The result was the clear observation of the internal structure of the cells. The acoustic impedance of the cells was spreading between 1.62 and 1.72 MNs/m(3). Cytoskeleton was indicated by high acoustic impedance. The introduction of cytochalasin-B led to a significant reduction in the acoustic impedance of the glioma cells; its effect on the glial cells was less significant. It is believed that this non-contact observation method will be useful for continuous cell inspections. PMID:26163739

  13. Bulk Email Forensics

    NASA Astrophysics Data System (ADS)

    Cohen, Fred

    Legal matters related to unsolicited commercial email often involve several hundred thousand messages. Manual examination and interpretation methods are unable to deal with such large volumes of evidence. Furthermore, as the actors gain experience, it is increasingly difficult to show evidence of spoliation and detect intentional evidence construction. This paper presents improved automated techniques for bulk email analysis and presentation to aid in evidence interpretation.

  14. Acoustic metamaterials: From local resonances to broad horizons.

    PubMed

    Ma, Guancong; Sheng, Ping

    2016-02-01

    Within a time span of 15 years, acoustic metamaterials have emerged from academic curiosity to become an active field driven by scientific discoveries and diverse application potentials. This review traces the development of acoustic metamaterials from the initial findings of mass density and bulk modulus frequency dispersions in locally resonant structures to the diverse functionalities afforded by the perspective of negative constitutive parameter values, and their implications for acoustic wave behaviors. We survey the more recent developments, which include compact phase manipulation structures, superabsorption, and actively controllable metamaterials as well as the new directions on acoustic wave transport in moving fluid, elastic, and mechanical metamaterials, graphene-inspired metamaterials, and structures whose characteristics are best delineated by non-Hermitian Hamiltonians. Many of the novel acoustic metamaterial structures have transcended the original definition of metamaterials as arising from the collective manifestations of constituent resonating units, but they continue to extend wave manipulation functionalities beyond those found in nature. PMID:26933692

  15. Acoustically induced stark effect for excitons in intrinsic semiconductors.

    PubMed

    Ivanov, A L; Littlewood, P B

    2001-09-24

    A Stark effect for excitons parametrically driven by coherent acoustic phonons is proposed. Our scheme refers to a low-temperature intrinsic semiconductor or semiconductor nanostructure pumped by an acoustic wave (frequency band nu(ac) approximately equal to 1-40 GHz and intensity range I(ac) approximately equal to 10(-2)-10(2) W/cm(2)) and probed by low-intensity light. Tunable optical band gaps, which strongly change the spectral shape of the exciton line, are induced in the polariton spectrum by acoustic pumping. We develop an exactly solvable model of the acoustic Stark effect and apply our results to GaAs driven by bulk or surface acoustic waves. PMID:11580613

  16. Acoustic metamaterials: From local resonances to broad horizons

    PubMed Central

    Ma, Guancong; Sheng, Ping

    2016-01-01

    Within a time span of 15 years, acoustic metamaterials have emerged from academic curiosity to become an active field driven by scientific discoveries and diverse application potentials. This review traces the development of acoustic metamaterials from the initial findings of mass density and bulk modulus frequency dispersions in locally resonant structures to the diverse functionalities afforded by the perspective of negative constitutive parameter values, and their implications for acoustic wave behaviors. We survey the more recent developments, which include compact phase manipulation structures, superabsorption, and actively controllable metamaterials as well as the new directions on acoustic wave transport in moving fluid, elastic, and mechanical metamaterials, graphene-inspired metamaterials, and structures whose characteristics are best delineated by non-Hermitian Hamiltonians. Many of the novel acoustic metamaterial structures have transcended the original definition of metamaterials as arising from the collective manifestations of constituent resonating units, but they continue to extend wave manipulation functionalities beyond those found in nature. PMID:26933692

  17. Examining surface and bulk structures using combined nonlinear vibrational spectroscopies.

    PubMed

    Zhang, Chi; Wang, Jie; Khmaladze, Alexander; Liu, Yuwei; Ding, Bei; Jasensky, Joshua; Chen, Zhan

    2011-06-15

    We combined sum-frequency generation (SFG) vibrational spectroscopy with coherent anti-Stokes Raman scattering (CARS) spectroscopy in one system to examine both surface and bulk structures of materials with the same geometry and without the need to move the sample. Poly(methyl methacrylate) (PMMA) and polystyrene (PS) thin films were tested before and after plasma treatment. The sensitivities of SFG and CARS were tested by varying polymer film thickness and using a lipid monolayer. PMID:21685990

  18. 16 CFR 501.1 - Camera film.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Camera film. 501.1 Section 501.1 Commercial... 500 § 501.1 Camera film. Camera film packaged and labeled for retail sale is exempt from the net... should be expressed, provided: (a) The net quantity of contents on packages of movie film and bulk...

  19. 16 CFR 501.1 - Camera film.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Camera film. 501.1 Section 501.1 Commercial... 500 § 501.1 Camera film. Camera film packaged and labeled for retail sale is exempt from the net... should be expressed, provided: (a) The net quantity of contents on packages of movie film and bulk...

  20. 16 CFR 501.1 - Camera film.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 1 2012-01-01 2012-01-01 false Camera film. 501.1 Section 501.1 Commercial... 500 § 501.1 Camera film. Camera film packaged and labeled for retail sale is exempt from the net... should be expressed, provided: (a) The net quantity of contents on packages of movie film and bulk...

  1. 16 CFR 501.1 - Camera film.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Camera film. 501.1 Section 501.1 Commercial... 500 § 501.1 Camera film. Camera film packaged and labeled for retail sale is exempt from the net... should be expressed, provided: (a) The net quantity of contents on packages of movie film and bulk...

  2. 16 CFR 501.1 - Camera film.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 1 2013-01-01 2013-01-01 false Camera film. 501.1 Section 501.1 Commercial... 500 § 501.1 Camera film. Camera film packaged and labeled for retail sale is exempt from the net... should be expressed, provided: (a) The net quantity of contents on packages of movie film and bulk...

  3. The effect of confinement on the crystalline microstructure of polymer: fullerene bulk heterojunctions

    SciTech Connect

    Ashraf, A.; Dissanayake, D. M. N. M.; Eisaman, M. D.

    2015-07-01

    We investigate the effect of confinement on the coherence length and the crystalline microstructure of the polymer component of polymer: fullerene bulk heterojunction thin films using grazing incidence wide angle x-ray scattering. We find that the polymer crystallite size decreases and the alignment of the molecules along the surface normal increases, as the thin-film thickness is reduced from 920nm to < 20nm and approaches the thin-film confinement regime. Furthermore, we find that the polymer crystallite size near the surface (air interface) is lower than the crystallite size in the bulk or the bottom (substrate interface) of bulk heterojunction films thicker than the confinement regime. Variation in polymer crystallite size can cause changes in charge carrier mobility and recombination rates, which in turn affect the performance of bulk heterojunction thin film devices such as photovoltaics and photodetectors

  4. The effect of confinement on the crystalline microstructure of polymer : fullerene bulk heterojunctions.

    PubMed

    Ashraf, A; Dissanayake, D M N M; Eisaman, M D

    2015-09-28

    We investigate the effect of confinement on the crystalline microstructure of the polymer component of polymer : fullerene bulk heterojunction thin films using grazing incidence wide angle X-ray scattering. We find that the polymer crystallite size decreases and the alignment of the molecules along the surface normal increases, as the thin-film thickness is reduced from 920 nm to <20 nm and approaches the thin-film confinement regime. Furthermore, we find that the polymer crystallite size near the surface (air interface) is lower than the crystallite size in the bulk or the bottom (substrate interface) of bulk heterojunction films thicker than the confinement regime. Variation in polymer crystallite size can cause changes in charge carrier mobility and recombination rates, which in turn affect the performance of bulk heterojunction thin film devices such as photovoltaics and photodetectors. PMID:26156795

  5. The effect of confinement on the crystalline microstructure of polymer: fullerene bulk heterojunctions

    DOE PAGESBeta

    Ashraf, A.; Dissanayake, D. M. N. M.; Eisaman, M. D.

    2015-07-01

    We investigate the effect of confinement on the coherence length and the crystalline microstructure of the polymer component of polymer: fullerene bulk heterojunction thin films using grazing incidence wide angle x-ray scattering. We find that the polymer crystallite size decreases and the alignment of the molecules along the surface normal increases, as the thin-film thickness is reduced from 920nm to < 20nm and approaches the thin-film confinement regime. Furthermore, we find that the polymer crystallite size near the surface (air interface) is lower than the crystallite size in the bulk or the bottom (substrate interface) of bulk heterojunction films thickermore » than the confinement regime. Variation in polymer crystallite size can cause changes in charge carrier mobility and recombination rates, which in turn affect the performance of bulk heterojunction thin film devices such as photovoltaics and photodetectors« less

  6. Propagation of plate acoustic waves in contact with fluid medium

    NASA Astrophysics Data System (ADS)

    Ghatadi Suraji, Nagaraj

    The characteristics of acoustic waves propagating in thin piezoelectric plates in the presence of a fluid medium contacting one or both of the plate surfaces are investigated. If the velocity of plate wave in the substrate is greater than velocity of bulk wave in the fluid, then a plate acoustic wave (PAW) traveling in the substrate will radiate a bulk acoustic wave (BAW) in the fluid. It is found that, under proper conditions, efficient conversion of energy from plate acoustic waves to bulk acoustic waves and vice versa can be obtained. For example, using the fundamental anti symmetric plate wave mode (A0 mode) propagating in a lithium niobate substrate and water as the fluid, total mode conversion loss (PAW to BAW and back from BAW to PAW) of less than 3 dB has been obtained. This mode conversion principle can be used to realize miniature, high efficiency transducers for use in ultrasonic flow meters. Similar type of transducer based on conversion of energy from surface acoustic wave (SAW) to bulk acoustic wave (BAW) has been developed previously. The use of plate waves has several advantages. Since the energy of plate waves is present on both plate surfaces, the inter digital transducer (IDT) can be on the surface opposite from that which is in contact with the fluid. This protects the IDT from possible damage due to the fluid and also simplifies the job of making electrical connections to the IDT. Another advantage is that one has wider choice of substrate materials with plate waves than is the case with SAWs. Preliminary calculations indicate that the mode conversion principle can also be used to generate and detect ultrasonic waves in air. This has potential applications for realizing transducers for use in non-contact ultrasonic's. The design of an ASIC (Application Specific Integrated Circuit) chip containing an amplifier and frequency counter for use with ultrasonic transducers is also presented in this thesis.

  7. Observation of a Bulk Nodal-Gap in Overdoped Y $_{0.9} 0.9 Ca _{0.1} 0.1 Ba _{2} 2 Cu _{3} 3 O _{7-delta }$ 7 - δ Thin Films

    NASA Astrophysics Data System (ADS)

    Bachar, N.; Bechor, Y.; Gorshunov, B.; Farber, E.

    2015-04-01

    Complex conductivity of overdoped YCaBaCuO thin films was measured in Terahertz frequency using frequency and time domain methods. The films were measured in the frequency range of 3-100 cm and in the temperature range of 20-300 K. Results show a possible deviation from a pure -wave superconductor, indicated by the existence of an energy sub-gap in overdoped YCaBaCuO films. Evidence for this sub-gap appears as non-monotonic behavior of as a function of frequency followed by a sharp decrease at low frequencies, and a dip in the imaginary part of the optical conductivity multiplied by frequency, . The mentioned features were observed at energy of about 1.2 meV in 10 % Ca-doped YBCO thin films. Our complex conductivity spectra are in agreement with the theoretical prediction obtained by using a mixed symmetry order parameter within the Born limit, shown by Schürrer et al. We suggest that these observations are direct evidence for a nodal gap obtained in a -wave superconductor and can be theoretically clarified by adding an imaginary component as or to the main -wave order parameter.

  8. Anisotropic Swirling Surface Acoustic Waves from Inverse Filtering for On-Chip Generation of Acoustic Vortices

    NASA Astrophysics Data System (ADS)

    Riaud, Antoine; Thomas, Jean-Louis; Charron, Eric; Bussonnière, Adrien; Bou Matar, Olivier; Baudoin, Michael

    2015-09-01

    From radio-electronics signal analysis to biological sample actuation, surface acoustic waves (SAWs) are involved in a multitude of modern devices. However, only the most simple standing or progressive waves such as plane and focused waves have been explored so far. In this paper, we expand the SAW toolbox with a wave family named "swirling surface acoustic waves" which are the 2D anisotropic analogue of bulk acoustic vortices. Similarly to their 3D counterpart, they appear as concentric structures of bright rings with a phase singularity in their center resulting in a central dark spot. After the rigorous mathematical definition of these waves, we synthesize them experimentally through the inverse filtering technique revisited for surface waves. For this purpose, we design a setup combining arrays of interdigitated transducers and a multichannel electronic that enables one to synthesize any prescribed wave field compatible with the anisotropy of the substrate in a region called the "acoustic scene." This work opens prospects for the design of integrated acoustic vortex generators for on-chip selective acoustic tweezing.

  9. Bulk-barrier transistor

    NASA Astrophysics Data System (ADS)

    Mader, H.; Mueller, R.; Beinvogl, W.

    1983-10-01

    Experimental and theoretical results are presented on a bulk-barrier transistor (BBT). In this device the charge-carrier transportation is determined by an energy barrier, which is located inside a semiconductor. The barrier is the result of a space-charge region in a three-layered n-p-n or p-n-p structure with a very thin middle layer. The height of the energy barrier, which is adjustable by technological parameters, can be controlled by an external voltage.

  10. AST Launch Vehicle Acoustics

    NASA Technical Reports Server (NTRS)

    Houston, Janice; Counter, D.; Giacomoni, D.

    2015-01-01

    The liftoff phase induces acoustic loading over a broad frequency range for a launch vehicle. These external acoustic environments are then used in the prediction of internal vibration responses of the vehicle and components which result in the qualification levels. Thus, predicting these liftoff acoustic (LOA) environments is critical to the design requirements of any launch vehicle. If there is a significant amount of uncertainty in the predictions or if acoustic mitigation options must be implemented, a subscale acoustic test is a feasible pre-launch test option to verify the LOA environments. The NASA Space Launch System (SLS) program initiated the Scale Model Acoustic Test (SMAT) to verify the predicted SLS LOA environments and to determine the acoustic reduction with an above deck water sound suppression system. The SMAT was conducted at Marshall Space Flight Center and the test article included a 5% scale SLS vehicle model, tower and Mobile Launcher. Acoustic and pressure data were measured by approximately 250 instruments. The SMAT liftoff acoustic results are presented, findings are discussed and a comparison is shown to the Ares I Scale Model Acoustic Test (ASMAT) results.

  11. Sol-gel derived ? thin films on GaAs

    NASA Astrophysics Data System (ADS)

    Arscott, S.; Smith, N.; Kurchania, R.; Milne, S. J.; Miles, R. E.

    1998-02-01

    Sol-gel derived thin films of lead zirconate titanate (PZT) have been fabricated on a platinized GaAs substrate using a propane-1,3-diol based sol-gel route. PZT can be used as the piezoelectric component in bulk acoustic wave devices for monolithic microwave integrated circuit applications. A 100 nm silicon nitride buffer layer was deposited onto the GaAs by plasma-enhanced chemical vapour deposition in order to prevent gallium and arsenic outdiffusion during film fabrication. Rapid thermal processing (RTP) techniques were employed to decompose thermally the sol-gel layer to PZT in a further effort to minimize problems of gallium and arsenic outdiffusion. Adhesion between the bottom electrode and substrate was found to improve when an intermediate titanium layer deposited between the platinum and silicon nitride was oxidized prior to deposition of the platinum electrode. A crystalline PZT film was produced on the 0268-1242/13/2/016/img9 substrate configuration by firing the sol-gel coating at 0268-1242/13/2/016/img10C for 10 s using RTP. A single deposition of sol resulted in a film having a thickness of 0268-1242/13/2/016/img11. Ferroelectric hysteresis measurements yielded average values of remanant polarization and coercive field of 0268-1242/13/2/016/img12 and 0268-1242/13/2/016/img13 respectively.

  12. Transverse acoustic trapping using a Gaussian focused ultrasound

    PubMed Central

    Lee, Jungwoo; Teh, Shia-Yen; Lee, Abraham; Kim, Hyung Ham; Lee, Changyang; Shung, K. Kirk

    2009-01-01

    The optical tweezer has become a popular device to manipulate particles in nanometer scales, and to study the underlying principles of many cellular or molecular interactions. Theoretical analysis was previously carried out at the authors’ laboratory, to show that similar acoustic trapping of microparticles may be possible with a single beam ultrasound. This paper experimentally presents the transverse trapping of 125 μm lipid droplets under an acoustically transparent mylar film, which is an intermediate step toward achieving acoustic tweezers in 3D. Despite the lack of axial trapping capability in the current experimental arrangement, it was found that a 30 MHz focused beam could be used to laterally direct the droplets towards the focus. The spatial range within which acoustic traps may guide droplet motion was in the range of hundreds of micrometers, much greater than that of optical traps. This suggests that this acoustic device may offer an alternative for manipulating microparticles in a wider spatial range. PMID:20045590

  13. Acoustic Translation of an Acoustically Levitated Sample

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B.; Allen, J. L.

    1986-01-01

    Acoustic-levitation apparatus uses only one acoustic mode to move sample from one region of chamber to another. Sample heated and cooled quickly by translation between hot and cold regions of levitation chamber. Levitated sample is raised into furnace region by raising plunger. Frequency of sound produced by transducers adjusted by feedback system to maintain (102) resonant mode, which levitates sample midway between transducers and plunger regardless of plunger position.

  14. Integration of bulk piezoelectric materials into microsystems

    NASA Astrophysics Data System (ADS)

    Aktakka, Ethem Erkan

    Bulk piezoelectric ceramics, compared to deposited piezoelectric thin-films, provide greater electromechanical coupling and charge capacity, which are highly desirable in many MEMS applications. In this thesis, a technology platform is developed for wafer-level integration of bulk piezoelectric substrates on silicon, with a final film thickness of 5-100microm. The characterized processes include reliable low-temperature (200°C) AuIn diffusion bonding and parylene bonding of bulk-PZT on silicon, wafer-level lapping of bulk-PZT with high-uniformity (+/-0.5microm), and low-damage micro-machining of PZT films via dicing-saw patterning, laser ablation, and wet-etching. Preservation of ferroelectric and piezoelectric properties is confirmed with hysteresis and piezo-response measurements. The introduced technology offers higher material quality and unique advantages in fabrication flexibility over existing piezoelectric film deposition methods. In order to confirm the preserved bulk properties in the final film, diaphragm and cantilever beam actuators operating in the transverse-mode are designed, fabricated and tested. The diaphragm structure and electrode shapes/sizes are optimized for maximum deflection through finite-element simulations. During tests of fabricated devices, greater than 12microm PP displacement is obtained by actuation of a 1mm2 diaphragm at 111kHz with <7mW power consumption. The close match between test data and simulation results suggests that the piezoelectric properties of bulk-PZT5A are mostly preserved without any necessity of repolarization. Three generations of resonant vibration energy harvesters are designed, simulated and fabricated to demonstrate the competitive performance of the new fabrication process over traditional piezoelectric deposition systems. An unpackaged PZT/Si unimorph harvester with 27mm3 active device volume produces up to 205microW at 1.5g/154Hz. The prototypes have achieved the highest figure-of-merits (normalized

  15. Growth study of nonpolar Zn{sub 1-x}Mg{sub x}O epitaxial films on a-plane bulk ZnO by plasma-assisted molecular beam epitaxy

    SciTech Connect

    Laumer, Bernhard; Schuster, Fabian; Stutzmann, Martin; Bergmaier, Andreas; Dollinger, Guenther; Vogel, Stephen; Gries, Katharina I.; Volz, Kerstin; Eickhoff, Martin

    2012-09-17

    Nonpolar Zn{sub 1-x}Mg{sub x}O epitaxial films were grown by plasma-assisted molecular beam epitaxy on a-plane ZnO substrates. A smooth surface morphology was accomplished under oxygen-rich growth conditions. The benefits of the use of ZnO substrates on the structural properties are reflected by a low-density of threading dislocations. Furthermore, no indications for the generation of basal plane stacking faults are found. The pseudomorphic growth on a-plane ZnO substrates efficiently locks the epitaxial Zn{sub 1-x}Mg{sub x}O films to the wurtzite structure up to x = 0.25. The Mg concentration is not constant and increases with larger thickness. The optical properties reflect the influence of alloy disorder.

  16. Nonlinear Acoustics in Fluids

    NASA Astrophysics Data System (ADS)

    Lauterborn, Werner; Kurz, Thomas; Akhatov, Iskander

    At high sound intensities or long propagation distances at in fluids sufficiently low damping acoustic phenomena become nonlinear. This chapter focuses on nonlinear acoustic wave properties in gases and liquids. The origin of nonlinearity, equations of state, simple nonlinear waves, nonlinear acoustic wave equations, shock-wave formation, and interaction of waves are presented and discussed. Tables are given for the nonlinearity parameter B/A for water and a range of organic liquids, liquid metals and gases. Acoustic cavitation with its nonlinear bubble oscillations, pattern formation and sonoluminescence (light from sound) are modern examples of nonlinear acoustics. The language of nonlinear dynamics needed for understanding chaotic dynamics and acoustic chaotic systems is introduced.

  17. Chip scale mechanical spectrum analyzers based on high quality factor overmoded bulk acouslic wave resonators

    SciTech Connect

    Olsson, R. H., III

    2012-03-01

    The goal of this project was to develop high frequency quality factor (fQ) product acoustic resonators matched to a standard RF impedance of 50 {Omega} using overmoded bulk acoustic wave (BAW) resonators. These resonators are intended to serve as filters in a chip scale mechanical RF spectrum analyzer. Under this program different BAW resonator designs and materials were studied theoretically and experimentally. The effort resulted in a 3 GHz, 50 {Omega}, sapphire overmoded BAW with a fQ product of 8 x 10{sup 13}, among the highest values ever reported for an acoustic resonator.

  18. Bulk material handling system

    DOEpatents

    Kleysteuber, William K.; Mayercheck, William D.

    1979-01-01

    This disclosure relates to a bulk material handling system particularly adapted for underground mining and includes a monorail supported overhead and carrying a plurality of conveyors each having input and output end portions with the output end portion of a first of the conveyors positioned above an input end portion of a second of the conveyors, a device for imparting motion to the conveyors to move the material from the input end portions toward the output end portions thereof, a device for supporting at least one of the input and output end portions of the first and second conveyors from the monorail, and the supporting device including a plurality of trolleys rollingly supported by the monorail whereby the conveyors can be readily moved therealong.

  19. Bulk amorphous materials

    SciTech Connect

    Schwarz, R.B.; Archuleta, J.I.; Sickafus, K.E.

    1998-12-01

    This is the final report for a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this work was to develop the competency for the synthesis of novel bulk amorphous alloys. The authors researched their synthesis methods and alloy properties, including thermal stability, mechanical, and transport properties. The project also addressed the development of vanadium-spinel alloys for structural applications in hostile environments, the measurement of elastic constants and thermal expansion in single-crystal TiAl from 300 to 750 K, the measurement of elastic constants in gallium nitride, and a study of the shock-induced martensitic transformations in NiTi alloys.

  20. Bulk muscles, loose cables.

    PubMed

    Liyanage, Chamari R D G; Kodali, Venkata

    2014-01-01

    The accessibility and usage of body building supplements is on the rise with stronger internet marketing strategies by the industry. The dangers posed by the ingredients in them are underestimated. A healthy young man came to the emergency room with palpitations and feeling unwell. Initial history and clinical examination were non-contributory to find the cause. ECG showed atrial fibrillation. A detailed history for any over the counter or herbal medicine use confirmed that he was taking supplements to bulk muscle. One of the components in these supplements is yohimbine; the onset of symptoms coincided with the ingestion of this product and the patient is symptom free after stopping it. This report highlights the dangers to the public of consuming over the counter products with unknown ingredients and the consequential detrimental impact on health. PMID:25326558

  1. Creating bulk nanocrystalline metal.

    SciTech Connect

    Fredenburg, D. Anthony; Saldana, Christopher J.; Gill, David D.; Hall, Aaron Christopher; Roemer, Timothy John; Vogler, Tracy John; Yang, Pin

    2008-10-01

    Nanocrystalline and nanostructured materials offer unique microstructure-dependent properties that are superior to coarse-grained materials. These materials have been shown to have very high hardness, strength, and wear resistance. However, most current methods of producing nanostructured materials in weapons-relevant materials create powdered metal that must be consolidated into bulk form to be useful. Conventional consolidation methods are not appropriate due to the need to maintain the nanocrystalline structure. This research investigated new ways of creating nanocrystalline material, new methods of consolidating nanocrystalline material, and an analysis of these different methods of creation and consolidation to evaluate their applicability to mesoscale weapons applications where part features are often under 100 {micro}m wide and the material's microstructure must be very small to give homogeneous properties across the feature.

  2. Explosive bulk charge

    DOEpatents

    Miller, Jacob Lee

    2015-04-21

    An explosive bulk charge, including: a first contact surface configured to be selectively disposed substantially adjacent to a structure or material; a second end surface configured to selectively receive a detonator; and a curvilinear side surface joining the first contact surface and the second end surface. The first contact surface, the second end surface, and the curvilinear side surface form a bi-truncated hemispherical structure. The first contact surface, the second end surface, and the curvilinear side surface are formed from an explosive material. Optionally, the first contact surface and the second end surface each have a substantially circular shape. Optionally, the first contact surface and the second end surface consist of planar structures that are aligned substantially parallel or slightly tilted with respect to one another. The curvilinear side surface has one of a smooth curved geometry, an elliptical geometry, and a parabolic geometry.

  3. Acoustic design by topology optimization

    NASA Astrophysics Data System (ADS)

    Dühring, Maria B.; Jensen, Jakob S.; Sigmund, Ole

    2008-11-01

    To bring down noise levels in human surroundings is an important issue and a method to reduce noise by means of topology optimization is presented here. The acoustic field is modeled by Helmholtz equation and the topology optimization method is based on continuous material interpolation functions in the density and bulk modulus. The objective function is the squared sound pressure amplitude. First, room acoustic problems are considered and it is shown that the sound level can be reduced in a certain part of the room by an optimized distribution of reflecting material in a design domain along the ceiling or by distribution of absorbing and reflecting material along the walls. We obtain well defined optimized designs for a single frequency or a frequency interval for both 2D and 3D problems when considering low frequencies. Second, it is shown that the method can be applied to design outdoor sound barriers in order to reduce the sound level in the shadow zone behind the barrier. A reduction of up to 10 dB for a single barrier and almost 30 dB when using two barriers are achieved compared to utilizing conventional sound barriers.

  4. Quantum ion-acoustic wave oscillations in metallic nanowires

    SciTech Connect

    Moradi, Afshin

    2015-05-15

    The low-frequency electrostatic waves in metallic nanowires are studied using the quantum hydrodynamic model, in which the electron and ion components of the system are regarded as a two-species quantum plasma system. The Poisson equation as well as appropriate quantum boundary conditions give the analytical expressions of dispersion relations of the surface and bulk quantum ion-acoustic wave oscillations.

  5. Localized acoustic surface modes

    NASA Astrophysics Data System (ADS)

    Farhat, Mohamed; Chen, Pai-Yen; Bağcı, Hakan

    2016-04-01

    We introduce the concept of localized acoustic surface modes. We demonstrate that they are induced on a two-dimensional cylindrical rigid surface with subwavelength corrugations under excitation by an incident acoustic plane wave. Our results show that the corrugated rigid surface is acoustically equivalent to a cylindrical scatterer with uniform mass density that can be represented using a Drude-like model. This, indeed, suggests that plasmonic-like acoustic materials can be engineered with potential applications in various areas including sensing, imaging, and cloaking.

  6. Low frequency acoustic microscope

    DOEpatents

    Khuri-Yakub, Butrus T.

    1986-11-04

    A scanning acoustic microscope is disclosed for the detection and location of near surface flaws, inclusions or voids in a solid sample material. A focused beam of acoustic energy is directed at the sample with its focal plane at the subsurface flaw, inclusion or void location. The sample is scanned with the beam. Detected acoustic energy specularly reflected and mode converted at the surface of the sample and acoustic energy reflected by subsurface flaws, inclusions or voids at the focal plane are used for generating an interference signal which is processed and forms a signal indicative of the subsurface flaws, inclusions or voids.

  7. Acoustic dispersive prism.

    PubMed

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz-1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium. PMID:26739504

  8. Acoustic dispersive prism

    PubMed Central

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R.

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz–1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium. PMID:26739504

  9. Acoustic dispersive prism

    NASA Astrophysics Data System (ADS)

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R.

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz-1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium.

  10. Bulk solitary waves in elastic solids

    NASA Astrophysics Data System (ADS)

    Samsonov, A. M.; Dreiden, G. V.; Semenova, I. V.; Shvartz, A. G.

    2015-10-01

    A short and object oriented conspectus of bulk solitary wave theory, numerical simulations and real experiments in condensed matter is given. Upon a brief description of the soliton history and development we focus on bulk solitary waves of strain, also known as waves of density and, sometimes, as elastic and/or acoustic solitons. We consider the problem of nonlinear bulk wave generation and detection in basic structural elements, rods, plates and shells, that are exhaustively studied and widely used in physics and engineering. However, it is mostly valid for linear elasticity, whereas dynamic nonlinear theory of these elements is still far from being completed. In order to show how the nonlinear waves can be used in various applications, we studied the solitary elastic wave propagation along lengthy wave guides, and remarkably small attenuation of elastic solitons was proven in physical experiments. Both theory and generation for strain soliton in a shell, however, remained unsolved problems until recently, and we consider in more details the nonlinear bulk wave propagation in a shell. We studied an axially symmetric deformation of an infinite nonlinearly elastic cylindrical shell without torsion. The problem for bulk longitudinal waves is shown to be reducible to the one equation, if a relation between transversal displacement and the longitudinal strain is found. It is found that both the 1+1D and even the 1+2D problems for long travelling waves in nonlinear solids can be reduced to the Weierstrass equation for elliptic functions, which provide the solitary wave solutions as appropriate limits. We show that the accuracy in the boundary conditions on free lateral surfaces is of crucial importance for solution, derive the only equation for longitudinal nonlinear strain wave and show, that the equation has, amongst others, a bidirectional solitary wave solution, which lead us to successful physical experiments. We observed first the compression solitary wave in the

  11. Acoustic and dynamic mechanical properties of a polyurethane rubber

    NASA Astrophysics Data System (ADS)

    Mott, Peter H.; Roland, C. Michael; Corsaro, Robert D.

    2002-04-01

    Acoustical and dynamic mechanical measurements were carried out on a commercial polyurethane rubber, DeSoto PR1547. The sound speed and attenuation were measured over the range from 12.5 to 75 kHz and 3.9 to 33.6 °C. Shear modulus was measured from 10-4 to 2 Hz and -36 to 34 °C. The peak heights of the shear loss tangent varied with temperature, demonstrating thermorheological complexity. At higher temperatures, time-temperature superpositioning could be applied, with the shift factors following the Williams-Landel-Ferry equation. From the combined acoustical and mechanical measurements, values for the dynamic bulk modulus were determined. Moreover, superposition of the bulk modulus data was achieved using the shift factors determined from the dynamic mechanical shear measurements. Finally, this work illustrates the capability and the working rules of acoustical measurements in a small tank.

  12. Ferroelectric nanomesa formation from polymer Langmuir-Blodgett films

    NASA Astrophysics Data System (ADS)

    Bai, Mengjun; Ducharme, Stephen

    2004-10-01

    We report the fabrication and characterization of nanoscale ferroelectric structures consisting of disk-shaped nanomesas averaging 8.7±0.4nm in height and 95±22nm in diameter, and nanowells 9.8±3.3nm in depth and 128±37nm in diameter, formed from Langmuir-Blodgett films of vinylidene fluoride copolymers after annealing in the paraelectric phase. The nanomesas retain the ferroelectric properties of the bulk material and so may be suitable for use in high-density nonvolatile random-access memories, acoustic transducer arrays, or infrared imaging arrays. The nanomesa and nanowell patterns may provide useful templates for nanoscale molding or contact-printing.

  13. Acoustical model of a Shoddy fibre absorber

    NASA Astrophysics Data System (ADS)

    Manning, John Peter

    Shoddy fibres or "Shoddies" are a mixture of post-consumer and post-industrial fibres diverted from textile waste streams and recycled into their raw fibre form. They have found widespread use as a raw material for manufacturing sound absorbers that include, but are not limited to: automotive, architectural and home appliance applications. The purpose of this project is to develop a simple acoustic model to describe the acoustic behaviour of sound absorbers composed primarily of Shoddy fibres. The model requires knowledge of the material's bulk density only. To date, these materials have not been the focus of much published research and acoustical designers must rely on models that were developed for other materials or are overly complex. For modelling purposes, an equivalent fluid approach is chosen to balance complexity and accuracy. In deriving the proposed model, several popular equivalent fluid models are selected and the required input parameters for each model identified. The models are: the model of Delaney and Bazley, two models by Miki, the model of Johnson in conjunction with the model of Champoux and Allard and the model of Johnson in conjunction with the model of Lafarge. Characterization testing is carried out on sets of Shoddy absorbers produced using three different manufacturing methods. The measured properties are open porosity, tortuosity, airflow resistivity, the viscous and thermal characteristic lengths and the static thermal permeability. Empirical relationships between model parameters and bulk density are then derived and used to populate the selected models. This yields several 'simplified' models with bulk density as the only parameter. The most accurate model is then selected by comparing each model's prediction to the results of normal incidence sound absorption tests. The model of Johnson-Lafarge populated with the empirical relations is the most accurate model over the range of frequencies considered (approx. 300 Hz - 4000 Hz

  14. Control and characterization of the metallic surface state of bulk insulating Bi2Se3

    NASA Astrophysics Data System (ADS)

    Fuhrer, Michael

    2015-03-01

    Bi2Se3 is a three dimensional strong topological insulator with a conducting two-dimensional surface state whose existence is guaranteed by topology. The bulk Bi2Se3 has a 300 meV bandgap, but is often a degenerately n-doped metal in as-grown material. I will discuss our efforts to remove this doping in thin crystals and films to achieve surface-dominated conduction. Electrochemical gating (using PEO+LiClO4 electrolyte) or molecular doping (using F4-TCNQ) is shown to effectively bring the Fermi energy of thin (3-20 nm) exfoliated Bi2Se3 crystals to the conduction band edge, where it can be further modulated at low temperature using field-effect gating. These techniques allowed us to reveal the gapless ambipolar transport in the topological surface, and measure the minimum conductivity, electron-acoustic phonon scattering, thermopower, and inter-surface coupling of the topological surfaces. Recently we have developed techniques to measure the transport properties of Bi2Se3 in situ during growth in ultra-high vacuum, enabling better understanding of the doping mechanisms. We have also studied vacuum-deposited MoO3 as a highly effective acceptor dopant which remains stable on air exposure for time scales of days. This work is supported by NSF Grants DMR-1105224, DMR-0520471, and DMR-0952716, and an ARC Laureate Fellowship.

  15. Lattice dynamics in elemental modulated Sb 2 Te 3 films: Lattice dynamics in elemental modulated Sb 2 Te 3 films

    DOE PAGESBeta

    Bessas, D.; Winkler, M.; Sergueev, I.; König, J. D.; Böttner, H.; Hermann, R. P.

    2015-09-03

    We investigate the crystallinity and the lattice dynamics in elemental modulated Sbinline imageTeinline image films microscopically using high energy synchrotron radiation diffraction combined with inline imageSb nuclear inelastic scattering. The correlation length is found to be finite but less than 100 . Moreover, the element specific density of phonon states is extracted. A comparison with the element specific density of phonon states in bulk Sbinline imageTeinline image confirms that the main features in the density of phonon states arise from the layered structure. The average speed of sound at inline image inline image, is almost the same compared to bulkmore » Sbinline imageTeinline image at inline image, inline image. Similarly, the change in the acoustic cut-off energy is within the experimental detection limit. Therefore, we suggest that the lattice thermal conductivity in elemental modulated Sbinline imageTeinline image films should not be significantly changed from its bulk value.« less

  16. Ultrafast magnetoacoustics in nickel films.

    PubMed

    Kim, Ji-Wan; Vomir, Mircea; Bigot, Jean-Yves

    2012-10-19

    We report about the magnetization dynamics of a ferromagnetic nickel film at room temperature excited by acoustic pulses generated with femtosecond laser pulses. The ultrafast change of magnetization is detected from both the front and back sides of the nickel film. The propagating strain associated with the acoustic pulses modifies the magnetic anisotropy and induces a precession of the magnetization. We model the time-dependent magnetoacoustic response of the metallic film by combining a three temperature model for the temperatures of the charges, the spins, and the lattice, the wave equation for the strain, and the Landau-Lifshitz-Gilbert equation for the magnetization. It is shown that the precession dynamics can be controlled by matching the precession period with the round trip time of the acoustic echoes. The calculation of the time-dependent precession torque τ=|M×H(eff)| allows understanding the underlying physics. PMID:23215104

  17. Probing mechanical properties of liposomes using acoustic sensors.

    PubMed

    Melzak, Kathryn A; Bender, Florian; Tsortos, Achilleas; Gizeli, Electra

    2008-08-19

    Acoustic devices were employed to characterize variations in the mechanical properties (density and viscoelasticity) of liposomes composed of 1-oleoyl-2-palmitoyl- sn-glycero-3-phosphocholine (POPC) and cholesterol. Liposome properties were modified in three ways. In some experiments, the POPC/cholesterol ratio was varied prior to deposition on the device surface. Alternatively, the ratio was changed in situ via either insertion of cholesterol or removal of cholesterol with beta-cyclodextrin. This was done for liposomes adsorbed directly on the device surface and for liposomes attached via a biotin-terminated poly(ethylene glycol) linker. The acoustic measurements make use of two simultaneous time-resolved signals: one signal is related to the velocity of the acoustic wave, while the second is related to dissipation of acoustic energy. Together, they provide information not only about the mass (or density) of the probed medium but also about its viscoelastic properties. The cholesterol-induced increase in the surface density of the lipid bilayer was indeed observed in the acoustic data, but the resulting change in signal was larger than expected from the change in surface density. In addition, increasing the bilayer resistance to stretching was found to lead to a greater dissipation of the acoustic energy. The acoustic response is assessed in terms of the possible distortions of the liposomes and the known effects of cholesterol on the mechanical properties of the lipid bilayer that encloses the aqueous core of the liposome. To aid the interpretation of the acoustic response, it is discussed how the above changes in the lipid bilayer will affect the effective viscoelastic properties of the entire liposome/solvent film on the scale of the acoustic wavelength. It was found that the acoustic device is very sensitive to the mechanical properties of lipid vesicles; the response of the acoustic device is explained, and the basic underlying mechanisms of interaction are

  18. Bulk Data Mover

    SciTech Connect

    2011-01-03

    Bulk Data Mover (BDM) is a high-level data transfer management tool. BDM handles the issue of large variance in file sizes and a big portion of small files by managing the file transfers with optimized transfer queue and concurrency management algorithms. For example, climate simulation data sets are characterized by large volume of files with extreme variance in file sizes. The BDN achieves high performance using a variety of techniques, including multi-thraded concurrent transfer connections, data channel caching, load balancing over multiple transfer servers, and storage i/o pre-fetching. Logging information from the BDM is collected and analyzed to study the effectiveness of the transfer management algorithms. The BDM can accept a request composed of multiple files or an entire directory. The request also contains the target site and directory where the replicated files will reside. If a directory is provided at the source, then the BDM will replicate the structure of the source directory at the target site. The BDM is capable of transferring multiple files concurrently as well as using parallel TCP streams. The optimal level of concurrency or parallel streams depends on the bandwidth capacity of the storage systems at both ends of the transfer as well as achievable bandwidth of the wide-area network. Hardware req.-PC, MAC, Multi-platform & Workstation; Software req.: Compile/version-Java 1.50_x or ablove; Type of files: source code, executable modules, installation instructions other, user guide; URL: http://sdm.lbl.gov/bdm/

  19. Acoustics Critical Readiness Review

    NASA Technical Reports Server (NTRS)

    Ballard, Kenny

    2010-01-01

    This presentation reviews the status of the acoustic equipment from the medical operations perspective. Included is information about the acoustic dosimeters, sound level meter, and headphones that are planned for use while on orbit. Finally there is information about on-orbit hearing assessments.

  20. The challenge of acoustics

    NASA Astrophysics Data System (ADS)

    Lord, P.

    1981-01-01

    The various applications of acoustics, including sonar, ultrasonic examination of unborn foetuses and architectural applications, are briefly reviewed. Problems in traffic and industrial noise, auditorium design and explosive noise are considered in more detail. The educational aspects of acoustical science and technology are briefly considered.

  1. Nonlinear acoustics experimental characterization of microstructure evolution in Inconel 617

    SciTech Connect

    Yao, Xiaochu; Liu, Yang; Lissenden, Cliff J.

    2014-02-18

    Inconel 617 is a candidate material for the intermediate heat exchanger in a very high temperature reactor for the next generation nuclear power plant. This application will require the material to withstand fatigue-ratcheting interaction at temperatures up to 950°C. Therefore nondestructive evaluation and structural health monitoring are important capabilities. Acoustic nonlinearity (which is quantified in terms of a material parameter, the acoustic nonlinearity parameter, β) has been proven to be sensitive to microstructural changes in material. This research develops a robust experimental procedure to track the evolution of damage precursors in laboratory tested Inconel 617 specimens using ultrasonic bulk waves. The results from the acoustic non-linear tests are compared with stereoscope surface damage results. Therefore, the relationship between acoustic nonlinearity and microstructural evaluation can be clearly demonstrated for the specimens tested.

  2. Bulk limited conduction in electroluminescent polymer devices

    NASA Astrophysics Data System (ADS)

    Campbell, A. J.; Weaver, M. S.; Lidzey, D. G.; Bradley, D. D. C.

    1998-12-01

    The current-voltage (J-V) characteristics of ITO/polymer film/Al or Au structures of poly(phenylene vinylene) (PPV) and a dialkoxy PPV copolymer have been recorded for a range of different film thickness d and temperatures T. At high applied bias all the characteristics can be fitted over a given range to a power law J=KVm, where m increases with decreasing T, log(K) is proportional to m, and K is proportional to d-α m, where α˜2 (ITO/polymer film/Al devices) and ˜1 (ITO/polymer film/Au devices). Different single carrier space charge limited conduction theories have been used to try and explain this behavior. The analytical theory in which the carrier density is decreased by an exponential trap distribution lying below effectively isoelectronic transport states is in good agreement, but cannot explain the thickness dependence of the ITO/polymer film/Au devices and can be criticized as being physically unreasonable. A numerical analysis in which the mobility has the field and temperature dependence found for hopping transport in disordered systems is also in good agreement, but can only fit a small range of J and cannot explain the magnitude of K, the temperature dependence of m or the abrupt change in slope in the J-V characteristics with increasing bias. Mixed models are equally good but cannot explain the deviations from experiment. We consider that further experimental studies of carrier mobilities and the nature of the traps present in such materials is required to distinguish between these models and resolve the nature of bulk limited conduction in conjugated polymers.

  3. Dynamics of Bimodal Growth in Pentacene Thin Films

    SciTech Connect

    Mayer, Alex C.; Malliaras, George G.; Kazimirov, Alexander

    2006-09-08

    Previous studies have established that pentacene films deposited on silicon oxide consist of a substrate-induced 'thin-film' phase, with the bulk phase of pentacene detected in thicker films only. We show that the bulk phase nucleates as early as the first monolayer, and continues to nucleate as film growth progresses, shadowing the growth of the thin-film phase. Moreover, we find that the transition between the 'thin-film' and the bulk phase is not a continuous one, as observed in heteroepitaxial systems, but rather the two phases nucleate and grow independently.

  4. Highly directional acoustic receivers.

    PubMed

    Cray, Benjamin A; Evora, Victor M; Nuttall, Albert H

    2003-03-01

    The theoretical directivity of a single combined acoustic receiver, a device that can measure many quantities of an acoustic field at a collocated point, is presented here. The formulation is developed using a Taylor series expansion of acoustic pressure about the origin of a Cartesian coordinate system. For example, the quantities measured by a second-order combined receiver, denoted a dyadic sensor, are acoustic pressure, the three orthogonal components of acoustic particle velocity, and the nine spatial gradients of the velocity vector. The power series expansion, which can be of any order, is cast into an expression that defines the directivity of a single receiving element. It is shown that a single highly directional dyadic sensor can have a directivity index of up to 9.5 dB. However, there is a price to pay with highly directive sensors; these sensors can be significantly more sensitive to nonacoustic noise sources. PMID:12656387

  5. Ocean acoustic hurricane classification.

    PubMed

    Wilson, Joshua D; Makris, Nicholas C

    2006-01-01

    Theoretical and empirical evidence are combined to show that underwater acoustic sensing techniques may be valuable for measuring the wind speed and determining the destructive power of a hurricane. This is done by first developing a model for the acoustic intensity and mutual intensity in an ocean waveguide due to a hurricane and then determining the relationship between local wind speed and underwater acoustic intensity. From this it is shown that it should be feasible to accurately measure the local wind speed and classify the destructive power of a hurricane if its eye wall passes directly over a single underwater acoustic sensor. The potential advantages and disadvantages of the proposed acoustic method are weighed against those of currently employed techniques. PMID:16454274

  6. Acoustic Remote Sensing

    NASA Astrophysics Data System (ADS)

    Dowling, David R.; Sabra, Karim G.

    2015-01-01

    Acoustic waves carry information about their source and collect information about their environment as they propagate. This article reviews how these information-carrying and -collecting features of acoustic waves that travel through fluids can be exploited for remote sensing. In nearly all cases, modern acoustic remote sensing involves array-recorded sounds and array signal processing to recover multidimensional results. The application realm for acoustic remote sensing spans an impressive range of signal frequencies (10-2 to 107 Hz) and distances (10-2 to 107 m) and involves biomedical ultrasound imaging, nondestructive evaluation, oil and gas exploration, military systems, and Nuclear Test Ban Treaty monitoring. In the past two decades, approaches have been developed to robustly localize remote sources; remove noise and multipath distortion from recorded signals; and determine the acoustic characteristics of the environment through which the sound waves have traveled, even when the recorded sounds originate from uncooperative sources or are merely ambient noise.

  7. Acoustic integrated extinction

    PubMed Central

    Norris, Andrew N.

    2015-01-01

    The integrated extinction (IE) is defined as the integral of the scattering cross section as a function of wavelength. Sohl et al. (2007 J. Acoust. Soc. Am. 122, 3206–3210. (doi:10.1121/1.2801546)) derived an IE expression for acoustic scattering that is causal, i.e. the scattered wavefront in the forward direction arrives later than the incident plane wave in the background medium. The IE formula was based on electromagnetic results, for which scattering is causal by default. Here, we derive a formula for the acoustic IE that is valid for causal and non-causal scattering. The general result is expressed as an integral of the time-dependent forward scattering function. The IE reduces to a finite integral for scatterers with zero long-wavelength monopole and dipole amplitudes. Implications for acoustic cloaking are discussed and a new metric is proposed for broadband acoustic transparency. PMID:27547100

  8. Virtual acoustics displays

    NASA Technical Reports Server (NTRS)

    Wenzel, Elizabeth M.; Fisher, Scott S.; Stone, Philip K.; Foster, Scott H.

    1991-01-01

    The real time acoustic display capabilities are described which were developed for the Virtual Environment Workstation (VIEW) Project at NASA-Ames. The acoustic display is capable of generating localized acoustic cues in real time over headphones. An auditory symbology, a related collection of representational auditory 'objects' or 'icons', can be designed using ACE (Auditory Cue Editor), which links both discrete and continuously varying acoustic parameters with information or events in the display. During a given display scenario, the symbology can be dynamically coordinated in real time with 3-D visual objects, speech, and gestural displays. The types of displays feasible with the system range from simple warnings and alarms to the acoustic representation of multidimensional data or events.

  9. Cochlear bionic acoustic metamaterials

    NASA Astrophysics Data System (ADS)

    Ma, Fuyin; Wu, Jiu Hui; Huang, Meng; Fu, Gang; Bai, Changan

    2014-11-01

    A design of bionic acoustic metamaterial and acoustic functional devices was proposed by employing the mammalian cochlear as a prototype. First, combined with the experimental data in previous literatures, it is pointed out that the cochlear hair cells and stereocilia cluster are a kind of natural biological acoustic metamaterials with the negative stiffness characteristics. Then, to design the acoustic functional devices conveniently in engineering application, a simplified parametric helical structure was proposed to replace actual irregular cochlea for bionic design, and based on the computational results of such a bionic parametric helical structure, it is suggested that the overall cochlear is a local resonant system with the negative dynamic effective mass characteristics. There are many potential applications in the bandboard energy recovery device, cochlear implant, and acoustic black hole.

  10. Phobos: Observed bulk properties

    NASA Astrophysics Data System (ADS)

    Pätzold, Martin; Andert, Tom; Jacobson, Robert; Rosenblatt, Pascal; Dehant, Véronique

    2014-11-01

    This work is a review of the mass determinations of the Mars moon Phobos by spacecraft close flybys, by solving for the Martian gravity field and by the analysis of secular orbit perturbations. The absolute value and accuracy is sensitive on the knowledge and accuracy of the Phobos ephemeris, of the spacecraft orbit, other perturbing forces acting on the spacecraft and the resolution of the Martian gravity field besides the measurement accuracy of the radio tracking data. The mass value and its error improved from spacecraft mission to mission or from the modern analysis of “old” tracking data but these solutions depend on the accuracy of the ephemeris at the time of observation. The mass value seems to settle within the range of GMPh=(7.11±0.09)×10-4 km3 s-2 which covers almost all mass values from close flybys and “distant” encounters within its 3-σ error (1.5%). Using the volume value determined from MEX HRSC imaging, the bulk density is (1873±31) kg m-3 (3-σ error or 1.7%), a low value which suggests that Phobos is either highly porous, is composed partially of light material or both. The determination of the gravity coefficients C20 and C22 from the Mars Express 2010 close flyby does not allow to draw conclusion on the internal structure. The large errors do not distinguish whether Phobos is homogeneous or not. In view of theories of the Phobos' origin, one possibility is that Phobos is not a captured asteroid but accreted from a debris disk in Mars orbit as a second generation solar system object.

  11. Bulk Data Mover

    Energy Science and Technology Software Center (ESTSC)

    2011-01-03

    Bulk Data Mover (BDM) is a high-level data transfer management tool. BDM handles the issue of large variance in file sizes and a big portion of small files by managing the file transfers with optimized transfer queue and concurrency management algorithms. For example, climate simulation data sets are characterized by large volume of files with extreme variance in file sizes. The BDN achieves high performance using a variety of techniques, including multi-thraded concurrent transfer connections,more » data channel caching, load balancing over multiple transfer servers, and storage i/o pre-fetching. Logging information from the BDM is collected and analyzed to study the effectiveness of the transfer management algorithms. The BDM can accept a request composed of multiple files or an entire directory. The request also contains the target site and directory where the replicated files will reside. If a directory is provided at the source, then the BDM will replicate the structure of the source directory at the target site. The BDM is capable of transferring multiple files concurrently as well as using parallel TCP streams. The optimal level of concurrency or parallel streams depends on the bandwidth capacity of the storage systems at both ends of the transfer as well as achievable bandwidth of the wide-area network. Hardware req.-PC, MAC, Multi-platform & Workstation; Software req.: Compile/version-Java 1.50_x or ablove; Type of files: source code, executable modules, installation instructions other, user guide; URL: http://sdm.lbl.gov/bdm/« less

  12. Ocean seismo-acoustics. Low-frequency underwater acoustics

    SciTech Connect

    Akal, T.; berkson, J.M.

    1986-01-01

    This book presents information on seismo-acoustic propagation in seawater and sea beds that includes theoretical developments, modelling and experiments, and fluctuations. Boundary scatteiring, seismo-acoustic waves and seismo-acoustic noise are discussed. Technology and new approaches in seismo-acoustic measurements are presented.

  13. Electroabsorption spectroscopy of bulk heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Tzolov, Marian; Cohick, Zane; Green, Christopher

    Bulk heterojunction solar cells were fabricated using PCPDTBT polymer and PCBM in inert atmosphere. Electroabsorption (EA) spectroscopy was performed in the spectral range 350-1000 nm. The first derivative of the optical absorbance spectra explains satisfactory most of the bands in the EA spectra. The only deviation is in the spectral range around 760 nm. Control experiments with devices containing only a PCPDTBT film confirm that the band at 760 nm is associated with the presence of PCBM, despite that pristine PCBM is not expected to have such band. Electrical DC bias strongly affects this band. Negative DC bias almost completely eliminates this band, while positive bias enhances it. We interpret the band at 760 nm as due to photogenerated charge carriers trapped at defect states or at interfaces within the composite PCPDTBT/PCBM film. The effective transfer of photogenerated charge carriers between PCPDTBT and PCBM is confirmed by the quenching of the photoluminescence in the composite film, while the emission of electroluminescence from the devices confirms that PCPDTBT is an effective medium for recombination of charges injected in it.

  14. Acoustic cooling engine

    DOEpatents

    Hofler, Thomas J.; Wheatley, John C.; Swift, Gregory W.; Migliori, Albert

    1988-01-01

    An acoustic cooling engine with improved thermal performance and reduced internal losses comprises a compressible fluid contained in a resonant pressure vessel. The fluid has a substantial thermal expansion coefficient and is capable of supporting an acoustic standing wave. A thermodynamic element has first and second ends and is located in the resonant pressure vessel in thermal communication with the fluid. The thermal response of the thermodynamic element to the acoustic standing wave pumps heat from the second end to the first end. The thermodynamic element permits substantial flow of the fluid through the thermodynamic element. An acoustic driver cyclically drives the fluid with an acoustic standing wave. The driver is at a location of maximum acoustic impedance in the resonant pressure vessel and proximate the first end of the thermodynamic element. A hot heat exchanger is adjacent to and in thermal communication with the first end of the thermodynamic element. The hot heat exchanger conducts heat from the first end to portions of the resonant pressure vessel proximate the hot heat exchanger. The hot heat exchanger permits substantial flow of the fluid through the hot heat exchanger. The resonant pressure vessel can include a housing less than one quarter wavelength in length coupled to a reservoir. The housing can include a reduced diameter portion communicating with the reservoir. The frequency of the acoustic driver can be continuously controlled so as to maintain resonance.

  15. Acoustic mapping velocimetry

    NASA Astrophysics Data System (ADS)

    Muste, M.; Baranya, S.; Tsubaki, R.; Kim, D.; Ho, H.; Tsai, H.; Law, D.

    2016-05-01

    Knowledge of sediment dynamics in rivers is of great importance for various practical purposes. Despite its high relevance in riverine environment processes, the monitoring of sediment rates remains a major and challenging task for both suspended and bed load estimation. While the measurement of suspended load is currently an active area of testing with nonintrusive technologies (optical and acoustic), bed load measurement does not mark a similar progress. This paper describes an innovative combination of measurement techniques and analysis protocols that establishes the proof-of-concept for a promising technique, labeled herein Acoustic Mapping Velocimetry (AMV). The technique estimates bed load rates in rivers developing bed forms using a nonintrusive measurements approach. The raw information for AMV is collected with acoustic multibeam technology that in turn provides maps of the bathymetry over longitudinal swaths. As long as the acoustic maps can be acquired relatively quickly and the repetition rate for the mapping is commensurate with the movement of the bed forms, successive acoustic maps capture the progression of the bed form movement. Two-dimensional velocity maps associated with the bed form migration are obtained by implementing algorithms typically used in particle image velocimetry to acoustic maps converted in gray-level images. Furthermore, use of the obtained acoustic and velocity maps in conjunction with analytical formulations (e.g., Exner equation) enables estimation of multidirectional bed load rates over the whole imaged area. This paper presents a validation study of the AMV technique using a set of laboratory experiments.

  16. Development of anticavitation hydrophone using a titanium front plate: Effect of the titanium front plate in high-intensity acoustic field with generation of acoustic cavitation

    NASA Astrophysics Data System (ADS)

    Shiiba, Michihisa; Okada, Nagaya; Kurosawa, Minoru; Takeuchi, Shinichi

    2016-07-01

    Novel anticavitation hydrophones were fabricated by depositing a hydrothermally synthesized lead zirconate titanate polycrystalline film at the back of a titanium front plate. These anticavitation hydrophones were not damaged by the measurement of the acoustic field formed by a high-intensity focused ultrasound (HIFU) device. Their sensitivity was improved by approximately 20 dB over that of the conventional anticavitation hydrophone by modifying their basic structure and materials. The durability of the anticavitation hydrophone that we fabricated was compared by exposing it to a high-intensity acoustic field at the focal point of the HIFU field and in the water tank of an ultrasound cleaner. Therefore, the effect of the surface of the titanium front plate on acoustic cavitation was investigated by exposing such a surface to the high-intensity acoustic field. We found that the fabricated anticavitation hydrophone was robust and was not damaged easily, even in the focused acoustic field where acoustic cavitation occurs.

  17. Mars Acoustic Anemometer

    NASA Astrophysics Data System (ADS)

    Banfield, D. J.

    2012-12-01

    is far less susceptible to contaminating influences as other techniques (e.g., hot wire/hot film) that have been used for anemometry at Mars. Our instrument is conceptually derived from the commercial terrestrial sonic anemometers, but uses specialized acoustic transducers to optimally couple with the low density martian air as well as survive the extreme temperature swings on Mars. Additionally, we use sophisticated signal processing to extract as much information as possible in the low S/N environment that is achievable at Mars. We have developed our instrument through to TRL 5, proving it in a martian wind tunnel in Denmark. We found wind speed sensitivities and precision to be of order 3 cm/s, and with appropriate calibration, accuracy can be similar, even when operating at 20-100 Hz. We will also test this instrument at 120,000' altitude (i.e., equivalent to Mars atmospheric density) as an autonomous package on a stratospheric balloon. We are currently developing a TRL 6 version of the instrument that will be tested once again in the Denmark Mars Wind Tunnel. We expect our flight configuration instrument to be about 1 kg, including a 1.5m mast. It will also draw about 2-3W of power. This instrument is now ready to be proposed for future Mars missions, where we believe it will make a significant contribution and a step forward in Mars atmospheric science.

  18. Some Problems of modern acoustics

    NASA Technical Reports Server (NTRS)

    Stan, A.

    1974-01-01

    The multidisciplinary and interdisciplinary character of acoustics is considered and its scientific, technological, economical and social implications, as well as the role of acoustics in creating new machines and equipment and improving the quality of products are outlined. Research beyond audible frequencies, as well as to extremely high acoustic intensities, which requires the development of a nonlinear acoustics is elaborated.

  19. Photoacoustic characterization of the mechanical properties of thin film materials

    NASA Astrophysics Data System (ADS)

    Zhang, Feifei; Krishnaswamy, Sridhar; Fei, Dong; Rebinsky, Douglas A.

    2005-05-01

    Two high frequency photoacoustic techniques were applied to investigate the mechanical properties of two sets of thin film materials in this work. Broadband photoacoustic guided-wave method was used to measure the guided-wave phase velocity dispersion curves of nano-structured diamond-like carbon hard coatings. The experimental velocity spectra were analyzed by a nonlinear optimization approach in conjunction with a multi-layer wave-propagation model. The derived Young"s moduli using the broadband photoacoustic technique were compared with line-focus acoustic microscopy and nano-indentation tests and good quantitative agreement is found. In a second set of experiments, ultra-thin two-layer aluminum and silicon nitride thin film materials were tested using the femtosecond transient pump-probe method using high frequency bulk waves generated by the ultra-fast laser pulses. The measured moduli of silicon nitride thin layers are in the range of 270 - 340 GPa. Photoacoustic methods are shown to be suitable for in-situ and non-destructive evaluation of the mechanical properties of thin films.

  20. Surface Acoustic Wave Devices for Harsh Environment Wireless Sensing

    PubMed Central

    Greve, David W.; Chin, Tao-Lun; Zheng, Peng; Ohodnicki, Paul; Baltrus, John; Oppenheim, Irving J.

    2013-01-01

    Langasite surface acoustic wave devices can be used to implement harsh-environment wireless sensing of gas concentration and temperature. This paper reviews prior work on the development of langasite surface acoustic wave devices, followed by a report of recent progress toward the implementation of oxygen gas sensors. Resistive metal oxide films can be used as the oxygen sensing film, although development of an adherent barrier layer will be necessary with the sensing layers studied here to prevent interaction with the langasite substrate. Experimental results are presented for the performance of a langasite surface acoustic wave oxygen sensor with tin oxide sensing layer, and these experimental results are correlated with direct measurements of the sensing layer resistivity. PMID:23708273

  1. Surface acoustic wave devices for harsh environment wireless sensing

    SciTech Connect

    Greve, David W.; Chin, Tao -Lun; Zheng, Peng; Ohodnicki, Paul; Baltrus, John; Oppenheim, Irving J.

    2013-05-24

    In this study, langasite surface acoustic wave devices can be used to implement harsh environment wireless sensing of gas concentration and temperature. This paper reviews prior work on the development of langasite surface acoustic wave devices, followed by a report of recent progress toward the implementation of oxygen gas sensors. Resistive metal oxide films can be used as the oxygen sensing film, although development of an adherent barrier layer will be necessary with the sensing layers studied here to prevent interaction with the langasite substrate. Experimental results are presented for the performance of a langasite surface acoustic wave oxygen sensor with tin oxide sensing layer, and these experimental results are correlated with direct measurements of the sensing layer resistivity.

  2. Surface acoustic wave devices for harsh environment wireless sensing

    DOE PAGESBeta

    Greve, David W.; Chin, Tao -Lun; Zheng, Peng; Ohodnicki, Paul; Baltrus, John; Oppenheim, Irving J.

    2013-05-24

    In this study, langasite surface acoustic wave devices can be used to implement harsh environment wireless sensing of gas concentration and temperature. This paper reviews prior work on the development of langasite surface acoustic wave devices, followed by a report of recent progress toward the implementation of oxygen gas sensors. Resistive metal oxide films can be used as the oxygen sensing film, although development of an adherent barrier layer will be necessary with the sensing layers studied here to prevent interaction with the langasite substrate. Experimental results are presented for the performance of a langasite surface acoustic wave oxygen sensormore » with tin oxide sensing layer, and these experimental results are correlated with direct measurements of the sensing layer resistivity.« less

  3. Acoustic well cleaner

    DOEpatents

    Maki, Jr., Voldi E.; Sharma, Mukul M.

    1997-01-21

    A method and apparatus are disclosed for cleaning the wellbore and the near wellbore region. A sonde is provided which is adapted to be lowered into a borehole and which includes a plurality of acoustic transducers arranged around the sonde. Electrical power provided by a cable is converted to acoustic energy. The high intensity acoustic energy directed to the borehole wall and into the near wellbore region, redissolves or resuspends the material which is reducing the permeability of the formation and/or restricting flow in the wellbore.

  4. Acoustic rotation control

    NASA Technical Reports Server (NTRS)

    Elleman, D. D.; Croonquist, A. P.; Wang, T. G. (Inventor)

    1983-01-01

    A system is described for acoustically controlled rotation of a levitated object, which avoids deformation of a levitated liquid object. Acoustic waves of the same wavelength are directed along perpendicular directions across the object, and with the relative phases of the acoustic waves repeatedly switched so that one wave alternately leads and lags the other by 90 deg. The amount of torque for rotating the object, and the direction of rotation, are controlled by controlling the proportion of time one wave leads the other and selecting which wave leads the other most of the time.

  5. PRSEUS Acoustic Panel Fabrication

    NASA Technical Reports Server (NTRS)

    Nicolette, Velicki; Yovanof, Nicolette P.; Baraja, Jaime; Mathur, Gopal; Thrash, Patrick; Pickell, Robert

    2011-01-01

    This report describes the development of a novel structural concept, Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS), that addresses the demanding fuselage loading requirements for the Hybrid Wing or Blended Wing Body (BWB) airplane configuration with regards to acoustic response. A PRSEUS panel was designed and fabricated and provided to NASA-LaRC for acoustic response testing in the Structural Acoustics Loads and Transmission (SALT) facility). Preliminary assessments of the sound transmission characteristics of a PRSEUS panel subjected to a representative Hybrid Wing Body (HWB) operating environment were completed for the NASA Environmentally Responsible Aviation (ERA) Program.

  6. Acoustical heat pumping engine

    DOEpatents

    Wheatley, John C.; Swift, Gregory W.; Migliori, Albert

    1983-08-16

    The disclosure is directed to an acoustical heat pumping engine without moving seals. A tubular housing holds a compressible fluid capable of supporting an acoustical standing wave. An acoustical driver is disposed at one end of the housing and the other end is capped. A second thermodynamic medium is disposed in the housing near to but spaced from the capped end. Heat is pumped along the second thermodynamic medium toward the capped end as a consequence both of the pressure oscillation due to the driver and imperfect thermal contact between the fluid and the second thermodynamic medium.

  7. Acoustical heat pumping engine

    DOEpatents

    Wheatley, J.C.; Swift, G.W.; Migliori, A.

    1983-08-16

    The disclosure is directed to an acoustical heat pumping engine without moving seals. A tubular housing holds a compressible fluid capable of supporting an acoustical standing wave. An acoustical driver is disposed at one end of the housing and the other end is capped. A second thermodynamic medium is disposed in the housing near to but spaced from the capped end. Heat is pumped along the second thermodynamic medium toward the capped end as a consequence both of the pressure oscillation due to the driver and imperfect thermal contact between the fluid and the second thermodynamic medium. 2 figs.

  8. An Acoustical and Physiological Investigation of the Arabic /E/.

    ERIC Educational Resources Information Center

    Al-Ani, Salman H.

    Using acoustical evidence from spectrograms and physiological evidence from X-ray sound films, it appears that the most common allophone for the Arabic voiced pharyngeal fricative, at least in Iraqi, is a voiceless stop, and not a voiced fricative, as many believe. The author considers the phoneme in different environments and describes its…

  9. Acoustic Requirements for a Multi-Purpose Hall.

    ERIC Educational Resources Information Center

    Schulte, W. Allen

    2002-01-01

    This case study examines the proposed design of a new lecture/recital hall in Centennial Hall at Lynchburg College that will be used for lectures, public events, a film studies course, and musical recitals. It explores the audio-visual challenges presented by the differing acoustical requirements for the building. (EV)

  10. Design of a broadband ultra-large area acoustic cloak based on a fluid medium

    NASA Astrophysics Data System (ADS)

    Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Jiang, Ping

    2014-10-01

    A broadband ultra-large area acoustic cloak based on fluid medium was designed and numerically implemented with homogeneous metamaterials according to the transformation acoustics. In the present work, fluid medium as the body of the inclusion could be tuned by changing the fluid to satisfy the variant acoustic parameters instead of redesign the whole cloak. The effective density and bulk modulus of the composite materials were designed to agree with the parameters calculated from the coordinate transformation methodology by using the effective medium theory. Numerical simulation results showed that the sound propagation and scattering signature could be controlled in the broadband ultra-large area acoustic invisibility cloak, and good cloaking performance has been achieved and physically realized with homogeneous materials. The broadband ultra-large area acoustic cloaking properties have demonstrated great potentials in the promotion of the practical applications of acoustic cloak.

  11. Efficient organic photovoltaic cells with vertically ordered bulk heterojunctions.

    PubMed

    Yu, Bo; Wang, Haibo; Yan, Donghang

    2013-12-01

    Nanoscale morphology has been proved to be the key parameter deciding the exciton dissociation and charge transportation in bulk heterojunction (BHJ) solar cells. In this paper, we report a kind of small molecular organic photovoltaic cell (OPV) with a vertically ordered BHJ prepared by the weak epitaxial growth method. By this method, zinc phthalocyanine (ZnPc) can easily be formed into a highly ordered and continuous thin film and C60 is inclined to become dispersed crystalline grains in ZnPc film. Furthermore, we can control both the size and distribution density of C60 crystalline grains in ZnPc thin film without destroying the order of the ZnPc thin film. The OPVs with the vertically ordered BHJ show a high fill factor and a power conversion efficiency over 3% has been achieved. PMID:24196430

  12. Efficient organic photovoltaic cells with vertically ordered bulk heterojunctions

    NASA Astrophysics Data System (ADS)

    Yu, Bo; Wang, Haibo; Yan, Donghang

    2013-12-01

    Nanoscale morphology has been proved to be the key parameter deciding the exciton dissociation and charge transportation in bulk heterojunction (BHJ) solar cells. In this paper, we report a kind of small molecular organic photovoltaic cell (OPV) with a vertically ordered BHJ prepared by the weak epitaxial growth method. By this method, zinc phthalocyanine (ZnPc) can easily be formed into a highly ordered and continuous thin film and C60 is inclined to become dispersed crystalline grains in ZnPc film. Furthermore, we can control both the size and distribution density of C60 crystalline grains in ZnPc thin film without destroying the order of the ZnPc thin film. The OPVs with the vertically ordered BHJ show a high fill factor and a power conversion efficiency over 3% has been achieved.

  13. Acoustic Neuroma Association

    MedlinePlus

    ... Platinum Sponsors More from this sponsor... Platinum Sponsor Gold Sponsor University of Colorado Acoustic Neuroma Program Rocky Mountain Gamma Knife Center Gold Sponsor NYU Langone Medical Center Departments of Neurosurgery ...

  14. Compact acoustic refrigerator

    DOEpatents

    Bennett, Gloria A.

    1992-01-01

    A compact acoustic refrigeration system actively cools components, e.g., electrical circuits (22), in a borehole environment. An acoustic engine (12, 14) includes first thermodynamic elements (12) for generating a standing acoustic wave in a selected medium. An acoustic refrigerator (16, 26, 28) includes second thermodynamic elements (16) located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements (16) and a relatively hot temperature at a second end of the second thermodynamic elements (16). A resonator volume (18) cooperates with the first and second thermodynamic elements (12, 16) to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements (12, 16), first heat pipes (24, 26) transfer heat from the heat load (22) to the second thermodynamic elements (16) and second heat pipes (28, 32) transfer heat from first and second thermodynamic elements (12, 16) to the borehole environment.

  15. Acoustic imaging system

    DOEpatents

    Smith, Richard W.

    1979-01-01

    An acoustic imaging system for displaying an object viewed by a moving array of transducers as the array is pivoted about a fixed point within a given plane. A plurality of transducers are fixedly positioned and equally spaced within a laterally extending array and operatively directed to transmit and receive acoustic signals along substantially parallel transmission paths. The transducers are sequentially activated along the array to transmit and receive acoustic signals according to a preestablished sequence. Means are provided for generating output voltages for each reception of an acoustic signal, corresponding to the coordinate position of the object viewed as the array is pivoted. Receptions from each of the transducers are presented on the same display at coordinates corresponding to the actual position of the object viewed to form a plane view of the object scanned.

  16. Acoustics lecturing in Mexico

    NASA Astrophysics Data System (ADS)

    Beristain, Sergio

    2002-11-01

    Some thirty years ago acoustics lecturing started in Mexico at the National Polytechnic Institute in Mexico City, as part of the Bachelor of Science degree in Communications and Electronics Engineering curricula, including the widest program on this field in the whole country. This program has been producing acoustics specialists ever since. Nowadays many universities and superior education institutions around the country are teaching students at the B.Sc. level and postgraduate level many topics related to acoustics, such as Architectural Acoustics, Seismology, Mechanical Vibrations, Noise Control, Audio, Audiology, Music, etc. Also many institutions have started research programs in related fields, with participation of medical doctors, psychologists, musicians, engineers, etc. Details will be given on particular topics and development.

  17. Compact acoustic refrigerator

    SciTech Connect

    Bennett, G.A.

    1991-12-31

    This invention is comprised of a compact acoustic refrigeration system that actively cools components, e.g., electrical circuits, in a borehole environment. An acoustic engine includes first thermodynamic elements for generating a standing acoustic wave in a selected medium. An acoustic refrigerator includes second thermodynamic elements located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements and a relatively hot temperature at a second end of the second thermodynamic elements. A resonator volume cooperates with the first and second thermodynamic elements to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements, first heat pipes transfer heat from the heat load to the second thermodynamic elements and second heat pipes transfer heat from first and second thermodynamic elements to the borehole environment.

  18. Compact acoustic refrigerator

    DOEpatents

    Bennett, G.A.

    1992-11-24

    A compact acoustic refrigeration system actively cools components, e.g., electrical circuits, in a borehole environment. An acoustic engine includes first thermodynamic elements for generating a standing acoustic wave in a selected medium. An acoustic refrigerator includes second thermodynamic elements located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements and a relatively hot temperature at a second end of the second thermodynamic elements. A resonator volume cooperates with the first and second thermodynamic elements to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements, first heat pipes transfer heat from the heat load to the second thermodynamic elements and second heat pipes transfer heat from first and second thermodynamic elements to the borehole environment. 18 figs.

  19. Numerical Techniques in Acoustics

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J. (Compiler)

    1985-01-01

    This is the compilation of abstracts of the Numerical Techniques in Acoustics Forum held at the ASME's Winter Annual Meeting. This forum was for informal presentation and information exchange of ongoing acoustic work in finite elements, finite difference, boundary elements and other numerical approaches. As part of this forum, it was intended to allow the participants time to raise questions on unresolved problems and to generate discussions on possible approaches and methods of solution.

  20. Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface.

    PubMed

    Xie, Yangbo; Wang, Wenqi; Chen, Huanyang; Konneker, Adam; Popa, Bogdan-Ioan; Cummer, Steven A

    2014-01-01

    Metasurfaces are a family of novel wavefront-shaping devices with planar profile and subwavelength thickness. Acoustic metasurfaces with ultralow profile yet extraordinary wave manipulating properties would be highly desirable for improving the performance of many acoustic wave-based applications. However, designing acoustic metasurfaces with similar functionality to their electromagnetic counterparts remains challenging with traditional metamaterial design approaches. Here we present a design and realization of an acoustic metasurface based on tapered labyrinthine metamaterials. The demonstrated metasurface can not only steer an acoustic beam as expected from the generalized Snell's law, but also exhibits various unique properties such as conversion from propagating wave to surface mode, extraordinary beam-steering and apparent negative refraction through higher-order diffraction. Such designer acoustic metasurfaces provide a new design methodology for acoustic signal modulation devices and may be useful for applications such as acoustic imaging, beam steering, ultrasound lens design and acoustic surface wave-based applications. PMID:25418084

  1. Prediction of the acoustic impedance of duct liners

    NASA Technical Reports Server (NTRS)

    Zorumski, W. E.; Tester, B. J.

    1976-01-01

    Recent research which contributes to the prediction of the acoustic impedance of duct liners is reviewed. This review includes the linear and nonlinear properties of sheet and bulk type materials and methods for the measurement of these properties. It also includes the effect of grazing flow on the acoustic properties of materials. Methods for predicting the properties of single or multilayered, point reacting or extended reaction, and flat or curved liners are discussed. Based on this review, methods for predicting the properties of the duct liners which are typically used in aircraft engines are recommended. Some areas of needed research are discussed briefly.

  2. Acoustic communication by ants

    NASA Astrophysics Data System (ADS)

    Hickling, Robert

    2002-05-01

    Many ant species communicate acoustically by stridulating, i.e., running a scraper over a washboard-like set of ridges. Ants appear to be insensitive to airborne sound. Consequently, myrmecologists have concluded that the stridulatory signals are transmitted through the substrate. This has tended to diminish the importance of acoustic communication, and it is currently believed that ant communication is based almost exclusively on pheromones, with acoustic communication assigned an almost nonexistent role. However, it can be shown that acoustic communication between ants is effective only if the medium is air and not the substrate. How, then, is it possible for ants to appear deaf to airborne sound and yet communicate through the air? An explanation is provided in a paper [R. Hickling and R. L. Brown, ``Analysis of acoustic communication by ants,'' J. Acoust. Soc. Am. 108, 1920-1929 (2000)]. Ants are small relative to the wavelengths they generate. Hence, they create a near field, which is characterized by a major increase in sound velocity (particle velocity of sound) in the vicinity of the source. Hair sensilla on the ants' antennae respond to sound velocity. Thus, ants are able to detect near-field sound from other ants and to exclude extraneous airborne sound.

  3. Acoustic detection of pneumothorax

    NASA Astrophysics Data System (ADS)

    Mansy, Hansen A.; Royston, Thomas J.; Balk, Robert A.; Sandler, Richard H.

    2003-04-01

    This study aims at investigating the feasibility of using low-frequency (<2000 Hz) acoustic methods for medical diagnosis. Several candidate methods of pneumothorax detection were tested in dogs. In the first approach, broadband acoustic signals were introduced into the trachea during end-expiration and transmitted waves were measured at the chest surface. Pneumothorax was found to consistently decrease pulmonary acoustic transmission in the 200-1200-Hz frequency band, while less change was observed at lower frequencies (p<0.0001). The ratio of acoustic energy between low (<220 Hz) and mid (550-770 Hz) frequency bands was significantly different in the control (healthy) and pneumothorax states (p<0.0001). The second approach measured breath sounds in the absence of an external acoustic input. Pneumothorax was found to be associated with a preferential reduction of sound amplitude in the 200- to 700-Hz range, and a decrease of sound amplitude variation (in the 300 to 600-Hz band) during the respiration cycle (p<0.01 for each). Finally, chest percussion was implemented. Pneumothorax changed the frequency and decay rate of percussive sounds. These results imply that certain medical conditions may be reliably detected using appropriate acoustic measurements and analysis. [Work supported by NIH/NHLBI #R44HL61108.

  4. Ocean acoustic reverberation tomography.

    PubMed

    Dunn, Robert A

    2015-12-01

    Seismic wide-angle imaging using ship-towed acoustic sources and networks of ocean bottom seismographs is a common technique for exploring earth structure beneath the oceans. In these studies, the recorded data are dominated by acoustic waves propagating as reverberations in the water column. For surveys with a small receiver spacing (e.g., <10 km), the acoustic wave field densely samples properties of the water column over the width of the receiver array. A method, referred to as ocean acoustic reverberation tomography, is developed that uses the travel times of direct and reflected waves to image ocean acoustic structure. Reverberation tomography offers an alternative approach for determining the structure of the oceans and advancing the understanding of ocean heat content and mixing processes. The technique has the potential for revealing small-scale ocean thermal structure over the entire vertical height of the water column and along long survey profiles or across three-dimensional volumes of the ocean. For realistic experimental geometries and data noise levels, the method can produce images of ocean sound speed on a smaller scale than traditional acoustic tomography. PMID:26723303

  5. Thermoelastic response of thin metal films and their adjacent materials

    SciTech Connect

    Kang, S.; Yoon, Y.; Kim, J.; Kim, W.

    2013-01-14

    A pulsed laser beam applied to a thin metal film is capable of launching an acoustic wave due to thermal expansion. Heat transfer from the thin metal film to adjacent materials can also induce thermal expansion; thus, the properties of these adjacent materials (as well as the thin metal film) should be considered for a complete description of the thermoelastic response. Here, we show that adjacent materials with a small specific heat and large thermal expansion coefficient can generate an enhanced acoustic wave and we demonstrate a three-fold increase in the peak pressure of the generated acoustic wave on substitution of parylene for polydimethylsiloxane.

  6. Adaptive Back Sheet Material for Acoustic Liner Applications-ARMD Seedling Fund Phase I Final Report

    NASA Technical Reports Server (NTRS)

    Gerhold, Carl H.; Jones, Michael G.; Farrar, Dawnielle

    2014-01-01

    A recently developed piezo-electric composite film is evaluated for its usefulness in application in acoustic liners. Researchers at the NASA Langley Research Center Liner Technology Facility developed experiments to measure the electrical response of the material to acoustic excitation and the vibrational response of the material to electrical excitation. The robustness of the piezo-electric film was also assessed. The material's electrical response to acoustic excitation is found to be comparable to a commercial microphone in the range of frequencies from 500 to 3000 Hz. However, the vibrational response to electrical excitation in the frequency range of interest is an order of magnitude less than may be necessary for application to acoustic liners. Nevertheless, experimental results indicate that the potential exists for the material to produce a measurable change in the impedance spectrum of a liner. Work continues to improve the authority of the piezo-electric film.

  7. Phonon anharmonicity in bulk Td-MoTe2

    NASA Astrophysics Data System (ADS)

    Joshi, Jaydeep; Stone, Iris R.; Beams, Ryan; Krylyuk, Sergiy; Kalish, Irina; Davydov, Albert V.; Vora, Patrick M.

    2016-07-01

    We examine anharmonic contributions to the optical phonon modes in bulk Td-MoTe2 through temperature-dependent Raman spectroscopy. At temperatures ranging from 100 K to 200 K, we find that all modes redshift linearly with temperature in agreement with the Grüneisen model. However, below 100 K, we observe nonlinear temperature-dependent frequency shifts in some modes. We demonstrate that this anharmonic behavior is consistent with the decay of an optical phonon into multiple acoustic phonons. Furthermore, the highest frequency Raman modes show large changes in intensity and linewidth near T ≈ 250 K that correlate well with the T d → 1 T ' structural phase transition. These results suggest that phonon-phonon interactions can dominate anharmonic contributions at low temperatures in bulk Td-MoTe2, an experimental regime that is currently receiving attention in efforts to understand Weyl semimetals.

  8. Frequency and Time Domain Modeling of Acoustic Liner Boundary Conditions

    NASA Technical Reports Server (NTRS)

    Bliss, Donald B.

    1982-01-01

    As part of a research program directed at the acoustics of advanced subsonic propulsion systems undertaken at NASA Langley, Duke University was funded to develop a boundary condition model for bulk-reacting nacelle liners. The overall objective of the Langley program was to understand and predict noise from advanced subsonic transport engines and to develop related noise control technology. The overall technical areas included: fan and propeller source noise, acoustics of ducts and duct liners, interior noise, subjective acoustics, and systems noise prediction. The Duke effort was directed toward duct liner acoustics for the development of analytical methods to characterize liner behavior in both frequency domain and time domain. A review of duct acoustics and liner technology can be found in Reference [1]. At that time, NASA Langley was investigating the propulsion concept of an advanced ducted fan, with a large diameter housed inside a relatively short duct. Fan diameters in excess of ten feet were proposed. The lengths of both the inlet and exhaust portions of the duct were to be short, probably less than half the fan diameter. The nacelle itself would be relatively thin-walled for reasons of aerodynamic efficiency. The blade-passage frequency was expected to be less than I kHz, and very likely in the 200 to 300 Hz range. Because of the design constraints of a short duct, a thin nacelle, and long acoustic wavelengths, the application of effective liner technology would be especially challenging. One of the needs of the NASA Langley program was the capability to accurately and efficiently predict the behavior of the acoustic liner. The traditional point impedance method was not an adequate model for proposed liner designs. The method was too restrictive to represent bulk reacting liners and to allow for the characterization of many possible innovative liner concepts. In the research effort at Duke, an alternative method, initially developed to handle bulk

  9. Thin films for material engineering

    NASA Astrophysics Data System (ADS)

    Wasa, Kiyotaka

    2016-07-01

    Thin films are defined as two-dimensional materials formed by condensing one by one atomic/molecular/ionic species of matter in contrast to bulk three-dimensional sintered ceramics. They are grown through atomic collisional chemical reaction on a substrate surface. Thin film growth processes are fascinating for developing innovative exotic materials. On the basis of my long research on sputtering deposition, this paper firstly describes the kinetic energy effect of sputtered adatoms on thin film growth and discusses on a possibility of room-temperature growth of cubic diamond crystallites and the perovskite thin films of binary compound PbTiO3. Secondly, high-performance sputtered ferroelectric thin films with extraordinary excellent crystallinity compatible with MBE deposited thin films are described in relation to a possible application for thin-film MEMS. Finally, the present thin-film technologies are discussed in terms of a future material science and engineering.

  10. Acoustic calibration apparatus for calibrating plethysmographic acoustic pressure sensors

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J. (Inventor); Davis, David C. (Inventor)

    1995-01-01

    An apparatus for calibrating an acoustic sensor is described. The apparatus includes a transmission material having an acoustic impedance approximately matching the acoustic impedance of the actual acoustic medium existing when the acoustic sensor is applied in actual in-service conditions. An elastic container holds the transmission material. A first sensor is coupled to the container at a first location on the container and a second sensor coupled to the container at a second location on the container, the second location being different from the first location. A sound producing device is coupled to the container and transmits acoustic signals inside the container.

  11. Dynamic measurement of bulk modulus

    NASA Technical Reports Server (NTRS)

    Dowler, W. L.; Strand, L. D.

    1979-01-01

    Technique based on measuring phase difference between microwave reference and test signals and has been used to determine change in bulk modulus of solid-fuel rocket propellants should be useful in studying other dielectric materials.

  12. Bulk pesticide storage - state perspective

    SciTech Connect

    Buzicky, G.

    1994-12-31

    State bulk pesticide storage regulations continue to evolve differentially due, in large part, to the absence of federal regulations. This is about to change because of the pending promulgation of 40 CFR Part 165, as amended in 1988 by the Environmental Protection Agency (EPA) rules regarding storage, handling and disposal. Until final adoption of the rules by EPA, states continue to address bulk pesticide storage and handling according to individual state statute, rules and guidelines.

  13. Nonlinear acoustic detection of weathered, low compliance landmines

    NASA Astrophysics Data System (ADS)

    Sabatier, James M.; Alberts, W. C. Kirkpatrick; Korman, Murray S.

    2005-09-01

    Two potential impediments to acoustic landmine detection are soil weathering processes and low compliance landmines. To bury landmines, the soil within a mine diameter is removed and replaced such that bulk density, compression, and shear strength all decrease, leaving an acoustic scar detectable with the linear acoustic measurement technique. After a few soil wetting and drying cycles, this contrast is reduced. Linear acoustic mine detection measurements were made on a low impedance contrast landmine before the first rainfall on several occasions over the subsequent 5 years. During this period of time, both the spatial and frequency resolution had to be increased to maintain an on/off target velocity ratio that allowed detection. In some cases, the landmine remains undetectable. To address this, two-tone nonlinear acoustic measurements have been made on these landmines. When the landmine is detectable with linear acoustics, two tones are broadcast at the frequency where the on/off target velocity ratio is the largest. For the cases when the landmine is undetectable, a two-tone sweep is performed and the operator observes the real-time velocity FFT, noting nonlinear sidebands. Next, two-tone tests are conducted at these sidebands to determine nonlinear velocity profiles. [Work supported by U.S. Army RDECOM, NVESD.

  14. Investigation of Local Elastic Properties in Friction Stir Welded TI-6AL-4V Using Scanning Acoustic Microscopy

    NASA Astrophysics Data System (ADS)

    Martin, Richard W.; Sathish, Shamachary; Jata, Kumar V.

    2008-02-01

    Local changes in the microstructure and ultrasonic wave velocity variation across a friction weld in Ti-6A1-4V are investigated using scanning acoustic microscopy. Surface and bulk acoustic wave velocity and amplitude measurements performed across the weld are presented. The changes in the characteristics of the surface waves are related to the near surface microstructure in different parts of the weld. The bulk velocity and amplitude changes thru the thickness show bright and dark bands particularly in the nugget region. Possible reasons for formation of such bands are discussed. Application of acoustic microscopy to detect localized process induced defects in friction stir welds is discussed.

  15. 49 CFR 178.519 - Standards for plastic film bags.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Standards for plastic film bags. 178.519 Section...-bulk Performance-Oriented Packaging Standards § 178.519 Standards for plastic film bags. (a) The identification code for a plastic film bag is 5H4. (b) Construction requirements for plastic film bags are...

  16. 49 CFR 178.519 - Standards for plastic film bags.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Standards for plastic film bags. 178.519 Section...-bulk Performance-Oriented Packaging Standards § 178.519 Standards for plastic film bags. (a) The identification code for a plastic film bag is 5H4. (b) Construction requirements for plastic film bags are...

  17. 49 CFR 178.519 - Standards for plastic film bags.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Standards for plastic film bags. 178.519 Section...-bulk Performance-Oriented Packaging Standards § 178.519 Standards for plastic film bags. (a) The identification code for a plastic film bag is 5H4. (b) Construction requirements for plastic film bags are...

  18. 49 CFR 178.519 - Standards for plastic film bags.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Standards for plastic film bags. 178.519 Section...-bulk Performance-Oriented Packaging Standards § 178.519 Standards for plastic film bags. (a) The identification code for a plastic film bag is 5H4. (b) Construction requirements for plastic film bags are...

  19. Measuring acoustic habitats

    PubMed Central

    Merchant, Nathan D; Fristrup, Kurt M; Johnson, Mark P; Tyack, Peter L; Witt, Matthew J; Blondel, Philippe; Parks, Susan E

    2015-01-01

    1. Many organisms depend on sound for communication, predator/prey detection and navigation. The acoustic environment can therefore play an important role in ecosystem dynamics and evolution. A growing number of studies are documenting acoustic habitats and their influences on animal development, behaviour, physiology and spatial ecology, which has led to increasing demand for passive acoustic monitoring (PAM) expertise in the life sciences. However, as yet, there has been no synthesis of data processing methods for acoustic habitat monitoring, which presents an unnecessary obstacle to would-be PAM analysts. 2. Here, we review the signal processing techniques needed to produce calibrated measurements of terrestrial and aquatic acoustic habitats. We include a supplemental tutorial and template computer codes in matlab and r, which give detailed guidance on how to produce calibrated spectrograms and statistical analyses of sound levels. Key metrics and terminology for the characterisation of biotic, abiotic and anthropogenic sound are covered, and their application to relevant monitoring scenarios is illustrated through example data sets. To inform study design and hardware selection, we also include an up-to-date overview of terrestrial and aquatic PAM instruments. 3. Monitoring of acoustic habitats at large spatiotemporal scales is becoming possible through recent advances in PAM technology. This will enhance our understanding of the role of sound in the spatial ecology of acoustically sensitive species and inform spatial planning to mitigate the rising influence of anthropogenic noise in these ecosystems. As we demonstrate in this work, progress in these areas will depend upon the application of consistent and appropriate PAM methodologies. PMID:25954500

  20. [INVITED] Laser generation and detection of ultrafast shear acoustic waves in solids and liquids

    NASA Astrophysics Data System (ADS)

    Pezeril, Thomas

    2016-09-01

    The aim of this article is to provide an overview of the up-to-date findings related to ultrafast shear acoustic waves. Recent progress obtained for the laser generation and detection of picosecond shear acoustic waves in solids and liquids is reviewed. Examples in which the transverse isotropic symmetry of the sample structure is broken in order to permit shear acoustic wave generation through sudden laser heating are described in detail. Alternative photo-induced mechanisms for ultrafast shear acoustic generation in metals, semiconductors, insulators, magnetostrictive, piezoelectric and electrostrictive materials are reviewed as well. With reference to key experiments, an all-optical technique employed to probe longitudinal and shear structural dynamics in the GHz frequency range in ultra-thin liquid films is described. This technique, based on specific ultrafast shear acoustic transducers, has opened new perspectives that will be discussed for ultrafast shear acoustic probing of viscoelastic liquids at the nanometer scale.