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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. Ferroelectric film bulk acoustic wave resonators for liquid viscosity sensing

    NASA Astrophysics Data System (ADS)

    Vorobiev, A.; Gevorgian, S.

    2013-08-01

    A concept of accurate liquid viscosity sensing, using bulk acoustic wave (BAW) resonators, is proposed. The proposed BAW resonators use thin ferroelectric films with the dc field induced piezoelectric effect allowing for generation of pure longitudinal acoustic waves in the thickness excitation mode. This makes it possible to utilize exclusively shear liquid particle displacement at the resonator side walls and, therefore, accurate viscosity evaluation. The BAW resonators with the dc field induced piezoelectric effect in 0.67BiFeO3-0.33BaTiO3 ferroelectric films are fabricated and their liquid viscosity sensing properties are characterized. The resonator response is analyzed using simple model of a harmonic oscillator damped by a viscous force. It is shown that the resonator Q-factor is inversely proportional to the square root of the viscosity-density product. The viscosity measurement resolution is estimated to be as high as 0.005 mPa.s, which is 0.5% of the water viscosity.

  3. 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).

  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. CMOS-Integrated Film Bulk Acoustic Resonators for Label-Free Biosensing

    PubMed Central

    Nirschl, Martin; Rantala, Arto; Tukkiniemi, Kari; Auer, Sanna; Hellgren, Ann-Charlotte; Pitzer, Dana; Schreiter, Matthias; Vikholm-Lundin, Inger

    2010-01-01

    The throughput is an important parameter for label-free biosensors. Acoustic resonators like the quartz crystal microbalance have a low throughput because the number of sensors which can be used at the same time is limited. Here we present an array of 64 CMOS-integrated film bulk acoustic resonators. We compare the performance with surface plasmon resonance and the quartz crystal microbalance and demonstrate the performance of the sensor for multiplexed detection of DNA. PMID:22399875

  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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    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 {K}_{eff}^2 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.

  8. Temperature Sensing by Using Film Bulk Acoustic Resonator at 2.4 GHz Band

    NASA Astrophysics Data System (ADS)

    Kao, Yao-Huang; Lin, Jon-Hong

    2009-11-01

    A four-layered film bulk acoustic resonator (FBAR) with an Al/AlN/SiN/Au composite structure was fabricated. The FBAR is composed of a surface micromachined cantilever whose copper scarification layer is released by wet etching. A temperature coefficient (TC) of resonant frequency of -34.5 ppm/°C in the temperature range from 10 to 80 °C at 2.4 GHz is obtained. Using this resonator, an oscillator for temperature sensing was constructed, in which temperature can be detected easily by measuring the shift in oscillation frequency. The TC of the oscillator is almost the same as that of the resonator.

  9. Sensitivity study of multilayer thin-film bulk acoustic resonator for mass sensor application

    NASA Astrophysics Data System (ADS)

    Liu, Haiqiang; Li, Fang; Qin, Lifeng; Wang, Qing-Ming

    2016-10-01

    The sensitivity of multilayer thin-film bulk acoustic resonators (MTFBARs) used as mass sensors is investigated. MTFBAR sensors with the structure of a mass-sensitive layer/electrode layer/piezo layer/electrode layer were used. Two methods, one using electric impedance and the other displacement, were adopted for the determination of sensitivity. Simulation results show that the two methods agree well, and the characteristic acoustic impedance and thickness of the non-piezo layers strongly affect mass sensitivity. It was found that high acoustic impedance in the non-piezo layer is not helpful for sensitivity improvement. Sensitivity is improved by choosing an appropriate thickness for the low acoustic impedance non-piezo layer, and the maximum sensitivity can be obtained by choosing suitable thickness combinations for the layers. Moreover, it was found that MTFBAR quality factor and sensitivity are simultaneously improved by adopting a high-quality-factor non-piezo layer with low acoustic impedance for an air working environment, whereas a balance between quality factor and sensitivity is found through optimization of the non-piezo layers for a water working environment. These results can be used for the design and application of MTFBAR mass sensors.

  10. Micro-electromechanical film bulk acoustic sensor for plasma and whole blood coagulation monitoring.

    PubMed

    Chen, Da; Song, Shuren; Ma, Jilong; Zhang, Zhen; Wang, Peng; Liu, Weihui; Guo, Qiuquan

    2017-05-15

    Monitoring blood coagulation is an important issue in the surgeries and the treatment of cardiovascular diseases. In this work, we reported a novel strategy for the blood coagulation monitoring based on a micro-electromechanical film bulk acoustic resonator. The resonator was excited by a lateral electric field and operated under the shear mode with a frequency of 1.9GHz. According to the apparent step-ladder curves of the frequency response to the change of blood viscoelasticity, the coagulation time (prothrombin time) and the coagulation kinetics were measured with the sample consumption of only 1μl. The procoagulant activity of thromboplastin and the anticoagulant effect of heparin on the blood coagulation process were illustrated exemplarily. The measured prothrombin times showed a good linear correlation with R(2)=0.99969 and a consistency with the coefficient of variation less than 5% compared with the commercial coagulometer. The proposed film bulk acoustic sensor, which has the advantages of small size, light weight, low cost, simple operation and little sample consumption, is a promising device for miniaturized, online and automated analytical system for routine diagnostics of hemostatic status and personal health monitoring. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. ZnO Film Bulk Acoustic Resonator for the Kinetics Study of Human Blood Coagulation

    PubMed Central

    Chen, Da; Zhang, Zhen; Ma, Jilong; Wang, Wei

    2017-01-01

    Miniaturized and rapid blood coagulation assay technologies are critical in many clinical settings. In this paper, we present a ZnO film bulk acoustic resonator for the kinetic analysis of human blood coagulation. The resonator operated in thickness shear resonance mode at 1.4 GHz. When the resonator contacted the liquid environment, the viscous loading effect was considered as the additional resistance and inductance in the equivalent circuits, resulting in a linear relationship with a slope of approximately −217 kHz/cP between the liquid viscosity and the frequency of the resonator. The downshift of the resonant frequency and the viscosity change during the blood coagulation were correlated to monitor the coagulation process. The sigmoidal trend was observed in the frequency response for the blood samples activated by thromboplastin and calcium ions. The coagulation kinetics involving sequential phases of steady reaction, growth and saturation were revealed through the time-dependent frequency profiles. The enzymatic cascade time, the coagulation rate, the coagulation time and the clot degree were provided by fitting the time-frequency curves. The prothrombin times were compared with the results measured by a standard coagulometer and show a good correlation. Thanks to the excellent potential of integration, miniaturization and the availability of direct digital signals, the film bulk acoustic resonator has promising application for both clinical and personal use coagulation testing technologies. PMID:28467374

  12. Long thickness-extensional waves in thin film bulk acoustic wave filters affected by interdigital electrodes.

    PubMed

    Liu, Jing; Du, Jianke; Wang, Ji; Yang, Jiashi

    2017-03-01

    We studied free vibrations of thin-film bulk acoustic wave filters with interdigital electrodes theoretically using the scalar differential equations by Tiersten and Stevens. The filters are made from AlN or ZnO films on Si substrates with ground and driving electrodes. They operate with thickness-extensional modes. The basic vibration characteristics including resonant frequencies and mode shapes were obtained. Their dependence on various geometric parameters was examined. It was found that for properly design filters there exist trapped modes whose vibrations are strong in regions with a driving electrode and decay away from the electrode edges. These trapped modes are essentially long plate thickness-extensional modes modulated by the electrode fingers. The number of trapped modes is sensitive to the geometric parameters.

  13. 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.

  14. 3.4 GHz composite thin film bulk acoustic wave resonator for miniaturized atomic clocks

    NASA Astrophysics Data System (ADS)

    Artieda, Alvaro; Muralt, Paul

    2011-06-01

    Triple layer SiO2/AlN/SiO2 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 87Rb atoms. The quality factor (Q) was equal to 2300 and the temperature coefficient of the resonance frequency fr amounted to 1.5 ppm/K. A figure of merit Qfr of ˜ 0.8 × 1013 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.

  15. A lateral field excited ZnO film bulk acoustic wave sensor working in viscous environments

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    We present a lateral field excited ZnO film bulk acoustic resonator (FBAR) operated in pure-shear mode and analyze its performances in viscous liquids. The electrodes of the device are located on the film surface and normal to the c-axis of the ZnO film. The proposed device works near 1.44 GHz with a Q-factor up to 360 in air and 310 in water, which are higher than those of the quasi-shear thickness field excited FBAR. The resonant frequency is decreased with the increasing square root of the product of the viscosity and density with a linear dependence in the viscosity below 148.7 mPa s. The mass sensitivity of 670 Hz cm2 ng-1 was measured by monitoring the frequency change during the volatilization of saline solution loaded on the resonator. In addition, the levels of the noise and the mass resolutions were measured in various viscous environments. The proposed device yields the mass resolution of 670 Hz cm2 ng-1 and the high mass resolution of 0.06 ng cm-2. These results indicated that the lateral field excited ZnO FBAR had superior sensitivity for the bio-sensing applications in viscous biological liquids.

  16. A film bulk acoustic resonator oscillator based humidity sensor with graphene oxide as the sensitive layer

    NASA Astrophysics Data System (ADS)

    Xuan, Weipeng; Cole, Marina; Gardner, Julian W.; Thomas, Sanju; Villa-López, Farah-Helúe; Wang, Xiaozhi; Dong, Shurong; Luo, Jikui

    2017-05-01

    A film bulk acoustic wave resonator (FBAR) is a type of resonator with high frequency and small dimensions, particularly suitable for use as a sensor for physical and biochemical sensing with high sensitivity. FBAR-based sensors have been extensively studied, however they commonly use discrete devices and network analyzers for evaluation, and therefore are far from being able to be used in practical applications. This paper reports the design and analysis of an FBAR-based Pierce oscillator and a field-programmable gate array (FPGA)-based frequency counter, and the use of the oscillator as a humidity sensor with the frequency counter as the measuring circuit. Graphene oxide (GO) is used as the sensitive film to improve the sensitivity. The resonant frequency of the oscillator with a GO film shows a linear decrease with an increase in relative humidity, with a sensitivity of ca. 5 kHz per %RH (relative humidity) in the range of 3%RH to 70%RH, and a higher frequency shift is induced above 70%RH. The FBAR oscillator sensor shows excellent stability and repeatability, demonstrating the feasibility and potential sensing application using the integrated FBAR chip and simple frequency counter, particularly suitable for portable electronics.

  17. 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.

  18. Real-time monitoring of human blood clotting using a lateral excited film bulk acoustic resonator

    NASA Astrophysics Data System (ADS)

    Chen, Da; Wang, Jingjng; Wang, Peng; Guo, Qiuquan; Zhang, Zhen; Ma, Jilong

    2017-04-01

    Frequent assay of hemostatic status is an essential issue for the millions of patients using anticoagulant drugs. In this paper, we presented a micro-fabricated film bulk acoustic sensor for the real-time monitoring of blood clotting and the measurement of hemostatic parameters. The device was made of an Au/ZnO/Si3N4 film stack and excited by a lateral electric field. It operated under a shear mode resonance with the frequency of 1.42 GHz and had a quality factor of 342 in human blood. During the clotting process of blood, the resonant frequency decreased along with the change of blood viscosity and showed an apparent step-ladder curve, revealing the sequential clotting stages. An important hemostatic parameter, prothrombin time, was quantitatively determined from the frequency response for different dilutions of the blood samples. The effect of a typical anticoagulant drug (heparin) on the prothrombin time was exemplarily shown. The proposed sensor displayed a good consistency and clinical comparability with the standard coagulometric methods. Thanks to the availability of direct digital signals, excellent potentials of miniaturization and integration, the proposed sensor has promising application for point-of-care coagulation technologies.

  19. Pulsed laser deposition of piezoelectric ZnO thin films for bulk acoustic wave devices

    NASA Astrophysics Data System (ADS)

    Serhane, Rafik; Abdelli-Messaci, Samira; Lafane, Slimane; Khales, Hammouche; Aouimeur, Walid; Hassein-Bey, Abdelkadder; Boutkedjirt, Tarek

    2014-01-01

    Piezoelectric properties of ZnO thin films have been investigated for micro-electro-mechanical systems (MEMS). Wurtzite ZnO structure was prepared on different substrates (Si (1 0 0), Pt (1 1 1)/Ti/SiO2/Si and Al (1 1 1)/SiO2/Si) at different substrate temperatures (from 100 to 500 °C) by a pulsed laser deposition (PLD) technique. X-ray diffraction (XRD) characterization showed that the ZnO films were highly c-axis (0 0 2) oriented, which is of interest for various piezoelectric applications. Scanning electron microscopy (SEM) showed evidence of honeycomb-like structure on the surface and columnar structure on the cross-section. In the case of ZnO on Al, ZnO exhibited an amorphous phase at the ZnO/Al interface. The XRD measurements indicated that the substrate temperature of 300 °C was the optimum condition to obtain high quality (strongest (0 0 2) peak with the biggest associated grain size) of crystalline ZnO on Pt and on Al and that 400 °C was the optimum one on Si. ZnO on Al exhibits smallest rocking curve width than on Pt, leading to better crystalline quality. The ZnO films were used in bulk acoustic wave (BAW) transducer. Electrical measurements of the input impedance and S-Parameters showed evidence of piezoelectric response. The electromechanical coupling coefficient was evaluated as Keff2    =    5 .0 9 %, with a quality factor Qr = 1001.4.

  20. A poly(vinylidene fluoride)-coated ZnO film bulk acoustic resonator for nerve gas detection

    NASA Astrophysics Data System (ADS)

    Chen, Da; Wang, Jingjing; Li, Dehua; Liu, Yijian; Song, Hongwei; Liu, Qixin

    2011-08-01

    We apply the film bulk acoustic resonator for the detection of nerve gas. The resonator is consisted of a ZnO piezoelectric stack and a W/SiO2 Bragg reflector. Poly(vinylidene fluoride) (PVDF) is used as the sensing coating to adsorb the analyte under test. The testing results show that our proposed sensor can yield a sensitive, reversible and reproducible response to nerve gas. The relationship between the frequency shifts and the concentrations of the nerve gas exhibits a perfect linear correlation in the range of 10-50 ppm. The gas sensitivity of the proposed sensor is 718 kHz ppm-1, which is several orders of magnitude higher than that of a quartz crystal microbalance with the same sensitive coating. This study proves that it is feasible to use the PVDF-coated thin film bulk acoustic resonator for the detection of the traced nerve gas.

  1. High-Q AlN/SiO2 symmetric composite thin film bulk acoustic wave resonators.

    PubMed

    Artieda, Alvaro; Muralt, Paul

    2008-11-01

    High-Q, bulk acoustic wave composite resonators based on a symmetric layer sequence of SiO(2)-AlN-SiO(2) sandwiched between electrodes have been developed. Acoustic isolation was achieved by means of deep silicon etching to obtain membrane type thin film bulk acoustic wave resonators (TFBARs). Three different device versions were investigated. The SiO(2) film thicknesses were varied (0 nm, 70 nm, 310 nm, and 770 nm) while the piezoelectric AlN film had a constant thickness of 1.2 microm. The sputter-deposited AlN film grown on the amorphous, sputter-deposited SiO(2) layer exhibited a d(33,f) of 4.0 pm/V. Experimental results of quality factors (Q) and coupling coefficients (k(t)(2)) are in agreement with finite element calculations. A Q of 2000 is observed for the first harmonic of the 310 nm oxide devices. The most intense resonance of the 770 nm oxide device is the third harmonic reaching Q factors of 1450. The temperature drift reveals the impact of the SiO(2) layers, which is more pronounced on the first harmonic, reducing the TCF to 4 ppm/K for the 3rd harmonic of the 310 nm oxide devices.

  2. Sensing characteristics of pure-shear film bulk acoustic resonator in viscous liquids

    NASA Astrophysics Data System (ADS)

    Chen, Da; Song, Shuren; Zhang, Dexue; Wang, Peng; Liu, Weihui

    2017-03-01

    We presented a pure-shear film bulk acoustic resonator (FBAR) and investigated its sensing characteristics in viscous liquids. In the resonator, the electrodes were located on the surface of c-axis-oriented AlN film to generate the lateral electric field and excite the shear acoustic resonance. Compared with the typical quasi-shear film bulk acoustic resonator based on inclined c-axis-oriented AlN or ZnO piezoelectric film, the proposed device exhibits significantly higher Q-factors and a notably improved detection limit, particularly in water and viscous liquids. The frequency shifts show a linear dependency on the square root of the product of the liquid viscosity and density of the glycerol solution in the viscosity range of 1-5 mPaṡs. Furthermore, we measured the mass sensitivity through real-time monitoring of the frequency change during the volatilization process of the loaded saline solutions. The proposed device shows the mass sensitivity of 465 Hzṡcm2/ng and the mass resolutions of 0.17 ng/cm2 in air, 0.25 ng/cm2 in water and 2.08 ng/cm2 in 50% glycerol solution, respectively. The obtained results clearly indicate that the proposed device is capable of using in liquid phase detection with high sensitivity requirements.

  3. Large electromechanical coupling factor film bulk acoustic resonator with X-cut LiNbO3 layer transfer

    NASA Astrophysics Data System (ADS)

    Pijolat, M.; Loubriat, S.; Queste, S.; Mercier, D.; Reinhardt, A.; Defaÿ, E.; Deguet, C.; Clavelier, L.; Moriceau, H.; Aïd, M.; Ballandras, S.

    2009-11-01

    As layer transfer techniques have been notably improved in the past years, lithium niobate (LiNbO3) appears as a candidate for the next generation of ultrawide band radio frequency (rf) filters. Depending on the crystalline orientation, LiNbO3 can achieve electromechanical coupling factors Kt2 more than six times larger than those of sputtered aluminum nitride films. In this letter, a process based on direct bonding, grinding, polishing, and deep reactive ion etching is proposed to fabricate a single crystal LiNbO3 film bulk acoustic resonator. From the fabricated test vehicles, Kt2 of 43% is measured confirming the values predicted by theoretical computations.

  4. Highly sensitive detection of organophosphorus pesticides by acetylcholinesterase-coated thin film bulk acoustic resonator mass-loading sensor.

    PubMed

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

    2013-03-15

    An acetylcholinesterase-coated thin film bulk acoustic resonator has been developed for the detection of organophosphorus pesticides. The thin film bulk acoustic resonator acts as a robust mass-sensitive transducer for bio-sensing. This device works in thickness shear mode with a resonance at 1.97 GHz. The detection is based on the inhibitory effects of organophosphorus compounds on the enzymatic activity of the acetylcholinesterase immobilized on one of the faces of the acoustic resonator. The enzyme reaction in the substrate solution and the inhibitory effect is observed are real time by measuring the frequency shift. The presence of organophosphorus pesticides can be detected from the diminution of the frequency shift compared with the levels found in their absence. The device exhibits linear responses, good reproducibility, simple operation, portability and a low detection limit of 5.3×10(-11) M for paraoxon. The detection results of organophosphorus pesticide residues in practical samples show that the proposed sensor has the feasibility and sensing accuracy comparable to gas chromatography.

  5. Influence of crystal quality on the excitation and propagation of surface and bulk acoustic waves in polycrystalline AlN films.

    PubMed

    Clement, Marta; Olivares, Jimena; Capilla, Jose; Sangrador, Jesús; Iborra, Enrique

    2012-01-01

    We investigate the excitation and propagation of acoustic waves in polycrystalline aluminum nitride films along the directions parallel and normal to the c-axis. Longitudinal and transverse propagations are assessed through the frequency response of surface acoustic wave and bulk acoustic wave devices fabricated on films of different crystal qualities. The crystalline properties significantly affect the electromechanical coupling factors and acoustic properties of the piezoelectric layers. The presence of misoriented grains produces an overall decrease of the piezoelectric activity, degrading more severely the excitation and propagation of waves traveling transversally to the c-axis. It is suggested that the presence of such crystalline defects in c-axis-oriented films reduces the mechanical coherence between grains and hinders the transverse deformation of the film when the electric field is applied parallel to the surface. © 2012 IEEE

  6. Dual-mode thin film bulk acoustic wave resonators for parallel sensing of temperature and mass loading.

    PubMed

    García-Gancedo, L; Pedrós, J; Zhao, X B; Ashley, G M; Flewitt, A J; Milne, W I; Ford, C J B; Lu, J R; Luo, J K

    2012-01-01

    Thin film bulk acoustic wave resonator (FBAR) devices supporting simultaneously multiple resonance modes have been designed for gravimetric sensing. The mechanism for dual-mode generation within a single device has been discussed, and theoretical calculations based on finite element analysis allowed the fabrication of FBARs whose resonance modes have opposite reactions to temperature changes; one of the modes exhibiting a positive frequency shift for a rise of temperature whilst the other mode exhibits a negative shift. Both modes exhibit negative frequency shift for a mass load and hence by monitoring simultaneously both modes it is possible to distinguish whether a change in the resonance frequency is due to a mass load or temperature variation (or a combination of both), avoiding false positive/negative responses in gravimetric sensing without the need of additional reference devices or complex electronics.

  7. A film bulk acoustic resonator-based high-performance pressure sensor integrated with temperature control system

    NASA Astrophysics Data System (ADS)

    Zhang, Mengying; Zhao, Zhan; Du, Lidong; Fang, Zhen

    2017-04-01

    This paper presented a high-performance pressure sensor based on a film bulk acoustic resonator (FBAR). The support film of the FBAR chip was made of silicon nitride and the part under the resonator area was etched to enhance the sensitivity and improve the linearity of the pressure sensor. A micro resistor temperature sensor and a micro resistor heater were integrated in the chip to monitor and control the operating temperature. The sensor chip was fabricated, and packaged in an oscillator circuit for differential pressure detection. When the detected pressure ranged from  ‑100 hPa to 600 hPa, the sensitivity of the improved FBAR pressure sensor was  ‑0.967 kHz hPa‑1, namely  ‑0.69 ppm hPa‑1, which was 19% higher than that of existing sensors with a complete support film. The nonlinearity of the improved sensor was less than  ±0.35%, while that of the existing sensor was  ±5%. To eliminate measurement errors from humidity, the temperature control system integrated in the sensor chip controlled the temperature of the resonator up to 75 °C, with accuracy of  ±0.015 °C and power of 20 mW.

  8. Materials for Bulk Acoustic Resonators and Filters

    NASA Astrophysics Data System (ADS)

    Loebl, Hans-Peter

    2003-03-01

    Highly selective solidly mounted bulk acoustic wave (BAW) band pass filters are suited for mobile and wireless systems in the GHz frequency range between 0.8 and 10 GHz. Electro-acoustic thin film BAW resonators are the building blocks these BAW filters. Piezoelectric materials used in these resonators include mainly AlN or ZnO which can be deposited by dedicated thin film sputter deposition techniques. Using these piezo-electric materials and using suited materials for the acoustic Bragg reflector, BAW resonators with high quality factors can be fabricated. The achievable filter bandwidth is approximately 4Alternatively, also ferroelectric thin films might be used to achieve higher coupling coefficient and thus filter bandwidth. BAW resonators and filters have been designed and fabricated on 6" Silicon and glass wafers. Results are presented for resonators and filters operating between 1.95 and 8 GHz. The talk will give an overview of the material aspects which are important for BAW devices. It will be shown that modeling of the resonator and filter response using 1D electro-acoustic simulation (1,2) which includes losses is essential to extract acoustic and electrical material parameters. (1) Solidly Mounted Bulk Acoustic Wave Filters for the Ghz Frequency Range, H.P. Loebl, C. Metzmacher , D.N.Peligrad , R. Mauczok , M. Klee , W. Brand , R.F. Milsom , P.Lok , F.van Straten , A. Tuinhout , J.W.Lobeek, IEEE 2002 Ultrasonics Symposium Munich, October 2002. (2) Combined Acoustic-Electromagnetic Simulation Of Thin-Film Bulk Acoustic Wave Filters, R.F. Milsom, H-P. Löbl, D.N. Peligrad, J-W. Lobeek, A. Tuinhout, R. H. ten Dolle IEEE 2002 Ultrasonics Symposium Munich, October 2002.

  9. Detection of DNA hybridisation in a diluted serum matrix by surface plasmon resonance and film bulk acoustic resonators.

    PubMed

    Auer, Sanna; Nirschl, Martin; Schreiter, Matthias; Vikholm-Lundin, Inger

    2011-05-01

    Nanomolar quantities of single-stranded DNA products ~100 nucleotides long can be detected in diluted 1% serum by surface plasmon resonance (SPR) and film bulk acoustic resonators (FBARs). We have used a novel FBAR sensor in parallel with SPR and obtained promising results with both the acoustic and the optical device. Oligonucleotides and a repellent lipoamide, Lipa-DEA, were allowed to assemble on the sensor chip surfaces for only 15 min by dispensing. Lipa-DEA surrounds the analyte-binding probes on the surface and effectively reduces the non-specific binding of bovine serum albumin and non-complementary strands. In a highly diluted serum matrix, the non-specific binding is, however, a hindrance, and the background response must be reduced. Nanomolar concentrations of short complementary oligos could be detected in buffer, whereas the response was too low to be measured in serum. DNA strands that are approximately 100 base pairs long at concentrations as low as 1-nM could be detected both in buffer and in 1% serum by both SPR and the FBAR resonator.

  10. 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.

  11. Nitrogen [N]-incorporated ZnO piezoelectric thin films and their application for ultra-small film bulk acoustic wave resonator device fabrication

    SciTech Connect

    Lee, Eunju; Zhang Ruirui; Yoon, Giwan

    2011-10-01

    Nitrogen [N]-incorporated ZnO films with columnar grains of a preferred c-axis orientation were deposited on p-Si (100) wafers, using an RF magnetron sputter deposition technique. For the N incorporation into the ZnO films, an N{sub 2}O gas was used as a doping source and also various process conditions such as N{sub 2}O gas fraction and RF power were applied. Besides, some of the ZnO films were treated with the post annealing process. And then, the micro-structural characteristics of the N-incorporated ZnO films were investigated by a scanning electron microscope, an X-ray diffractometer, and an atomic force microscope techniques. Finally, employing the N-incorporated ZnO films, the solidly mounted resonator-type film bulk acoustic wave resonator devices were fabricated and their resonance characteristics were extracted. As a result, an excellent return loss (S{sub 11}) of- 63 dB was observed at{approx} 0.6 GHz, better than ever reported.

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

    PubMed

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

    2015-03-16

    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 ~ 10(17) cm(-3). A large frequency downshift is observed when UV light irradiates the FBAR. With 365 nm UV light of intensity 1.7 mW/cm(2), 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.

  13. 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

  14. Longitudinal bulk acoustic mass sensor

    NASA Astrophysics Data System (ADS)

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

    2009-07-01

    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=10-15 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.

  15. 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.

  16. Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

    SciTech Connect

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

    2016-05-15

    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.

  17. Characterization of sol-gel Pb(Zr0.53Ti0.47O3) in thin film bulk acoustic resonators.

    PubMed

    Conde, Janine; Muralt, Paul

    2008-01-01

    The behavior of {f111g}-textured Pb(Zr(0.53Ti0.47O3) (PZT) deposited by the sol-gel technique in thin film bulk acoustic resonators (TFBAR's) was investigated at a resonance frequency of about 1 GHz. The resonators were fabricated on Si wafers using deep silicon etching to create a membrane structure and using platinum as top and bottom electrodes. The best response of the resonators was observed at a bias voltage of -15 kV/cm with values of about 10% for the coupling constant and about 50 for the quality factor. This voltage corresponds to optimal values of piezoelectric constant d33 and dielectric constant measured as a function of the electric field. The influence of a bias voltage on the resonance frequency, antiresonance frequency, and coupling constant were observed. Both the resonance and antiresonance frequency show a hysteretic change with applied bias. This effect can be used to shift the whole band of a filter by applying a voltage. The TFBAR structure also allowed us to extract values for materials parameters of the PZT film. Dielectric, piezoelectric, and elastic properties of the f111g-textured PZT film are reported and compared to direct measurements and to literature values.

  18. 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).

  19. 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).

  20. Investigation of Shallow Bulk Acoustic Waves

    DTIC Science & Technology

    1981-11-12

    with the theoretical calculation using equivalent circuit model. How- ever, the spurious bulk wave level at high frequencies is much lower than that of...effect of a metallic grating on SBAW devices on quartz. 7 A periodic metallic structure will support horizontal shear surface waves if the finger...We have extensively investigated shallow bulk acoustic waves in. terms of material aspects, transducer equivalent circuits and device dev-.iopment

  1. Effects of thermal annealing of W/SiO2 multilayer Bragg reflectors on resonance characteristics of film bulk acoustic resonator devices with cobalt electrodes

    NASA Astrophysics Data System (ADS)

    Yim, Munhyuk; Kim, Dong-Hyun; Chai, Dongkyu; Yoon, Giwan

    2004-05-01

    In this article, we present the thermal annealing effects of the W/SiO2 multilayer reflectors in ZnO-based film bulk acoustic resonator (FBAR) devices with cobalt (Co) electrodes in comparison with those with aluminum (Al) electrodes. Various thermal annealing conditions have been implemented on the W/SiO2 multilayer reflectors formed on p-type (100) silicon substrates. The resonance characteristics could be significantly improved due to the thermal annealing and were observed to depend strongly on the annealing conditions applied to the reflectors. Particularly, the FBAR devices with the W/SiO2 multilayer reflectors annealed at 400 °C/30 min have shown superior resonance characteristics in terms of return loss and quality factor. In addition, the use of Co electrodes has resulted in the further improvement of the resonance characteristics as compared with the Al electrodes. As a result, the combined use of both the thermal annealing and Co electrodes seems very useful to more effectively improve the resonance characteristics of the FBAR devices with the W/SiO2 multilayer reflectors. .

  2. Applications of surface acoustic and shallow bulk acoustic wave devices

    NASA Astrophysics Data System (ADS)

    Campbell, Colin K.

    1989-10-01

    Surface acoustic wave (SAW) device coverage includes delay lines and filters operating at selected frequencies in the range from about 10 MHz to 11 GHz; modeling with single-crystal piezoelectrics and layered structures; resonators and low-loss filters; comb filters and multiplexers; antenna duplexers; harmonic devices; chirp filters for pulse compression; coding with fixed and programmable transversal filters; Barker and quadraphase coding; adaptive filters; acoustic and acoustoelectric convolvers and correlators for radar, spread spectrum, and packet radio; acoustooptic processors for Bragg modulation and spectrum analysis; real-time Fourier-transform and cepstrum processors for radar and sonar; compressive receivers; Nyquist filters for microwave digital radio; clock-recovery filters for fiber communications; fixed-, tunable-, and multimode oscillators and frequency synthesizers; acoustic charge transport; and other SAW devices for signal processing on gallium arsenide. Shallow bulk acoustic wave device applications include gigahertz delay lines, surface-transverse-wave resonators employing energy-trapping gratings, and oscillators with enhanced performance and capability.

  3. Effect of growth conditions on microstructure of BiFeO{sub 3}-0.33BaTiO{sub 3} films and performance of bulk acoustic wave resonators

    SciTech Connect

    Vorobiev, A. Gevorgian, S.; Löffler, M.; Olsson, E.

    2014-02-28

    The effect of growth conditions on the microstructure of BiFeO{sub 3}-0.33BaTiO{sub 3} (BF-BT) films and the performance of bulk acoustic wave (BAW) resonators is analyzed using test structures with the BF-BT films grown at different positions relative to the plume axis in the pulsed laser deposition system. The BF-BT film grain size and surface roughness reveal a strong asymmetric surface distribution and decrease significantly in the film region facing the laser beam-plume interaction area. The (100) BF-BT texturing is enhanced in this film region. The variations in the BF-BT film microstructure result in corresponding variations of the BAW resonator performance. Their correlations are established using the model of the roughness induced attenuation of the reflected acoustic waves and theory of the dc field induced piezoelectric effect. The BAW resonators with the highest parameters are obtained in the BF-BT film region facing the laser beam-plume interaction area. The BAW resonators located in this film region reveal a mechanical Q-factor of 200 at 4.2 GHz, an effective electromechanical coupling coefficient of 10% and a tunability of the series resonance frequency of 4.5%.

  4. Dual Mode Thin Film Bulk Acoustic Resonators (FBARs) Based on AlN, ZnO and GaN Films with Tilted c-Axis Orientation

    DTIC Science & Technology

    2010-01-01

    P. Löbl, M. Klee , R. Milsom, R. Dekker, C. Metzmacher, W. Brand, and P. Lok, J. Eur. Ceram. Soc. 21, 2633 2001. 6J. W. Grate, S. J. Martin, and R...trol, vol. 49, pp. 535–539, Apr. 2002. [5] H. P. Löbl, M. Klee , R. Milsom, R. Dekker, C. Metzmacher, W. Brand, and P. Lok, “Materials for bulk

  5. Studies of acoustical properties of bulk porous flexible materials

    NASA Technical Reports Server (NTRS)

    Lambert, R. F.

    1984-01-01

    Acoustic prediction and measurement of bulk porous materials with flexible frames is investigated. The acoustic properties of Kevlar 29 are examined. Various acoustic tests are employed to determine impedance, sound wave propagation, and wave pressure equations for the highly porous fiber composites. The derivation of design equations and future research goals are included.

  6. 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

  7. Switchable and tunable film bulk acoustic resonator fabricated using barium strontium titanate active layer and Ta{sub 2}O{sub 5}/SiO{sub 2} acoustic reflector

    SciTech Connect

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

    2016-08-01

    A solidly mounted acoustic resonator was fabricated using a Ba{sub 0.60}Sr{sub 0.40}TiO{sub 3} (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 Ta{sub 2}O{sub 5}/SiO{sub 2} 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 (K{sub t}{sup 2}) of 7.0% at 11 V.

  8. Switchable and Tunable Ferroelectric Bulk Acoustic Wave Resonators and Filters

    NASA Astrophysics Data System (ADS)

    Saddik, George Nabih

    Ferroelectric materials such as barium titanate (BaTiO 3 or BTO), strontium titanate (SrTiO3 or STO), and their solid solution barium strontium titanate (BaxSr1-xTiO 3 or BST) have been under investigation for over 50 years. BTO, STO, and BST are high-k dielectric materials, with a field dependent permittivity and a perovskite crystal structure. At room temperature BTO is a ferroelectric with a ferroelectric to paraelectric transition temperature of about 116°C (Curie temperature), while STO has no ferroelectric phase. The formation of a solid solution between BTO and STO allows for the engineering of the Curie temperature; the Curie temperature decreses as the mole ratio of barium decreases. Extensive research went into understanding the properties of BST and developing RF circuits such as tunable capacitors, tunable matching networks, tunable filters, phase shifters and harmonic generators. BST tunable capacitors have always had anomalous resonances in the one port scattering parameter measurements, although they are very small they degrade the quality factor of the device, and research went into reducing these resonances as much as possible. The goal of this thesis is to investigate these anomalous resonances and exploit them into RF devices and circuits. Careful investigation showed that these resonances were field induced piezoelectric resonance. Piezoelectric materials such as AlN, ZnO, and PZT are used in many applications, such as resonators, and filters. Thin film bulk acoustic wave resonators (FBAR) have been in use by research and industry since the early 1980s, and in high volume production for cell phone duplexers since early 2000s. FBAR filters and duplexers have several advantages over surface acoustic wave (SAW) and ceramic devices such as high quality factors necessary for sharp filter skirts, small size, high performance, and ease of integration. There are two approaches to designing bulk acoustic wave resonators. The first is an FBAR where a

  9. Dielectric and acoustical high frequency characterisation of PZT thin films

    NASA Astrophysics Data System (ADS)

    Conde, Janine; Muralt, Paul

    2010-02-01

    Pb(Zr, Ti)O3 (PZT) is an interesting material for bulk acoustic wave resonator applications due to its high electromechanical coupling constant, which would enable fabrication of large bandwidth frequency filters. The major challenge of the PZT solid solution system is to overcome mechanical losses generally observed in PZT ceramics. To increase the understanding of these losses in textured thin films, thin film bulk acoustic resonators (TFBAR's) based on PZT thin films with compositions either in the tetragonal region or at the morphotropic phase boundary and (111) or {100} textures were fabricated and studied up to 2 GHz. The dielectric and elastic materials coefficients were extracted from impedance measurements at the resonance frequency. The dispersion of the dielectric constant was obtained from impedance measurements up to 2 GHz. The films with varying compositions, textures and deposition methods (sol-gel or sputtering) were compared in terms of dielectric and acoustical properties.

  10. Anisotropic diffraction of bulk acoustic wave beams in lithium niobate.

    PubMed

    Naumenko, Natalya F; Chizhikov, Sergey I; Molchanov, Vladimir Ya; Yushkov, Konstantin B

    2015-12-01

    The formalism of planar diffraction tensor was applied to the analysis of anisotropy of bulk acoustic wave diffraction and to build a full map of anisotropic diffractional coefficients for three bulk acoustic wave modes propagating in lithium niobate. For arbitrary propagation direction the diffractional coefficients derived allow estimation of ultrasonic beam divergence in far-field. Analysis of obtained data revealed that the maxima of acousto-optic figure of merit for anisotropic diffraction in the YZ plane correspond to moderate diffractional spreading of the beams exceeding isotropic diffraction 2-3 times.

  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. 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)

  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.

  14. Measurement of evanescent wave properties of a bulk acoustic wave resonator.

    PubMed

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

    2012-03-01

    Acoustic wave fields in a thin-film bulk acoustic wave resonator are studied using a heterodyne laser interferometer. The measurement area is extended outside the active electrode region of the resonator, so that wave fields in both the active and surrounding regions can be characterized. At frequencies at which the region surrounding the resonator does not support laterally propagating acoustic waves, the analysis of the measurement data shows exponentially decaying amplitude fields outside the active resonator area, as suggested by theory. The magnitude of the imaginary wave vectors is determined by fitting an exponential function to the measured amplitude data, and thereby the experimentally determined dispersion diagram is extended into the region of imaginary wave numbers.

  15. Measured acoustic properties of variable and low density bulk absorbers

    NASA Technical Reports Server (NTRS)

    Dahl, M. D.; Rice, E. J.

    1985-01-01

    Experimental data were taken to determine the acoustic absorbing properties of uniform low density and layered variable density samples using a bulk absober with a perforated plate facing to hold the material in place. In the layered variable density case, the bulk absorber was packed such that the lowest density layer began at the surface of the sample and progressed to higher density layers deeper inside. The samples were placed in a rectangular duct and measurements were taken using the two microphone method. The data were used to calculate specific acoustic impedances and normal incidence absorption coefficients. Results showed that for uniform density samples the absorption coefficient at low frequencies decreased with increasing density and resonances occurred in the absorption coefficient curve at lower densities. These results were confirmed by a model for uniform density bulk absorbers. Results from layered variable density samples showed that low frequency absorption was the highest when the lowest density possible was packed in the first layer near the exposed surface. The layers of increasing density within the sample had the effect of damping the resonances.

  16. Magnetophonon oscillations caused by acoustic phonons in bulk conductors

    NASA Astrophysics Data System (ADS)

    Raichev, O. E.

    2016-09-01

    The interaction of electrons with acoustic phonons under a magnetic field leads to a remarkable kind of magnetophonon oscillation of transport coefficients, recently discovered in two-dimensional electron systems. The present study shows that similar oscillations exist in bulk conductors and provides a theory of this phenomenon for the case of spherical Fermi surfaces. The resonance peaks occur when the product of the Fermi surface diameter by the sound velocity is a multiple of the cyclotron frequency. Theoretical predictions may facilitate the experimental observation of the phenomenon.

  17. 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.

  18. 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.

  19. Surface acoustic wave propagation in graphene film

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    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.

  20. Excitation and propagation of shear-horizontal-type surface and bulk acoustic waves.

    PubMed

    Hashimoto, K Y; Yamaguchi, M

    2001-09-01

    This paper reviews the basic properties of shear-horizontal (SH)-type surface acoustic waves (SAWs) and bulk acoustic waves (BAWs). As one of the simplest cases, the structure supporting Bleustein-Gulyaev-Shimizu waves is considered, and their excitation and propagation are discussed from various view points. First, the formalism based on the complex integral theory is presented, where the surface is assumed to be covered with an infinitesimally thin metallic film, and it is shown how the excitation and propagation of SH-type waves are affected by the surface perturbation. Then, the analysis is extended to a periodic grating structure, and the behavior of SH-type SAWs under the grating structure is discussed. Finally, the origin of the leaky nature is explained.

  1. 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.

  2. Opportunities for shear energy scaling in bulk acoustic wave resonators.

    PubMed

    Jose, Sumy; Hueting, Raymond J E

    2014-10-01

    An important energy loss contribution in bulk acoustic wave resonators is formed by so-called shear waves, which are transversal waves that propagate vertically through the devices with a horizontal motion. In this work, we report for the first time scaling of the shear-confined spots, i.e., spots containing a high concentration of shear wave displacement, controlled by the frame region width at the edge of the resonator. We also demonstrate a novel methodology to arrive at an optimum frame region width for spurious mode suppression and shear wave confinement. This methodology makes use of dispersion curves obtained from finite-element method (FEM) eigenfrequency simulations for arriving at an optimum frame region width. The frame region optimization is demonstrated for solidly mounted resonators employing several shear wave optimized reflector stacks. Finally, the FEM simulation results are compared with measurements for resonators with Ta2O5/ SiO2 stacks showing suppression of the spurious modes.

  3. Acoustic phonon dynamics in thin-films of the topological insulator Bi2Se3

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    Transient reflectivity traces measured for nanometer-sized films (6-40 nm) of the topological insulator Bi2Se3 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 Bi2Se3 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 Bi2Se3.

  4. 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.

  5. Switchable and Tunable Bulk Acoustic Wave Devices Based on Ferroelectric Material

    NASA Astrophysics Data System (ADS)

    Mansour, Almonir

    The explosive development of personal communications systems, navigation, satellite communications as well as personal computer and data processing systems together with the constant demand for higher speeds and larger bandwidths has driven fabrication technology to its limits. This, in turn, necessitates the development of novel functional materials for the fabrication of devices with superior performance and higher capacity at reduced manufacturing costs. Ferroelectric materials such as barium strontium titanate (BST) and strontium titanium oxide (STO) have received more attention by researchers and industry because of their field-induced piezoelectric property. This property gives these types of ferroelectric materials the ability to be switchable and tunable in the presence of an electric field. These features have allowed the ferroelectric materials to be used in many applications such as non-volatile memory and DRAMs, sensors, pyroelectric detectors, and tunable microwave devices. Therefore, with the ever increasing complexity in RF front-end receivers, and the demand for services (which in turn requires more functionalities), ferroelectric bulk acoustic wave (BAW) resonators and filters that are intrinsically switchable and tunable promise to reduce the size and complexity of component parts. In this work, we present the design, fabrication and experimental evaluation of switchable and tunable thin film bulk acoustic wave (BAW) resonators, filters and duplexers for radio frequency (RF) applications. The switchability and tunability of these devices come from utilizing the electrostrictive effect of ferroelectric materials such as barium strontium titanate (BST) with the application of an external DC-bias voltage. The BAW resonators, filters and duplexers in this work were fabricated on different substrates as solidly mounted resonator (SMR) structure with number of periodic layers of silicon dioxide and tantalum oxide as a Bragg reflector in order to

  6. Multimode filter composed of single-mode surface acoustic wave/bulk acoustic wave resonators

    NASA Astrophysics Data System (ADS)

    Huang, Yulin; Bao, Jingfu; Tang, Gongbin; Wang, Yiling; Omori, Tatsuya; Hashimoto, Ken-ya

    2017-07-01

    This paper discusses the possibility of realizing multimode filters composed of multiple single-mode resonators by using radio frequency surface and bulk acoustic wave (SAW/BAW) technologies. First, the filter operation and design principle are given. It is shown that excellent filter characteristics are achievable by combining multiple single-mode resonators with identical capacitance ratios provided that their resonance frequencies and clamped capacitances are set properly. Next, the effect of balun performance is investigated. It is shown that the total filter performance is significantly degraded by balun imperfections such as the common-mode rejection. Then, two circuits are proposed to improve the common-mode rejection, and their effectiveness is demonstrated.

  7. Bulk saturable absorption in topological insulator thin films

    NASA Astrophysics Data System (ADS)

    Gopal, Radha Krishna; Ambast, Deepak K. S.; Singh, Sourabh; Sarkar, Jit; Pal, Bipul; Mitra, Chiranjib

    2017-07-01

    We present nonlinear optical absorption properties of pulsed laser deposited thin films of topological insulator (TI), Bi2Se3 on a quartz substrate, using an open aperture z-scan technique. We observed saturable absorption with a low saturation intensity in as deposited thin films. Past results from the literature are inconclusive in establishing whether the saturable absorption in TI is coming from surface states or the bulk. Specifically designed experiments with magnetically doped TI samples allow us to attribute the saturable absorption characteristic of TI to the bulk states. Detailed experimental procedures and possible explanation of observed results have been discussed.

  8. 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

  9. 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.

    1992-01-01

    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 silical 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 thin film samples 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 conditions out of concern that the film might be modified.

  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.

    1992-01-01

    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 silical 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 thin film samples 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 conditions out of concern that the film might be modified.

  11. 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.

  12. Modulated exponential films generated by surface acoustic waves and their role in liquid wicking and aerosolization at a pinned drop.

    PubMed

    Taller, Daniel; Go, David B; Chang, Hsueh-Chia

    2013-05-01

    The exponentially decaying acoustic pressure of scattered surface acoustic waves (SAWs) at the contact line of a liquid film pinned to filter paper is shown to sustain a high curvature conic tip with micron-sized modulations whose dimension grows exponentially from the tip. The large negative capillary pressure in the film, necessary for offsetting the large positive acoustic pressure at the contact line, also creates significant negative hydrodynamic pressure and robust wicking action through the paper. An asymptotic analysis of this intricate pressure matching between the quasistatic conic film and bulk drop shows that the necessary SAW power to pump liquid from the filter paper and aerosolize, expressed in terms of the acoustic pressure scaled by the drop capillary pressure, grows exponentially with respect to twice the acoustic decay constant multiplied by the drop length, with a universal preexponential coefficient. Global rapid aerosolization occurs at a SAW power twice as high, beyond which the wicking rate saturates.

  13. Modulated exponential films generated by surface acoustic waves and their role in liquid wicking and aerosolization at a pinned drop

    NASA Astrophysics Data System (ADS)

    Taller, Daniel; Go, David B.; Chang, Hsueh-Chia

    2013-05-01

    The exponentially decaying acoustic pressure of scattered surface acoustic waves (SAWs) at the contact line of a liquid film pinned to filter paper is shown to sustain a high curvature conic tip with micron-sized modulations whose dimension grows exponentially from the tip. The large negative capillary pressure in the film, necessary for offsetting the large positive acoustic pressure at the contact line, also creates significant negative hydrodynamic pressure and robust wicking action through the paper. An asymptotic analysis of this intricate pressure matching between the quasistatic conic film and bulk drop shows that the necessary SAW power to pump liquid from the filter paper and aerosolize, expressed in terms of the acoustic pressure scaled by the drop capillary pressure, grows exponentially with respect to twice the acoustic decay constant multiplied by the drop length, with a universal preexponential coefficient. Global rapid aerosolization occurs at a SAW power twice as high, beyond which the wicking rate saturates.

  14. 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}.

  15. Transport and Magnetism in Bulk and Thin Film Strontium Titanate

    NASA Astrophysics Data System (ADS)

    Ambwani, Palak

    SrTiO3 is a wide band-gap perovskite oxide semiconductor that is widely investigated in the bulk form, due to its remarkable electronic properties. These properties arise from its quantum paraelectric nature which enables unique features, such as, a high-mobility low-density metallic state, quantum transport in an unusual limit, and the most dilute superconducting state thus reported. Recent advances in deposition of oxide thin films and heterostructures have further led to some remarkable observations, such as, the strain-enhancement of mobility in doped thin films of SrTiO3, and the presence of 2D electron gases at interfaces and in delta-doped layers. The presence of magnetic moments and their possible ordering, and the simultaneous observation of quantum oscillations and superconductivity, have been reported in these 2D electron gases. While magnetism has been observed in heterostructures of SrTiO3 , there have been limited reports on magnetism in bulk SrTiO3. The first part of this thesis (Chapter 3) discusses how circularly polarized light can induce an extremely long-lived magnetic moment in slightly oxygen-deficient but otherwise nominally pure SrTiO3-delta bulk crystals. These magnetic signals, which are induced at zero applied magnetic field and at low temperatures below ˜ 18 K, can be controlled in both magnitude and sign by means of the circular polarization and wavelength of sub-bandgap illumination (400-500 nm), and point to the existence of optically polarizable VO-related complexes in the forbidden gap of SrTiO 3-delta, rather than collective or long-range magnetic order. The methods used to detect optically induced magnetization are also discussed (Appendix A). The phenomenal progress reported in thin films and heterostructures of SrTiO3 has been possible only by precise control of stoichiometry and defect density in SrTiO3 using techniques such as oxide/LASER MBE or high-temperature PLD. The next part of the thesis (Chapter 4) demonstrates that

  16. Interface and bulk properties of HfO2 films

    NASA Astrophysics Data System (ADS)

    Biswas, Nivedita; Harris, Harlan; Choi, Kisik; Temkin, Henryk; Gangopadhyay, Shubhra

    2003-03-01

    HfO2 films of varying thickness were deposited on silicon and titanium by reactive electron beam evaporation. Metal gates of Titanium were deposited to form MIS and MIM structures. Capacitance-voltage and conductance-voltage measurements were performed to analyze the HfO2/Si interface and HfO2 bulk. For samples having thickness between 30 and 300 Å the C-V curves of the as-deposited samples were marked by charge leakage, huge hysteresis and frequency dispersion. However, annealing the sample in H2 ambient reduced charge leakage, hysteresis and the frequency dispersion of the C-V curves. A dielectric constant of the annealed films was calculated to be 17. The interface state density as calculated using the method of Nicollian and Brews was 2-3E10 cm-2eV-1 close to the midgap. To study the bulk properties, HfO2 films of thickness 2100 Å with platinum electrodes were deposited on silicon and titanium nitride. The C-V and G-V curves of both as-deposited and annealed samples were measured. Interface state density was found to be comparable to that of the thin samples. Thus the passivation of bulk and interface states with hydrogen annealing is independent of thickness. The gap state densities were found compatible with the observed hysteresis of the as-deposited ( 1E16-1E17 eV-1cm-3) and annealed sample (1E14-1E15eV-1cm-3).

  17. 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.

  18. Acoustical performance of an electrostrictive polymer film loudspeaker

    PubMed

    Heydt; Pelrine; Joseph; Eckerle; Kornbluh

    2000-02-01

    A new type of loudspeaker that generates sound by means of the electrostrictive response of a thin polymer film is described. Electrostrictive polymer film (EPF) loudspeakers are constructed with inexpensive, lightweight materials and have a very low profile. The films are typically silicone and are coated with compliant electrodes to allow large film deformations. Acoustical frequency response measurements from 5 x 5 cm (planar dimensions) prototype EPF loudspeakers are presented. Measurements of harmonic distortion are also shown, along with results demonstrating reduced harmonic distortion achieved with square-root wave shaping. Applications of EPF loudspeakers include active noise control and general-purpose flat-panel loudspeakers.

  19. 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.

  20. Label-free detection of protein-ligand interactions in real time using micromachined bulk acoustic resonators

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Pang, Wei; Marma, Mong S.; Lee, Chuang-Yuan; Kamal-Bahl, Sanat; Kim, Eun Sok; McKenna, Charles E.

    2010-03-01

    In this paper, we present a micromachined film bulk acoustic resonator (FBAR) to detect protein-ligand interactions in real-time. The surface of the FBAR device has a thin layer of gold deposited on it to immobilize thiol-modified biotin. The resonant frequency of the biotin modified FBAR was measured to decrease by 170 ppm when exposed to streptavidin solution with a concentration of 5×10-7 M, corresponding to an added mass of 120 pg on the FBAR surface due to the biotin-streptavidin interaction. Consequently, the biotin modified FBAR can be used to observe in real time the biotin-streptavidin interaction without the use of labeling or molecular tags. The FBAR can be used in a variety of protein-ligand systems, and be designed for testing in array formats to give high throughput screening for drug discovery.

  1. 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.

  2. 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.

  3. 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.

  4. Surface acoustic wave devices including Langmuir-Blodgett films (Review)

    NASA Astrophysics Data System (ADS)

    Plesskii, V. P.

    1991-06-01

    Recent theoretical and experimental research related to the use of Langmuir-Blodgett (LB) films in surface acoustic wave (SAW) devices is reviewed. The sensitivity of the different cuts of quartz and lithium niobate to inertial loading is investigated, and it is shown that some cuts in lithium niobate are twice as sensitive to mass loading than the commonly used YZ-cut. The large variety of organic compounds suitable for the production of LB films makes it possible to create SAW sensors reacting selectively to certain substances. The existing SAW sensors based on LB films are characterized by high sensitivity and fast response.

  5. Surface acoustic wave gas sensor based on film conductivity changes

    NASA Astrophysics Data System (ADS)

    Ricco, A. J.; Martin, S. J.; Zipperian, T. E.

    1985-12-01

    The first surfce acoustic wave (SAW) sensor that functions via changes in conductivity of a thin surface film is reported. A lead phthalocyanine (PbPc) thin film is deposted on the acoustic progagation path of a LiNbO3 SAW delay line, which serves as the feedback element of an oscillator circuit. Reaction with strongly oxidizing gases, in particular NO2, increases the conductivity of the PbPc film. Acoustoelectric coupling of the traveling electric potential wave associated with the SAW-to-charge carriers in the PbPc film slows the acoustic wave velocity, altering the oscillation frequency of the circuit. This sensor is about 1000 times more sensitive, in terms of the number of NO2 molecules that can be detected (10 to the 16th molecules/cu cm of PbPc film), than an identical SAW sensor functioning via mass loading would be. Sensitivity to a few ppm of NO2 in N2 has been demonstrated.

  6. Surface acoustic wave gas sensor based on film conductivity changes

    NASA Astrophysics Data System (ADS)

    Ricco, A. J.; Martin, S. J.; Zipperian, T. E.

    The first surface acoustic wave (SAW) sensor that functions via changes in conductivity of a thin surface film is reported. A lead phthalocyanine (PbPc) thin film is deposited on the acoustic propagation path of a LiNbO3 SAW delay line, which serves as the feedback element of an oscillator circuit. Reaction with strongly oxidizing gases, in particular NO2, increases the conductivity of the PbPc film. Acoustoelectic coupling of the traveling electric potential wave associated with the SAW-to-charge carriers in the PbPc film slows the acoustic wave velocity, altering the oscillation frequency of the circuit. This sensor is about 1000 times more sensitive, in terms of the number of NO2 molecules that can be detected (10 to the 16th molecules/cu cm of PbPc film), than an identical SAW sensor functioning via mass loading would be. Sensitivity to a few ppm of NO2 in Ne was demonstrated.

  7. New Magnetic Materials and Phenomena for Radar and Microwave Signal Processing Devices - Bulk and Thin Film Ferrites and Metallic Films

    DTIC Science & Technology

    2009-02-15

    deposited and liquid phase epitaxy films of low loss cubic yttrium iron garnet (YIG) and lithium ferrite , uniaxial barium hexaferrite, and planar zinc ...barium hexaferrite with losses which are as good as the best bulk single crystals, and (9) the successful PLD growth of low loss zinc lithium ferrite ...Signal Processing Devices - Bulk and Thin Film Ferrites and Metallic Films ONR N00014-07-1-0597, 02 February 2007 - 30 September 2008 Carl E

  8. Finite Element Analysis of Bulk-Acoustic-Wave Devices: Model Setup and Applications.

    PubMed

    Thalhammer, Robert; Larson, John

    2016-04-20

    In this work, the principles of finite element modeling for the electro-acoustic simulation of bulk-acoustic- wave devices will be summarized. We will outline model setup including governing equations and boundary conditions, as well as its efficient computer implementation. Particular emphasis will be given to tailoring the model dimension to the specific requirements of the desired investigation. As 3D simulations still require a major effort, it will be illustrated that various aspects of device physics and design can be addressed already by fast and efficient 2D simulations. Multiple theoretical and experimental evidence will be presented to demonstrate the validity of the modeling concepts. Based on various examples it will be sketched how to benefit from numerical simulations for understanding fundamental effects, designing devices for actual products, and exploring novel technologies.

  9. 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.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    We demonstrate a previously unobserved nonlinear phenomenon in an ultra-low loss quartz bulk acoustic wave cavity ( Q > 3 > 10 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.

  12. Solitary surface acoustic waves and bulk solitons in nanosecond and picosecond laser ultrasonics.

    PubMed

    Hess, Peter; Lomonosov, Alexey M

    2010-02-01

    Recent achievements of nonlinear acoustics concerning the realization of solitons and solitary waves in crystals and their surfaces attained by nanosecond and picosecond laser ultrasonics are discussed and compared. The corresponding pump-probe setups are described, which allow an all-optical contact-free excitation and detection of short strain pulses in the broad frequency range between 10 MHz and about 300 GHz. The formation of solitons in the propagating longitudinal strain pulses is investigated for nonlinear media with intrinsic lattice-based dispersion. The excitation of solitary surface acoustic waves is realized by a geometric film-based dispersion effect. Future developments and potential applications of nonlinear nanosecond and picosecond ultrasonics are discussed.

  13. 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

  14. 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

    2016-02-26

    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.

  15. 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.

  16. Acoustic emissions during 3.1 MHz ultrasound bulk ablation in vitro.

    PubMed

    Mast, T Douglas; Salgaonkar, Vasant A; Karunakaran, Chandrapriya; Besse, John A; Datta, Saurabh; Holland, Christy K

    2008-09-01

    uncorrelated with subharmonic emissions. Subharmonic emissions were found to depend strongly on temperature in a nonlinear manner, with significant emissions occurring within different temperature ranges for each sonication amplitude. These results suggest potential roles for passive detection of acoustic emissions in guidance and control of bulk US ablation treatments.

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

    PubMed

    Jing, Xiaodong; Meng, Yang; Sun, Xiaofeng

    2015-11-05

    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.

  18. 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.

  19. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    Using a high-resolution X-Ray diffraction measurement method, the surface acoustic wave (SAW) propagation in a graphene film on the surface of a Ca3TaGa3Si2O14 (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.

  1. 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

  2. Composition, Constitution and Phase Transformation Behavior in Thin-Film and Bulk Ti-Ni-Y

    NASA Astrophysics Data System (ADS)

    König, D.; Frowein, P.; Wieczorek, A.; Frenzel, J.; Hamann, S.; Eggeler, G.; Ludwig, A.

    2017-01-01

    Advanced engineering applications require new and improved shape memory alloys in bulk and thin-film form. While many Ti-Ni-based systems have been studied so far, the Ti-Ni-Y materials system was not studied in detail concerning its bulk and thin-film shape memory properties. For this reason, a Ti-Ni-Y thin-film materials library focussing on compositions close to Ni50Ti50 was fabricated by combinatorial magnetron sputtering. This library was characterized by high-throughput methods and the compositional range where phase transformations occur was identified. Ti-Ni-Y thin films exhibit a very narrow hysteresis width ∆T and allow to precisely adjust ∆T. Based on the promising results of Ti-Ni-Y thin films, which can be directly applied in microsystems, bulk alloys were fabricated in order to explore how thin-film and bulk properties of different Ti-Ni-Y compositions correlate. It turned out that Ti-Ni-Y bulk materials show different phase transformation properties compared to thin films, most importantly higher ∆T. The differences between thin-film and bulk material are discussed.

  3. Composition, Constitution and Phase Transformation Behavior in Thin-Film and Bulk Ti-Ni-Y

    NASA Astrophysics Data System (ADS)

    König, D.; Frowein, P.; Wieczorek, A.; Frenzel, J.; Hamann, S.; Eggeler, G.; Ludwig, A.

    2017-03-01

    Advanced engineering applications require new and improved shape memory alloys in bulk and thin-film form. While many Ti-Ni-based systems have been studied so far, the Ti-Ni-Y materials system was not studied in detail concerning its bulk and thin-film shape memory properties. For this reason, a Ti-Ni-Y thin-film materials library focussing on compositions close to Ni50Ti50 was fabricated by combinatorial magnetron sputtering. This library was characterized by high-throughput methods and the compositional range where phase transformations occur was identified. Ti-Ni-Y thin films exhibit a very narrow hysteresis width ∆ T and allow to precisely adjust ∆ T. Based on the promising results of Ti-Ni-Y thin films, which can be directly applied in microsystems, bulk alloys were fabricated in order to explore how thin-film and bulk properties of different Ti-Ni-Y compositions correlate. It turned out that Ti-Ni-Y bulk materials show different phase transformation properties compared to thin films, most importantly higher ∆ T. The differences between thin-film and bulk material are discussed.

  4. Characterization of organic film with scanning acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Miyasaka, Chiaki; Du, Jikai; Tittmann, Bernhard R.

    2003-08-01

    The present article reports a technique to measure velocity of an organic film deposited on a homogeneous substrate, wherein the thickness of the film and the diameter of the measured area of the specimen are in the order of a few microns. A thinly sliced human kidney was selected as an example of an organic film. The thickness of the specimen was substantially 3 μm. For the substrate, fused quartz was used because its elastic properties are known and stable. The spherical acoustic lens was used to determine the position for measurement. The frequencies at 400 MHz and 600 MHz were used for the measurement and the visualization, respectively. The generation of the Rayleigh waves under the above conditions was simulated by numerical calculations based onthe wave propagation theory for layered media.

  5. In situ Magnetotransport Measurements in Ultrathin Bi Films: Evidence for Surface-Bulk Coherent Transport

    NASA Astrophysics Data System (ADS)

    Aitani, Masaki; Hirahara, Toru; Ichinokura, Satoru; Hanaduka, Masahiro; Shin, Dongyoon; Hasegawa, Shuji

    2014-11-01

    We performed in situ magnetotransport measurements on ultrathin Bi(111) films [4-30 bilayers (BLs), 16-120 Å thick] to elucidate the role of bulk or surface states in the transport phenomena. We found that the temperature dependence of the film conductivity shows no thickness dependence for the 6-16 BL films and is affected by the electron-electron scattering, suggesting surface-state dominant contribution. In contrast, the weak antilocalization effect observed by applying a magnetic field shows clear thickness dependence, indicating bulk transport. This apparent inconsistency is explained by a coherent bulk-surface coupling that produces a single channel transport. For the films thicker than 20 BLs, the behavior changes drastically which can likely be interpreted as a bulk dominant conduction.

  6. Acoustic behavior of a fibrous bulk material. [Kevlar 29 sound absorber

    NASA Technical Reports Server (NTRS)

    Hersh, A. S.; Walker, B.

    1979-01-01

    A semiempirical model is presented describing the acoustic behavior of Kevlar 29, a bulk absorbing material. The model is based on an approximate solution to the one-dimensional equations representing conservation of fluctuating mass, momentum and energy. By treating the material as a momentum sink, theoretical expressions of the material complex propagation constants and characteristic impedance were derived in terms of a single constant. Evaluating the constant at a single frequency for a particular specimen, excellent agreement between prediction and measurement was achieved for a large range of sound frequencies and material porosities and thicknesses. Results show that Kevlar 29 absorbs sound efficiently even at low frequencies. This is explained in terms of a frequency dependent material phase speed.

  7. Bulk acoustic wave sensor for investigating hemorheological characteristics of plasma and its coagulation.

    PubMed

    Si, S H; Xu, Y J; Nie, L H; Yao, S Z

    1996-02-05

    A method of using a bulk acoustic wave (BAW) device to study the hemorheological phenomena is proposed. By measuring the resonant resistance of a BAW device, the dependence of the plasma viscosity on its composition is investigated. It has been found that during the process of the plasma coagulation, the frequency response of a BAW device is dominated by the change in plasma viscoelasticity, and useful information such as the coagulation time and the viscoelasticity of coagulated plasma can be obtained from the curve of frequency response. Based on the BAW quartz detection system, effects of fibrinogen, thrombin and some drugs on the plasma coagulation are investigated. The results show that the BAW device based on the oscillator method possesses some advantages, such as high sensitivity, simplicity of use, cost effectiveness and small sample volume for clinical hemorheological study.

  8. 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.

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

    NASA Astrophysics Data System (ADS)

    Li, L. L.; Xu, W.

    2014-08-01

    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.

  10. Engineered nanostructured thin films for enhanced surface acoustic wave sensors

    NASA Astrophysics Data System (ADS)

    Kwan, Jonathan Kwok Wah

    Sensor technologies profoundly impact all aspects of our everyday lives. Advances have led to smaller devices, faster response times, reduced costs, higher specificity and sensitivity, and even new sensing technologies. Surface acoustic wave (SAW) technology, which has been around for many decades already, is an example of a newer sensing technology that has begun to be studied for sensing applications. Many advantages of SAW sensors have been identified, in particular the high sensitivity, low cost and wireless capability. However, as the technology is still in its infancy for sensing applications, many improvements and refinements on the platform have yet to be explored. With the arrival of nanotechnology, many existing technologies have benefited from integrating with the new findings that nanotechnology has brought forth. This thesis investigates the enhancement of existing SAW sensors using nanostructured films fabricated by a thin film deposition process known as glancing angle deposition (GLAD). The GLAD technique is a highly flexible and precise thin film fabrication method that is able to create high-surface-area thin films. This high-surface-area characteristic of these films is the driving motivation in their utilization to enhance the performance of SAW sensors. This thesis first demonstrates that dense, extremely high surface area films can be deposited on SAW sensors without adversely affecting device performance. These modified sensors were then studied as humidity sensors to demonstrate improved sensitivity with the addition of the GLAD films. Before the sensors with GLAD films could be tested in a liquid environment, ion-milling was investigated as a method of eliminating the clustering of the individual structures typically seen after exposure to liquids. These modified films were extended for use on the SAW sensors to investigate liquid sensing performance. The performance of SAW devices with clustered films was also studied for comparison. Both

  11. 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.

  12. Acoustic attenuation imaging of tissue bulk properties with a priori information

    PubMed Central

    Hooi, Fong Ming; Kripfgans, Oliver; Carson, Paul L.

    2016-01-01

    Attenuation of ultrasound waves traversing a medium is not only a result of absorption and scattering within a given tissue, but also of coherent scattering, including diffraction, refraction, and reflection of the acoustic wave at tissue boundaries. This leads to edge enhancement and other artifacts in most reconstruction algorithms, other than 3D wave migration with currently impractical, implementations. The presented approach accounts for energy loss at tissue boundaries by normalizing data based on variable sound speed, and potential density, of the medium using a k-space wave solver. Coupled with a priori knowledge of major sound speed distributions, physical attenuation values within broad ranges, and the assumption of homogeneity within segmented regions, an attenuation image representative of region bulk properties is constructed by solving a penalized weighted least squares optimization problem. This is in contradistinction to absorption or to conventional attenuation coefficient based on overall insertion loss with strong dependence on sound speed and impedance mismatches at tissue boundaries. This imaged property will be referred to as the bulk attenuation coefficient. The algorithm is demonstrated on an opposed array setup, with mean-squared-error improvements from 0.6269 to 0.0424 (dB/cm/MHz)2 for a cylindrical phantom, and 0.1622 to 0.0256 (dB/cm/MHz)2 for a windowed phantom. PMID:27914403

  13. Ferroelectric Tungsten Bronze Bulk Crystals and Epitaxial Thin Films for Electro-Optic Device Applications

    DTIC Science & Technology

    1983-05-01

    23 FERROELECTRIC TUNGSTEN BRONZE BULK CRYSTALS AND EPITAXIAL THIN FILMS FOR ELECTRO-OPTIC DEVICE APPLICATIONS 10 CO O Semi-Annual Technical... THIN FILMS FOR ELECTRO-OPTIC DEVICE APPLICATIONS s TV^C or REPORT * pcmoo COVCHCO Semi-Annual Tec1! Rpt #1 for period 09/30/82-03/31/83...months, considerable progress has been made in several areas, including single crystal and thin film growth and characteriza- tion. The new

  14. Acoustoelectric effects in reflection of leaky-wave-radiated bulk acoustic waves from piezoelectric crystal-conductive liquid interface.

    PubMed

    Rimeika, Romualdas; Čiplys, Daumantas; Jonkus, Vytautas; Shur, Michael

    2016-01-01

    The leaky surface acoustic wave (SAW) propagating along X-axis of Y-cut lithium tantalate crystal strongly radiates energy in the form of an obliquely propagating narrow bulk acoustic wave (BAW) beam. The reflection of this beam from the crystal-liquid interface has been investigated. The test liquids were solutions of potassium nitrate in distilled water and of lithium chloride in isopropyl alcohol with the conductivity varied by changing the solution concentration. The strong dependences of the reflected wave amplitude and phase on the liquid conductivity were observed and explained by the acoustoelectric interaction in the wave reflection region. The novel configuration of an acoustic sensor for liquid media featuring important advantages of separate measuring and sensing surfaces and rigid structure has been proposed. The application of leaky-SAW radiated bulk waves for identification of different brands of mineral water has been demonstrated.

  15. Interface Selective Transient Grating Spectroscopy: Theory and Applications to Thermal Flow and Acoustic Propagation in Thin Films.

    NASA Astrophysics Data System (ADS)

    Marshall, Christopher David

    A general theoretical and experimental treatment of transient grating diffraction is developed for interfacial holographic gratings in thin film structures. The gratings are assumed to have nonuniform spatial amplitude throughout the sample. Both reflection and transmission diffraction geometries are examined where the probe beam is incident on either side of the film-substrate interface with the grating wave-vector parallel to the interface. For samples in which the grating amplitude perpendicular to the sample interface varies slowly relative to the optical wavelength, the majority of the reflection geometry signal amplified is shown to arise from the surface or interfacial region. In contrast, the transmission geometry signal amplitude is dominated by contributions from the bulk of the sample. Three different material systems are examined. The first is a thin (<1 mm) molecular anthracene crystal on a glass substrate in which electronic (exciton) and wave-guided acoustic gratings are generated and probed. Four different transient grating geometries are shown to yield unique time dependent responses illustrating the sensitivity of the transient grating geometry to the spatial origin of the signal. A theoretical model is developed to demonstrate the spatial selectivity of the technique. The second and third systems are thin (50-350 nm thick) films of the high temperature superconductor YBa_2Cu _3O_{rm 7-x} (YBCO) on either MgO or SrTiO _3 substrates. Anisotropic thermal diffusion constants in the YBCO films are measured over a 17 to 300 K temperature range. A detailed understanding is obtained of the time dependent heat flow in the regions adjacent to the film-substrate interface, the free film surface, and the bulk of the film. A temperature dependent thermal barrier that significantly restricts heat transfer from the film into the MgO substrate is observed and quantified. The rate of flow thru the YBCO/MgO interface is measured to be 10 to 100 times less than the

  16. 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.

  17. Fatigue crack monitoring with coupled piezoelectric film acoustic emission sensors

    NASA Astrophysics Data System (ADS)

    Zhou, Changjiang

    Fatigue-induced cracking is a commonly seen problem in civil infrastructures reaching their original design life. A number of high-profile accidents have been reported in the past that involved fatigue damage in structures. Such incidences often happen without prior warnings due to lack of proper crack monitoring technique. In order to detect and monitor the fatigue crack, acoustic emission (AE) technique, has been receiving growing interests recently. AE can provide continuous and real-time monitoring data on damage progression in structures. Piezoelectric film AE sensor measures stress-wave induced strain in ultrasonic frequency range and its feasibility for AE signal monitoring has been demonstrated recently. However, extensive work in AE monitoring system development based on piezoelectric film AE sensor and sensor characterization on full-scale structures with fatigue cracks, have not been done. A lack of theoretical formulations for understanding the AE signals also hinders the use of piezoelectric film AE sensors. Additionally, crack detection and source localization with AE signals is a very important area yet to be explored for this new type of AE sensor. This dissertation presents the results of both analytical and experimental study on the signal characteristics of surface stress-wave induced AE strain signals measured by piezoelectric film AE sensors in near-field and an AE source localization method based on sensor couple theory. Based on moment tensor theory, generalized expression for AE strain signal is formulated. A special case involving the response of piezoelectric film AE sensor to surface load is also studied, which could potentially be used for sensor calibration of this type of sensor. A new concept of sensor couple theory based AE source localization technique is proposed and validated with both simulated and experimental data from fatigue test and field monitoring. Two series of fatigue tests were conducted to perform fatigue crack

  18. 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.

  19. Detection of shorter-than-skin-depth acoustic pulses in a metal film via transient reflectivity

    NASA Astrophysics Data System (ADS)

    Manke, K. J.; Maznev, A. A.; Klieber, C.; Temnov, V. V.; Makarov, D.; Baek, S.-H.; Eom, C.-B.; Nelson, Keith A.

    2012-12-01

    Short acoustic pulses are generated in SrRuO3 transducers and detected at the surface of gold films by transient reflectivity. Contrary to expectations, acoustic pulses that are shorter than the optical skin depth of gold are resolved. A comparison of gold detection films that were grown under different deposition conditions demonstrates that the microstructure of a detection film can impact the shape of the detected signal.

  20. 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

    2015-05-21

    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.

  1. 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

  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

    2016-03-06

    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.

  3. 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

  4. Modeling of Lorentz forces and radiated wave fields for bulk wave electromagnetic acoustic transducers

    NASA Astrophysics Data System (ADS)

    Zhai, Guofu; Wang, Kaican; Wang, Yakun; Su, Riliang; Kang, Lei

    2013-08-01

    Currently, the finite element method (FEM) and analytical calculation are widely employed for the modeling of electromagnetic acoustic transducers (EMATs). However, it takes long time for finite element calculation. Previous analytical models for bulk wave EMATs are generally considered separately and incompletely, and expressions of radiated wave fields contain infinite integrations and multiple singular points, which result in complex numerical computation. A complete model containing the Lorentz force and radiated wave field calculation for the EMAT with a spiral coil and a NdFeB permanent magnet is established. By introducing a current loop instead of the permanent magnet and adopting the truncated region eigenfunction expansion (TREE) method, the distributions of static and dynamic magnetic fields and their generated Lorentz forces are calculated. A series expansion method is proposed for the computation of radiated wave fields, which replaces the integration by series operation and avoids the solutions of singular points effectively. The Lorentz forces and radiated wave fields of a typical transducer are computed. The validity of the model is verified by FEM and experiments. Their good agreements verify the accuracy and validity of the model.

  5. Thick Films acoustic sensors devoted to MTR environment measurements. Thick Films acoustic sensors devoted to Material Testing Reactor environment measurements

    SciTech Connect

    Very, F.; Rosenkrantz, E.; Combette, P.; Ferrandis, J.Y.; Fourmentel, D.; Destouches, C.; Villard, J.F.

    2015-07-01

    The development of advanced instrumentation for in-pile experiments in Material Testing Reactor constitutes a main goal for the improvement of the nuclear fuel behavior knowledge. An acoustic method for fission gas release detection was tested with success during a first experiment called REMORA 3 in 2010 and 2011, and the results were used to differentiate helium and fission gas release kinetics under transient operating conditions. This experiment was lead at OSIRIS reactor (CEA Saclay, France). The maximal temperature on the sensor during the irradiation was about 150 deg. C. In this paper we present a thick film transducer produce by screen printing process. The screen printing of piezoelectric offers a wide range of possible applications for the development of acoustic sensors and piezoelectric structure for measurements in high temperature environment. We firstly produced a Lead Zirconate Titanate (PZT) based paste composed of Pz27 powder from Ferroperm, CF7575 glass, and organic solvent ESL 400. Likewise a Bismuth Titanate based paste synthesized in our laboratory was produced. With these inks we produced thick film up to 130 μm by screen printing process. Material properties characterizations of these thick-film resonators are essential for device design and applications. The piezoelectric coefficients d33 and pyro-electric P(T) coefficient are investigated. The highest P(T) and d33 are respectively 80 μC.m{sup -2}.K{sup -1} and 130 μC.N{sup -1} for the PZT transducer -which validates the fabrication process-. In view of the development of this transducer oriented for high temperature and irradiation environment, we investigated the electrical properties of the transducers for different ranges of frequencies and temperature - from 20 Hz up to 40 MHz between 30 and 400 deg. C. We highlight the evolution of the impedance response and piezoelectric parameters of screen printed piezoelectric structures on alumina. Shortly an irradiation will be realized in

  6. 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.

  7. Spin Orbit Torque in TbCo Films with Bulk Perpendicular Magnetic Anisotropy

    NASA Astrophysics Data System (ADS)

    Ueda, Kohei; Mann, Maxwell; Tan, Aik-Jun; Beach, Geoffrey. S. D.

    Spin-orbit torque (SOT) has generated considerable interest for manipulating magnetization in spintronic devices with ultra-low dissipation. Recent research has demonstrated that highly efficient magnetization control can be driven by current-induced SOT in ferromagnet/heavy metals bilayers with strong spin orbit coupling. However, most work on SOT has focused on ultra-thin magnetic films with interfacial perpendicular magnetic anisotropy (PMA), whereas future devices will require bulk PMA for sufficient thermal stability. Recently, Zhao et al reported SOT induced magnetization switching in a bulk PMA material; however, the films examined were still rather thin. Here we examine spin orbit torques in TbCo alloy films with bulk PMA, sandwiched between top and bottom Ta layers. By performing conventional harmonic and current-induced switching measurements, we quantified the current-induced effective fields generated by damping-like (DL) and field-like (FL) torques. The DL torque is much larger than FL torque, and corresponds to an effective spin Hall angle consistent with that of Ta. Owing to the relatively small saturation magnetized of these ferrimagnetic materials, the current-induced effective field is comparable to that observed in nm-thick Co films, despite the much larger film thicknesses used here. These results demonstrate ferromagnetic alloys with bulk PMA can be engineered to simultaneously provide thermal stability and efficient SOT switching.

  8. Triboelectrification-based organic film nanogenerator for acoustic energy harvesting and self-powered active acoustic sensing.

    PubMed

    Yang, Jin; Chen, Jun; Liu, Ying; Yang, Weiqing; Su, Yuanjie; Wang, Zhong Lin

    2014-03-25

    As a vastly available energy source in our daily life, acoustic vibrations are usually taken as noise pollution with little use as a power source. In this work, we have developed a triboelectrification-based thin-film nanogenerator for harvesting acoustic energy from ambient environment. Structured using a polytetrafluoroethylene thin film and a holey aluminum film electrode under carefully designed straining conditions, the nanogenerator is capable of converting acoustic energy into electric energy via triboelectric transduction. With an acoustic sensitivity of 9.54 V Pa(-1) in a pressure range from 70 to 110 dB and a directivity angle of 52°, the nanogenerator produced a maximum electric power density of 60.2 mW m(-2), which directly lit 17 commercial light-emitting diodes (LEDs). Furthermore, the nanogenerator can also act as a self-powered active sensor for automatically detecting the location of an acoustic source with an error less than 7 cm. In addition, an array of devices with varying resonance frequencies was employed to widen the overall bandwidth from 10 to 1700 Hz, so that the nanogenerator was used as a superior self-powered microphone for sound recording. Our approach presents an adaptable, mobile, and cost-effective technology for harvesting acoustic energy from ambient environment, with applications in infrastructure monitoring, sensor networks, military surveillance, and environmental noise reduction.

  9. 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.

  10. 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.

  11. Response of acoustic and elastic properties to pressure and crystallization of Ce-based bulk metallic glass

    NASA Astrophysics Data System (ADS)

    Zhang, B.; Wang, R. J.; Wang, W. H.

    2005-09-01

    The density and acoustic velocities of a Ce70Al10Ni10Cu10 bulk metallic glass (BMG) under hydrostatic-pressure (up to 0.5GPa ) and in crystallized state in ambient conditions were measured in situ by a pulse echo overlap method. The pressure derivatives of velocities and Grüneisen parameters as well as the equation of state (EOS) of the BMG were determined and compared to those of various other BMGs and nonmetallic glasses. Surprisingly, the BMG, unlike other BMGs with normal mode stiffness, exhibits an anomalous soft longitudinal acoustic mode under pressure similar to that of typical oxide glasses. An unusually large softening of longitudinal acoustic phonons in the BMG, relative to its crystalline state, is also observed, analogous with that in oxide glasses. The possible origin for the anomaly is the intrinsic glassy structure containing short-range covalent bonds.

  12. Weak localization and antilocalization in topological insulator thin films with coherent bulk-surface coupling

    NASA Astrophysics Data System (ADS)

    Garate, Ion

    2014-03-01

    This talk will review the theory and experiments concerning quantum corrections to conductivity in thin films of three dimensional topological insulators. In particular, I will discuss how the magnitude and sign of the low-field magnetoresistance are influenced by bulk-surface coupling, gate voltage, size quantization effects and magnetic order. The speaker is financially supported by Canada's NSERC.

  13. Optical properties of Bi2Se3: from bulk to ultrathin films

    NASA Astrophysics Data System (ADS)

    Eddrief, M.; Vidal, F.; Gallas, B.

    2016-12-01

    We report on the determination of the dielectric functions of Bi2Se3 thin films and bulk material. The Bi2Se3 thin films with thicknesses ranging from 3-54 quintuple layers (QL) were grown by molecular beam epitaxy on GaAs(1 1 1)B substrates and the optical properties were determined from spectroscopic ellipsometry in the range of 0.5 eV-6 eV. We observed five absorption bands in the bulk sample, with a strong maximum near 2 eV, which were also present in the films down to 19 QL. Reducing the number below 19 QL in the Bi2Se3 films caused dampening and broadening of the bulk absorption bands below 2 eV, and a shift to a higher energy of the band near 2 eV. Our experimental results thus provide evidence of marked changes in the joint density of states of Bi2Se3 below 19 QL, indicating that the whole bulk band structure is affected for the ultrathin epilayers.

  14. Layered surface acoustic wave devices for film characterization and sensor applications

    NASA Astrophysics Data System (ADS)

    Pedrick, Michael K.

    2007-05-01

    This work has introduced novel applications for Layered Surface Acoustic Wave (SAW) devices along with concepts for enhanced sensitivity via refined modeling techniques. The derivation of Love Wave and Rayleigh wave propagation pertinent to SAW substrates with thin film overlayers was explored. Novel aspects were presented for Finite Element analysis of Layered SAW sensors. This included coordinate transformations of model geometries to coincide with crystallographic orientations known to generate Surface Skimming Bulk Waves (SSBW) and various Rayleigh wave types of propagation in ST Quartz, 90° rotated ST Quartz, and 77° Y rotated Lithium Tantalate. This work has shown for the first time, FEM prediction of SSBW, Generalized SAW and High Velocity SAW waves. Rayleigh damping properties were extended to develop a Finite element model capable of predicting Layered SAW response to glass transition in a polymer film. The ability to monitor localized mechanical behavior in a PMMA film was explored with Love Waves generated by 90° rotated ST Quartz and Shear Vertical (SV)-SAWs generated by 77° Y rotated Lithium Tantalate. Similar trends were found experimentally as compared to the Finite element models. The capability of Love Wave devices for monitoring polymer film curing behavior was investigated. The ability to qualitatively assess the bond quality between film and substrate was also demonstrated based on the characteristics of the transmitted frequency response. The results of these developments have laid the ground work for developing diagnostic tools to better characterize film behavior in practical applications. Several sensor applications for Layered SAW devices were discussed. The Shear Horizontal displacement of the Love Wave device was exploited to demonstrate the capability of such a sensor for ice detection. A clear distinction between air, water, and ice loading was found with Love Waves whereas SV-SAWs were unable to distinguish between liquid and ice

  15. Acoustic streaming in two-dimensional freely suspended smectic liquid crystal films

    NASA Astrophysics Data System (ADS)

    Yablonskii, S. V.; Kurbatov, N. M.; Parfenyev, V. M.

    2017-01-01

    We study horizontal streaming excited by means of a low-frequency and low-intensity acoustic wave in 2D freely suspended films of thermotropic smectic liquid crystals. Acoustic pressure induces fast periodic transverse oscillations of the film, which produce in-plane stationary couples of vortices slowly rotating in opposite directions owing to hydrodynamic nonlinearity. The parameters of the vortices are measured using a new method, based on tracking solidlike disk-shaped islands. The horizontal motion occurs only when the amplitude of the acoustic pressure exceeds the threshold value, which can be explained by Bingham-like behavior of the smectic film. The measurements above threshold are in good agreement with existing theoretical predictions. We demonstrate experimentally that in-plane flow is well controlled by changing the acoustic pressure, excitation frequency, and geometry of the film. The observations open the way to using the phenomenon in nondisplay applications.

  16. Thick-film acoustic emission sensors for use in structurally integrated condition-monitoring applications.

    PubMed

    Pickwell, Andrew J; Dorey, Robert A; Mba, David

    2011-09-01

    Monitoring the condition of complex engineering structures is an important aspect of modern engineering, eliminating unnecessary work and enabling planned maintenance, preventing failure. Acoustic emissions (AE) testing is one method of implementing continuous nondestructive structural health monitoring. A novel thick-film (17.6 μm) AE sensor is presented. Lead zirconate titanate thick films were fabricated using a powder/sol composite ink deposition technique and mechanically patterned to form a discrete thick-film piezoelectric AE sensor. The thick-film sensor was benchmarked against a commercial AE device and was found to exhibit comparable responses to simulated acoustic emissions.

  17. 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.

  18. 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.

  19. 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.

  20. 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

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

    SciTech Connect

    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 was 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.

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

    SciTech Connect

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

    2016-10-01

    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 was 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.

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

    DOE PAGES

    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

  4. Bulk-impurity induced noise in large-area epitaxial thin films of topological insulators

    NASA Astrophysics Data System (ADS)

    Islam, Saurav; Bhattacharyya, Semonti; Kandala, Abhinav; Richardella, Anthony; Samarth, Nitin; Ghosh, Arindam

    2017-08-01

    We report a detailed study on low-frequency 1 /f -noise in large-area molecular-beam epitaxy grown thin ( ˜10 nm) films of topological insulators as a function of temperature, gate voltage, and magnetic field. When the Fermi energy is within the bulk valence band, the temperature dependence reveals a clear signature of generation-recombination noise in the defect states in the bulk band gap. However, when the Fermi energy is tuned to the bulk band gap, the gate voltage dependence of noise shows that the resistance fluctuations in surface transport are caused by correlated mobility-number density fluctuations due to the activated defect states present in the bulk of the topological insulator crystal with a density of Di t=3.2 ×1017 cm-2 eV-1. In the presence of the magnetic field, noise in these materials follows a parabolic dependence, which is qualitatively similar to mobility and charge-density fluctuation noise in non-degenerately doped trivial semiconductors. Our studies reveal that even in thin films of (Bi,Sb)2Te3 with thickness as low as 10 nm, the internal bulk defects are the dominant source of noise.

  5. 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.

  6. Determination of sound velocity and acoustic impedance of thin chitosan films by phase-sensitive acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Kamanyi, Albert E.; Ahmed Mohamed, Esam T.; Ngwa, Wilfred; Grill, Wolfgang

    2010-03-01

    The biomaterial chitosan is used in the paper manufacturing industry, as a wound healing agent and in filtration amongst others. In this paper the longitudinal sound velocity and acoustic impedance of thin films of chitosan of varying thicknesses are determined by vector-contrast acoustic microscopy. The exploitation of the relative reflectivity information from the maximum amplitude images and a comparison of the experimentally obtained V(z) curves with simulations using appropriate models are applied for the evaluation of the sound velocity. These results were compared to those previously obtained results with the same instrument.

  7. 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.

  8. Temperature-dependent differences in the nonlinear acoustic behavior of ultrasound contrast agents revealed by high-speed imaging and bulk acoustics.

    PubMed

    Mulvana, Helen; Stride, Eleanor; Tang, Mengxing; Hajnal, Jo V; Eckersley, Robert

    2011-09-01

    Previous work by the authors has established that increasing the temperature of the suspending liquid from 20°C to body temperature has a significant impact on the bulk acoustic properties and stability of an ultrasound contrast agent suspension (SonoVue, Bracco Suisse SA, Manno, Lugano, Switzerland). In this paper the influence of temperature on the nonlinear behavior of microbubbles is investigated, because this is one of the most important parameters in the context of diagnostic imaging. High-speed imaging showed that raising the temperature significantly influences the dynamic behavior of individual microbubbles. At body temperature, microbubbles exhibit greater radial excursion and oscillate less spherically, with a greater incidence of jetting and gas expulsion, and therefore collapse, than they do at room temperature. Bulk acoustics revealed an associated increase in the harmonic content of the scattered signals. These findings emphasize the importance of conducting laboratory studies at body temperature if the results are to be interpreted for in vivo applications. Copyright © 2011 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  9. Communication: Distinguishing between bulk and interface-enhanced crystallization in nanoscale films of amorphous solid water

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    The crystallization of amorphous solid water (ASW) nanoscale films was investigated using reflection absorption infrared spectroscopy. Two ASW film configurations were studied. In one case the ASW film was deposited on top of and capped with a decane layer ("sandwich" configuration). In the other case, the ASW film was deposited on top of a decane layer and not capped ("no cap" configuration). Crystallization of ASW films in the "sandwich" configuration is about eight times slower than in the "no cap." Selective placement of an isotopic layer (5% D2O in H2O) at various positions in an ASW (H2O) film was used to determine the crystallization mechanism. In the "sandwich" configuration, the crystallization kinetics were independent of the isotopic layer placement whereas in the "no cap" configuration the closer the isotopic layer was to the vacuum interface, the earlier the isotopic layer crystallized. These results are consistent with a mechanism whereby the decane overlayer suppresses surface nucleation and provide evidence that the observed ASW crystallization in "sandwich" films is the result of uniform bulk nucleation.

  10. Spin mapping of surface and bulk Rashba states in ferroelectric α -GeTe(111) films

    NASA Astrophysics Data System (ADS)

    Elmers, H. J.; Wallauer, R.; Liebmann, M.; Kellner, J.; Morgenstern, M.; Wang, R. N.; Boschker, J. E.; Calarco, R.; Sánchez-Barriga, J.; Rader, O.; Kutnyakhov, D.; Chernov, S. V.; Medjanik, K.; Tusche, C.; Ellguth, M.; Volfova, H.; Borek, St.; Braun, J.; Minár, J.; Ebert, H.; Schönhense, G.

    2016-11-01

    The breaking of bulk inversion symmetry in ferroelectric semiconductors causes a Rashba-type spin splitting of electronic bulk bands. This is shown by a comprehensive mapping of the spin polarization of the electronic bands in ferroelectric α -GeTe(111) films using a time-of-flight momentum microscope equipped with an imaging spin filter that enables a simultaneous measurement of more than 10 000 data points. The experiment reveals an opposite spin helicity of the inner and outer Rashba bands with a different spin polarization in agreement with theoretical predictions, confirming a complex spin texture of bulk Rashba states. The outer band has about twice larger spin polarization than the inner one, giving evidence of a spin-orbit effect being related to the orbital composition of the band states. The switchable inner electric field of GeTe implies new functionalities for spintronic devices.

  11. Bulk photovoltaic effect in monodomain BiFeO3 thin films

    NASA Astrophysics Data System (ADS)

    Yang, Ming-Min; Luo, Zheng-Dong; Kim, Dong Jik; Alexe, Marin

    2017-05-01

    The bulk photovoltaic effect of ferroelectric semiconductors is increasingly being studied for potential applications in solar energy harvesting thanks to their unique charge separation mechanism and the resultant anomalous photovoltage. However, the intrinsic properties regarding the temperature dependence of photovoltaic current and its correlation with the ferroelectric polarization in such systems still require proper understanding. Here, by studying monodomain BiFeO3 thin films with only a single ferroelectric variant, we demonstrate that the photovoltaic current of BiFeO3 ferroelectric semiconductors possesses a preferred direction depending on the light polarization direction and working temperature, which is not along the ferroelectric polarization direction. The results indicate that the bulk photovoltaic effect originates from non-centrosymmetry of ferroelectric semiconductors but is independent of the ferroelectric polarization. Moreover, we showed that the bulk photovoltaic effect can be tailored by modifying the activity of sub-band gap levels via chemical doping, thus enhancing the power conversion efficiency in ferroelectric semiconductors.

  12. Effect of magnetoelastic film thickness on power absorption in acoustically driven ferromagnetic resonance

    NASA Astrophysics Data System (ADS)

    Labanowski, D.; Jung, A.; Salahuddin, S.

    2017-09-01

    Surface acoustic waves (SAWs) traveling on the surface of a piezoelectric substrate are capable of exciting magnetoelastic ferromagnets into resonance. In this work, we explore the effects of magnetoelastic film thickness on the coupling of SAWs into such magnetic thin films. We find that power absorption as a function of film thickness begins to saturate above thicknesses of ≈20 nm. This is contrary to current models that predict an exponential increase of the absorption as a function of increasing film thickness. We show that the saturation happens due to an increase in the damping of the film beyond this thickness range.

  13. 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.

  14. Self-separated PZT thick films with bulk-like piezoelectric and electromechanical properties

    PubMed Central

    Su, Qing; Zhu, Benpeng; Lee, Joon Hwan; Bi, Zhenxing; Shung, Kirk; Zhou, Qifa; Takeuchi, Shinichi; Park, Bae Ho; Jia, Quanxi; Wang, Haiyan

    2011-01-01

    Self-separated Pb(Zr0.52Ti0.48)O3 (PZT) films were processed by a hydrothermal deposition and a rapid thermal separation method, followed by a sol–gel filling and sintering process. The films possess excellent piezoelectric and electromechanical properties close to those of bulk material. The maximum remnant polarization is over 30 μC/cm2 and the electromechanical coupling factor (kt) reaches as high as 0.52. The unique microstructure characteristics of the PZT films, such as their highly dense structure, columnar grains, well-connected grain boundaries, and well-dispersed nanopores, could all contribute to the enhanced piezoelectric and electromechanical properties. PMID:21852893

  15. 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.

  16. Sputtered nickel oxide thin film for efficient hole transport layer in polymer–fullerene bulk-heterojunction organic solar cell

    SciTech Connect

    Widjonarko, N. Edwin; Ratcliff, Erin L.; Perkins, Craig L.; Sigdel, Ajaya K.; Zakutayev, Andriy; Ndione, Paul F.; Gillaspie, Dane T.; Ginley, David S.; Olson, Dana C.; Berry, Joseph J.

    2012-03-01

    Bulk-heterojunction (BHJ) organic photovoltaics (OPV) are promising thin-film renewable energy conversion options due to low production cost by high-throughput roll-to-roll manufacturing, an expansive list of compatible materials, and flexible device fabrication.

  17. Effect of Initial Bulk Material Composition on Thermoelectric Properties of Bi2Te3 Thin Films

    NASA Astrophysics Data System (ADS)

    Budnik, A. V.; Rogacheva, E. I.; Pinegin, V. I.; Sipatov, A. Yu.; Fedorov, A. G.

    2013-07-01

    V2VI3 compounds and solid solutions based on them are known to be the best low-temperature thermoelectric (TE) materials. The predicted possibility of enhancement of the TE figure of merit in two-dimensional (2D) structures has stimulated studies of the properties of these materials in the thin-film state. The goal of the present work is to study the dependences of the Seebeck coefficient S, electrical conductivity σ, Hall coefficient R H, charge carrier mobility μ H, and TE power factor P = S 2 σ of Bi2Te3 thin films on the composition of the initial bulk material used for preparing them. Thin films with thickness d = 200 nm to 250 nm were grown by thermal evaporation in vacuum of stoichiometric Bi2Te3 crystals (60.0 at.% Te) and of crystals with 62.8 at.% Te onto glass substrates at temperatures T S of 320 K to 500 K. It was established that the conductivity type of the initial material is reproduced in films fairly well. For both materials, an increase in T S leads to an increase in the thin-film structural perfection, better correspondence between the film composition and that of the initial material, and increase in S, R H, μ H, σ, and P. The room-temperature maximum values of P for the films grown from crystals with 60.0 at.% and 62.8 at.% Te are P = 7.5 × 10-4 W/K2 m and 35 × 10-4 W/K2 m, respectively. Thus, by using Bi2Te3 crystals with different stoichiometry as initial materials, one can control the conductivity type and TE parameters of the films, applying a simple and low-cost method of thermal evaporation from a single source.

  18. Subsurface defect of amorphous carbon film imaged by near field acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Zeng, J. T.; Zhao, K. Y.; Zeng, H. R.; Song, H. Z.; Zheng, L. Y.; Li, G. R.; Yin, Q. R.

    2008-05-01

    Amorphous carbon films were examined by low frequency scanning-probe acoustic microscopy (LF-SPAM). Local elastic properties as well as topography were imaged in the acoustic mode. Two kinds of subsurface defects were revealed by the LF-SPAM method. The influence of the subsurface defects on the elastic properties was also discussed. The ability to image subsurface defects was dependent on the scan area and the scan speed. Our results showed that the low frequency scanning-probe acoustic microscopy is a useful method for imaging subsurface defects with high resolution.

  19. Magnetic resonance study of bulk and thin film EuTiO3

    NASA Astrophysics Data System (ADS)

    Laguta, V. V.; Kamba, S.; Maryško, M.; Andrzejewski, B.; Kachlík, M.; Maca, K.; Lee, J. H.; Schlom, D. G.

    2017-03-01

    Magnetic resonance spectra of EuTiO3 in both bulk and thin film form were taken at temperatures from 3–350 K and microwave frequencies from 9.2–9.8 and 34 GHz. In the paramagnetic phase, magnetic resonance spectra are determined by magnetic dipole and exchange interactions between Eu2+ spins. In the film, a large contribution arises from the demagnetization field. From detailed analysis of the linewidth and its temperature dependence, the parameters of spin–spin interactions were determined: the exchange frequency is 10.5 GHz and the estimated critical exponent of the spin correlation length is  ≈0.4. In the bulk samples, the spectra exhibited a distinct minimum in the linewidth at the Néel temperature, T N  ≈  5.5 K, while the resonance field practically does not change even on cooling below T N. This is indicative of a small magnetic anisotropy ~320 G in the antiferromagnetic phase. In the film, the magnetic resonance spectrum is split below T N into several components due to excitation of the magnetostatic modes, corresponding to a non-uniform precession of magnetization. Moreover, the film was observed to degrade over two years. This was manifested by an increase of defects and a change in the domain structure. The saturated magnetization in the film, estimated from the magnetic resonance spectrum, was about 900 emu cm‑3 or 5.5 µ B/unit cell at T  =  3.5 K.

  20. Frequency-domain Harman technique for rapid characterization of bulk and thin film thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Moran, Samuel

    Nanostructured thermoelectrics, often in the form of thin films, may potentially improve the generally poor efficiency of bulk thermoelectric power generators and coolers. In order to characterize the efficiency of these new materials it is necessary to measure their thermoelectric figure of merit, ZT. The only direct measurement of ZT is based on the Harman technique and relies on measuring the voltage drop across a sample subjected to a passing continuous current. Application of this technique to thin films is currently carried out as a time-domain measurement of the voltage as the thermal component decays after switching off an applied voltage. This work develops a technique for direct simultaneous measurement of figure of merit and Seebeck coefficient from the harmonic response of a thermoelectric material under alternating current excitation. A thermocouple mounted on the top surface measures voltage across the device as the frequency of the applied voltage is varied. A thermal model allows the sample thermal conductivity to also be determined and shows good agreement with measurements. This technique provides improved signal-to-noise ratio and accuracy compared to time-domain ZT measurements for comparable conditions while simultaneously measuring Seebeck coefficient. The technique is applied to both bulk and thin film thermoelectric samples.

  1. Transient gratings in thin films and bulk azo-dye-containing poly(methyl methacrylate) matrix

    NASA Astrophysics Data System (ADS)

    Luo, Duanbin; Lu, Wei; Wu, Shuizhu

    2005-02-01

    Using holographic recording technology, two kinds of transient diffraction gratings were demonstrated in azo-dye doped Poly(methyl methacrylate) (PMMA) films and bulk matrices respectively. In PMMA films containing azo-dye Disperse Red 13 (DR13), the refractive index gratings came from the reorientation of azo-dye molecules in different areas with different polarization distribution of recording beams. The characteristics of the transient gratings in films samples which were recorded by two mutually parallel polarization beams (PP and SS) as well as orthogonal linear polarization beams (PS and +/-45°) from an Ar ion laser (514nm) were investigated by monitoring the first order diffraction intensity of the readout He-Ne laser beam (632.8nm). With the interaction of bi-photonic lights at 514nm and 632.8nm, the transient gratings in azo-dye DR13 doped PMMA bulk matrices was a kind of population gratings of Trans and Cis isomers, which was attributed to the weak absorption of Cis isomers at 632.8nm and the positive dichroism of Trans isomers at 514nm. Furthermore, the all-optical switching behavior of the two kinds of transient holographic gratings were observed repeatedly by turning on and off the writing beams, and a response time at the magnitude of ten milliseconds order could be obtained.

  2. Comparative AFM nanoscratching tests in air of bulk copper and electrogenerated cuprous oxide films

    NASA Astrophysics Data System (ADS)

    Chaal, Lila; Debiemme-Chouvy, Catherine; Deslouis, Claude; Maurin, Georges; Pailleret, Alain; Saidani, Boualem

    2011-01-01

    The normal and lateral spring constants of rectangular silicon AFM cantilevers bearing pyramidal silicon tips were accurately calibrated using a procedure that takes into account their tilt compared to horizontal orientation and their trapezoidal cross section. Such systems were used to carry out nanoscratching tests in air on technical substrates presenting a moderate roughness (RMS ≈ 40 nm) and made either from bulk copper or from cuprous oxide thin films electrogenerated on copper. The various events occurring during these nanoscratching procedures were characterized in details. In particular, the features of the scars appearing on the scratched zones and SEM observations of the AFM tips used during the nanoscratching procedures are described and exploited to establish a better understanding of the effects of the nanoscratching procedures on the targeted samples. In the case of electrodeposited Cu 2O films, these effects are discussed with the help of chemical and structural characterizations using XPS and XRD studies. All this set of information is used i) to describe the history of the nanoscratching tests and ii) to compare mechanical resistance of bulk copper and electrogenerated Cu 2O thin films using these nanoscratching tests carried out in air. The wear mechanism occurring during nanoscratching tests is discussed for both kinds of samples and compared with the one observed during erosion in erosion-corrosion tests.

  3. High-dielectric-constant ferroelectric thin film and bulk ceramic capacitors for power electronics.

    SciTech Connect

    Auciello, O. H.; Baldo, P.; Baumann, P.; Erck, R. A.; Giumarra, J.; Im, J.; Kaufman, D. Y.; Lanagan, M. T.; Pan, M. J.; Streiffer, S. K.; Zebrowski, J.

    1999-08-10

    Significant effort is presently focused on reducing the size and weight of power electronic modules. To achieve these goals in high-power capacitors, alternative materials and fabrication processes are needed. Thin film (<0.5 {micro}m) and bulk capacitors that use perovskite-based ferroelectric dielectrics are promising alternative technologies. Ferroelectrics possess high dielectric constants, thus offering substantial increases in volumetric capacitance. In thin film form, these materials display low loss and high breakdown strength. The unique properties of some of these materials, such as a nonlinear dielectric response or a high energy-storage capacity accompanying a phase change, can be exploited for power electronic capacitors. Prototype capacitors of two such materials, (Ba,Sr)TiO{sub 3} and PbZrO{sub 3}, have been fabricated in both thin film and bulk ceramic form. The influence of fabrication conditions on dielectric properties has been studied. Initial studies have demonstrated the viability of perovskite ferroelectrics for next-generation capacitor components.

  4. Spectroscopic imaging of photopotentials and photoinduced potential fluctuations in a bulk heterojunction solar cell film.

    PubMed

    Luria, Justin L; Hoepker, Nikolas; Bruce, Robert; Jacobs, Andrew R; Groves, Chris; Marohn, John A

    2012-11-27

    We present spatially resolved photovoltage spectra of a bulk heterojunction solar cell film composed of phase-separated poly(9,9'-dioctylfluorene-co-benzothiadiazole) (F8BT) and poly(9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-1,4-phenylenediamine) (PFB) polymers prepared on ITO/PEDOT:PSS and aluminum substrates. Over both PFB- and F8BT-rich domains, the photopotential spectra were found to be proportional to a linear combination of the polymers' absorption spectra. Charge trapping in the film was studied using photopotential fluctuation spectroscopy, in which low-frequency photoinduced electrostatic potential fluctuations were measured by observing noise in the oscillation frequency of a nearby charged atomic force microscope cantilever. Over both F8BT- and PFB-rich regions, the magnitude, distance dependence, frequency dependence, and illumination wavelength dependence of the observed cantilever frequency noise are consistent with photopotential fluctuations arising from stochastic light-driven trapping and detrapping of charges in F8BT. Taken together, our findings suggest a microscopic mechanism by which intermixing of phases leads to charge trapping and thereby to suppressed open-circuit voltage and decreased efficiency in this prototypical bulk heterojunction solar cell film.

  5. Semicylindrical acoustic transducer from a dielectric elastomer film with compliant electrodes.

    PubMed

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

    2011-08-01

    A semicylindrical acoustic transducer was constructed using a dielectric elastomer film with compliant electrodes that is an electroactive polymer composed of a polyurethane elastomer base and polyethylene dioxythiophene/polystyrene sulfonate electrodes. The use of this dielectric elastomer is advantageous because polyurethane is a common material that keeps its shape without any rigid frame. Because the dielectric elastomer films are essentially incompressible, electric-field-induced thickness changes are usually translated into much larger changes of the film area and side length. Here it is proposed that this change in side length can be utilized for sound generation when the film is bent into a semicylindrical shape. Accordingly, a semicylindrical acoustic transducer was fabricated using a film of thickness of 300 μm and its acoustic characteristics were investigated. The transducer can be operated at low applied voltages by reducing the film thickness, as long as the film is thick enough to generate sufficient force to overcome sound radiation impedance. The second harmonic distortion of the transducer was also investigated as a function of the ratio of the direct current bias voltage to the alternating current audio signal amplitude.

  6. Generation of acoustic waves by power microwave pulses with the use of thin metal films

    NASA Astrophysics Data System (ADS)

    Andreev, V. G.; Vdovin, V. A.

    2005-10-01

    We study the features of excitation of acoustic waves by high-power microwave pulses in thin metal films bordering on liquid. Aluminum films with thicknesses 1 10 nm deposited onto a quartz substrate were used in experiments. It is shown theoretically that the absorption coefficient of microwaves is maximum for film thickness from 2 to 3 nm and the value of this maximum is determined by the dielectric permittivity of the bordering liquid. Theoretical calculations and experiments are performed for water and ethyl alcohol. The sound generation in a layered system quartz-aluminum film-liquid is analyzed with the help of the step-by-step approach. At the first step, microwave energy is absorbed in the film and heat is released. Then heat almost instantly diffuses into a liquid whose thermal expansion creates an acoustic signal. Profiles of acoustic signals excited in aluminum films by microwave pulses with a 5-ns duration and an energy of up to 1 mJ are experimentally detected. The most efficient transduction was observed for an aluminum film 3.5 nm thick.

  7. Thermal Conductivity in Nanostructured Films: From Single Cellulose Nanocrystals to Bulk Films

    Treesearch

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

    2014-01-01

    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...

  8. Method for the determination of bulk and interface density of states in thin-film transistors

    SciTech Connect

    Lui, O. K. B.; Tam, S. W.-B.; Migliorato, P.; Shimoda, T.

    2001-06-01

    In this article we present a method for the accurate determination of interface and bulk density of states (DOS) in thin-film transistors (TFTs), based on the combined analysis of transfer (I{sub D}{endash}V{sub GS}) and capacitance{endash}voltage characteristics. This analysis has achieved a number of results, eliminating sources of inaccuracies that are known to be present in other methods. A procedure for the determination of the electron and hole flatband conductances and bulk Fermi energy is demonstrated. A recursive procedure is employed to extract the bulk DOS directly from Poisson{close_quote}s equation. The advantages of this method are the greater immunity to noise from the original data, the use of the complete Fermi function (no 0 K approximation), and the applicability to thin active layers. This method yields the interface state density spectrum as well as the bulk DOS. This information is very important for device design, process characterization, and modeling of TFTs. {copyright} 2001 American Institute of Physics.

  9. Effect of the photoreaction solvent on surface and bulk properties of poly(lactic acid) and poly(hydroxyalkanoate) films.

    PubMed

    Rasal, Rahul M; Bohannon, Bradley G; Hirt, Douglas E

    2008-05-01

    The major objective of this research was to modify the surface properties of poly(lactic acid) (PLA) and poly(hydroxyalkanoate) (PHA) films by using a sequential two-step photografting approach. In step 1, benzophenone was photografted on the film surface and in step 2, hydrophilic monomers acrylamide and acrylic acid were photopolymerized from the film surfaces. Another objective was to study the effect of the reaction solvent in step 2 on surface and bulk properties of these films. ATR-FTIR spectroscopy and water contact angle goniometry were used to characterize the resultant film surfaces. When ethanol was used as the solvent in step 2, there was significant penetration of the monomers into the films, and bulk properties such as toughness and percent elongation at break were drastically affected. The penetration of these monomers into the bulk was characterized using transmission FTIR microspectroscopy. Microtomed sections of the surface-modified films were placed in a diamond compression cell to perform the FTIR microspectroscopic analyses. The observed monomer penetration into the films was successfully reduced by using water instead of ethanol in step 2, and resultant films showed higher toughness and percent elongation at break than films surface-modified using ethanol as a solvent in step 2.

  10. 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

  11. Electrically detected and conventional magnetic resonance investigation of surface and bulk states in polyaniline thin films

    NASA Astrophysics Data System (ADS)

    Castro, Fernando A.; Graeff, Carlos F. O.

    2007-04-01

    Electrically detected magnetic resonance (EDMR) and electron paramagnetic resonance (EPR) were used to investigate emeraldine base polyaniline films. The magnetic susceptibility presented a Curie (localized spins)—Pauli (delocalized spins) transition at 240 K, when we also observed a transition in the dependence of the g factor with temperature (T). Peak-to-peak linewidth decreases with increasing temperature, reflecting that motional narrowing limits the hyperfine and dipolar broadening in this polymer. EDMR spectra could only be observed above 250 K in accordance to EPR results. Surface and bulk transport could be separated and their analysis reflected the effect of magnetic interaction with oxygen.

  12. Self Assembled Spin Coated and Bulk Films of a Novel Polydiacetylene as Second Order NLO Polymers

    DTIC Science & Technology

    1994-05-31

    T Code: 4132016 W.H. Kim, B. Bihari, R. Moody, N. B. Kodali , J.KumarS.K. Dr. JoAnn Milliken Tripathy. 7. PHI-OUHMING OFH-NIZATION NAMIE(S) AND...Self Assembled Spin Coated and Bulk Films of a Novel Polydiacetylene as Second Order NLO Polymers by W.H. Kim, B. Bihari, R. Moody, N. B. Kodali ...POLYMERS W. H. Kim, B. Bihari+, R. Moody+, N. B. Kodali , J. Kumar+, and S. K. Tripathy, University of Massachusetts-Lowell, Center for Advanced Materials

  13. High-performance flexible thin-film transistors exfoliated from bulk wafer.

    PubMed

    Zhai, Yujia; Mathew, Leo; Rao, Rajesh; Xu, Dewei; Banerjee, Sanjay K

    2012-11-14

    Mechanically flexible integrated circuits (ICs) have gained increasing attention in recent years with emerging markets in portable electronics. Although a number of thin-film-transistor (TFT) IC solutions have been reported, challenges still remain for the fabrication of inexpensive, high-performance flexible devices. We report a simple and straightforward solution: mechanically exfoliating a thin Si film containing ICs. Transistors and circuits can be prefabricated on bulk silicon wafer with the conventional complementary metal-oxide-semiconductor (CMOS) process flow without additional temperature or process limitations. The short channel MOSFETs exhibit similar electrical performance before and after exfoliation. This exfoliation process also provides a fast and economical approach to producing thinned silicon wafers, which is a key enabler for three-dimensional (3D) silicon integration based on Through Silicon Vias (TSVs).

  14. Nano-structured TiO(2) film fabricated at room temperature and its acoustic properties.

    PubMed

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

    2008-01-01

    Nano-structured TiO(2) 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.

  15. Bulk and compound-specific isotopic characterisation of illicit heroin and cling film.

    PubMed

    Idoine, Fay A; Carter, James F; Sleeman, Richard

    2005-01-01

    Comparative analysis involves various but complementary methods and can be used for forensic intelligence purposes to group seizures of heroin into batches. Much forensic analysis now combines expertise in the traditional area of drugs investigation with a detailed understanding of supply, packaging, distribution, and drugs intelligence. It was the intention of this research to determine whether illicit heroin seizures and packaging material can be grouped according to isotopic compositions, and to explore factors that affect the isotopic compositions. In order to achieve these aims, 14 samples of seized heroin, thirteen provided by Avon and Somerset Constabulary (UK), were analysed by elemental analysis/isotope ratio mass spectrometry (EA/IRMS) and gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) for carbon and hydrogen isotopes. These tests elucidated that a combination of the delta13C, delta15N, delta18O and delta2H results from EA/IRMS is able to distinguish between most samples of bulk heroin. We speculate that the delta13C values of the alkaloids, obtained by GC/C/IRMS, give indications of different geographical or temporal origins of some of the heroin samples. GC/C/IRMS of the cutting agent, caffeine, provides a means to link dilution events. Fifteen retail cling film samples and seven cling film samples from heroin seizures were analysed by EA/IRMS. A multivariate comparison of the carbon, hydrogen and oxygen isotope ratios was able to distinguish between most of the samples. This technique enabled the cling films from the heroin to be grouped according to seizure. Three solvents were tested on two samples of cling film of known composition. Methanol and chloroform were both found to extract material from PVC and from non-PVC cling films. Water-treated PVC was indistinguishable from the untreated PVC and thus water was found to be the most suitable solvent when washing cling film prior to IRMS analysis.

  16. 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.

  17. Near field acoustic holography measurements of carbon nanotube thin film speakers.

    PubMed

    Asgarisabet, Mahsa; Barnard, Andrew R; Bouman, Troy M

    2016-12-01

    Carbon nanotube (CNT) thin film speakers produce sound with the thermoacoustic effect. Better understanding of the physical acoustic properties of these speakers will drive future design improvements. Measuring acoustic properties at the surface of the CNT thin film is difficult because the films, themselves, do not vibrate, are fragile and have a high surface temperature. In order to measure the surface particle velocity and sound pressure level (SPL), near field acoustic holography (NAH) has been used by employing probe microphones. NAH images the acoustic quantities of the source system using the set of acoustic pressure measurements on a hologram parallel to the source surface. It is shown that the particle velocity at the surface of an open-air, double-sided speaker is nominally zero, as expected. However, the SPL distribution is not uniform on the source surface, contrary to common lumped parameter model assumptions. Also, particle velocity and sound intensity distributions on the hologram have been obtained in this study. Finally, measured directivity patterns of the planar CNT speaker are reported.

  18. Translational diffusion across a free-standing smectic film above the bulk smectic-A-isotropic transition temperature.

    PubMed

    Śliwa, Izabela; Zakharov, A V

    2017-01-01

    Calculations of translational self-diffusion coefficient in free-standing smectic films during a series of layer-thinning transitions as the temperature is raised above the bulk smectic-A-isotropic transition have been carried out. A molecular model based upon the random walk theory is applied for calculating the translational diffusion coefficient (TDC) D_{∥} across the smectic film both in the bulk of the film, as well as in the vicinity of the bounding surfaces. Calculations of D_{∥} require the set of the orientational and translational order parameters (OPs) which have been obtained by using the extended McMillan approach with anisotropic forces. The effect of E on the orientational and translational OPs, as well as on the TDC of smectic films has been investigated. A reasonable agreement between the theoretically predicted and the experimentally obtained data on the TDC in the bulk of the partially fluorinated H10F5MOPP film has been obtained. We also found, in agreement with the experimentally observed behavior of D_{∥}(N)(N=25,13,11,10), that the translational diffusion coefficient in the bulk of the film gradually increases as the film thickness N is decreased.

  19. Translational diffusion across a free-standing smectic film above the bulk smectic-A -isotropic transition temperature

    NASA Astrophysics Data System (ADS)

    Śliwa, Izabela; Zakharov, A. V.

    2017-01-01

    Calculations of translational self-diffusion coefficient in free-standing smectic films during a series of layer-thinning transitions as the temperature is raised above the bulk smectic-A -isotropic transition have been carried out. A molecular model based upon the random walk theory is applied for calculating the translational diffusion coefficient (TDC) D∥ across the smectic film both in the bulk of the film, as well as in the vicinity of the bounding surfaces. Calculations of D∥ require the set of the orientational and translational order parameters (OPs) which have been obtained by using the extended McMillan approach with anisotropic forces. The effect of E on the orientational and translational OPs, as well as on the TDC of smectic films has been investigated. A reasonable agreement between the theoretically predicted and the experimentally obtained data on the TDC in the bulk of the partially fluorinated H10F5MOPP film has been obtained. We also found, in agreement with the experimentally observed behavior of D∥(N )(N =25 ,13 ,11 ,10 ) , that the translational diffusion coefficient in the bulk of the film gradually increases as the film thickness N is decreased.

  20. Characterization of Homopolymer and Polymer Blend Films by Phase Sensitive Acoustic Microscopy

    NASA Astrophysics Data System (ADS)

    Ngwa, Wilfred; Wannemacher, Reinhold; Grill, Wolfgang

    2003-03-01

    CHARACTERIZATION OF HOMOPOLYMER AND POLYMER BLEND FILMS BY PHASE SENSITIVE ACOUSTIC MICROSCOPY W Ngwa, R Wannemacher, W Grill Institute of Experimental Physics II, University of Leipzig, 04103 Leipzig, Germany Abstract We have used phase sensitive acoustic microscopy (PSAM) to study homopolymer thin films of polystyrene (PS) and poly (methyl methacrylate) (PMMA), as well as PS/PMMA blend films. We show from our results that PSAM can be used as a complementary and highly valuable technique for elucidating the three-dimensional (3D) morphology and micromechanical properties of thin films. Three-dimensional image acquisition with vector contrast provides the basis for: complex V(z) analysis (per image pixel), 3D image processing, height profiling, and subsurface image analysis of the polymer films. Results show good agreement with previous studies. In addition, important new information on the three dimensional structure and properties of polymer films is obtained. Homopolymer film structure analysis reveals (pseudo-) dewetting by retraction of droplets, resulting in a morphology that can serve as a starting point for the analysis of polymer blend thin films. The outcome of confocal laser scanning microscopy studies, performed on the same samples are correlated with the obtained results. Advantages and limitations of PSAM are discussed.

  1. Surface acoustic wave properties of freestanding diamond films.

    PubMed

    Flannery, Colm M; Whitfield, Michael D; Jackman, Richard B

    2004-03-01

    "Ideal" diamond has the highest acoustic velocity of any material known, and is of great interest as a substrate material for high frequency surface acoustic wave (SAW) device structures. However, little is known of the acoustic wave propagation properties of polycrystalline diamond grown by chemical vapour deposition (CVD) techniques, the commercially accessible form of this material. We report on propagation of laser-generated SAW on three forms of freestanding CVD diamond samples, "white" polycrystalline, "black" polycrystalline, and "highly oriented" diamond. Despite differing sample nature, SAW waves propagating along the smooth (nucleation) side of the diamond showed similar velocities in the range 10600-11900 ms(-1). These results are discussed in terms of the potential of each form of CVD diamond for SAW device fabrication.

  2. 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.

  3. Nonlinear optical observation of coherent acoustic Dirac plasmons in thin-film topological insulators

    PubMed Central

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

    2016-01-01

    Low-energy collective electronic excitations exhibiting sound-like linear dispersion have been intensively studied both experimentally and theoretically for a long time. However, coherent acoustic plasmon modes appearing in time-domain measurements are rarely observed due to Landau damping by the single-particle continua. Here we report on the observation of coherent acoustic Dirac plasmon (CADP) modes excited in indirectly (electrostatically) opposite-surface coupled films of the topological insulator Bi2Se3. Using transient second-harmonic generation, a technique capable of independently monitoring the in-plane and out-of-plane electron dynamics in the films, the GHz-range oscillations were observed without corresponding oscillations in the transient reflectivity. These oscillations were assigned to the transverse magnetic and transverse electric guided CADP modes induced by the evanescent guided Lamb acoustic waves and remained Landau undamped due to fermion tunnelling between the opposite-surface Dirac states. PMID:27687867

  4. Nonlinear optical observation of coherent acoustic Dirac plasmons in thin-film topological insulators

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    Low-energy collective electronic excitations exhibiting sound-like linear dispersion have been intensively studied both experimentally and theoretically for a long time. However, coherent acoustic plasmon modes appearing in time-domain measurements are rarely observed due to Landau damping by the single-particle continua. Here we report on the observation of coherent acoustic Dirac plasmon (CADP) modes excited in indirectly (electrostatically) opposite-surface coupled films of the topological insulator Bi2Se3. Using transient second-harmonic generation, a technique capable of independently monitoring the in-plane and out-of-plane electron dynamics in the films, the GHz-range oscillations were observed without corresponding oscillations in the transient reflectivity. These oscillations were assigned to the transverse magnetic and transverse electric guided CADP modes induced by the evanescent guided Lamb acoustic waves and remained Landau undamped due to fermion tunnelling between the opposite-surface Dirac states.

  5. Efficient bulk heterojunction photovoltaic cells using small-molecular-weight organic thin films.

    PubMed

    Peumans, Peter; Uchida, Soichi; Forrest, Stephen R

    2003-09-11

    The power conversion efficiency of small-molecular-weight and polymer organic photovoltaic cells has increased steadily over the past decade. This progress is chiefly attributable to the introduction of the donor-acceptor heterojunction that functions as a dissociation site for the strongly bound photogenerated excitons. Further progress was realized in polymer devices through use of blends of the donor and acceptor materials: phase separation during spin-coating leads to a bulk heterojunction that removes the exciton diffusion bottleneck by creating an interpenetrating network of the donor and acceptor materials. The realization of bulk heterojunctions using mixtures of vacuum-deposited small-molecular-weight materials has, on the other hand, posed elusive: phase separation induced by elevating the substrate temperature inevitably leads to a significant roughening of the film surface and to short-circuited devices. Here, we demonstrate that the use of a metal cap to confine the organic materials during annealing prevents the formation of a rough surface morphology while allowing for the formation of an interpenetrating donor-acceptor network. This method results in a power conversion efficiency 50 per cent higher than the best values reported for comparable bilayer devices, suggesting that this strained annealing process could allow for the formation of low-cost and high-efficiency thin film organic solar cells based on vacuum-deposited small-molecular-weight organic materials.

  6. 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.

  7. The design and flight test of an engine inlet bulk acoustic liner

    NASA Technical Reports Server (NTRS)

    Lester, H. C.; Preisser, J. S.; Parrott, T. L.

    1983-01-01

    This paper summarizes the design, fabrication and flight evaluation of a Kevlar acoustic liner configuration for a JT15D turbofan engine. The liner was designed to suppress, by a measurable amount, a dominant (13,0) BPF tone. This tone or spinning mode was produced for research purposes by installing 41 circumferentially distributed small diameter rods upstream of the 28 fan blades. Duct liner attenuations calculated by a finite element procedure were compared to far field power (insertion) losses deduced from flight data. The finite element program modeled the variable geometry of the JT15D inlet and used a uniform flow with a boundary layer roll-off to model the inlet flow field. Calculated liner losses were generally conservative. That is, measured far field power losses were generally greater than attenuations calculated by the finite element computer program.

  8. 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.

  9. Dynamic fluid-film interferometry as a predictor of bulk foam properties.

    PubMed

    Frostad, John M; Tammaro, Daniele; Santollani, Luciano; Bochner de Araujo, Simone; Fuller, Gerald G

    2016-11-23

    Understanding and enabling the control of the properties of foams is important for a variety of commercial processes and consumer products. In these systems, the role of surface active compounds has been the subject of many investigations using a wide range of techniques. The study of their influence on simplified geometries such as two bubbles in a liquid or a thin film of solution (such as in the well-known Scheludko cell), has yielded important fundamental understanding. Similarly, in this work an interferometric technique is used to study the dynamic evolution of the film formed by a single bubble being pressed against a planar air-liquid interface. Here interferometry is used to dynamically measure the total volume of liquid contained within the thin-film region between the bubble and the planar interface. Three different small-molecule, surfactant solutions were investigated and the data obtained via interferometry were compared to measurements of the density of bulk foams of the same solutions. The density measurements were collected with a simple, but novel technique using a conical-shaped bubbling apparatus. The results reveal a strong correlation between the measurements on single bubbles and complete foams. This suggests that further investigations using interferometric techniques can be instrumental to building a more detailed mechanistic understanding of how different surface-active compounds influence foam properties. The results also reveal that the commonly used assumption that surfactant-laden interfaces may be modeled as immobile, is too simplistic to accurately model interfaces with small-molecule surfactants.

  10. Structural Relaxations in Bulk and Thin Film Polymers: Role of Macromolecular Architecture

    NASA Astrophysics Data System (ADS)

    Green, Peter

    2014-03-01

    Structural relaxations that occur in polymers quenched below the glass transition temperature, Tg, are responsible for time-dependent changes in physical properties that include optical, specific volume and the enthalpy. This phenomenon, physical aging, has been of interest in bulk polymers for decades and much is understood. The aging rate, R, is known to increase as the temperature at which the glass ages, T' , decreases below Tg, due to the increasing departure from structural equilibrium; it then decreases with further decreases in T. We show that the aging rates of star-shaped polymers are slower than their linear analogs of the same degree of polymerization, N. Whereas the temperature dependence of R is independent of N for linear chains, it depends on the functionality, f , and on the degree of polymerization per arm, N', of the star-shaped macromolecules. R decreases with increasing f , for N' less than a threshold degree of polymerization, which increases with increasing f. The aging of very thin films (h ~ 100 nm) is dependent on the distance, z, from an external interface. With the use positron annihilation spectroscopy (PALS) we determined the z-dependence of the Tg in thin films and showed that the aging rate is largely determined by the difference between the local glass transition temperature of the films and T'. Finally we show that the aging rates of linear and star-shaped macromolecules are consistent with experimental findings of glassy dynamics in both systems.

  11. 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.

  12. 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.

  13. 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.

  14. Optical, photo-acoustic and electrical switching studies of amorphous GeS2 thin films

    NASA Astrophysics Data System (ADS)

    Ananth Kumar, R. T.; Das, Chandasree; Asokan, S.; Sanjeeviraja, C.; Pathinettam Padiyan, D.

    2014-06-01

    This paper reports optical, photo-acoustic and electrical switching investigations of GeS2 amorphous thin films of different thicknesses, deposited on glass substrates in vacuum. The Tauc parameter ( B 1/2) and Urbach energy ( E U) have been determined from the transmittance spectra, to understand the changes in structural disorder; it is found that B 1/2 increases whereas E U decreases as the thickness of the films increases. Based on the results, it is suggested that bond re-arrangement, i.e. transformation from homopolar bonds to heteropolar bonds, takes place with increase in thickness. The thermal diffusivity values of GeS2 thin films also show the presence of a chemically ordered network in the GeS2 thin films. Further, it is found that these films exhibit memory-type electrical switching. The observed variation in the switching voltages has been understood on the basis of increase in chemical order.

  15. 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.

  16. Deviation from bulk in the pressure-temperature phase diagram of V2O3 thin films

    NASA Astrophysics Data System (ADS)

    Valmianski, I.; Ramirez, Juan Gabriel; Urban, C.; Batlle, X.; Schuller, Ivan K.

    2017-04-01

    We found atypical pressure dependence in the transport measurements of the metal to insulator transition (MIT) in epitaxial thin films of vanadium sesquioxide (V2O3 ). Three different crystallographic orientations and four thicknesses, ranging from 40 to 500 nm, were examined under hydrostatic pressures (Ph) of up to 1.5 GPa. All of the films at transition exhibited a four order of magnitude resistance change, with transition temperatures ranging from 140 to 165 K, depending on the orientation. This allowed us to build pressure-temperature phase diagrams of several orientations and film thicknesses. Interestingly, for pressures below 500 MPa, all samples deviate from bulk behavior and show a weak transition temperature (Tc) pressure dependence (d Tc/d Ph=1.2 ×10-2±0.3 ×10-2K /MPa ), which recovers to bulklike behavior (3.9 ×10-2±0.3 ×10-2K /MPa ) at higher pressures. Furthermore, we found that pressurization leads to morphological but not structural changes in the films. This indicates that the difference in the thin film and bulk pressure-temperature phase diagrams is most probably due to pressure-induced grain boundary relaxation, as well as both plastic and elastic deformations in the film microstructure. These results highlight the difference between bulk and thin films behaviors.

  17. Pr0.67Ba0.33MnO3 in Bulk and Thin Film Ceramic

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    Bulk polycrystalline of Pr0.67Ba0.33MnO3 (PBMO) ceramic prepared via solid-state reaction and converted into thin films on corning glass, fused silica and MgO (100) by pulsed laser deposition (PLD) technique. As compared to bulk PBMO, the unit cell in thin film PBMO experienced positive misfit due to lattice strain induced by substrate used resulting MnO6 to deform (change in Mn-O-Mn bond angle and Mn-O bond length). Bulk PBMO had large grains (˜1.5μm) as compared to thin film which are nano-sized (<100 nm). Two metal-insulator transition temperatures, TP (156 K and 190 K) were observed in bulk due to core-shell effect as proposed by Zhang et al.. In summary, variation of electrical behaviour was observed between bulk and thin film samples which believed to be due to the difference of ordering in core (body) and grain surface.

  18. Solution-Processed Cu2Se Nanocrystal Films with Bulk-Like Thermoelectric Performance.

    PubMed

    Forster, Jason D; Lynch, Jared J; Coates, Nelson E; Liu, Jun; Jang, Hyejin; Zaia, Edmond; Gordon, Madeleine P; Szybowski, Maxime; Sahu, Ayaskanta; Cahill, David G; Urban, Jeffrey J

    2017-06-05

    Thermoelectric power generation can play a key role in a sustainable energy future by converting waste heat from power plants and other industrial processes into usable electrical power. Current thermoelectric devices, however, require energy intensive manufacturing processes such as alloying and spark plasma sintering. Here, we describe the fabrication of a p-type thermoelectric material, copper selenide (Cu2Se), utilizing solution-processing and thermal annealing to produce a thin film that achieves a figure of merit, ZT, which is as high as its traditionally processed counterpart, a value of 0.14 at room temperature. This is the first report of a fully solution-processed nanomaterial achieving performance equivalent to its bulk form and represents a general strategy to reduce the energy required to manufacture advanced energy conversion and harvesting materials.

  19. Solution-Processed Cu2Se Nanocrystal Films with Bulk-Like Thermoelectric Performance

    DOE PAGES

    Forster, Jason D.; Lynch, Jared J.; Coates, Nelson E.; ...

    2017-06-05

    Thermoelectric power generation can play a key role in a sustainable energy future by converting waste heat from power plants and other industrial processes into usable electrical power. Current thermoelectric devices, however, require energy intensive manufacturing processes such as alloying and spark plasma sintering. Here, we describe the fabrication of a p-type thermoelectric material, copper selenide (Cu 2 Se), utilizing solution-processing and thermal annealing to produce a thin film that achieves a figure of merit, ZT, which is as high as its traditionally processed counterpart, a value of 0.14 at room temperature. This is the first report of a fullymore » solution-processed nanomaterial achieving performance equivalent to its bulk form and represents a general strategy to reduce the energy required to manufacture advanced energy conversion and harvesting materials.« less

  20. Hydrogen in tin dioxide films and bulk ceramics: An attempt to identify the most hidden impurity

    SciTech Connect

    Watanabe, Ken; Hashiguchi, Minako; Sakaguchi, Isao; Bryant, Alex Adachi, Yutaka; Zhen, Yuhua Ohgaki, Takeshi; Ohsawa, Takeo; Haneda, Hajime; Ohashi, Naoki

    2014-01-27

    Hydrogen impurities in SnO{sub 2} films and bulk ceramics were investigated in terms of mass transport and electron transport. The hydrogen concentration (n[H]) in these samples was found to be 10{sup 19} cm{sup −3} or higher. Further increase in n[H] could be achieved by annealing the samples in a humid atmosphere. The isotope tracer ({sup 1}H/{sup 2}H exchange) study revealed that a part of the hydrogen in these samples showed rapid migration even at 300 °C. However, electrical measurements revealed that the electron concentration in the samples was much less than n[H]. These results could be explained by assuming the presence of defect-hydrogen complexes.

  1. Wavelength-Versatile Graphene-Gold Film Saturable Absorber Mirror for Ultra-Broadband Mode-Locking of Bulk Lasers

    PubMed Central

    Ma, Jie; Xie, Guoqiang; Lv, Peng; Gao, Wenlan; Yuan, Peng; Qian, Liejia; Griebner, Uwe; Petrov, Valentin; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang

    2014-01-01

    An ultra-broadband graphene-gold film saturable absorber mirror (GG-SAM) with a spectral coverage exceeding 1300 nm is experimentally demonstrated for mode-locking of bulk solid-state lasers. Owing to the p-type doping effect caused by graphene-gold film interaction, the graphene on gold-film substrate shows a remarkably lower light absorption relative to pristine graphene, which is very helpful to achieve continuous-wave mode-locking in low-gain bulk lasers. Using the GG-SAM sample, stable mode-locking is realized in a Yb:YCOB bulk laser near 1 μm, a Tm:CLNGG bulk laser near 2 μm and a Cr:ZnSe bulk laser near 2.4 μm. The saturable absorption is characterised at an intermediate wavelength of 1.56 μm by pump-probe measurements. The as-fabricated GG-SAM with ultra-broad bandwidth, ultrafast recovery time, low absorption, and low cost has great potential as a universal saturable absorber mirror for mode-locking of various bulk lasers with unprecedented spectral coverage. PMID:24853072

  2. 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.

  3. 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

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

    PubMed

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

    2016-02-16

    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.

  5. 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

  6. Magnetic domain walls in bulk and thin film Fe: first principles noncollinear magnetism study

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Takeda, Y.; Akiyama, T.; Ito, T.; Freeman, A. J.

    2004-03-01

    We investigate the electronic and magnetic structures of domain walls in ferromagnetic Fe bulk and Fe(110) monolayer by using the first-principles FLAPW method(Wimmer, Krakauer, Weinert and Freeman, PRB 24, 864(1981)) including noncollinear magnetism with no shape approximation of the magnetization density.(Nakamura, Freeman, Wang, Zhong, and Fernandez-de-Castro, PRB 65, 12402 (2002); 67, 14420 (2003)) In the bulk case, the self-consistent LSDA results demonstrate that the magnetic moments change continuously from one orientation to another as seen in a Bloch wall, and reveal that the formation energy of the domain wall significantly decreases when the domain wall thickness increases, as expected from phenomenological theory. The domain walls in thin film behave very differently: Surprisingly, the magnetic moment directions change rapidly; thus the wall width is only about 8 ÅThis consists and supports the atomically sharp domain wall in Fe/W(110) by the recently proposed SP-STM measurements.(Pratzer, Elmers, Bode, Pietzsch, Kubetzka and Wiesendanger, PRL 87, 127201 (2001))

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. A laser probe based on a Sagnac interferometer with fast mechanical scan for RF surface and bulk acoustic wave devices.

    PubMed

    Hashimoto, Ken-ya; Kashiwa, Keiskue; Wu, Nan; Omori, Tatsuya; Yamaguchi, Masatsune; Takano, Osamu; Meguro, Sakae; Akahane, Koichi

    2011-01-01

    This paper describes the development of a phasesensitive laser probe with fast mechanical scan for RF surface and bulk acoustic wave (SAW/BAW) devices. The Sagnac interferometer composed of micro-optic elements was introduced for the selective detection of RF vertical motion associated with RF SAW/BAW propagation and vibration. A high-pass characteristic of the interferometer makes the measurement very insensitive to low-frequency vibration. This feature allows us to apply the fast mechanical scan to the interferometric measurement without badly sacrificing its SNR and spatial resolution. The system was applied to the visualization of a field pattern on the vibrating surface of an RF BAW resonator operating in the 2 GHz range. The field pattern was obtained in 17 min as a 2-D image (500 × 750 pixel with 0.4 μm resolution and SNR of 40 dB). The system was also applied to the characterization of an RF SAW resonator operating in the 1 GHz range, and the applicability of the system was demonstrated.

  13. Frequency flicker of 2.3 GHz AlN-sapphire high-overtone bulk acoustic resonators

    NASA Astrophysics Data System (ADS)

    Boudot, Rodolphe; Martin, Gilles; Friedt, Jean-Michel; Rubiola, Enrico

    2016-12-01

    We report the detailed characterization of 2.3 GHz AlN-Sapphire high-overtone bulk acoustic resonators (HBARs), with a typical loaded Q-factor of 25-30 × 103, 15-20 dB insertion loss, and resonances separated by about 10 MHz. The temperature coefficient of frequency of HBARs is measured to be about -25 ppm/K. We observe at high-input microwave power a significant distortion of the HBAR resonance lineshape, attributed to non-linear effects. The power-induced fractional frequency variation of the HBAR resonance is measured to be about -5 × 10-10/μW. The residual phase noise of a HBAR is measured in the range of -110 to -130 dBrad2/Hz at 1 Hz Fourier frequency, yielding resonator fractional frequency fluctuations at the level of -205 to -225 dB/Hz at 1 Hz and an ultimate HBAR-limited oscillator Allan deviation about 7 × 10-12 at 1 s integration time. The 1/f noise of the HBAR resonator is found to increase with the input microwave power. A HBAR resonator is used for the development of a low phase noise 2.3 GHz oscillator. An absolute phase noise of -60, -120, and -145 dBrad2/Hz for offset frequencies of 10 Hz, 1 kHz, and 10 kHz, respectively, in excellent agreement with the Leeson effect, is measured.

  14. 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

  15. 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

    2014-03-07

    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.

  16. Feasibility study of detection of dielectric breakdown of gate oxide film by using acoustic emission method

    NASA Astrophysics Data System (ADS)

    Kasashima, Yuji; Tabaru, Tatsuo; Uesugi, Fumihiko

    2016-12-01

    An in situ detection method for the dielectric breakdown of oxide films for MOS gates has been required in the plasma etching process. In this feasibility study, a conventional MOSFET device is used and an acoustic emission (AE) method is employed for the detection of the dielectric breakdown of a gate oxide film. A thin type AE sensor is attached at the backside of an electrostatic chuck (ESC), and the dielectric breakdown in a MOSFET, which is set on the ESC, is detected. The results demonstrate that the thin type AE sensor can detect the dielectric breakdown with an energy on the order of µJ.

  17. Accurate characterization of SiO2 thin films using surface acoustic waves.

    PubMed

    Knapp, Matthias; Lomonosov, Alexey M; Warkentin, Paul; Jäger, Philipp M; Ruile, Werner; Kirschner, Hans-Peter; Honal, Matthias; Bleyl, Ingo; Mayer, Andreas P; Reindl, Leonhard M

    2015-04-01

    We have investigated the acoustic properties of silicon dioxide thin films. Therefore, we determined the phase velocity dispersion of LiNbO3 substrate covered with SiO2 deposited by a plasma enhanced chemical vapor deposition and a physical vapor deposition (PVD) process using differential delay lines and laser ultrasonic method. The density p and the elastic constants (c11 and c44) can be extracted by fitting corresponding finite element simulations to the phase velocities within an accuracy of at least +4%. Additionally, we propose two methods to improve the accuracy of the phase velocity determination by dealing with film thickness variation of the PVD process.

  18. Phonons of single quintuple Bi2Te3 and Bi2Se3 films and bulk materials

    NASA Astrophysics Data System (ADS)

    Cheng, Wei; Ren, Shang-Fen

    2011-03-01

    Phonons of single quintuple films of Bi2Te3 and Bi2Se3 and corresponding bulk materials are calculated in detail by MedeA (a trademark of Materials Design) and Vienna ab initio simulation package (VASP). The calculated results with and without spin-orbit couplings are compared, and the important roles that the spin-orbit coupling plays in these materials are discussed. A symmetry breaking caused by the anharmonic potentials around Bi atoms in the single quintuple films is identified and discussed. The observed Raman intensity features in Bi2Te3 and Bi2Se3 quintuple films are explained.

  19. 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

  20. Finite element model of surface acoustic wave method for mechanical characterization of patterned thin films of the ultra-large scaled integrated interconnect.

    PubMed

    Xiao, Xia; Shan, Xingmeng; Tao, Ye; Sun, Yuan; Kikkawa, Takamaro

    2013-02-01

    Surface acoustic waves (SAWs) technique is a promising method to determine the mechanical properties of thin low dielectric constant (low-k) dielectrics by matching the experimental dispersion curve with the theoretical dispersion curves. However, it is difficult to calculate the dispersion curves when SAWs propagate along patterned structure. In this paper, finite element method (FEM) is applied to obtain the numerical dispersion results of SAWs propagating on patterned film. Periodic boundary condition and plane-strain model is used to improve the computation speed. Four structures of bulk silicon, single layered low-k film, two layered Cu and SiO2 film, and patterned film, are simulated in this paper. The dispersion curves of single low-k films derived from the FEM simulation agree very well with those calculated by traditional method, which verifies the correct employment of the FEM approach. Dispersion curves of two patterned film structure of Cu and SiO2 with difference metal wire width are obtained. Effective Young's moduli are achieved by fitting the FEM simulated results with those of traditional theoretical calculation through least square error method.

  1. 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.

  2. Double-mode lateral-field-excitation bulk acoustic wave characteristics of Ca3TaGa3Si2O14 crystals.

    PubMed

    Ma, Tingfeng; Zhang, Qiong; Yu, Fapeng; Xie, Chao; Wang, Ji; Du, Jianke; Huang, Bin; Huang, Jiahan; Zhang, Chao

    2017-08-01

    The double-mode lateral-field-excitation (LFE) bulk acoustic wave characteristics of Ca3TaGa3Si2O14 (CTGS) crystals are investigated. It is found that LFE devices based on (yxl)-57° CTGS crystals can work on both pure-LFE and pseudo-LFE modes when the driving electric field direction is normal to the crystallographic x axis of the piezoelectric substrate. Several double-mode LFE bulk acoustic wave devices based on CTGS crystals are designed and tested. The experimental results conform to the theoretical prediction well. Being able to operate in pure-LFE and pseudo-LFE modes, the double-mode LFE sensors show high sensitivity to both mechanical and electrical property changes of analytes. The results provide the crystal cut for double-mode LFE sensors, which is a critical basis of designing high-performance chemical and biological sensors by using double-mode LFE devices.

  3. Transitions between paraelectric and ferroelectric phases of bent-core smectic liquid crystals in the bulk and in thin freely suspended films

    NASA Astrophysics Data System (ADS)

    Eremin, Alexey; Floegel, Martin; Kornek, Ulrike; Stern, Stephan; Stannarius, Ralf; Nádasi, Hajnalka; Weissflog, Wolfgang; Zhu, Chenhui; Shen, Yongqiang; Park, Cheol Soo; Maclennan, Joseph; Clark, Noel

    2012-11-01

    We report on the contrasting phase behavior of a bent-core liquid crystal with a large opening angle between the mesogenic units in the bulk and in freely suspended films. Second-harmonic generation experiments and direct observation of director inversion walls in films in an applied electric field reveal that the nonpolar smectic C phase observed in bulk samples becomes a ferroelectric “banana” phase in films, showing that a mesogen with a small steric moment can give a phase with polar order in freely suspended films even when the corresponding bulk phase is paraelectric.

  4. 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

  5. Mossbauer studies of bulk and thin-film FeTe

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

    In study, dependence of Mossbauer parameters on film thickness and film substrate was measured and related to iron tellurium structure. Report also describes film deposition technique (flash deposition) and Mossbauer apparatus.

  6. Effect of viscoelastic film for shear horizontal surface acoustic wave on quartz

    NASA Astrophysics Data System (ADS)

    Goto, Mikihiro; Yatsuda, Hiromi; Kondoh, Jun

    2015-07-01

    A numerical analysis for the mass loading sensitivity of shear horizontal surface acoustic wave (SH-SAW) immunoassay biosensors on quartz has already been studied. However, the mass loading analysis is insufficient to explain the actual biosensor performance. To understand the SH-SAW biosensor performance, we analyze the effect of a viscoelastic film on SH-SAW biosensors. In this paper, a numerical analysis using a simple viscoelastic model for the SH-SAW biosensors is presented. In the theoretical model, the bioreaction layer on the SH-SAW biosensors can be treated as a viscoelastic film. The velocity changes of the 250 MHz SH-SAWs on quartz substrates, which are covered with bovine serum albumin (BSA) layers of different thicknesses, were measured and compared with the theoretical results obtained using the proposed viscoelastic model. Good agreement of the velocity changes of SH-SAWs versus changes in the viscoelastic film thickness between theoretical and experimental results was obtained.

  7. Impact of lattice dynamics on the phase stability of metamagnetic FeRh: Bulk and thin films

    NASA Astrophysics Data System (ADS)

    Wolloch, M.; Gruner, M. E.; Keune, W.; Mohn, P.; Redinger, J.; Hofer, F.; Suess, D.; Podloucky, R.; Landers, J.; Salamon, S.; Scheibel, F.; Spoddig, D.; Witte, R.; Roldan Cuenya, B.; Gutfleisch, O.; Hu, M. Y.; Zhao, J.; Toellner, T.; Alp, E. E.; Siewert, M.; Entel, P.; Pentcheva, R.; Wende, H.

    2016-11-01

    We present phonon dispersions, element-resolved vibrational density of states (VDOS) and corresponding thermodynamic properties obtained by a combination of density functional theory (DFT) and nuclear resonant inelastic x-ray scattering (NRIXS) across the metamagnetic transition of B2 FeRh in the bulk material and thin epitaxial films. We see distinct differences in the VDOS of the antiferromagnetic (AF) and ferromagnetic (FM) phases, which provide a microscopic proof of strong spin-phonon coupling in FeRh. The FM VDOS exhibits a particular sensitivity to the slight tetragonal distortions present in epitaxial films, which is not encountered in the AF phase. This results in a notable change in lattice entropy, which is important for the comparison between thin film and bulk results. Our calculations confirm the recently reported lattice instability in the AF phase. The imaginary frequencies at the X point depend critically on the Fe magnetic moment and atomic volume. Analyzing these nonvibrational modes leads to the discovery of a stable monoclinic ground-state structure, which is robustly predicted from DFT but not verified in our thin film experiments. Specific heat, entropy, and free energy calculated within the quasiharmonic approximation suggest that the new phase is possibly suppressed because of its relatively smaller lattice entropy. In the bulk phase, lattice vibrations contribute with the same sign and in similar magnitude to the isostructural AF-FM phase transition as excitations of the electronic and magnetic subsystems demonstrating that lattice degrees of freedom need to be included in thermodynamic modeling.

  8. 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.

  9. Acoustic study of a linear low-density polyethylene film after modification of the crystalline structure by heating.

    PubMed

    Tohmyoh, Hironori; Sakamoto, Yuhei

    2014-02-01

    We report on a hybrid microscopy technique that enables us to measure the acoustic properties of a thin polymer film together with an optical microscope image of the corresponding area. Linear low-density polyethylene films are heated to various temperatures and examined by the technique. Density of the film is increased by heating and its sound velocity is decreased compared with a film without heating. Also, spherulites can clearly be seen in the optical microscope image, supporting the thermal shrinkage of the film which can be detected by the present technique.

  10. Evaluating local elasticity of the metal nano-films quantitatively based on referencing approach of atomic force acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Gaimei; He, Cunfu; Wu, Bin; Chen, Qiang

    2012-11-01

    Traditional technique such nanoindenter(NI) can't measure the local elastic modulus at nano-scale(lateral). Atomic force acoustic microscopy (AFAM) is a dynamic method, which can quantitatively determine indentation modulus by measuring the contact resonance spectra for high order modes of the cantilever. But there are few reports on the effect of experimental factors, such length of cantilever, contact stiffness on measured value. For three different samples, including copper(Cu) film with 110 nm thickness, zinc(Zn) film of 90 nm thickness and glass slides, are prepared and tested, using referencing approach in which measurements are performed on the test and reference samples (it's elastic modulus is known), and their contact resonance spectra are measured used the AFAM system experimentally. According to the vibration theory, from the lowest two contact resonance frequencies, the tip-sample contact stiffness is calculated, and then the values for the elastic properties of test sample, such as the indentation modulus, are determined. Using AFAM system, the measured indentation modulus of copper nano-film, zinc nano-film and glass slides are 113.53 GPa, 87.92 GPa and 57.04 GPa, which are agreement with literature values M Cu = 105-130 GPa, M Zn = 88.44 GPa and M Glass = 50-90 GPa. Furthermore, the sensitivity of contact resonance frequency to contact stiffness is analyzed theoretically. The results show that for the cantilevers with the length 160 μm, 225 μm and 520 μm respectively, when contact stiffness increases from 400 N/m to 600 N/m, the increments of first contact resonance frequency are 126 kHz, 93 kHz and 0.6 kHz, which show that the sensitivity of the contact resonance frequency to the contact stiffness reduces with the length of cantilever increasing. The novel method presented can characterize elastic modulus of near surface for nano-film and bulk material, and local elasticity of near surface can be evaluated by optimizing the experimental

  11. 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.

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

    DOE PAGES

    Liu, Mengkun; Sternbach, Aaron J.; Wagner, Martin; ...

    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

  13. The investigation of the defect structures for Co2+ in ZnO microwires, thin films and bulks

    NASA Astrophysics Data System (ADS)

    Ding, Chang-Chun; Wu, Shao-Yi; Wu, Li-Na; Xu, Yong-Qiang; Zhang, Li-Juan

    2017-07-01

    The defect structures for Co2+ in ZnO microwires, thin films and bulks are theoretically investigated by analyzing the electron paramagnetic resonance (EPR) parameters (zero-field splitting D, g factors g// and g⊥ and hyperfine structure constants A// and A⊥) for trigonally distorted tetrahedral 3d7 clusters in a consistent way. The impurities Co2+ are found to suffer the displacements (≈0.046, 0.044 and 0.045 Å) away from the ligand triangles along the C3 axis in ZnO microwires, thin films and bulks, respectively, which considerably reduce the trigonal distortions of the Zn2+ sites in the hosts. Apart from the contributions from the conventional crystal-field (CF) mechanism, those from the charge-transfer (CT) mechanism are important and should be included in the EPR analysis. The defect structures and spectral properties of the three ZnO:Co2+ systems are discussed.

  14. Electroabsorption modulators based on bulk GaN films and GaN/AlGaN multiple quantum wells

    NASA Astrophysics Data System (ADS)

    Kao, Chen-Kai; Bhattacharyya, Anirban; Thomidis, Christos; Paiella, Roberto; Moustakas, Theodore D.

    2011-04-01

    Ultraviolet electroabsorption modulators based on bulk GaN films and on GaN/AlGaN multiple quantum wells were developed and characterized. In both types of devices, the absorption edge at room temperature is dominated by excitonic effects and can be strongly modified through the application of an external electric field. In the bulk devices, the applied voltage causes a broadening and quenching of the excitonic absorption, leading to enhanced transmission. In the quantum-well devices, the external field partially cancels the built-in polarization-induced electric fields in the well layers, thereby increasing the absorption. Unlike optical modulators based on smaller-bandgap zinc blende semiconductors, the bulk devices here are shown to provide similar performance levels as the quantum well devices, which is mainly a consequence of the uniquely large exciton binding energies of nitride semiconductors.

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

    NASA Astrophysics Data System (ADS)

    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

    2014-07-01

    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.

  16. 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

  17. 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.

  18. A thin film electro-acoustic enzyme biosensor allowing the detection of trace organophosphorus pesticides.

    PubMed

    Chen, Da; Wang, Jingjing; Xu, Yan; Zhang, Luyin

    2012-10-01

    We report an analytical method using a thin film electro-acoustic resonator for the detection of organophosphorus pesticides. The acetylcholinesterase (AChE) enzyme was immobilized on the surface of the resonator. In the presence of organophosphorus compounds, the degree of inhibitory effect of organophosphorus compounds on the AChE activity and the concentration of pesticides were detected in real time by measuring the frequency shift of the resonator. The proposed device has a remarkably low detection limit of 1.8×10(-11)M and obvious advantages such as small size, simple operation, and integrated circuit compatibility, providing a promising tool for pesticide analysis.

  19. Determining the bubble cap film thickness of bursting bubbles from their acoustic emissions.

    PubMed

    Deane, Grant B

    2013-02-01

    A study of the sound generated by 2.5 mm radius bubbles bursting on the surface of fresh water is presented. The sound pulses are found to be sensitive to the time interval between the bubble reaching the water surface and bursting. Bubbles that burst within a few 10's of milliseconds behave like a Helmholtz resonator and radiate a swept chirp pulse. Bubbles that persist for 100's of milliseconds or more exhibit more complex acoustic behavior. An analysis of the resonator behavior provides an estimate of the film thickness in reasonable agreement with a fluid drainage model.

  20. High-frequency surface acoustic wave device based on thin-film piezoelectric interdigital transducers

    SciTech Connect

    Sarin Kumar, A.K.; Paruch, P.; Triscone, J.-M.; Daniau, W.; Ballandras, S.; Pellegrino, L.; Marre, D.; Tybell, T.

    2004-09-06

    Using high-quality epitaxial c-axis Pb(Zr{sub 0.2}Ti{sub 0.8})O{sub 3} films grown by off-axis magnetron sputtering onto metallic (001) Nb-doped SrTiO{sub 3} substrates, a nonconventional thin-film surface acoustic wave device based on periodic piezoelectric transducers was realized. The piezoelectric transducers consist of a series of ferroelectric domains with alternating polarization states. The artificial modification of the ferroelectric domain structure is performed by using an atomic force microscope tip as a source of electric field, allowing local switching of the polarization. Devices with 1.2 and 0.8 {mu}m wavelength, defined by the modulation period of the polarization, and corresponding to central frequencies in the range 1.50-3.50 GHz have been realized and tested.

  1. Evolution of multilayer Ar films on graphite below and above the bulk triple point: a neutron diffraction study

    NASA Astrophysics Data System (ADS)

    Gay, J. M.; Suzanne, J.; Dash, J. G.; Lauter, H. J.

    1991-09-01

    Neutron diffraction is used to study the growth behavior of thin films of argon adsorbed on graphite foam in the temperature range 55.5 K-90.5 K. It is shown that a uniform film is condensed at 65.5 K for thicknesses below 4.5 layers. For higher coverages, bulk crystallites start to grow into capillaries whereas the uniform film grows much more slowly to reach a thickness of 6.4 layers for a total coverage of about 20 statistical layers. A model is presented showing that the capillary condensation probably occurs in conical pores and open corners. At 80.5 K, a liquid-like phase, 1.5 layer thick, is observed revealing the occurrence of surface melting. Above the bulk melting point (T_m=83.8 K), all the bulk crystallites have melted but a solid film is still present on the graphite surface. Its thickness varies from 1 to 3-4 layers depending on total coverage and temperature. The melting temperatures of these solid films are reported. Finally, the uniform solid film is laterally compressed with respect to bulk (111) planes with a continuous relaxation when its thickness increases. On étudie par diffraction de neutrons le mode de croissance de films minces d'argon adsorbé sur de la mousse de graphite (foam) dans la gamme de températures 55,5 K-90,5 K. Un film uniforme est formé à 65,5 K lorsque l'épaisseur est inférieure à 4,5 couches. Pour des recouvrements plus grands, des cristallites commencent à se condenser tandis que le film uniforme continue à croître beaucoup plus lentement jusqu'à une épaisseur de 6,4 couches pour un taux de couverture total d'environ 20 couches statistiques. On présente un modèle qui montre que la condensation capillaire se produit dans des pores coniques et des coins. A 80,5 K, on observe une phase de type liquide de 1,5 couche qui est la signature de la fusion de surface. Au-dessus du point de fusion tridimensionnel (T_m=83,8 K), tous les cristallites ont fondu mais un film solide est toujours présent sur la surface de

  2. 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.

  3. Integration of bulk-quality thin film magneto-optical cerium-doped yttrium iron garnet on silicon nitride photonic substrates.

    PubMed

    Onbasli, Mehmet C; Goto, Taichi; Sun, Xueyin; Huynh, Nathalie; Ross, C A

    2014-10-20

    Cerium substituted yttrium iron garnet (Ce:YIG) films were grown on yttrium iron garnet (YIG) seed layers on silicon nitride films using pulsed laser deposition. Optimal process conditions for forming garnet films on silicon nitride are presented. Bulk or near-bulk magnetic and magneto-optical properties were observed for 160 nm thick Ce:YIG films grown at 640 °C on rapid thermal annealed 40 nm thick YIG grown at 640 °C and 2 Hz pulse rate. The effect of growth temperature and deposition rate on structural, magnetic and magneto-optical properties has been investigated.

  4. Effect of ethanol variation on the internal environment of sol-gel bulk and thin films with aging.

    PubMed

    Gupta, R; Mozumdar, S; Chaudhury, N K

    2005-10-15

    Sol-gel derived bulk and thin films were prepared from different compositions at low pH ( approximately 2.0) containing varying concentrations of ethanol from 15 to 60% at constant water (H(2)O)/tetraethyl-orthosilicate (TEOS) ratio (R=4). The fluorescence microscopic and spectroscopic measurements on fluorescent probe, Hoechst 33258 (H258) entrapped in these compositions were carried out at different days of storage to monitor the effects of concentration of ethanol on the internal environment of sol-gel materials. Fluorescence microscopic observations on sol-gel thin films, prepared by dip coating technique depicted uniform and cracked surface at withdrawal speed 1cm/min (high speed) and 0.1cm/min (low speed) respectively, which did not change during aging. Fluorescence spectral measurements showed emission maximum of H258 at approximately 535 nm in fresh sols at all concentrations of ethanol which depicted slight blue shift to 512 nm during aging in bulk. No such spectral shift has been observed in sol-gel thin films coated at high speed whereas thin films coated at low speed clearly showed an additional band at approximately 404 nm at 45 and 60% concentration of ethanol after about one month of storage. Analysis of the fluorescence lifetime data indicated single exponential decay (1.6-1.8 ns) in fresh sol and from third day onwards, invariably double exponential decay with a short (tau(1)) and a long (tau(2)) component were observed in sol-gel bulk with a dominant tau(1) at approximately 1.2 ns at all concentrations of ethanol. A double exponential decay consisting of a short component (tau(1)) at approximately 0.2 ns and a long component (tau(2)) at approximately 3.5 ns were observed at all ethanol concentrations in both fresh and aged sol-gel thin films. Further, distribution analysis of lifetimes of H258 showed two mean lifetimes with increased width in aged bulk and thin films. These results are likely to have strong implications in designing the internal

  5. Surface acoustic wave ammonia sensor based on ZnO/SiO2 composite film.

    PubMed

    Wang, Shuang-Yue; Ma, Jin-Yi; Li, Zhi-Jie; Su, H Q; Alkurd, N R; Zhou, Wei-Lie; Wang, Lu; Du, Bo; Tang, Yong-Liang; Ao, Dong-Yi; Zhang, Shou-Chao; Yu, Q K; Zu, Xiao-Tao

    2015-03-21

    A surface acoustic wave (SAW) resonator with ZnO/SiO2 (ZS) composite film was used as an ammonia sensor in this study. ZS composite films were deposited on the surface of SAW devices using the sol-gel method, and were characterized using SEM, AFM, and XRD. The performance of the sensors under ammonia gas was optimized by adjusting the molar ratio of ZnO:SiO2 to 1:1, 1:2 and 1:3, and the sensor with the ratio of ZnO to SiO2 equaling to 1:2 was found to have the best performance. The response of sensor was 1.132 kHz under 10 ppm NH3, which was much higher than that of the sensor based on a pristine ZnO film. Moreover, the sensor has good selectivity, reversibility and stability at room temperature. These can be attributed to the enhanced absorption of ammonia and unique surface reaction on composite films due to the existence of silica.

  6. Properties of II-VI Semiconductors: Bulk Crystals, Epitaxial Films, Quantum Well Structures, and Dilute Magnetic Systems. Materials Research Society Symposium Proceedings. Volume 161

    DTIC Science & Technology

    1990-11-21

    quantum well (MQW) structures, which can confine electrons and holes in a two-dimensional well , fabricated by MBE [2] and MOCVD [3]. Despite the...N Pie MA’ FERIA -LS - RESEAR(--’H -)CIFFY VOLUME 161 Properties of 11-VI Semiconductors: Bulk Crystals, Epitaxial Films, Quantum Well Structures...Semiconductors: Bulk Crystals, Epitaxial Films, Quantum Well Structures, and Dilute Magnet;-- Systems :1ity CodeS JLECTE0 Nov 15 1990 SDISTRI:7UTICN SAT EM~

  7. FAST TRACK COMMUNICATION: Nano-structured TiO2 film fabricated at room temperature and its acoustic properties

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

    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.

  8. Measurement of surface acoustic wave velocity using a variable-line-focus polyurea thin-film ultrasonic transducer.

    PubMed

    Aoyagi, Takahiro; Nakazawa, Marie; Tabaru, Masaya; Nakamura, Kentaro; Ueha, Sadayuki

    2009-08-01

    This paper presents the novel measurement method of the surface acoustic wave velocity by the variable-line- focus transducer using a polyurea piezoelectric ultrasonic transducer. First, a multiresonant polyurea thin-film ultrasonic transducer is fabricated by the vapor deposition polymerization process using 2 monomers. Second, the measurement system of surface acoustic wave velocity modified from the V(z) curve method is established. The system uses the fabricated polyurea thin film as a variable-line-focus transducer at the 30-MHz resonance frequency. The focal length is changed by varying the radius of curvature of the film transducer. To estimate the surface acoustic wave velocities from the measured data theoretically, the photographs of the transducer bent shapes are taken by using a digital microscope, and the bent transducer curvature is modeled by the 7th-order polynomial. To examine the performances of the variable-line-focus transducer, the surface acoustic wave velocities of an aluminum and a synthesized silica glass specimen have been measured. The measured surface acoustic velocities showed good agreement with the reference values.

  9. Comparison between experiment and theory in the temperature variation of film tension above the bulk isotropic transition in free-standing liquid-crystal films.

    PubMed

    Veum, M; Duelge, L; Droske, J; Nguyen, H T; Huang, C C; Mirantsev, L V

    2009-09-01

    Using differential scanning calorimetry, the transition enthalpies and temperatures for the bulk smectic-isotropic phase transition have been measured for a series of liquid-crystal compounds. For five compounds, those values were used as parameters in a microscopic mean-field model to predict the temperature dependence of the difference in free-energy density between a sample of material in a free-standing smectic film and that in the bulk. The model predicts a weak temperature dependence below the bulk clearing point and a pronounced monotonic increase with temperature above the transition temperature. The compounds used in this study were chosen specifically because they were also the subject of a previous independent experimental study [M. Veum, Phys. Rev. E 74, 011703 (2006)] that demonstrated a sudden monotonic increase in the free-standing film tension with temperature, which is qualitatively consistent with the predictions of the above-mentioned mean-field model. This study presents a direct and quantitative comparison between the predictions of the mean-field model and the results from previous tension experiments.

  10. Preparation of a high-quality PZT thick film with performance comparable to those of bulk materials for applications in MEMS

    NASA Astrophysics Data System (ADS)

    Xu, Xiao-Hui; Chu, Jia-Ru

    2008-06-01

    High-quality lead zirconate titanate (PZT) thick films have been prepared on silicon substrates by combining PZT-Si bonding and wet-etching technology. The bulk PZT wafer was first bonded to the silicon substrate using a 2 µm thick intermediate layer of epoxy resin with a bonding strength higher than 10 MPa. Then the bulk PZT was thinned by a wet-etching method. The thickness of the final PZT films depends on the etching time. The PZT thick films after being polished showed a surface roughness of about 20 nm (RMS), which can satisfy most of the requirements in MEMS. The prepared PZT thick films show a dielectric constant as high as 2400 below 100 kHz, remnant polarization of 13 µC cm-2, piezoelectric constant d31 of about -280 pm V-1 and Young's modulus of about 63 GPa. The measured electromechanical properties of the PZT thick films were comparable to those of the corresponding bulk ceramics. This approach makes it possible to obtain high-quality PZT films because it separates the PZT wafer fabrication from the target substrate and consequently allows integration of the PZT thick films onto many kinds of substrates. Finally, a self-sensing bulk PZT thick film actuator was fabricated as an example of a basic PZT-Si diaphragm structure that can be used in piezoelectric micropumps, and its sensing and actuating performances were also demonstrated.

  11. 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.

  12. 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.

  13. Near-field measurement of ZnS:Mn nanocrystal and bulk thin-film electroluminescent devices.

    PubMed

    Grmela, L; Macku, R; Tomanek, P

    2008-02-01

    A near-field study of the electro-optical phenomena and aging characteristics of nanostructured and bulk ZnS:Mn alternating-current thin-film electro-optical devices is presented. ZnS:Mn nanocrystals embedded in the glass matrices as well as ZnS:Mn thin-film phosphors contain four different concentrations of Mn (from 0.05 to 1.0 mol%). The activator impurity in the phosphor influences the spectral properties and, to a large extent, the temporal properties of optical emission and an aging process of the devices. Therefore, a local photoluminescence and electroluminescence investigation using a scanning near-field optical microscope technique is provided and the aging characteristics of ZnS:Mn nanocrystal structure also presented.

  14. Investigation of the full spectrum phonon lifetime in thin silicon films from the bulk spectral phonon mean-free-path distribution by using kinetic theory

    NASA Astrophysics Data System (ADS)

    Jin, Jae Sik

    2017-03-01

    Phonon dynamics in nanostructures is critically important to thermoelectric and optoelectronic devices because it determines the transport and other crucial properties. However, accurately evaluating the phonon lifetimes is extremely difficult. This study reports on the development of a new semi-empirical method to estimate the full-spectrum phonon lifetimes in thin silicon films at room temperature based on the experimental data on the phonon mean-free-path spectrum in bulk silicon and a phenomenological consideration of phonon transport in thin films. The bulk of this work describes the theory and the validation; then, we discuss the trend of the phonon lifetimes in thin silicon films when their thicknesses decrease.

  15. Two-band superconductivity of bulk and surface states in Ag thin films on Nb

    NASA Astrophysics Data System (ADS)

    Tomanic, Tihomir; Schackert, Michael; Wulfhekel, Wulf; Sürgers, Christoph; Löhneysen, Hilbert v.

    2016-12-01

    We use epitaxial strain to spatially tune the bottom of the surface-state band ESS of Ag(111) islands on Nb(110). Bulk and surface-state contributions to the Ag(111) local density of states (LDOS) can be separated with scanning tunneling spectroscopy. For thick islands (≈20 nm), the Ag surface states are decoupled from the Ag bulk states and the superconductive gap induced by proximity to Nb is due to bulk states only. However, for thin islands (3-4 nm), surface-state electrons develop superconducting correlations as identified by a complete energy gap in the LDOS when ESS is smaller than but close to the Fermi level. The induced superconductivity in this case is of a two-band nature and appears to occur when the surface-state wave function reaches down to the Ag/Nb interface.

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

    SciTech Connect

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

    2016-03-15

    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 (d{sub 33} = 270 pC/N and k{sub t} = 0.51) was employed for SBAT applications and a press-focusing technology was introduced. The obtained SBAT, acting at an operational frequency of 50 MHz, 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.

  17. 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

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

    PubMed

    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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Development of Highly Sensitive Bulk Acoustic Wave Device Biosensor Arrays for Screening and Early Detection of Prostate Cancer

    DTIC Science & Technology

    2009-01-01

    Chemie International Edition , vol. 39, pp. 29, 2000. [48] W. E. Newell, "Face-mounted piezoelectric resonators," Proceedings of the IEEE, vol. 53... International Edition , vol. 44, pp. 5456 - 5459, 2005. [132] S. Balamurugan, A. Obubuafo, S. A. Soper, and D. A. Spivak, "Surface immobilization methods...14. ABSTRACT In this research, I present several novel contributions to the field of microelectronic acoustic biosensors that approach the goal

  4. Electrochemical properties of the passive film on bulk Zr-Fe-Cr intermetallic fabricated by spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Bai, Yakui; Ling, Yunhan; Lai, Wensheng; Xing, Shupei; Ma, Wen

    2016-12-01

    Although Zr-based second phase particles (SPPs) are important factors influencing corrosion resistance of zircaloy cladding materials, the corrosion behavior of SPPs has not been investigated by means of electrochemical method so far. In order to clarify the role of SPPs commonly existed in zircaloy, bulk Zr-based intermetallics were firstly fabricated by spark plasma sintering (SPS) at temperatures 1373 K and an applied pressure of 60 MPa in this work. Both the natural passive film on surface and oxidation behavior of intermetallic has been investigated in this work. X-ray diffraction (XRD) pattern showed that as-prepared intermetallic of crystal structure belongs to Laves phase with AB2 type. Electrochemical measurement of passive film on surface of bulk Zr-based intermetallic exhibited significant difference with that of zirconium. Potentiodynamic measurements results revealed that intermetallic exhibited higher corrosion potential and lower corrosion current density than that of pure zirconium, implying that Zr-based second phase will act as cathode when they are included in zirconium matrix. Meanwhile, significant improvement of Zr-Fe-Cr intermetallic on the water chemistry corrosion resistance was demonstrated comparing with Zr-Fe and Zr-Cr binary intermetallics.

  5. Characterization of a 61-element bulk-PZT thick film deformable mirror and generation of Zernike polynomials

    NASA Astrophysics Data System (ADS)

    Ma, Jianqiang; Li, Baoqing; Chu, Jiaru

    2010-10-01

    This paper describes the characteristics of a 61 element piezoelectric deformable mirror (DM) based on bulk-PZT thick film and the generation of Zernike polynomials. This device consists of a continue silicon mirror supported by 61 element piezoelectric unimorph actuators which are arranged in a hexagonal grid with spacing of 5mm. Measurements of the displacement using a laser Doppler vibrometer demonstrated that the stroke of DM was 3.8μm at 100 volt with a displacement hysteresis of approximately 9% and the operating bandwidth was greater than 10KHz. A custom phasing-shifting interferometer based on Twyman-Green interferometer was developed to measure the mirror surface shape in response to the applied voltage. The influence function of the mirror measured accorded with Gaussian function with inter-actuator coupling of approximately 5%, which was similar to the traditional piezoelectric DM with stacked actuators. To examine the ability of the mirror to replicate optical aberrations described by the Zernike polynomials, low-order Zernike modes were reproduced by calculating the voltage on each actuator using an influence function matrix. The measurement demonstrated that the deformable mirror could produce the Zernike modes up to the ninth term. Considering the low-voltage actuation as well as the capability for miniaturization of the actuator size, deformable mirror actuated by bulk-PZT thick film has a potential application for low-cost adaptive optics.

  6. Mechanical response of nanocrystalline platinum via molecular dynamics: size effects in bulk versus thin-film samples

    NASA Astrophysics Data System (ADS)

    Kim, Hojin; Strachan, Alejandro

    2015-09-01

    We use large-scale molecular dynamics simulations to characterize the mechanical responses of nanocrystalline bulk and thin-film samples with average grain size ranging from 5 to 40 nm and at two strain rates. Our simulations show Hall-Petch maxima for both yield and flow stresses and for both sets of specimens. We find that the presence of free surface decreases both the yield and flow stresses and, interestingly, the Hall-Petch maximum for slabs occur at a larger grain size than for the bulk samples. A quantitative analysis of plastic slip on grain interiors and boundaries reveals that the shift in the maximum results from a combination of higher intergranular slip and weaker size dependence of dislocation activity in the slabs as compared with the bulk. Finally, increasing strain rate increases both yield and flow stresses and this rate effect is dominated by the plasticity involving full dislocations; plastic slip by partial dislocations and grain boundary processes exhibit weaker size effects.

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

    PubMed

    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

    2015-10-19

    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 ( 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 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.

  8. Elasticity study of textured barium strontium titanate thin films by X-ray diffraction and laser acoustic waves

    NASA Astrophysics Data System (ADS)

    Chaabani, Anouar; Njeh, Anouar; Donner, Wolfgang; Klein, Andreas; Hédi Ben Ghozlen, Mohamed

    2017-05-01

    Ba0.65Sr0.35TiO3 (BST) thin films of 300 nm were deposited on Pt(111)/TiO2/SiO2/Si(001) substrates by radio frequency magnetron sputtering. Two thin films with different (111) and (001) fiber textures were prepared. X-ray diffraction was applied to measure texture. The raw pole figure data were further processed using the MTEX quantitative texture analysis software for plotting pole figures and calculating elastic constants and Young’s modulus from the orientation distribution function (ODF) for each type of textured fiber. The calculated elastic constants were used in the theoretical studies of surface acoustics waves (SAW) propagating in two types of multilayered BST systems. Theoretical dispersion curves were plotted by the application of the ordinary differential equation (ODE) and the stiffness matrix methods (SMM). A laser acoustic waves (LAW) technique was applied to generate surface acoustic waves (SAW) propagating in the BST films, and from a recursive process, the effective Young’s modulus are determined for the two samples. These methods are used to extract and compare elastic properties of two types of BST films, and quantify the influence of texture on the direction-dependent Young’s modulus.

  9. 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

  10. Investigations of evanescent heat transfer and measurements of the acoustic reflection coefficient for thin metal films

    NASA Astrophysics Data System (ADS)

    Loomis, Jackson J.

    1998-10-01

    Evanescent waves are always present near the surfaces of materials and are generated by the random thermal motion of charges, which produce fluctuating electromagnetic fields that extend approximately a thermal wavelength, /hbar c/KBT beyond the surfaces of the materials. Evanescent waves can transfer energy from one material to another if the second material extends into the region where the evanescent waves have appreciable amplitude. In the first part of this thesis, we present a macroscopic, phenomenological theory for the heat flow mediated by evanescent waves between two material half-spaces of differing temperatures whose surfaces are separated by a vacuum gap of width l. For separations much larger than the thermal wavelength, our result reduces to the Stefan- Boltzmann law and for separations much less than the thermal wavelength, the thermal flux due to evanescent waves is orders of magnitude larger than blackbody radiation. For l sufficiently small, the heat transfer varies as l-2. As a special case, we explore the behavior of the heat flux between Drude materials and found that heat flow exhibits a wide range of behavior for different gap widths and electrical conductivities. In the second part of this thesis, we present a picosecond ultrasonic method for studying the interfacial bonding between a thin metal film and a substrate. In this method, a subpicosecond laser pulse produces a rapid heating of the film. Relaxation of the thermal stress created by the heating sets the film into vibration. The rate at which the film vibrations damp out via sound transmission into the substrate depends on both the interfacial bonding and the acoustic properties of the film and substrate. Measurements of the damping rate thus provide a means of assessing interfacial bond strength. As a demonstration, we modified the interfacial bonding by irradiating small areas of some samples with 2.5 He+ MeV ions, a procedure which is known to improve bonding. Measurements of the

  11. 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.

  12. Room temperature ferromagnetism in Cr-doped In2O3 on high vacuum annealing of thin films and bulk samples

    NASA Astrophysics Data System (ADS)

    Kharel, P.; Sudakar, C.; Sahana, M. B.; Lawes, G.; Suryanarayanan, R.; Naik, R.; Naik, V. M.

    2007-05-01

    We report on the observation of room temperature ferromagnetism in Cr-doped In2O3 bulk samples and spin-coated thin films. The samples showed a clear ferromagnetism above 300K with magnetic moments of 0.008 and 0.22μB/Cr at 300K for the bulk and thin film, respectively, only after high vacuum (HV) annealing at 600°C. The vacuum annealed Cr-doped In2O3 thin films showed a typical semiconducting behavior with a room temperature resistivity of 0.73Ωcm, while bulk samples were more conducting (23mΩcm). We present systematic investigations on the influence of HV annealing on the carrier concentrations, resistivity, and magnetic properties of the samples.

  13. 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.

  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. Soft electronic structure modulation of surface (thin-film) and bulk (ceramics) morphologies of TiO2-host by Pb-implantation: XPS-and-DFT characterization

    NASA Astrophysics Data System (ADS)

    Zatsepin, D. A.; Boukhvalov, D. W.; Gavrilov, N. V.; Zatsepin, A. F.; Shur, V. Ya.; Esin, A. A.; Kim, S. S.; Kurmaev, E. Z.

    2017-04-01

    The results of combined experimental and theoretical study of substitutional and clustering effects in the structure of Pb-doped TiO2-hosts (bulk ceramics and thin-film morphologies) are presented. Pb-doping of the bulk and thin-film titanium dioxide was made with the help of pulsed ion-implantation without posterior tempering (Electronic Structure Modulation Mode). The X-ray photoelectron spectroscopy (XPS) qualification of core-levels and valence bands and Density-Functional Theory (DFT) calculations were employed in order to study the yielded electronic structure of Pb-ion modulated TiO2 host-matrices. The combined XPS-and-DFT analysis has agreed definitely with the scenario of the implantation stimulated appearance of PbO-like structures in the bulk morphology of TiO2:Pb, whereas in thin-film morphology the PbO2-like structure becomes dominating, essentially contributing weak O/Pb bonding (PbxOy defect clusters). The crucial role of the oxygen hollow-type vacancies for the process of Pb-impurity "insertion" into the structure of bulk TiO2 was pointed out employing DFT-based theoretical background. Both experiment and theory established clearly the final electronic structure re-arrangement of the bulk and thin-film morphologies of TiO2 because of the Pb-modulated deformation and shift of the initial Valence Base-Band Width about 1 eV up.

  17. Pr{sub 0.67}Ba{sub 0.33}MnO{sub 3} in Bulk and Thin Film Ceramic

    SciTech Connect

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

    2011-03-30

    Bulk polycrystalline of Pr{sub 0.67}Ba{sub 0.33}MnO{sub 3}(PBMO) ceramic prepared via solid-state reaction and converted into thin films on corning glass, fused silica and MgO (100) by pulsed laser deposition (PLD) technique. As compared to bulk PBMO, the unit cell in thin film PBMO experienced positive misfit due to lattice strain induced by substrate used resulting MnO{sub 6} to deform (change in Mn-O-Mn bond angle and Mn-O bond length). Bulk PBMO had large grains ({approx}1.5{mu}m) as compared to thin film which are nano-sized (<100 nm). Two metal-insulator transition temperatures, T{sub P}(156 K and 190 K) were observed in bulk due to core-shell effect as proposed by Zhang et al.. In summary, variation of electrical behaviour was observed between bulk and thin film samples which believed to be due to the difference of ordering in core (body) and grain surface.

  18. Influence of thin-film metallic glass coating on fatigue behavior of bulk metallic glass: Experiments and finite element modeling

    DOE PAGES

    Yu, Chia-Chi; Chu, Jinn P.; Jia, Haoling; ...

    2017-03-21

    In this paper, a coating of the Zr-based thin-film metallic glass (TFMG) was deposited on the Zr50Cu30Al10Ni10 bulk metallic glass (BMG) to investigate shear-band evolution under four-point-bend fatigue testing. The fatigue endurance-limit of the TFMG-coated samples is ~ 33% higher than that of the BMG. The results of finite-element modeling (FEM) revealed a delay in the shear-band nucleation and propagation in TFMG-coated samples under applied cyclic-loading. The FEM study of spherical indentation showed that the redistribution of stress by the TFMG coating prevents localized shear-banding in the BMG substrate. Finally, the enhanced fatigue characteristics of the BMG substrates can bemore » attributed to the TFMG coatings retarding shear-band initiation at defects on the surface of the BMG.« less

  19. Anaerobic treatment of wastewater with high suspended solids from a bulk drug industry using fixed film reactor (AFFR).

    PubMed

    Rao, A Gangagni; Naidu, G Venkata; Prasad, K Krishna; Rao, N Chandrasekhar; Mohan, S Venkata; Jetty, Annapurna; Sarma, P N

    2004-07-01

    Studies are carried out on the treatment of wastewater from a bulk drug industry using an anaerobic fixed film reactor (AFFR) designed and fabricated in the laboratory. The chemical oxygen demand (COD) and total dissolved solids (TDS) of the wastewater are found to be very high with low Biochemical oxygen demand (BOD) to COD ratio and high total suspended solid (TSS) concentration. Acclimatization of seed consortia and start up of the reactor is carried out by directly using the wastewater, which resulted in reducing the period of startup to 30 days. The reactor is studied at different organic loading rates (OLR) and it is found that the optimum OLR is 10 kg COD/m3/day. The wastewater under investigation, which is having considerable quantity of SS, is treated anaerobically without any pretreatment. The COD and BOD of the reactor outlet wastewater are monitored and reduction at steady state and optimum OLR is observed to be 60-70% of COD and 80-90% of BOD. The reactor is subjected to organic shock loads at two different OLR and it is observed that the reactor could withstand shocks and performance could be restored to normalcy at that OLR. The results obtained indicated that AFFR could be used efficiently for the treatment of wastewater from a bulk drug industry having high COD, TDS and TSS. Copyright 2003 Elsevier Ltd.

  20. Anaerobic treatment of wastewater with high suspended solids from a bulk drug industry using fixed film reactor (AFFR).

    PubMed

    Gangagni Rao, A; Venkata Naidu, G; Krishna Prasad, K; Chandrasekhar Rao, N; Venkata Mohan, S; Jetty, Annapurna; Sarma, P N

    2005-01-01

    Studies were carried out on the treatment of wastewater from a bulk drug industry using an anaerobic fixed film reactor (AFFR) designed and fabricated in the laboratory. The chemical oxygen demand (COD) and total dissolved solids (TDS) of the wastewater were found to be very high with low biochemical oxygen demand (BOD) to COD ratio and high total suspended solid (TSS) concentration. Acclimatization of seed consortia and startup of the reactor was carried out by directly using the wastewater, which resulted in reducing the period of startup to 30 days. The reactor was studied at different organic loading rates (OLR) and it was found that the optimum OLR was 10 kg COD/m(3)/day. The wastewater under investigation, which had a considerable quantity of SS, was treated anaerobically without any pretreatment. COD and BOD of the reactor outlet wastewater were monitored and at steady state and optimum OLR 60-70% of COD and 80-90% of BOD were removed. The reactor was subjected to organic shock loads at two different OLR and the reaction could withstand the shocks and performance could be restored to normalcy at that OLR. The results obtained indicated that AFFR could be used efficiently for the treatment of wastewater from a bulk drug industry having high COD, TDS and TSS.

  1. Spin-orbit torques in Ta/TbxCo100-x ferrimagnetic alloy films with bulk perpendicular magnetic anisotropy

    NASA Astrophysics Data System (ADS)

    Ueda, Kohei; Mann, Maxwell; Pai, Chi-Feng; Tan, Aik-Jun; Beach, Geoffrey S. D.

    2016-12-01

    We quantified the bulk perpendicular magnetic anisotropy (PMA) and spin-orbit torques (SOTs) in bilayer Ta/TbxCo100-x ferrimagnetic alloy films with varying Tb concentration. The coercivity increases dramatically with increasing TbxCo100-x thickness and is enhanced by the presence of a Ta underlayer. The Ta underlayer simultaneously serves as a source of SOT due to the spin Hall effect, which we show provides an efficient means to manipulate the magnetization in bulk PMA materials. It is further shown that the sign of the anomalous Hall voltage is different for rare-earth (RE) and transition-metal (TM) dominated alloy compositions, whereas the sign of the SOT effective field remains the same, suggesting that the former is related to the TM sublattice magnetization whereas the latter is related to the net magnetization. Our results suggest that Ta/TbxCo100-x is a potential candidate for spin-orbitronic device applications and give insight into spin transport and SOTs in rare-earth/transition-metal alloys.

  2. Microwave Magnetic Materials for Radar and Signal Processing Devices - Thin Film and Bulk Oxides and Metals

    DTIC Science & Technology

    2007-11-29

    single crystals, and (9) the indicated below: successful PLD growth of low loss zinc lithium ferrite films. Visiting scientists: 2 In the area of...was a standard commercial nickel zinc spinel ferrite (NZF) from II. MATERIALS PREPARATION AND X-RAY Trans-Tech, 1T2- 111. The ferroelectric component...2.95 157 6 expected from dense nickel zinc ferrite materials. The data 100 3175 2.99 168 8 for the 27 and 16 vol % samples, however, showed that any

  3. Self Assembled Spin Coated and Bulk Films of a Novel Polydiacetylene as Second Order NLO Polymers

    DTIC Science & Technology

    1994-05-31

    NLO Polymers 6. AUTHOm(m) R&T Code: 4132016 W.H. Kim, B. Bihari, R. Moody, N. B. Kodali , J.Kumar,S.K. Dr. JoAnn MilUiken Tripathy. 7. PERFORMING...Polymers by W.H. Kim, B. Bihari, R. Moody, N. B. Kodali , J.Kumar,S.K. Tripathy. Submitted to Macromolecules University of Massachusetts Lowell Department...FILMS OF A NOVEL POLYDIACETYLENE AS SECOND ORDER NLO POLYMERS W. H. Kim, B. Bihari+, R. Moody+, N. B. Kodali , J. Kumar+, and S. K. Tripathy, University

  4. Excitonic resonances in thin films of WSe2: from monolayer to bulk material

    NASA Astrophysics Data System (ADS)

    Arora, Ashish; Koperski, Maciej; Nogajewski, Karol; Marcus, Jacques; Faugeras, Clément; Potemski, Marek

    2015-06-01

    We present optical spectroscopy (photoluminescence and reflectance) studies of thin layers of the transition metal dichalcogenide WSe2, with thickness ranging from mono- to tetra-layer and in the bulk limit. The investigated spectra show the evolution of excitonic resonances as a function of layer thickness, due to changes in the band structure and, importantly, due to modifications of the strength of Coulomb interactions as well. The observed temperature-activated energy shift and broadening of the fundamental direct exciton are well accounted for by standard formalisms used for conventional semiconductors. A large increase of the photoluminescence yield with temperature is observed in a WSe2 monolayer, indicating the existence of competing radiative channels. The observation of absorption-type resonances due to both neutral and charged excitons in the WSe2 monolayer is reported and the effect of the transfer of oscillator strength from charged to neutral excitons upon an increase of temperature is demonstrated.

  5. 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.

  6. 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.

  7. Highly textured growth of AlN films on sapphire by magnetron sputtering for high temperature surface acoustic wave applications

    SciTech Connect

    Aubert, T.; Assouar, M. B.; Legrani, O.; Elmazria, O.; Tiusan, C.; Robert, S.

    2011-03-15

    Piezoelectric aluminum nitride films were deposited onto 3 in. [0001] sapphire substrates by reactive magnetron sputtering to explore the possibility of making highly (002)-textured AlN films to be used in surface acoustic wave (SAW) devices for high temperature applications. The synthesized films, typically 1 {mu}m thick, exhibited a columnar microstructure and a high c-axis texture. The relationship between the microstructures and process conditions was examined by x-ray diffraction (XRD), transmission electron microscopy, and atomic force microscopy analyses. The authors found that highly (002)-textured AlN films with a full width at half maximum of the rocking curve of less than 0.3 deg. can be achieved under high nitrogen concentration and moderate growth temperature, i.e., 250 deg. C. The phi-scan XRD reveals the high in-plane texture of deposited AlN films. The SAW devices, based on the optimized AlN films on sapphire substrate, were characterized before and after an air annealing process at 800 deg. C for 90 min. The frequency response, recorded after the annealing process, confirmed that the thin films were still strong in a high temperature environment and that they had retained their piezoelectric properties.

  8. How to enable bulk-like martensitic transformation in epitaxial films

    NASA Astrophysics Data System (ADS)

    Wodniok, Marius; Teichert, Niclas; Helmich, Lars; Hütten, Andreas

    2017-05-01

    The present study is dedicated to the influence of different substrate and buffer layer materials on the martensitic transformation in sputter deposited epitaxial shape memory Heusler alloys. For this, the magnetocaloric Heusler alloy Ni-Co-Mn-Al [N. Teichert et al., Phys. Rev. B 91, 184405 (2015)] is grown on MgO(001), MgAl2O4(001), and MgO(001)/V substrates, which exhibit a lattice misfit to the Ni-Co-Mn-Al between -1.2% and 3.6%. By temperature dependent X-ray diffraction measurements it is shown that the optimum buffer layer for shape memory Heusler films is not one with minimum lattice misfit, but one with minimum Young's modulus and moderate misfit because an elastic buffer layer can deform during the martensitic transformation of the Heusler layer. Furthermore, epitaxial strain caused by a moderate lattice misfit does not significantly change the martensitic transformation temperatures.

  9. Plasmon-exciton interaction and screening of exciton in ZnO-based thin film on bulk Pt as analyzed by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Darma, Yudi; Dimas Satrya, Christoforus; Marlina, Resti; Kurniawan, Robi; Herng, Tun Seng; Ding, Jun; Rusydi, Andrivo

    2017-01-01

    We study plasmon-exciton interaction in ZnO-based thin film on bulk Pt by using high resolution spectroscopic ellipsometry. ZnO films on quartz are used as reference. This study shows the strong electronic interactions between ZnO film and Pt by considering the significant suppression of exciton in ZnO film, in comparison to ZnO film on quartz. We found that plasmon in Pt are responsible to provide transferred electron for electronic blocking of exciton in ZnO film induce by spontaneous recombination from Pt. In the case of Cu doped ZnO film, we confirm screening effects on exciton and a localized interband transition for both systems (ZnO film on Pt and ZnO film on quartz). In Cu-doped ZnO film, electronic blocking of exciton by Pt plasmon is more pronounce rather than screening effect by interband transition. Our results show the importance of plasmon from substrate and doping to modify the optical properties of wide bandgap semiconductor.

  10. 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.

  11. Simultaneous measurement of thermal conductivity and heat capacity of bulk and thin film materials using frequency-dependent transient thermoreflectance method.

    PubMed

    Liu, Jun; Zhu, Jie; Tian, Miao; Gu, Xiaokun; Schmidt, Aaron; Yang, Ronggui

    2013-03-01

    The increasing interest in the extraordinary thermal properties of nanostructures has led to the development of various measurement techniques. Transient thermoreflectance method has emerged as a reliable measurement technique for thermal conductivity of thin films. In this method, the determination of thermal conductivity usually relies much on the accuracy of heat capacity input. For new nanoscale materials with unknown or less-understood thermal properties, it is either questionable to assume bulk heat capacity for nanostructures or difficult to obtain the bulk form of those materials for a conventional heat capacity measurement. In this paper, we describe a technique for simultaneous measurement of thermal conductivity κ and volumetric heat capacity C of both bulk and thin film materials using frequency-dependent time-domain thermoreflectance (TDTR) signals. The heat transfer model is analyzed first to find how different combinations of κ and C determine the frequency-dependent TDTR signals. Simultaneous measurement of thermal conductivity and volumetric heat capacity is then demonstrated with bulk Si and thin film SiO2 samples using frequency-dependent TDTR measurement. This method is further testified by measuring both thermal conductivity and volumetric heat capacity of novel hybrid organic-inorganic thin films fabricated using the atomic∕molecular layer deposition. Simultaneous measurement of thermal conductivity and heat capacity can significantly shorten the development∕discovery cycle of novel materials.

  12. 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.

  13. Fabrication of Thin Sensitive Film of Ball Surface Acoustic Wave Sensor by Off-Axis Spin-Coating Method

    NASA Astrophysics Data System (ADS)

    Kobari, Kentaro; Yamamoto, Yutaro; Sakuma, Masanori; Akao, Shingo; Tsuji, Toshihiro; Yamanaka, Kazushi

    2009-07-01

    In environmental assessment and security, it is necessary to detect hazardous gases at low concentrations. The ball surface acoustic wave (SAW) sensor can have significantly improved sensitivity when the ultramultiple roundtrips (e.g., >100 turns) of the SAW is achieved. However, it is hindered by the thick and coarse organic sensitive film fabricated by the conventional spin-coating method. We propose an “off-axis spin coating method” in order to fabricate thin and highly uniform organic sensitive film with high reproducibility. Langasite ball SAW sensors were coated by polyisoprene, polyisobutylene, and polydimethylsiloxane sensitive films and were applied in detecting normal saturated hydrocarbons (pentane, hexane, heptane, octane, and nonane), a nerve gas simulant (dimethyl methylphosphonate: DMMP), and sick-house gases (benzene, toluene, and xylene). With the proposed method, we succeeded in realizing multiple roundtrips and in detecting DMMP at a sub-ppm concentration without preliminary condensation of the sample.

  14. Applications of laser-generated surface acoustic waves for copper film process monitoring in integrated circuit industry (abstract)

    NASA Astrophysics Data System (ADS)

    Gostein, Michael; Maznev, A. A.; Krastev, Plamen; Mazurenko, Alex

    2003-01-01

    We describe applications of a compact commercial instrument for laser generation and detection of surface acoustic waves (SAWs) to problems in metal film process control for the integrated circuit (IC) industry. [M. Gostein, M. Banet, M. Joffe, A. A. Maznev, R. Sacco, J. A. Rogers, and K. A. Nelson, in Handbook of Silicon Semiconductor Metrology, edited by A. C. Diebold (Marcel Dekker, New York, 2001)] The IC industry is undergoing dramatic changes with the continued drive to reduce feature size and increase circuit speed. One of the most important of these changes is the industry-wide move to replace circuit interconnect processes based on aluminum metallization with copper-based processes. The unique process challenges of copper metallization, coupled with the increasing cost of IC manufacturing in general, have resulted in an increased need for metal film thickness measurement for process control. Laser-generated and detected surface acoustic waves provide an ideal method for nondestructively measuring film thickness on product wafers as they move through an IC factory. A patented version of the technique has been incorporated into a commercial high-throughput measurement station. The measurement station analyzes specialized test structures in the scribe lines in between IC chips on a product wafer. Here, we describe application of the technique to all stages of the copper metallization process, including measurement of seed-layer copper and its associated underlying barrier metals, measurement of electroplated copper deposited atop the seed layer, and measurement of remaining copper film thickness following a chemical-mechanical polishing step. We highlight special capabilities to measure test arrays of submicron metal lines that closely resemble actual circuit elements. In addition, we discuss characterization of the elastic properties of typical and emerging thin film materials used in the semiconductor industry, which is a necessary step in setting up the

  15. Highly sensitive room-temperature surface acoustic wave (SAW) ammonia sensors based on Co₃O₄/SiO₂ composite films.

    PubMed

    Tang, Yong-Liang; Li, Zhi-Jie; Ma, Jin-Yi; Su, Hai-Qiao; Guo, Yuan-Jun; Wang, Lu; Du, Bo; Chen, Jia-Jun; Zhou, Weilie; Yu, Qing-Kai; Zu, Xiao-Tao

    2014-09-15

    Surface acoustic wave (SAW) sensors based on Co3O4/SiO2 composite sensing films for ammonia detection were investigated at room temperature. The Co3O4/SiO2 composite films were deposited onto ST-cut quartz SAW resonators by a sol-gel method. SEM and AFM characterizations showed that the films had porous structures. The existence of SiO2 was found to enhance the ammonia sensing property of the sensor significantly. The sensor based on a Co3O4/SiO2 composite film, with 50% Co3O4 loading, which had the highest RMS value (3.72), showed the best sensing property. It exhibited a positive frequency shift of 3500 Hz to 1 ppm ammonia as well as excellent selectivity, stability and reproducibility at room temperature. Moreover, a 37% decrease in the conductance of the composite film as well as a positive frequency shift of 12,500 Hz were observed when the sensor was exposed to 20 ppm ammonia, indicating the positive frequency shift was derived from the decrease in film conductance.

  16. 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.

  17. Microstructure and mechanical properties of stress-tailored piezoelectric AlN thin films for electro-acoustic devices

    NASA Astrophysics Data System (ADS)

    Reusch, Markus; Cherneva, Sabina; Lu, Yuan; Žukauskaitė, Agnė; Kirste, Lutz; Holc, Katarzyna; Datcheva, Maria; Stoychev, Dimitar; Lebedev, Vadim; Ambacher, Oliver

    2017-06-01

    Nanoindentation measurements along with atomic force microscopy, X-ray diffraction, and residual stress analyses on the basis of Raman measurements have been performed to characterize stress-tailored AlN thin films grown using reactive RF magnetron sputtering. The intrinsic stress gradient caused by the growing in-plane grain size along film thickness was minimized by increasing the N2 concentration in the Ar/N2 gas mixture during the growth process. The increase of N2 concentration did not degrade the device-relevant material properties such as crystallographic orientation, surface morphology, piezoelectric response, or indentation modulus. Due to comparable crystallographic film properties for all investigated samples it was concluded that mainly the AlN crystallites contribute to the mechanical film properties such as indentation modulus and hardness, while the film stress or grain boundaries had only a minor influence. Therefore, by tailoring the stress gradient in the AlN films, device performance, fabrication yield, and the design flexibility of electro-acoustic devices can be greatly improved.

  18. 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

  19. Determination of ammonium in Kjeldahl digests by gas-diffusion flow-injection analysis with a bulk acoustic wave-impedance sensor.

    PubMed

    Su, X L; Nie, L H; Yao, S Z

    1997-11-01

    A novel flow-injection analysis (FIA) system has been developed for the rapid and direct determination of ammonium in Kjeldahl digests. The method is based on diffusion of ammonia across a PTFE gas-permeable membrane from an alkaline (NaOH/EDTA) stream into a stream of diluted boric acid. The trapped ammonium in the acceptor is determined on line by a bulk acoustic wave (BAW)-impedance sensor and the signal is proportional to the ammonium concentration present in the digests. The proposed system exhibits a favorable frequency response to 5.0 x 10(-6)-4.0 x 10(-3) mol l(-1) ammonium with a detection limit of 1.0 x 10(-6) mol l(-1), and the precision was better than 1% (RSD) for 0.025-1.0 mM ammonium at a through-put of 45-50 samples h(-1). Results obtained for nitrogen determination in amino acids and for proteins determination in blood products are in good agreement with those obtained by the conventional distillation/titration method, respectively. The effects of composition of acceptor stream, cell constant of conductivity electrode, sample volume, flow rates and potential interferents on the FIA signals were discussed in detail.

  20. 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.

  1. 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.

  2. High performance bimorph piezoelectric MEMS harvester via bulk PZT thick films on thin beryllium-bronze substrate

    NASA Astrophysics Data System (ADS)

    Yi, Zhiran; Yang, Bin; Li, Guimiao; Liu, Jingquan; Chen, Xiang; Wang, Xiaolin; Yang, Chunsheng

    2017-07-01

    This letter presents a high performance bimorph piezoelectric MEMS harvester with bulk PZT thick films on both sides of a flexible thin beryllium-bronze substrate via bonding and thinning technologies. The upper and lower PZT layers are thinned down to about 53 μm and 76 μm, respectively, and a commercial beryllium bronze with the thickness of about 50 μm is used as the substrate. The effective volume of this device is 30.6 mm3. The harvester with a tungsten proof mass generated the close-circuit peak-to-peak voltage of 53.1 V, the output power of 0.979 mW, and the power density of 31.99 mW/cm3 with the matching load resistance of 360 kΩ at the applied acceleration amplitude of 3.5 g and the applied frequency of 77.2 Hz. Meanwhile, in order to evaluate the stability, the device was measured continuously under applied acceleration amplitudes of 1.0 g and 3.5 g for one hour and demonstrated a good stability. Then, the harvester was utilized to light up LEDs and about twenty-one serial LEDs were lighted up at resonance under an applied acceleration amplitude of 3.0 g.

  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. Impact of Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation (RIR-MAPLE) on Morphology and Charge Conduction in Conjugated Polymer and Bulk Heterojunction Thin Films

    NASA Astrophysics Data System (ADS)

    Stiff-Roberts, Adrienne; McCormick, Ryan; Atewologun, Ayomide

    2014-03-01

    An approach to improve organic photovoltaic efficiency is to increase vertical charge conduction by promoting out-of-plane π- π stacking in conjugated polymers. Resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) features multiple growth parameters that can be varied to achieve a desired organic thin film property. In addition, RIR-MAPLE enables nanoscale domains in blended polymeric films and multi-layer polymeric films regardless of constituent solubility. Thus, RIR-MAPLE deposition is compared to solution-cast films as a possible approach to increase out-of-plane charge transport in polymers and bulk heterojunctions. Two common, solar cell polymers are investigated: P3HT and PCPDTBT. Materials characterization includes grazing-incidence, wide angle x-ray scattering (GIWAXS) for structural information and two techniques to determine hole mobility: organic field effect transistors to measure in-plane mobility and charge extraction by linearly increasing voltage to measure out-of-plane mobility. Initial indications are that the RIR-MAPLE films have a fundamentally different morphology compared to solution-cast films. In the case of P3HT, an enhancement in out-of-plane π- π stacking was observed by GIWAXS in RIR-MAPLE films compared to solution-cast films. A portion of this research was conducted at CNMS at ORNL.

  5. Surface acoustic wave properties of proton-exchanged LiNbO3 waveguides with SiO2 film.

    PubMed

    Kao, Kuo-Sheng; Cheng, Chien-Chuan; Chung, Chung-Jen; Chen, Ying-Chung

    2005-03-01

    Surface acoustic wave (SAW) properties of proton-exchanged (PE) z-cut lithium niobate (LiNbO3) waveguides with silicon dioxide (SiO2) film layers were investigated using octanoic acid. The distribution of hydrogen measured by secondary ion mass spectrometry (SIMS) showed a step-like profile, which was assumed to be equal to the waveguide depth (d). The SiO2 film was deposited on z-cut LiNbO3 waveguide by radio frequency (rf) magnetron sputtering. We investigated the important parameters for the design of SAW devices such as phase velocity (Vp), insertion loss (IL) and temperature coefficient of frequency (TCF) by a network analyzer using thin-film aluminum interdigital transducer electrodes on the upper SiO2 film surface. The experimental results showed that the Vp of SAW decreased slightly with the increase of h/lambda, where h was the thickness of SiO2 films and lambda was the wavelength. The IL of SAW increased with increased h/lambda. The TCF of SAW calculated from the frequency change of the output of SAW delay line showed an evident decrease with the increase of h/lambda. The TCF for PE z-cut LiNbO3 was measured to be about -54.72 ppm/degreees C at h/lambda = 0.08. It revealed that the SiO2 films could compensate and improve the temperature stability as compared with the TCF of SAW on PE samples without SiO2 film.

  6. A surface acoustic wave humidity sensor with high sensitivity based on electrospun MWCNT/Nafion nanofiber films

    NASA Astrophysics Data System (ADS)

    Sheng, Lei; Dajing, Chen; Yuquan, Chen

    2011-07-01

    Humidity detection has been widely used in a variety of fields. A humidity sensor with high sensitivity is reported in this paper. A surface acoustic wave resonator (SAWR) with high resonance frequency was fabricated as a basic sensitive component. Various nanotechnologies were used to improve the sensor's performance. A multi-walled carbon nanotube/Nafion (MWCNT/Nafion) composite material was prepared as humidity-sensitive films, deposited on the surface of an SAWR by the electrospinning method. The electrospun MWCNT/Nafion nanofiber films showed a three-dimensional (3D) porous structure, which was profitable for improving the sensor's performance. The new nano-water-channel model of Nafion was also applied in the humidity sensing process. Compared to other research, the present sensor showed excellent sensitivity (above 400 kHz/% relative humidity (RH) in the range from 10% RH to 80% RH), good linearity (R2 > 0.98) and a short response time (~3 s@63%).

  7. Substrate-induced epitaxial mixing of bulk-immiscible La5/8Sr3/8MnO3/LuMnO3 films

    NASA Astrophysics Data System (ADS)

    Hur, N.; Cheong, S.-W.; Kale, S. N.; Ogale, S. B.; Choudhary, R.; Shinde, S. R.; Venkatesan, T.

    2005-03-01

    A mixture of a colossal magnetoresistance manganite (La5/8Sr3/8MnO3) and a multiferroic (LuMnO3), of potential interest for magnetoelectronics, was found to be bulk immiscible due to its structural/chemical incompatibility. Here, we demonstrate that thin-film epitaxy offers a route to achieve continuous perovskite solid solutions of such a bulk-immiscible mixture, allowing studies of their physical properties. The films grow with (110)- and (001)-preferred orientation on SrTiO3(100) and LaAlO3(100), respectively. The details of structural, magnetotransport, and magnetization data are discussed within the context of metal-insulator phase coexistence. Epitaxial stabilization of chemically immiscible phases clearly widens the scope of research on manganites as well as other materials.

  8. 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.

  9. 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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    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 rad2/Hz at 1 kHz offset and -150 dB rad2/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 × 10-9 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 × 10-11 τ-1/2 up to a few seconds and found to be limited by the signal-to-noise ratio of the detected CPT resonance.

  10. Assay and analysis for anti- and pro-oxidative effects of ascorbic acid on DNA with the bulk acoustic wave impedance technique.

    PubMed

    Guo, Bin; Yuan, Yu; Wu, Yaohui; Xie, Qingji; Yao, Shouzhuo

    2002-06-15

    A bulk acoustic wave (BAW) impedance sensor has been applied for in situ monitoring of the whole process of DNA oxidative damage induced by the vitamin C (Vc)-Fe (III) system, based on its real-time responses to the density-viscosity change of the tested solution due to the damages occurring on the DNA molecules. The results showed that Vc exhibited two conflicting effects, i.e., pro-oxidation and anti-oxidation on the DNA at different Vc concentrations in the damage system, and the "threshold" concentration of Vc for these two effects was estimated to be about 100 micromol/L. The end-point frequency change of the sensor (Deltaf(m)) was found to be linearly related to the initial concentration of the soybean DNA (C(DNA)) in the range of 40-1000 microg/mL, and the exponential relationship between the frequency change (Deltaf(0)) vs damaging time suggested that the Fe (III)-mediated DNA damage by Vc could be described as a first-order kinetics reaction. The effects of variations in concentrations of Vc and Fe3+ on the DNA oxidative damage were discussed, and based on investigations for the enhancing influence of H2O2 and inhibiting influence of HO* scavengers on the DNA damage, the nature and physiological toxicity of the damage in biological system were also examined. In addition, UV-vis spectra and electrophoresis analysis were also used, and the experimental observations were in good agreement with the above results. Copyright 2002 Elsevier Science (USA).

  11. Giant Rashba Splitting in Pb1-x Snx Te (111) Topological Crystalline Insulator Films Controlled by Bi Doping in the Bulk.

    PubMed

    Volobuev, Valentine V; Mandal, Partha S; Galicka, Marta; Caha, Ondřej; Sánchez-Barriga, Jaime; Di Sante, Domenico; Varykhalov, Andrei; Khiar, Amir; Picozzi, Silvia; Bauer, Günther; Kacman, Perla; Buczko, Ryszard; Rader, Oliver; Springholz, Gunther

    2017-01-01

    The topological properties of lead-tin chalcogenide topological crystalline insulators can be widely tuned by temperature and composition. It is shown that bulk Bi doping of epitaxial Pb1-x Snx Te (111) films induces a giant Rashba splitting at the surface that can be tuned by the doping level. Tight binding calculations identify their origin as Fermi level pinning by trap states at the surface.

  12. Improving the properties of zinc oxide thin-film surface acoustic wave device on glass substrate by introducing double alumina layers

    NASA Astrophysics Data System (ADS)

    Shih, Wen-Ching; Huang, Yi-Fan; Wu, Mu-Shiang

    2017-10-01

    ZnO films with c-axis (0002) orientation have been successfully grown by RF magnetron sputtering on Al2O3/glass substrates. The alumina films were firstly deposited on glass substrates, and then secondly deposited on interdigital transducer/ZnO film/alumina film/glass substrates by electron beam evaporation. The crystalline structure and surface roughness of the films were investigated by X-ray diffraction and atomic force microscopy, respectively. The phase velocity and coupling coefficient of the surface acoustic wave (SAW) device were both increased when we deposited the double alumina layers. On the other hand, the temperature coefficient of frequency becomes better if we increase the thickness of the lower alumina film. The experimental result is beneficial for improving the performance of the ZnO thin-film SAW devices on inexpensive glass substrates.

  13. 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.

  14. Transition metal and rare earth-doped ZnO: a comparison of optical, magnetic, and structural behavior of bulk and thin films

    NASA Astrophysics Data System (ADS)

    Fenwick, W. E.; Kane, M. H.; Varatharajan, R.; Zaidi, T.; Fang, Z.; Nemeth, B.; Keeble, D. J.; El-Mkami, H.; Smith, G. M.; Nause, J.; Summers, C. J.; Ferguson, I. T.

    2007-02-01

    Recent theoretical predictions of ferromagnetic behavior in transition metal (TM)-doped ZnO have focused significant attention on these materials for use as spintronic materials. Moreover, rare earth (RE) elements in wide bandgap semiconductors would be useful not only in spintronics but also in optoelectronic applications. This work presents results obtained from an investigation into the optical, magnetic, and structural properties of transition-metal (TM)- doped ZnO and rare earth (RE) doped ZnO (TM = Mn, Co, Ni, and Fe; RE = Gd, Eu, and Tb) bulk crystals and thin films. Properties of TM- and RE-doped ZnO bulk crystals and thin films were studied and compared in order to better understand the nature of these dopant centers and their effects on the properties of the host crystal. Optical properties confirm the incorporation of substitutional transition metal ions on cation sites. While most thin film samples show ferromagnetic behavior, the magnetic response of the bulk crystals varies. This suggests that the magnetic behavior of TM-doped ZnO is highly dependent on growth conditions, and growth conditions which favor the formation of grain boundaries and interfaces may be more likely to result in ferromagnetic behavior. Origins of this ferromagnetic behavior are still under investigation. Defect luminescence observed in the RE-doped samples suggests that these materials may prove useful in optoelectonic applications as well.

  15. Effect of an Eu{sup 3+} impurity on the antiferrodistortion and ferroelectric instabilities in an EuTiO{sub 3} bulk crystal and thin films

    SciTech Connect

    Zhandun, V. S. Zamkova, N. G.; Zinenko, V. I.

    2015-01-15

    The existence of an antiferrodistortion transition in EuTiO{sub 3} is disputable, and this question needs to be answered. One of the possible causes is the presence of an Eu{sup 3+} impurity in a sample. A nonempirical polarizable ion model is used to study the effect of a trivalent Eu{sup 3+} ion impurity on the antiferrodistortion and ferroelectric instabilities of an EuTiO{sub 3} crystal in the bulk and the thin-film states. Lattice dynamics calculation shows that a bulk impurity-free EuTiO{sub 3} crystal has no unstable modes throughout the entire phase space volume. The addition of an Eu{sup 3+} impurity leads to a significant softening of the rotational mode, the distortion in which makes tetragonal phase I4/mcm (which is experimentally observed) energetically favorable. In going from the bulk crystal to the thin film, the vibration spectrum of the impurity-free film has unstable antiferrodistortion and rotational modes. The addition of an Eu{sup 3+} impurity enhances the antiferrodistortion instability, which fully or partly suppresses ferroelectricity.

  16. 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. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Reorientation of the diagonal double-stripe spin structure at Fe1+yTe bulk and thin-film surfaces

    NASA Astrophysics Data System (ADS)

    Hänke, Torben; Singh, Udai Raj; Cornils, Lasse; Manna, Sujit; Kamlapure, Anand; Bremholm, Martin; Hedegaard, Ellen Marie Jensen; Iversen, Bo Brummerstedt; Hofmann, Philip; Hu, Jin; Mao, Zhiqiang; Wiebe, Jens; Wiesendanger, Roland

    2017-01-01

    Establishing the relation between ubiquitous antiferromagnetism in the parent compounds of unconventional superconductors and their superconducting phase is important for understanding the complex physics in these materials. Going from bulk systems to thin films additionally affects their phase diagram. For Fe1+yTe, the parent compound of Fe1+ySe1-xTex superconductors, bulk-sensitive neutron diffraction revealed an in-plane oriented diagonal double-stripe antiferromagnetic spin structure. Here we show by spin-resolved scanning tunnelling microscopy that the spin direction at the surfaces of bulk Fe1+yTe and thin films grown on the topological insulator Bi2Te3 is canted out of the high-symmetry directions of the surface unit cell resulting in a perpendicular spin component, keeping the diagonal double-stripe order. As the magnetism of the Fe d-orbitals is intertwined with the superconducting pairing in Fe-based materials, our results imply that the superconducting properties at the surface of the related superconducting compounds might be different from the bulk.

  18. Reorientation of the diagonal double-stripe spin structure at Fe1+yTe bulk and thin-film surfaces

    DOE PAGES

    Hanke, Torben; Singh, Udai Raj; Cornils, Lasse; ...

    2017-01-06

    Here, establishing the relation between ubiquitous antiferromagnetism in the parent compounds of unconventional superconductors and their superconducting phase is important for understanding the complex physics in these materials. Going from bulk systems to thin films additionally affects their phase diagram. For Fe1+yTe, the parent compound of Fe1+ySe1$-x$Tex superconductors, bulk-sensitive neutron diffraction revealed an in-plane oriented diagonal double-stripe antiferromagnetic spin structure. Here we show by spin-resolved scanning tunnelling microscopy that the spin direction at the surfaces of bulk Fe1+yTe and thin films grown on the topological insulator Bi2Te3 is canted out of the high-symmetry directions of the surface unit cell resultingmore » in a perpendicular spin component, keeping the diagonal double-stripe order. As the magnetism of the Fe d-orbitals is intertwined with the superconducting pairing in Fe-based materials, our results imply that the superconducting properties at the surface of the related superconducting compounds might be different from the bulk.« less

  19. Reorientation of the diagonal double-stripe spin structure at Fe1+yTe bulk and thin-film surfaces

    PubMed Central

    Hänke, Torben; Singh, Udai Raj; Cornils, Lasse; Manna, Sujit; Kamlapure, Anand; Bremholm, Martin; Hedegaard, Ellen Marie Jensen; Iversen, Bo Brummerstedt; Hofmann, Philip; Hu, Jin; Mao, Zhiqiang; Wiebe, Jens; Wiesendanger, Roland

    2017-01-01

    Establishing the relation between ubiquitous antiferromagnetism in the parent compounds of unconventional superconductors and their superconducting phase is important for understanding the complex physics in these materials. Going from bulk systems to thin films additionally affects their phase diagram. For Fe1+yTe, the parent compound of Fe1+ySe1−xTex superconductors, bulk-sensitive neutron diffraction revealed an in-plane oriented diagonal double-stripe antiferromagnetic spin structure. Here we show by spin-resolved scanning tunnelling microscopy that the spin direction at the surfaces of bulk Fe1+yTe and thin films grown on the topological insulator Bi2Te3 is canted out of the high-symmetry directions of the surface unit cell resulting in a perpendicular spin component, keeping the diagonal double-stripe order. As the magnetism of the Fe d-orbitals is intertwined with the superconducting pairing in Fe-based materials, our results imply that the superconducting properties at the surface of the related superconducting compounds might be different from the bulk. PMID:28059102

  20. 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.

  1. Structure-Processing Relationships in Solution Processable Polymer Thin Film Transistors and Small Molecule Bulk Heterojunction Solar Cells

    NASA Astrophysics Data System (ADS)

    Perez, Louis A.

    A regio-regular (RR) conjugated copolymer based on cyclopenta[2,1-b:3,4- b]dithiophene (CDT) and pyridal[2,1,3]thiadiazole (PT) structural units was prepared by using polymerization reactions involving reactants specifically designed to avoid random orientation of the asymmetric PT heterocycle. Compared to its regio-irregular (RI) counterpart, the RR polymer exhibits a two orders of magnitude increase in hole mobility from 0.005 to 0.6 cm2V -1s-1. To probe the reason for this difference in mobility, we examined the crystalline structure and its orientation in thin films of both copolymers as a function of depth via grazing incidence wide angle X-ray scattering (GIWAXS). In the RI film, the pi-pi stacking direction of the crystallites is mainly perpendicular to the substrate normal (edge-on orientation) while in the RR film the crystallites adopt a mixed pi-pi stacking orientation in the center of the film as well as near the interface between the polymer and the dielectric layer. These results demonstrate that control of backbone regularity is another important design criterion to consider in the synthesis and optimization of new conjugated copolymers with asymmetric structural units. Solution processed organic photovoltaic devices (OPVs) have emerged as a promising sustainable energy technology due to their ease of fabrication, potential to enable low-cost manufacturing, and ability to be incorporated onto light-weight flexible substrates. To date, the most efficacious OPV device architecture, the bulk heterojunction (BHJ), consists of a blend of a light-harvesting conjugated organic electron donating molecule and a strong electron-accepting compound (usually a soluble fullerene derivative e.g. [6,6]-phenyl C71 butyric acid methyl ester (PC71BM). BHJ layer morphology, which has been shown to be highly dependent on processing, has a significant effect on OPV performance. It is postulated that optimal BHJ morphologies consist of discrete bicontinuous nanoscale

  2. Fluorescence behavior of globular proteins from their bulk and thin film conformations in presence of mono-, di- and tri-valent ions.

    PubMed

    Bhowal, Ashim Chandra; Das, Kaushik; Kundu, Sarathi

    2015-09-01

    Photoluminescence behavior of globular proteins, lysozyme and bovine serum albumin (BSA), from their bulk and thin film conformations have been studied in presence of mono-, di- and tri-valent ions by using fluorescence and UV-Vis spectroscopy at two different temperatures and the morphology of the protein thin films have been studied by using atomic force microscopy. Protein- and ion-dependent dynamic and static quenching behaviors have been identified. While dynamic quenching is observed for lysozyme for all the three different valent ions, BSA shows no quenching for mono-valent (Na(+)) ions, dynamic quenching for di-valent (Ni(2+)) ions and static quenching for tri-valent (Fe(3+)) ions at pH≈5.5. After heat treatment, as the conformation of the protein molecules changes, the quenching efficiency for lysozyme in presence of ions decreases but shows enhancement for BSA. In thin film geometry, the molecular conformation of both lysozyme and BSA modifies on the solid surfaces and hence quenching efficiency also modifies in comparison with that of bulk and as a result the quenching efficiency for lysozyme increases but decreases for the BSA film. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    NASA Astrophysics Data System (ADS)

    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 VO2 layers in complex multilayer devices, it is necessary to understand the relation between bulk and surface/interface properties. Highly oriented VO2 thin films were grown on (0001) sapphire single crystal substrates with reactive bias target ion beam deposition. In the analysis of the VO2 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 525K. Prior to annealing the VO2 films exhibit the transition from the monoclinic to the tetragonal phase with the concurrent change in conductivity by more than a factor of 103 and their phase purity is confirmed by XRD. Annealing to 425K and thus cycling across the metal-insulator transition (MIT) temperature has no impact on the bulk properties of the VO2 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 (525K ) 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 for this behavior. The onset of bulk

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

    NASA Astrophysics Data System (ADS)

    Kumar, Mohit; Basu, Tanmoy; Som, Tapobrata

    2015-08-01

    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 (˜1020 cm-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.

  5. 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.

  6. X-ray diffraction and surface acoustic wave analysis of BST/Pt/TiO2/SiO2/Si thin films

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

    High dielectric constant and electrostriction property of (Ba, Sr)Ti03 (BST) thin films result in an increasing interest for dielectric devices and microwave acoustic resonator. Barium strontium titanate (Ba0.645Sr0.355TiO3) films of about 300 nm thickness are grown on Pt(111)/TiO2/SiO2/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 ν of TiO2, 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.

  7. Study on the interfacial adhesion property of low-k thin film by the surface acoustic waves with cohesive zone model

    NASA Astrophysics Data System (ADS)

    Xiao, Xia; Qi, Haiyang; Tao, Ye; Kikkawa, Takamaro

    2016-12-01

    The cohesive zone model being increasingly used in discrete fracture processes simulation is adopted to study the interfacial adhesion property of low dielectric constant film deposited on the silicon substrate in this work. The two parameters, maximum normal traction and normal interface characteristic length in cohesive zone model, are taken into account to calculate the theoretical surface acoustic wave dispersion curves. Broadband surface acoustic wave signals with effective frequency up to 200 MHz are generated by short pulse ultraviolet laser source and detected by a piezoelectric transducer. The interfacial adhesion properties of dense and porous films determined accurately by matching the experimental dispersion curves with the calculated theoretical dispersion curves are 10.7 PPa/m and 2.8 PPa/m, respectively. The results show that the adhesion quality of dense low dielectric constant film is better than that of the porous. The study exhibits that the adhesion properties determined by improved laser-generated surface acoustic wave technique have the same trends with the test results of the nanoscratch technique, which indicates that the surface acoustic wave technique with cohesive zone model is a promising and nondestructive method for determining interfacial adhesion properties between low dielectric constant film and substrate.

  8. Physical modeling and characterization of thermo-acoustic loudspeakers made of silver nano-wire films

    NASA Astrophysics Data System (ADS)

    La Torraca, P.; Larcher, L.; Bobinger, M.; Pavan, P.; Seeber, B.; Lugli, P.

    2017-06-01

    Recent developments of ultra-low heat capacity nanostructured materials revived the interest in the thermo-acoustic (TA) loudspeaker technology, which shows important advantages compared to the classical dynamic loudspeakers as they feature a lower cost and weight, flexibility, conformability to the surface of various shapes, and transparency. The development of the TA loudspeaker technology requires accurate physical models connecting the material properties to the thermal and acoustic speaker's performance. We present here a combined theoretical and experimental analysis of TA loudspeakers, where the electro-thermal and the thermo-acoustic transductions are handled separately, thus allowing an in-depth description of both the pressure and temperature dynamics. The electro-thermal transduction is analyzed by accounting for all the heat flow processes taking place between the TA loudspeaker and the surrounding environment, with focus on their frequency dependence. The thermo-acoustic conversion is studied by solving the coupled thermo-acoustic equations, derived from the Navier-Stokes equations, and by exploiting the Huygens-Fresnel principle to decompose the TA loudspeaker surface into a dense set of TA point sources. A general formulation of the 3D pressure field is derived summing up the TA point source contributions via a Rayleigh integral. The model is validated against temperature and sound pressure level measured on the TA loudspeaker sample made of a Silver Nanowire random network deposited on a polyimide substrate. A good agreement is found between measurements and simulations, demonstrating that the model is capable of connecting material properties to the thermo-acoustic performance of the device, thus providing a valuable tool for the design and optimization of TA loudspeakers.

  9. In situ characterization of local elastic properties of thin shape memory films by surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Grabec, Tomáš; Sedlák, Petr; Stoklasová, Pavla; Thomasová, Martina; Shilo, Doron; Kabla, Meni; Seiner, Hanuš; Landa, Michal

    2016-12-01

    The impulse stimulated thermal scattering experimental technique is used for contactless in situ detection of phase transitions in thin nickel-titanium films deposited on silicon substrates. It is shown that this technique enables the determination of the local properties of the film over a fully coated wafer, in particular the thickness of the film and the temperature dependence of the Young’s modulus, and can thus be used for monitoring of the spatial distribution of the functional properties in films prepared by a combinatorial sputtering approach.

  10. 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 .

  11. 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

  12. 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

    2016-02-08

    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.

  13. An Integrated Laser-Induced Piezoelectric/Differential Confocal Surface Acoustic Wave System for Measurement of Thin Film Young's Modulus

    PubMed Central

    Yang, Fei; Dorantes-Gonzalez, Dante J.; Chen, Kun; Lu, Zimo; Jin, Baoyin; Li, Yanning; Chen, Zhi; Hu, Xiaotang

    2012-01-01

    The present paper presents the design and development results of a system setup for measuring Young's modulus of thin films by laser-induced surface acoustic waves based on the integration of two detection methods, namely, piezoelectric transducer detection and differential confocal detection, which may be used for conducting consecutive or simultaneous measurements. After demonstrating the capabilities of each detection approach, it is shown how, depending on a wider range of applications, sample materials and measurement environments, the developed integrated system inherits and harnesses the main characteristics of its detection channels, resulting in an more practical and flexible equipment for determining Young's modulus than traditional nanoindentation equipment, and also suitable for cross-validation purposes.

  14. 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

  15. 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.

  16. Elastic characterization of Au thin films utilizing laser induced acoustic Rayleigh waves

    NASA Astrophysics Data System (ADS)

    Haim, A.; Bar-Ad, S.; Azoulay, A.

    2011-01-01

    Wide frequency-band Rayleigh waves (~100 MHz) were utilized to characterize the elastic constants of thin Au/Cr films deposited on glass substrates. The Rayleigh waves were excited utilizing laser induced thermoelastic mechanism and detected using a knife-edge technique apparatus. The dispersion of the signals in glass substrates coated with Au/Cr was measured and fitted to theory using a non-linear regression algorithm. From the fitting, the Au films Young modulus and the film thickness were extracted. The results were analyzed with regards to AFM scans performed on the samples and independent thickness measurement done by a dektak3 profiler. Results show a good agreement between the two measurements.

  17. 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.

  18. Surface acoustic wave response to optical absorption by graphene composite film.

    PubMed

    Chivukula, Venkata S; Ciplys, Daumantas; Kim, Jin Ho; Rimeika, Romualdas; Xu, Jimmy M; Shur, Michael S

    2012-02-01

    Propagation of surface acoustic waves in YZ LiNbO3 overlaid with graphene flakes has been investigated and its optical response to illumination by 633-nm light from a He-Ne laser was studied. The heating of the sample surface caused by optical absorption by the graphene led to a downshift in the transmitted SAW phase caused by the wave velocity's dependence on temperature. The proposed simple model based on optothermal SAW phase modulation was found to be in good agreement with the experimental results.

  19. Pinning in high performance MgB2 thin films and bulks: Role of Mg-B-O nano-scale inhomogeneities

    NASA Astrophysics Data System (ADS)

    Prikhna, Tatiana; Shapovalov, Andrey; Eisterer, Michael; Shaternik, Vladimir; Goldacker, Wilfried; Weber, Harald W.; Moshchil, Viktor; Kozyrev, Artem; Sverdun, Vladimir; Boutko, Viktor; Grechnev, Gennadiy; Gusev, Alexandr; Kovylaev, Valeriy; Shaternik, Anton

    2017-02-01

    The comparison of nano-crystalline MgB2 oxygen-containing thin film (140 nm) and highly dense bulk materials showed that the critical current density, Jc, depends on the distribution of Mg-B-O nano-scale inhomogeneities. It has been shown that MgB2 bulks with high Jc in low (∼106 A/cm2 in 0-1 T at 10 K) and medium magnetic fields contain MgB0.6-0.8O0.8-0.9 nano-inclusions, where δTc or a combined δTc (dominant) / δl pinning mechanism prevails, while in bulk MgB2 with high Jc in high magnetic fields (Birr(18.5 K) = 15 T, Bc2(0 K) = 42.1 T) MgB1.2-2.7O1.8-2.5 nano-layers are present and δl pinning prevails. The structure of oxygen-containing films with high Jc in low and high magnetic fields (Jc (0 Т) = 1.8 × 107 А/сm2 and Jc (5 Т) = 2 × 106 А/сm2 at 10 К) contains very fine oxygen-enriched Mg-B-O inhomogeneities and δl pinning is realized. The results of DOS calculations in MgB2-xOx cells for x = 0, 0.125, 0.25, 0.5, 1 demonstrate that all compounds are conductors with metal-like behaviour. In the case of ordered oxygen substitution for boron the binding energy, Eb, does not increase sufficiently as compared with that for MgB2, while when oxygen atoms form zigzag chains the calculated Eb is even lower (Eb = -1.15712 Ry).

  20. 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.

  1. 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.

  2. Fabrication and Properties of Bulk and Thick Film YTTRIUM(1) BARIUM(2) COPPER(3) OXYGEN(7-DELTA) Superconductors

    NASA Astrophysics Data System (ADS)

    Bailey, Andrew

    Many of the applications envisaged for the new high critical temperature cuprate superconductors require the ability to produce high quality material in layers of 1-100mum thickness which can be used as prepared, or after patterning into discrete forms. Among the possible applications in the foreseeable future are EMI/EMC shielding, pcb interconnects, inductances, stripline, mixers and resonators. Consequently it is important to establish methods of 'thick film' manufacture which provide the versatility necessary for the wide range of uses. During the course of this research, a variety of processing methods have been studied in an attempt to optimize the important film parameters of density, adhesion, strength and good stable superconducting characteristics. Details will be given of substrate-layer interaction for the various substrates that were studied, which included alumina, sapphire, single crystal (100)MgO and yttria stabilised zirconia together with a number of methods of substrate passivation. To date, the most successful substrate for Y_1Ba_2Cu_3O_{7-delta } thick film production has been yttria stabilised zirconia. This thesis will discuss the results of investigations, using yttria stabilised zirconia substrates, which have identified satisfactory means of obtaining superconducting layers with T_{c} = 91.5K and J_{c~ }3000 Acm^{-2} in zero applied magnetic field. At the time of writing, this value of critical current density remains the highest reported value for Y_1Ba_2Cu _3O_{7-delta} thick films. These high quality thick films were then used in a study of conduction mechanisms and the results are interpreted in terms of flux pinning and thermodynamic fluctuation theory. These results highlighted the complex nature of the conduction process in these new ceramics, which is dominated by the weak-link intergranular contacts. Finally, details are given of Josephson characteristics that were observed in variable thickness microbridges patterned into the

  3. Manipulating femtosecond laser interactions in bulk glass and thin-film with spatial light modulation (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Alimohammadian, Ehsan; Ho, Stephen; Ertorer, Erden; Gherghe, Sebastian; Li, Jianzhao; Herman, Peter R.

    2017-03-01

    Spatial Light Modulators (SLM) are emerging as a power tool for laser beam shaping whereby digitally addressed phase shifts can impose computer-generated hologram patterns on incoming laser light. SLM provide several additional advantages with ultrashort-pulsed lasers in controlling the shape of both surface and internal interactions with materials. Inside transparent materials, nonlinear optical effects can confine strong absorption only to the focal volume, extend dissipation over long filament tracks, or reach below diffraction-limited spot sizes. Hence, SLM beam shaping has been widely adopted for laser material processing applications that include parallel structuring, filamentation, fiber Bragg grating formation and optical aberration correction. This paper reports on a range of SLM applications we have studied in femtosecond processing of transparent glasses and thin films. Laser phase-fronts were tailored by the SLM to compensate for spherical surface aberration, and to further address the nonlinear interactions that interplay between Kerr-lens self-focusing and plasma defocusing effects over shallow and deep focusing inside the glass. Limits of strong and weak focusing were examined around the respective formation of low-loss optical waveguides and long uniform filament tracks. Further, we have employed the SLM for beam patterning inside thin film, exploring the limits of phase noise, resolution and fringe contrast during interferometric intra-film structuring. Femtosecond laser pulses of 200 fs pulse duration and 515 nm wavelength were shaped by a phase-only LCOS-SLM (Hamamatsu X10468-04). By imposing radial phase profiles, axicon, grating and beam splitting gratings, volume shape control of filament diameter, length, and uniformity as well as simultaneous formation of multiple filaments has been demonstrated. Similarly, competing effects of spherical surface aberration, self-focusing, and plasma de-focusing were studied and delineated to enable formation

  4. Separating Bulk and Surface Contributions to Electronic Excited-State Processes in Hybrid Mixed Perovskite Thin Films via Multimodal All-Optical Imaging

    DOE PAGES

    Simpson, Mary Jane; Doughty, Benjamin; Das, Sanjib; ...

    2017-07-04

    A comprehensive understanding of electronic excited-state phenomena underlying the impressive performance of solution-processed hybrid halide perovskite solar cells requires access to both spatially resolved electronic processes and corresponding sample morphological characteristics. In this paper, we demonstrate an all-optical multimodal imaging approach that enables us to obtain both electronic excited-state and morphological information on a single optical microscope platform with simultaneous high temporal and spatial resolution. Specifically, images were acquired for the same region of interest in thin films of chloride containing mixed lead halide perovskites (CH3NH3PbI3–xClx) using femtosecond transient absorption, time-integrated photoluminescence, confocal reflectance, and transmission microscopies. Comprehensive image analysismore » revealed the presence of surface- and bulk-dominated contributions to the various images, which describe either spatially dependent electronic excited-state properties or morphological variations across the probed region of the thin films. Finally, these results show that PL probes effectively the species near or at the film surface.« less

  5. Correlation between propagation loss and silicon dioxide film properties for surface acoustic wave devices.

    PubMed

    Matsuda, Satoru; Miura, Michio; Matsuda, Takashi; Ueda, Masanori; Satoh, Yoshio; Hashimoto, Ken-Ya

    2013-05-01

    The correlation between the propagation loss and SiO2 film properties has been studied for temperature-compensated SAW devices using the SiO2/LiNbO3 structure. The SAW devices were prepared under different deposition temperatures for SiO2 film. Although they possessed excellent temperature coefficient of elasticity characteristics, devices prepared at lower temperature showed lower Q-factors. The SiO2 films were also deposited on a Si substrate under the same deposition conditions used for the SAW device preparation. Optical characterization was performed with Fourier transform infrared spectroscopy (FT-IR), spectrometer measurement, and Raman spectroscopy. IR absorbance spectra were almost same in the FT-IR measurement. However, optical attenuation in the UV region decreased with the deposition temperature in the spectrometer measurement. The optical attenuation is caused by the increase of the extinction coefficient in the SiO2 layer, and its optical wavelength dependence indicated that observed excess attenuation is caused by Rayleigh scattering. The Raman scattering also decreased with the deposition temperature in the Raman spectroscopy. The scattering is caused by the distortion of the SiO2 network. These results indicate that the Rayleigh scattering caused by the distortion of the SiO2 network is the main contributor to the excess SAW propagation loss in this case.

  6. Aluminum nitride thin film based acoustic wave sensors for biosensing applications

    NASA Astrophysics Data System (ADS)

    Xu, Jianzeng

    In recent years, SAW devices have drawn enormous interest from the analytical assay and sensing business, especially in the biosensing area where highly sensitive, cost efficient and miniaturized sensors are in urgent needs. This dissertation focuses on the development of AIN thin film based SAW devices suitable for biosensing applications. AIN thin films have been synthesized on different orientations of sapphire substrates by a plasma source molecular beam epitaxy system. Surface and structural characterization techniques have been applied to investigate the film quality and the results show that high quality c-plane AIN was epitaxially grown on both c-plane and a-plane sapphire substrates. Complete process flows have been developed for the fabrication of SAW delay line and resonator devices. Important electrical parameters such as the insertion loss, bandwidth, and impedance have been measured to assist the design optimization and derivation the phase velocity, electromechanical coupling coefficient, and temperature coefficient of frequency. On both c-plane and a-plane sapphire substrates, the SAW phase velocities (˜5700 m/s) and electromechanical coupling coefficients (˜0.3%) have been thoroughly mapped out with respect to the propagation direction and film thickness to wavelength ratio. The data are of practical importance for designing AIN-based SAW devices. A higher velocity (>6000 m/s) shear horizontal SAW mode has been discovered only at isolated propagating directions. This mode is especially suitable for aqueous biosensing due to its weak energy coupling to liquid. Much stronger response of the SH-SAW mode has been detected on the c-plane AIN on a-plane sapphire structure than on the c-plane AIN on c-plane sapphire structure, which could be attributed to large anisotropy in a-plane sapphire substrate. Linear frequency-temperature relationship has also been observed for both modes. We further quantify the mass sensitivity of the SAW and SH-SAW by

  7. Transient absorption spectroscopy studies on polythiophene-fullerene bulk heterojunction organic blend films sensitized with a low-bandgap polymer.

    PubMed

    Löslein, Heiko; Ameri, Tayebeh; Matt, Gebhard J; Koppe, Markus; Egelhaaf, Hans J; Troeger, Anna; Sgobba, Vito; Guldi, Dirk M; Brabec, Christoph J

    2013-07-12

    Recently, the concept of near-infrared sensitization is successfully employed to increase the light harvesting in large-bandgap polymer-based solar cells. To gain deeper insights into the operation mechanism of ternary organic solar cells, a comprehensive understanding of charge transfer-charge transport in ternary blends is a necessity. Herein, P3HT:PCPDTBT:PCBM ternary blend films are investigated by transient absorption spectroscopy. Hole transfer from PCPDTBT-positive polarons to P3HT in the P3HT:PCPDTBT:PCBM 0.9:0.1:1 blend film can be visualized. This process evolves within 140 ps and is discussed with respect to the proposed charge-generation mechanisms.

  8. 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.

  9. Acoustic wave based MEMS devices for biosensing applications.

    PubMed

    Voiculescu, Ioana; Nordin, Anis Nurashikin

    2012-03-15

    This paper presents a review of acoustic-wave based MEMS devices that offer a promising technology platform for the development of sensitive, portable, real-time biosensors. MEMS fabrication of acoustic wave based biosensors enables device miniaturization, power consumption reduction and integration with electronic circuits. For biological applications, the biosensors are integrated in a microfluidic system and the sensing area is coated with a biospecific layer. When a bioanalyte interacts with the sensing layer, mass and viscosity variations of the biospecific layer can be detected by monitoring changes in the acoustic wave properties such as velocity, attenuation, resonant frequency and delay time. Few types of acoustic wave devices could be integrated in microfluidic systems without significant degradation of the quality factor. The acoustic wave based MEMS devices reported in the literature as biosensors and presented in this review are film bulk acoustic wave resonators (FBAR), surface acoustic waves (SAW) resonators and SAW delay lines. Different approaches to the realization of FBARs, SAW resonators and SAW delay lines for various biochemical applications are presented. Methods of integration of the acoustic wave MEMS devices in the microfluidic systems and functionalization strategies will be also discussed.

  10. Evaluation and criterion determination of the low-k thin film adhesion by the surface acoustic waves with cohesive zone model

    NASA Astrophysics Data System (ADS)

    Xiao, Xia; Qi, Haiyang; Sui, Xiaole; Kikkawa, Takamaro

    2017-03-01

    The cohesive zone model (CZM) is introduced in the surface acoustic wave (SAW) technique to characterize the interfacial adhesion property of the low-k thin film deposited on the Silicon substrate. The ratio of the two parameters in the CZM, the maximum normal traction and normal interface characteristic length, is derived to evaluate the interfacial adhesion properties quantitatively. In this study, the adhesion criterion to judge the adhesion property is newly proposed by the CZM-SAW technique. The criterion determination processes of two kinds of film, dense and porous Black Diamond with different film thicknesses, are presented in this paper. The interfacial adhesion properties of the dense and porous Black Diamond films with different thicknesses are evaluated by the CZM-SAW technique quantitatively and nondestructively. The quantitative adhesion properties are obtained by fitting the experimental dispersion curves with maximum frequency up to 220 MHz with the theoretical ones. Results of the nondestructive CZM-SAW technique and the destructive nanoscratch exhibit the same trend in adhesion properties, which means that the CZM-SAW technique is a promising method for determining the interfacial adhesion. Meanwhile, the adhesion properties of the detected samples are judged by the determined criterion. The test results show that different test film materials with different film thicknesses ranging from 300 nm to 1000 nm are in different adhered conditions. This paper exhibits the advantage of the CZM-SAW technique which can be a universal method to characterize the film adhesion.

  11. Influence of magnetic anisotropy on dynamic magnonic crystals created by surface acoustic waves in yttrium iron garnet films

    NASA Astrophysics Data System (ADS)

    Kryshtal, R. G.; Medved, A. V.

    2017-03-01

    Experimental results on the investigation of the influence of magnetic crystallographic anisotropy onto parameters of dynamic magnonic crystals arising at surface acoustic wave (SAW) propagation in yttrium iron garnet (YIG) films are presented. The main features of such an influence, as we have shown, are: 1) appearance of extra magnonic band gaps together with the normal magnonic band gap existing without anisotropy, 2) the absence of reflections of the incident surface magnetostatic wave at the frequency of these extra gaps, 3) the same depth for the extra gaps was achieved with a relatively small SAW power, almost by the order of magnitude less than in the case of normal magnonic gaps caused by SAW. A possible explanation of the features is given on the base of inelastic scattering of surface magnetostatic waves by SAW with the transformation of the reflected surface wave to the anisotropic direct volume magnetostatic wave existence of which is due to cubic crystallographic anisotropy in YIG. These results may be useful in designing new devices of information processing.

  12. 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.

  13. 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.

  14. Determining the Thickness of Pb Film Similar to Bulk with Energy Dispersion Derived from Quantum Well States

    NASA Astrophysics Data System (ADS)

    Chan, Wen-Yuan; Huang, Hsu-Sheng; Su, Wei-Bin; Hoffmann, Germar; Lu, Shin-Ming; Chang, Chia-Seng; Wu, Maw-Kuen; Tsong, Tien-Tzou

    2013-03-01

    It is known that the energy spacing between adjacent empty quantum well (QW) states in Pb islands on Cu(111) would reveal the shrinking characteristic originating from the effect of the image potential. Using the phase accumulation model, including a phase factor contributed from the image potential, the shrinking energy spacing can be quantitatively explained with the assumption of the parabolic energy versus wave vector (E-k) dispersion. However, an experimental dispersion acquired from analyzing the energies of the QW state reveals a linear E-k relationship corresponding to the Pb bulk band structure, implying the assumed parabolic dispersion is not appropriate. By combining the linear dispersion with the image potential effect in the calculation, it is found that the calculated values of energy spacing of island thickness below eight atomic layers are not in agreement with the experimental measurements. This implies that the electronic structure of Pb islands would be similar to that of the bulk when their thicknesses reach eight-atomic layers.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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

    NASA Astrophysics Data System (ADS)

    Carlie, N.; Anheier, N. C.; Qiao, H. A.; Bernacki, B.; Phillips, M. C.; Petit, L.; Musgraves, J. D.; Richardson, K.

    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.

  20. First-principles simulation of the optical response of bulk and thin-film α-quartz irradiated with an ultrashort intense laser pulse

    SciTech Connect

    Lee, Kyung-Min; Min Kim, Chul; Moon Jeong, Tae; Sato, Shunsuke A.; Otobe, Tomohito; Shinohara, Yasushi; Yabana, Kazuhiro

    2014-02-07

    A computational method based on a first-principles multiscale simulation has been used for calculating the optical response and the ablation threshold of an optical material irradiated with an ultrashort intense laser pulse. The method employs Maxwell's equations to describe laser pulse propagation and time-dependent density functional theory to describe the generation of conduction band electrons in an optical medium. Optical properties, such as reflectance and absorption, were investigated for laser intensities in the range 10{sup 10} W/cm{sup 2} to 2 × 10{sup 15} W/cm{sup 2} based on the theory of generation and spatial distribution of the conduction band electrons. The method was applied to investigate the changes in the optical reflectance of α-quartz bulk, half-wavelength thin-film, and quarter-wavelength thin-film and to estimate their ablation thresholds. Despite the adiabatic local density approximation used in calculating the exchange–correlation potential, the reflectance and the ablation threshold obtained from our method agree well with the previous theoretical and experimental results. The method can be applied to estimate the ablation thresholds for optical materials, in general. The ablation threshold data can be used to design ultra-broadband high-damage-threshold coating structures.

  1. Bulk heterojunction thin film formation by single and dual feed ultrasonic spray method for application in organic solar cells

    NASA Astrophysics Data System (ADS)

    Marathe, D. M.; Tarkas, H. S.; Mahajan, M. S.; Lonkar, G. S.; Tak, S. R.; Sali, J. V.

    2016-09-01

    We here present a way of preparing the polymer: fullerene BHJ using dual feed method which can lead to formation of pure phases. In this report, we present results of our initial experiments in this direction. The effect of process parameters on the thickness and surface roughness of the active layer has been discussed. The structural and optical properties have been studied using the optical microscope, UV—visible spectroscopy and photoluminescence spectroscopy. Significant PL quenching indicates efficient charge separation in the BHJ formed using this technique. We have also compared the BHJ thin films prepared with this dual feed ultrasonic technique with the single feed spray method. The BHJ formed using this technique has been used as an active layer in OSC. supported by the University Grants Commission, New Delhi, under Faculty Improvement Programme (No. 33-02/12(WRO) Dt.19.03.2013) and the Special Assistance Programme (530/2/DRS/2010(SAP-I)) Phase-II.

  2. The Vibration and Acoustic Properties of Pipes with Squeeze Film and Some Friction Damping Systems.

    NASA Astrophysics Data System (ADS)

    Li, Meng

    1991-01-01

    Available from UMI in association with The British Library. This study was motivated by the need to decrease the noise radiation and vibration of pipework in power plants, particularly at elevated temperature. A thin circular cylindrical shell has been studied theoretically. The exact solutions for natural frequencies of the symmetrical and anti-symmetrical modes for cylindrical shell vibration have been derived in matrix form. Using this theory, numerical results for natural frequencies and mode shapes with free-free, clamped-free and clamped -clamped boundary conditions have been evaluated. Based upon studies of the thin cylindrical shell theory and the physical phenomenon of air film damping of two parallel plates, the theory for predicting the loss factor of an annular double pipe damping system with a very small air gap has been developed. Flugge's thin shell equations of motion and the Navier-Stokes equation for viscous fluid were employed in the analysis. The fluid motion was expressed in terms of the shell displacement by using a travelling wave type solution. The solutions gave the fluid velocity profiles and stresses in the clearance between two cylindrical, concentric shells. According to the definition of energy dissipated in the fluid, an equation was derived for predicting the loss factor of the whole damping system. Based on the principle of similarity, an optimum design for a system generating squeeze film damping in pipes has been made. The theory was then extended to study the damping caused by various kinds of viscous fluid in the gap between the two annular structures. Experiments have been carried out to investigate the loss factor of the double pipe system with in-phase and out-of-phase modes of vibration. Friction damping has been studied experimentally on a thin-walled pipe with a coiled steel spring or wire rope attached or with a mineral wool wrapping. Flexural vibration was examined in the experiments. This study included an experimental

  3. Kinetics of electrochemically controlled surface reactions on bulk and thin film metals studied with Fourier transform impedance spectroscopy and surface plasmon resonance techniques

    NASA Astrophysics Data System (ADS)

    Assiongbon, Kankoe A.

    2005-07-01

    In the work presented in this thesis, the surface sensitive electrochemical techniques of cyclic voltametry (CV), potential step (PS) and Fourier transform impedance spectroscopy (FT-EIS), as well as the optical technique of surface plasmon resonance (SPR), were used to probe a wide variety of surface processes at various metal/liquid interface. Three polycrystalline metals (Au, Ta and Cu) and a Cr-coated gold film were used for these studies in different aqueous environments. A combination of CV with FT-EIS and PS was used to investigate electronic and structural proprieties of a modified bulk electrode of Au. This experimental system involved under potential deposition (UPD) of Bi3+ on Au in a supporting aqueous electrolyte containing ClO-4 . UPD range of Bi3+ was determined, and adsorption kinetics of Bi3+ in the presence of coadsorbing anion, ClO-4 were quantified. Potentiodynamic growth of oxide films of Ta in the following electrolytes NaNO3, NaNO3 + 5wt% H2O2, NaOH and NaOH + 5wt% H2O2 had been investigated. The oxide films were grown in the range -0.1 → +0.4V (high electric field) at a scan rate of 10 mV/s. Time resolved A.C. impedance spectroscopy measurements in the frequency range (0.1--20 KHz) were performed to characterize the surface reactions of oxide formation. The results are interpreted in terms of charge conductivity O2- through the oxide film, and disintegration of H2O2 into OH-. In a high pH medium (pH 12), dissociation of H2O2 was catalytically enhanced. This led to destabilization of the electrogenerated tantalum oxide surface film in the form of a soluble hexatantalate species. In contrast with the electrolytes, NaNO3, NaNO3 + 5wt% H2O2, NaOH, where only the oxide growth was observed, the A.C. impedance spectroscopy measurements in NaOH + 5wt% H 2O2 showed competition between oxide formation and its removal. These results are relevant for chemical slurry design in chemical mechanical polishing (CMP) of Ta. Further investigations were

  4. Self-assembly of linear and cyclic siloxane-containing mesogens: investigation of layered structures in bulk and thin films.

    PubMed

    Heinz, Paul; Hindelang, Konrad; Golosova, Anastasia; Papadakis, Christine M; Rieger, Bernhard

    2011-12-23

    Silicon-containing materials which possess the ability to form mesophases are promising systems for applications in the fields of electro-optical devices, nonlinear optics, and information storage media. In this work, the formation of supramolecular assemblies of a series of low molecular weight siloxane-containing mesogens is presented. Besides a novel synthesis route via Ru(II) -catalyzed hydrosilylation of phenyl acetylene derivatives, mesophase characterization by modern analysis techniques is performed. As linker groups, leading to bi- and tetramesogens, linear disiloxane and cyclic tetrasiloxane are utilized. In the resulting class of materials, high thermal stability, induced by the formation of layered smectic-type structures, is predominant. The smectic-type phases were found to be monotropic. Layer distances in the assemblies, as well as the phase transition temperatures, can be controlled by the substitution motif on the mesogens (number and length of alkyl chains). In spin-cast thin films, the layered domains are visualized by atomic force microscopy; furthermore, domain dimensions and electron densities are determined by grazing-incidence small-angle X-ray scattering.

  5. 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.

  6. 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.

  7. Acoustic neuroma

    MedlinePlus

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

  8. 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

    2016-02-07

    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.

  9. XPS and DFT study of pulsed Bi-implantation of bulk and thin-films of ZnO-The role of oxygen imperfections

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    An atomic and electronic structure of the bulk and thin-film morphologies of ZnO were modified using pulsed Bi-ion implantation (1 × 1017 cm-2 fluence, 70 min exposure under Bi-ion beam, EBi+ = 30 keV, pulsed ion-current density of not more than 0.8 mA/cm2 with a repetition rate of 12.5 Hz). The final samples were qualified by X-ray photoelectron core-level and valence band mapping spectroscopy applying ASTM materials science standard. The spectroscopy data obtained was discussed on the basis of DFT-models for Bi-embedding into ZnO host-matrices. It was established that in the case of direct Bi-impurities insertion into the employed ZnO-host for both studied morphologies neither the only ;pure; Bi2O3-like phase nor the only ;pure; Bi-metal will be preferable to appear as a secondary phase. An unfavorability of the large cluster agglomeration of Bi-impurities in ZnO-hosts has been shown and an oxygen 2s electronic states pleomorphizm was surely established.

  10. Characterization of Atomic Structure, Relaxation and Phase Transformation Mechanisms in Bulk and Thin Film Amorphous Chalcogenides and Gallium Antimonide

    NASA Astrophysics Data System (ADS)

    Edwards, Trenton Gerard

    intermediate between a randomly connected and a fully clustered network of GeSe4 tetrahedra and Se chains. Additionally, a new two-dimensional NMR spectroscopic technique is developed and applied to Ge-Se glasses that allowed the separation of isotropic and anisotropic chemical shifts. Through the analysis of the anisotropic sideband pattern in the second dimension it is possible to detect up to four distinct types of Se environments in the glass structure on the basis of their characteristic chemical shift anisotropies. 125Te NMR chemical shift systematics is established for coordination environments of Te atoms in a wide range of crystalline and glassy tellurides in the Ga-As-Sb-Te system. 125Te NMR spectroscopy is then used to investigate the short-range structure of amorphous and crystalline Ge1Sb2 Te4 and Ge2Sb2Te5 phase change alloys. Both alloys are found to consist of only heteropolar Ge/Sb-Te bonds in the amorphous and crystalline state and strong vacancy clustering in the nanocrystalline state that may facilitate a rapid displacive transformation between the amorphous and crystalline states without the need of significant atomic rearrangement or diffusion. Based on these 125Te NMR results a Te-centric model of the phase change mechanism in GST alloys is proposed. Structure and phase changes in amorphous Ga-Sb alloys are studied using synchrotron x-ray diffraction and 71Ga and 121Sb NMR spectroscopy. Pressure induced phase transformations in amorphous GaSb is shown to be consistent with the existence of an underlying polyamorphic phase transition between a low and a high-density amorphous phase. NMR results for amorphous Ga46Sb54 indicate that both Ga and Sb atoms are fourfold coordinated with 40% of these atoms participating in homopolar bonding in the as-deposited film. Subsequent crystallization into the zinc blend structure therefore requires extensive bond switching and elimination of homopolar bonds. For amorphous Ga14Sb86 both Ga and Sb atoms are found to be

  11. Acoustically actuated ultra-compact NEMS magnetoelectric antennas.

    PubMed

    Nan, Tianxiang; Lin, Hwaider; Gao, Yuan; Matyushov, Alexei; Yu, Guoliang; Chen, Huaihao; Sun, Neville; Wei, Shengjun; Wang, Zhiguang; Li, Menghui; Wang, Xinjun; Belkessam, Amine; Guo, Rongdi; Chen, Brian; Zhou, James; Qian, Zhenyun; Hui, Yu; Rinaldi, Matteo; McConney, Michael E; Howe, Brandon M; Hu, Zhongqiang; Jones, John G; Brown, Gail J; Sun, Nian Xiang

    2017-08-22

    State-of-the-art compact antennas rely on electromagnetic wave resonance, which leads to antenna sizes that are comparable to the electromagnetic wavelength. As a result, antennas typically have a size greater than one-tenth of the wavelength, and further miniaturization of antennas has been an open challenge for decades. Here we report on acoustically actuated nanomechanical magnetoelectric (ME) antennas with a suspended ferromagnetic/piezoelectric thin-film heterostructure. These ME antennas receive and transmit electromagnetic waves through the ME effect at their acoustic resonance frequencies. The bulk acoustic waves in ME antennas stimulate magnetization oscillations of the ferromagnetic thin film, which results in the radiation of electromagnetic waves. Vice versa, these antennas sense the magnetic fields of electromagnetic waves, giving a piezoelectric voltage output. The ME antennas (with sizes as small as one-thousandth of a wavelength) demonstrates 1-2 orders of magnitude miniaturization over state-of-the-art compact antennas without performance degradation. These ME antennas have potential implications for portable wireless communication systems.The miniaturization of antennas beyond a wavelength is limited by designs which rely on electromagnetic resonances. Here, Nan et al. have developed acoustically actuated antennas that couple the acoustic resonance of the antenna with the electromagnetic wave, reducing the antenna footprint by up to 100.

  12. The effect of geometry and post-annealing on surface acoustic wave characteristics of AlN thin films prepared by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Phan, Duy-Thach; Chung, Gwiy-Sang

    2011-08-01

    This paper describes experimental relationship between surface acoustic wave (SAW) properties of two-port SAW resonators based on polycrystalline aluminum nitride (AlN) thin films grown on Si substrates by using a pulsed reactive magnetron sputtering system and their geometry's parameters. Moreover, the influence of post-deposition heat treatment on SAW properties of AlN thin films was investigated at different annealing temperature (600 °C and 900 °C). The measurement results show the number of the inter-digital transducers (IDT) finger pairs ( N), the number of reflectors grating pairs ( R) and the IDT center-to-center distance ( L) related to insertion loss of SAW resonators. The best result of insertion loss was 15.6 dB for SAW resonators with R = 160 pair, N = 5 pair and L = 750 μm. At the same geometry parameters, the SAW velocity and insertion loss were improved slightly after annealing at 600 °C and were worse for the films annealed at 900 °C by changes in the surface morphology and stress on the film.

  13. Experimental study of the acoustical properties of polymers utilized to construct PVDF ultrasonic transducers and the acousto-electric properties of PVDF and P(VDF/TrFE) films.

    PubMed

    Bloomfield, P E; Lo, W J; Lewin, P A

    2000-01-01

    Several acoustic transmission and reflection technique measurements were carried out to determine mechanical properties (acoustic attenuation and velocity) versus frequency of polyvinylidene-fluoride (PVDF) and six other polymers. Acoustic measurements (0.5 to 12 MHz) included time-delay spectrometry (TDS; in which separate transmitting and receiving transducers utilize a swept frequency signal) and two pulse-echo methods (short tone burst echoes utilizing transducers with different center frequencies and Fourier analysis of echoes sent and received by damped transducers operating in the broadband pulse mode). Electrical impedance measurements of piezoelectric thin films of PVDF and P(VDF/TrFE) yielded comparable high frequency mechanical parameters. Of the seven acoustically examined polymers, PVDF had the greatest acoustic impedance, lowest acoustic velocity, and greatest mechanical loss (13.4 dB/cm per MHz). Polymethyl-methacrylate (PMMA; lucite) and polydimethyl-pentane (TPX) had the lowest loss. PMMA had the highest acoustic velocity, and TPX had the lowest acoustic impedance and a velocity almost identical to that of PVDF. These data are useful in the design of backing, matching, and lens materials to be used in association with PVDF transducers.

  14. Acoustic Transduction Materials and Devices

    DTIC Science & Technology

    1998-01-01

    are to Cymbal and Tonpilz transducer arrays for 3 - 50 kHz sonars, thin/thick film transducers for 10 - 100 MHz medical acoustic devices...Cymbal arrayed projectors, PMN Tonpilz tunable transducers , thin/thick film micro- Tonpilz transducers and controlling electronics. The Center for...emphasis is shifting to the acoustic vector sensor. Film transducers The goal is to use the tonpilz design to facilitate development of high

  15. 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.

  16. High-acoustic-impedance tantalum oxide layers for insulating acoustic reflectors.

    PubMed

    Capilla, Jose; Olivares, Jimena; Clement, Marta; Sangrador, Jesús; Iborra, Enrique; Devos, Arnaud

    2012-03-01

    This work describes the assessment of the acoustic properties of sputtered tantalum oxide films intended for use as high-impedance films of acoustic reflectors for solidly mounted resonators operating in the gigahertz frequency range. The films are grown by sputtering a metallic tantalum target under different oxygen and argon gas mixtures, total pressures, pulsed dc powers, and substrate biases. The structural properties of the films are assessed through infrared absorption spectroscopy and X-ray diffraction measurements. Their acoustic impedance is assessed by deriving the mass density from X-ray reflectometry measurements and the acoustic velocity from picosecond acoustic spectroscopy and the analysis of the frequency response of the test resonators.

  17. XPS-and-DFT analyses of the Pb 4f - Zn 3s and Pb 5d - O 2s overlapped ambiguity contributions to the final electronic structure of bulk and thin-film Pb-modulated zincite

    NASA Astrophysics Data System (ADS)

    Zatsepin, D. A.; Boukhvalov, D. W.; Gavrilov, N. V.; Kurmaev, E. Z.; Zatsepin, A. F.; Cui, L.; Shur, V. Ya.; Esin, A. A.

    2017-05-01

    The electronic structures of zincite Pb-modulated bulk and thin-films were studied via X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) techniques. Both XPS data and DFT-calculations allowed the derivation of two different Pb-embedding scenarios into the ZnO-hosts. These included the high-interaction mode of Pb-impurity with initial zinc-oxygen host-lattice for the bulk morphology, accompanied with low Pb-metal losses; and the low-interaction mode for thin-films, where there was intake of Pb-impurities into the hollows of the surface. Despite dissimilar mechanisms of Pb-impurity accumulation and distribution in the bulk and thin-films zincite host-matrices, the strong Pb 4f - Zn 3s and Pb 5d - O 2s overlapped ambiguity contribution to the appropriate core-level structure and valence bands was established by XPS analysis and reproduced with the help of DFT-calculations. It was shown that the microscopic structure of the embedded lead-impurity played a crucial role in the Pb ion-beam stimulated synthesis of secondary lead-oxygen phases via large-area defect fabrication, and the difference among zincite and wurzite polymorphs played almost no role in this case.

  18. Nanomechanical and optical properties of highly a-axis oriented AlN films

    NASA Astrophysics Data System (ADS)

    Jose, Feby; Ramaseshan, R.; Tripura Sundari, S.; Dash, S.; Tyagi, A. K.; Kiran, M. S. R. N.; Ramamurty, U.

    2012-12-01

    This paper reports optical and nanomechanical properties of predominantly a-axis oriented AlN thin films. These films were deposited by reactive DC magnetron sputtering technique at an optimal target to substrate distance of 180 mm. X-ray rocking curve (FWHM = 52 arcsec) studies confirmed the preferred orientation. Spectroscopic ellipsometry revealed a refractive index of 1.93 at a wavelength of 546 nm. The hardness and elastic modulus of these films were 17 and 190 GPa, respectively, which are much higher than those reported earlier can be useful for piezoelectric films in bulk acoustic wave resonators.

  19. Photoinduced coherent acoustic phonon dynamics inside Mott insulator Sr2IrO4 films observed by femtosecond X-ray pulses

    NASA Astrophysics Data System (ADS)

    Zhang, Bing-Bing; Liu, Jian; Wei, Xu; Sun, Da-Rui; Jia, Quan-Jie; Li, Yuelin; Tao, Ye

    2017-04-01

    We investigate the transient photoexcited lattice dynamics in a layered perovskite Mott insulator Sr2IrO4 film by femtosecond X-ray diffraction using a laser plasma-based X-ray source. The ultrafast structural dynamics of Sr2IrO4 thin films are determined by observing the shift and broadening of (0012) Bragg diffraction after excitation by 1.5 eV and 3.0 eV pump photons for films with different thicknesses. The observed transient lattice response can be well interpreted as a distinct three-step dynamics due to the propagation of coherent acoustic phonons generated by photoinduced quasiparticles (QPs). Employing a normalized phonon propagation model, we found that the photoinduced angular shifts of the Bragg peak collapse into a universal curve after introducing normalized coordinates to account for different thicknesses and pump photon energies, pinpointing the origin of the lattice distortion and its early evolution. In addition, a transient photocurrent measurement indicates that the photoinduced QPs are charge neutral excitons. Mapping the phonon propagation and correlating its dynamics with the QP by ultrafast X-ray diffraction (UXRD) establish a powerful way to study electron-phonon coupling and uncover the exotic physics in strongly correlated systems under nonequilibrium conditions.

  20. 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.

  1. Modern Acoustics, Based on Metamaterials

    NASA Astrophysics Data System (ADS)

    Gan, Woon S.

    We discover parity invariance in acoustic field equation. Acoustic metamaterials are a special type of metamaterials with negative mass density and negative bulk modulus and the Poynting vector in opposite direction to wave propagation. This is also known as lefthanded material because the Poynting vector with mass density and bulk modulus form a lefthanded set. For lefthanded material the parity is -1. Double negativity and Poynting vector in opposite direction to wave propagation give rise to new phenomena in refraction diffraction and scattering of acoustic waves. These three are the basic mechanisms of sound propagation in medium. For each new mechanism, there are several new acoustic devices to be developed. Hence we call this the new acoustics. The PHONONICS 2011 to be held in Santa Fe, New Mexico, USA on May 29 - June 2, 2011 supports our idea of New Acoustics.

  2. Strain evolution of epitaxial tetragonal-like BiFeO3 thin films on LaAlO3(001) substrates prepared by sputtering and their bulk photovoltaic effect

    NASA Astrophysics Data System (ADS)

    Nakashima, Seiji; Uchida, Tomohisa; Doi, Kentaro; Saitoh, Koh; Fujisawa, Hironori; Sakata, Osami; Katsuya, Yoshio; Tanaka, Nobuo; Shimizu, Masaru

    2016-10-01

    The structural evolution of high-quality 3.3-73.2-nm-thick tetragonal-like BiFeO3 (T-BFO) thin films grown on LaAlO3(001) substrates and the bulk photovoltaic effect of the films were investigated. The T-BFO films were grown by rf magnetron sputtering, showing the Peudellösung fringes around the T-BFO (001) diffraction peak in X-ray diffraction θ-2θ patterns. These indicate the structural coherence between the surface and the interface in the surface normal direction of the films. High-resolution synchrotron X-ray diffraction analysis and transmission electron microscopy reveal that the lattice relaxation behavior from the MA monoclinic to MC monoclinic structure occurs as the film thickness increases. The domain structure was partly controlled by using a vicinal LAO (001) substrate along [100]. Regarding the current-voltage characteristics of the Pt/T-BFO/Pt coplanar capacitor under violet laser illumination, T-BFO films show an anomalous photovoltaic effect with an open-circuit voltage of 6.1 V and a short-circuit current of -290 pA along the [100]T-BFO direction.

  3. Donor-acceptor stacking arrangements in bulk and thin-film high-mobility conjugated polymers characterized using molecular modelling and MAS and surface-enhanced solid-state NMR spectroscopy.

    PubMed

    Chaudhari, Sachin R; Griffin, John M; Broch, Katharina; Lesage, Anne; Lemaur, Vincent; Dudenko, Dmytro; Olivier, Yoann; Sirringhaus, Henning; Emsley, Lyndon; Grey, Clare P

    2017-04-01

    Conjugated polymers show promising properties as cheap, sustainable and solution-processable semiconductors. A key challenge in the development of these materials is to determine the polymer chain structure, conformation and packing in both the bulk polymer and in thin films typically used in devices. However, many characterisation techniques are unable to provide atomic-level structural information owing to the presence of disorder. Here, we use molecular modelling, magic-angle spinning (MAS) and dynamic nuclear polarisation surface-enhanced NMR spectroscopy (DNP SENS) to characterise the polymer backbone group conformations and packing arrangement in the high-mobility donor-acceptor copolymer diketopyrrolo-pyrrole-dithienylthieno[3,2-b]thiophene (DPP-DTT). Using conventional (1)H and (13)C solid-state MAS NMR coupled with density functional theory calculations and molecular dynamics simulations, we find that the bulk polymer adopts a highly planar backbone conformation with a laterally-shifted donor-on-acceptor stacking arrangement. DNP SENS enables acquisition of (13)C NMR data for polymer films, where sensitivity is limiting owing to small sample volumes. The DNP signal enhancement enables a two-dimensional (1)H-(13)C HETCOR spectrum to be recorded for a drop-cast polymer film, and a (13)C CPMAS NMR spectrum to be recorded for a spin-coated thin-film with a thickness of only 400 nm. The results show that the same planar backbone structure and intermolecular stacking arrangement is preserved in the films following solution processing and annealing, thereby rationalizing the favourable device properties of DPP-DTT, and providing a protocol for the study of other thin film materials.

  4. Effect of film thickness and viscoelasticity on separability of vapour classes by wavelet and principal component analyses of polymer-coated surface acoustic wave sensor transients

    NASA Astrophysics Data System (ADS)

    Singh, Prashant; Yadava, R. D. S.

    2011-02-01

    The transient response of a polymer-coated surface acoustic wave (SAW) vapour sensor depends on partitioning and diffusion of vapour species into the polymer in conjunction with its thickness and viscoelastic properties. The shapes of transient signals carry information about vapour identities due to specificity of the partition coefficient and the diffusion coefficient. The analysis of transient signals therefore offers a simpler approach for vapour identification in comparison to conventional electronic nose systems that employ a broadly selective sensor array. The transient response-based methods are however not developed to a similar level of maturity as their sensor array counterparts. The main reason for this is associated with complex signal generation kinetics and polymer viscoelasticity. The latter is independent of vapour identities (assuming low concentrations) but influences sensor response through nonlinear dependences on polymer thickness and viscoelastic coefficients. In this paper, we endeavour to find out whether viscoelasticity and its manifestation through thickness dependences could be turned into an advantage for transient-based vapour identification. Using an established SAW sensor model with additive noise we analyse sensor transients by wavelet decomposition and principal component analysis (PCA) for various combinations of polymer thickness, viscoelastic storage and loss moduli and noise level. We calculate vapour class separability measures defined on the basis of scatter matrices of principal components of wavelet coefficients to determine the discrimination ability of sensor transients for various combinations of film thickness and viscoelastic parameters. The simulation experiments are performed by considering a polyisobutylene-coated SAW oscillator sensor under exposure to seven volatile organic compounds (chloroform, chlorobenzene, o-dichlorobenzene, n-heptane, toluene, n-hexane and n-octane). The film thicknesses are varied from thin

  5. Films.

    ERIC Educational Resources Information Center

    Philadelphia Board of Education, PA. Div. of Instructional Materials.

    The Affective Curriculum Research Project produced five films and two records during a series of experimental summer programs. The films and records form part of a curriculum designed to teach to the concerns of students. The films were an effort to describe the Philadelphia Cooperative Schools Program, to explain its importance, and to…

  6. Observation of guided longitudinal acoustic modes and nondestructive characterization of the elastic properties of hard films/coatings

    SciTech Connect

    Chirita, M.; Sooryakumar, R.; Xia, Hua; Monteiro, O. R.; Brown, I. G.

    1999-12-02

    We report on a new high frequency excitation, identified as a longitudinal guided mode, supported in a hard isotropic film deposited on a substrate. The observation of this mode allows for a direct determination of the C{sub 11} elastic constant of the film. The remaining constant, C{sub 44}, was determined through a least square fit to the dispersion of the pseudo surface wave. Properties of the observed excitations were investigated by evaluating their mode density and polarization characteristics.

  7. 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.

  8. Double-negative acoustic metamaterial.

    PubMed

    Li, Jensen; Chan, C T

    2004-11-01

    We show here the existence of acoustic metamaterial, in which both the effective density and bulk modulus are simultaneously negative, in the true and strict sense of an effective medium. Our double-negative acoustic system is an acoustic analogue of Veselago's medium in electromagnetism, and shares many unique consequences, such as negative refractive index. The double negativity in acoustics is derived from low-frequency resonances, as in the case of electromagnetism, but the negative density and modulus are derived from a single resonance structure as distinct from electromagnetism in which the negative permeability and negative permittivity originates from different resonance mechanisms.

  9. Acoustically controlled integrated laser for communications systems

    NASA Technical Reports Server (NTRS)

    Elachi, C.

    1975-01-01

    Acoustic wave creates fringes by producing periodic stresses in substrate and in film. Laser carrier frequency is then changed by simply changing acoustical frequency. When two acoustical sources are applied off beam axis, beam can be scanned at very rapid rates.

  10. Acoustic Neuroma

    MedlinePlus

    ... search IRSA's site Unique Hits since January 2003 Acoustic Neuroma Click Here for Acoustic Neuroma Practice Guideline ... to microsurgery. One doctor's story of having an acoustic neuroma In August 1991, Dr. Thomas F. Morgan ...

  11. Films

    NASA Astrophysics Data System (ADS)

    Li, Ming; Zhang, Yang; Shao, Yayun; Zeng, Min; Zhang, Zhang; Gao, Xingsen; Lu, Xubing; Liu, J.-M.; Ishiwara, Hiroshi

    2014-09-01

    In this paper, we investigated the microstructure and electrical properties of Bi2SiO5 (BSO) doped SrBi2Ta2O9 (SBT) films deposited by chemical solution deposition. X-ray diffraction observation indicated that the crystalline structures of all the BSO-doped SBT films are nearly the same as those of a pure SBT film. Through BSO doping, the 2Pr and 2Ec values of SBT films were changed from 15.3 μC/cm2 and 138 kV/cm of pure SBT to 1.45 μC/cm2 and 74 kV/cm of 10 wt.% BSO-doped SBT. The dielectric constant at 1 MHz for SBT varied from 199 of pure SBT to 96 of 10 wt.% BSO-doped SBT. The doped SBT films exhibited higher leakage current than that of non-doped SBT films. Nevertheless, all the doped SBT films still had small dielectric loss and low leakage current. Our present work will provide useful insights into the BSO doping effects to the SBT films, and it will be helpful for the material design in the future nonvolatile ferroelectric memories.

  12. Large enhancement of bulk spin polarization by suppressing Co{sub Mn} anti-sites in Co{sub 2}Mn(Ge{sub 0.75}Ga{sub 0.25}) Heusler alloy thin film

    SciTech Connect

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

    2016-03-21

    We have investigated the structure and magneto-transport properties of Co{sub 2}Mn(Ge{sub 0.75}Ga{sub 0.25}) (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 Co{sub Mn} 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 μm{sup 2} 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 Co{sub Mn}-antisites in CMGG films, being consistent with first-principle calculation results.

  13. Effects of working pressure and annealing on bulk density and nanopore structures in amorphous In-Ga-Zn-O thin-film transistors

    NASA Astrophysics Data System (ADS)

    Ide, Keisuke; Kikuchi, Mitsuho; Ota, Masato; Sasase, Masato; Hiramatsu, Hidenori; Kumomi, Hideya; Hosono, Hideo; Kamiya, Toshio

    2017-03-01

    Microstructures of amorphous In-Ga-Zn-O (a-IGZO) thin films of different densities were analyzed. Device-quality a-IGZO films were deposited under optimum conditions, e.g., the total pressure P tot = 0.55 Pa produced high film densities of ˜6.1 g/cm3, while a very high P tot = 5.0 Pa produced low film densities of 5.5 g/cm3. Both films formed uniform high-density layers in the vicinity of the glass substrate, 10-20 nm in thickness depending on P tot, while their growth mode changed to a sparse columnar structure in thicker regions. X-ray reflectivity and in situ spectroscopic ellipsometry provided different results on densification by post deposition thermal annealing; i.e., the latter has a higher sensitivity. High-Z-contrast images obtained by high-angle annular dark-field scanning transmission electron microscopy were also useful for detecting nanometer-size non uniformity even in device-quality a-IGZO films.

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

    PubMed

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

    2015-07-17

    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.

  15. 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

  16. 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.

  17. Virtual Acoustics

    NASA Astrophysics Data System (ADS)

    Lokki, Tapio; Savioja, Lauri

    The term virtual acoustics is often applied when sound signal is processed to contain features of a simulated acoustical space and sound is spatially reproduced either with binaural or with multichannel techniques. Therefore, virtual acoustics consists of spatial sound reproduction and room acoustics modeling.

  18. Identifying barriers to charge-carriers in the bulk and surface regions of Cu2ZnSnS4 nanocrystal films by x-ray absorption fine structures (XAFSs).

    PubMed

    Turnbull, Matthew J; Vaccarello, Daniel; Yiu, Yun Mui; Sham, Tsun-Kong; Ding, Zhifeng

    2016-11-28

    Solar cell performance is most affected by the quality of the light absorber layer. For thin-film devices, this becomes a two-fold problem of maintaining a low-cost design with well-ordered nanocrystal (NC) structure. The use of Cu2ZnSnS4 (CZTS) NCs as the light absorber films forms an ideal low-cost design, but the quaternary structure makes it difficult to maintain a well-ordered layer without the use of high-temperature treatments. There is little understanding of how CZTS NC structures affect the photoconversion efficiency, the charge-carriers, and therefore the performance of the device manufactured from it. To examine these relationships, the measured photoresponse from the photo-generation of charge-carrier electron-hole pairs was compared against the crystal structure, as short-range and long-range crystal orders for the films. The photoresponse simplifies the electronic properties into three basic steps that can be associated with changes in energy levels within the band structure. These changes result in the formation of barriers to charge-carrier flow. The extent of these barriers was determined using synchrotron-based X-ray absorbance fine structure to probe the individual metal centers in the film, and comparing these to molecular simulations of the ideal extended x-ray absorbance fine structure scattering. This allowed for the quantification of bond lengths, and thus an interpretation of the distortions in the crystal lattice. The various characteristics of the photoresponse were then correlated to the crystallographic order and used to gain physical insight into barriers to charge-carriers in the bulk and surface regions of CZTS films.

  19. Identifying barriers to charge-carriers in the bulk and surface regions of Cu2ZnSnS4 nanocrystal films by x-ray absorption fine structures (XAFSs)

    NASA Astrophysics Data System (ADS)

    Turnbull, Matthew J.; Vaccarello, Daniel; Yiu, Yun Mui; Sham, Tsun-Kong; Ding, Zhifeng

    2016-11-01

    Solar cell performance is most affected by the quality of the light absorber layer. For thin-film devices, this becomes a two-fold problem of maintaining a low-cost design with well-ordered nanocrystal (NC) structure. The use of Cu2ZnSnS4 (CZTS) NCs as the light absorber films forms an ideal low-cost design, but the quaternary structure makes it difficult to maintain a well-ordered layer without the use of high-temperature treatments. There is little understanding of how CZTS NC structures affect the photoconversion efficiency, the charge-carriers, and therefore the performance of the device manufactured from it. To examine these relationships, the measured photoresponse from the photo-generation of charge-carrier electron-hole pairs was compared against the crystal structure, as short-range and long-range crystal orders for the films. The photoresponse simplifies the electronic properties into three basic steps that can be associated with changes in energy levels within the band structure. These changes result in the formation of barriers to charge-carrier flow. The extent of these barriers was determined using synchrotron-based X-ray absorbance fine structure to probe the individual metal centers in the film, and comparing these to molecular simulations of the ideal extended x-ray absorbance fine structure scattering. This allowed for the quantification of bond lengths, and thus an interpretation of the distortions in the crystal lattice. The various characteristics of the photoresponse were then correlated to the crystallographic order and used to gain physical insight into barriers to charge-carriers in the bulk and surface regions of CZTS films.

  20. Identification of acoustic waves in ZnO materials by Brillouin light scattering for SAW device applications

    NASA Astrophysics Data System (ADS)

    Zerdali, M.; Bechiri, F.; Hamzaoui, S.; Teherani, F. H.; Rogers, D. J.; Sandana, V. E.; Bove, P.; Djemia, P.; Roussigné, Y.

    2017-03-01

    Brillouin light scattering (BLS) was conducted on melt-grown ZnO bulk crystals and ZnO thin films grown by pulsed laser deposition. The bulk ZnO crystals presented both longitudinal and transverse bulk acoustic waves. Theoretical calculations agreed well with there being one piezoelectric longitudinal branch and two transverse branches. BLS measurements conducted on ZnO thin films also revealed Rayleigh surface acoustic waves (R-SAW) guided by only the surface of the layer and Sezawa modes, guided by the film thickness. Measurements were conducted for three incidence angles in order to investigate different SAW wave numbers. Higher frequency features were identified as being related to a new class of guided longitudinal (LG) SAW modes which are not usually detected for ZnO thin films. The LG-SAW modes were observed for two incidence angles (θ=45° and 55°) corresponding to frequencies of 17.88 and 20.75 GHz, respectively. BLS measurements enable us to estimate the LG-SAW velocity as 6500 m/s. This value is three times higher than that of the currently used R-SAW. Theoretical simulations were coherent with the presence of LG modes in the ZnO layers. Such LG-SAW modes are promising for the development of novel, higher-speed SAW devices operating in the GHz-band and which could be readily incorporated in Si-based integrated circuitry.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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.

  3. 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

    2004-11-05

    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).

  4. Linear degrees of freedom in speech production: analysis of cineradio- and labio-film data and articulatory-acoustic modeling.

    PubMed

    Beautemps, D; Badin, P; Bailly, G

    2001-05-01

    The following contribution addresses several issues concerning speech degrees of freedom in French oral vowels, stop, and fricative consonants based on an analysis of tongue and lip shapes extracted from cineradio- and labio-films. The midsagittal tongue shapes have been submitted to a linear decomposition where some of the loading factors were selected such as jaw and larynx position while four other components were derived from principal component analysis (PCA). For the lips, in addition to the more traditional protrusion and opening components, a supplementary component was extracted to explain the upward movement of both the upper and lower lips in [v] production. A linear articulatory model was developed; the six tongue degrees of freedom were used as the articulatory control parameters of the midsagittal tongue contours and explained 96% of the tongue data variance. These control parameters were also used to specify the frontal lip width dimension derived from the labio-film front views. Finally, this model was complemented by a conversion model going from the midsagittal to the area function, based on a fitting of the midsagittal distances and the formant frequencies for both vowels and consonants.

  5. Influence of static and dynamic dipolar fields in bulk YIG/thin film NiFe systems probed via spin rectification effect

    NASA Astrophysics Data System (ADS)

    Soh, Wee Tee; Tay, Z. J.; Yakovlev, N. L.; Peng, Bin; Ong, C. K.

    2017-03-01

    The characteristics of the static and dynamic components of the dipolar fields originating from a bulk polycrystalline yttrium iron garnet (YIG) substrate are probed by depositing a NiFe (Permalloy) layer on it, which acts as a detector. By measuring dc voltages generated via spin rectification effect (SRE) within the NiFe layer under microwave excitation, we characterize the influence of dipolar fields from bulk YIG on the NiFe layer. It is found that the dynamic YIG dipolar fields modify the self-SRE of NiFe, driving its own rectification voltages within the NiFe layer, an effect we term as non-local SRE. This non-local SRE only occurs near the simultaneous resonance of both YIG and NiFe. On the other hand, the static dipolar field from YIG manifests itself as a negative anisotropy in the NiFe layer which shifts the latter's ferromagnetic resonance frequency.

  6. Reducibility of ZrO2/Pt3Zr and ZrO2/Pt 2D films compared to bulk zirconia: a DFT+U study of oxygen removal and H2 adsorption.

    PubMed

    Ruiz Puigdollers, Antonio; Pacchioni, Gianfranco

    2017-05-25

    Oxide reducibility is an important property that determines the chemical and physical behavior of the materials under working conditions. Zirconia is a non-reducible oxide that exhibits high resistance to the loss of oxygen and low reactivity towards hydrogen, two typical processes involved in oxide reduction. Oxide reducibility can change substantially by nanostructuring (e.g. formation of nanoparticles). In this study, we investigate theoretically by means of DFT+U calculations including dispersion interactions the properties of 2D zirconia films supported on a Pt3Zr alloy and Pt metal surfaces, two systems recently prepared experimentally. The results show that the supported ZrO2 ultrathin films behave very differently from the corresponding bulk oxide, with a low formation energy of oxygen vacancies, and a clear tendency to split the H2 molecule homolytically with direct reduction of the oxide. The comparison of free-standing and supported ZrO2 films shows that these peculiar properties are not due to the formation of a 2D nanostructure, but rather to the presence of the metal support and of a metal/oxide interface. The results provide evidence for the uncommon properties of supported 2D oxides.

  7. A comprehensive study on the effects of temperature, surface age, added surfactant, salinity, and bulk viscosity on coalescence time, film rigidity, and interfacial tension: Topical report

    SciTech Connect

    Peru, D.A.; Lorenz, P.B.

    1988-01-01

    The interfacial behavior of a Wilmington crude oil was studied as part of our investigations of enhanced oil recovery by weakly alkaline solutions. For some systems, the spinning drop appratus can be used to measure transient interfacial tension (IFT) effects, coalescence times of oil drops, and film rigidity simultaneously, for rapid screening of chemical slug composition for the potential of improving oil recovery by the mechanisms of oil mobilization and oil bank formation. The experimental results presented include the effects of temperature, surface age, salinity, added surfactant, and polymer on coalescence time, film rigidity, and IFT behavior. Oil displacement tests were performed using surfactant-enhanced bicarbonte solutions formulated for improved mobility control and for improved oil mobilization and oil drop coalescence. The most significant result of this work was that we were able to measure the dynamics in IFT between 2 coalescing oil drops as perturbations in the equilibrium concentration of surfactant at the interface occurred during film drainage. The accuracy of the technique for measuring IFT and film rigidity improved as the contact radii between the oil drops increased. 17 refs., 13 figs., 11 tabs.

  8. Deep-level defects related to the emissive pits in thick InGaN films on GaN template and bulk substrates

    NASA Astrophysics Data System (ADS)

    Sumiya, Masatomo; Toyomitsu, Naoki; Nakano, Yoshitaka; Wang, Jianyu; Harada, Yoshitomo; Sang, Liwen; Sekiguchi, Takashi; Yamaguchi, Tomohiro; Honda, Tohru

    2017-01-01

    We studied the emissive pits in InGaN films grown on compressive and strain-free GaN underlying layers. Pit density decreased with the full width at half maximum of ω(0002) of InGaN. The films grew on compressive and strain-free GaN underlying layers with spiral and step-flow modes, respectively. Carbon impurities accumulated inside the pits. Comparison of cathodoluminescence inside the pits and steady-state photocapacitance spectra showed that the energy level of the carbon impurities appeared at ˜2.8 eV below the conduction band (Ec) for both types of pits. Deep-level defects at Ec -2.4 eV resulting in green fluorescence emission were considered to originate from pits related to screw dislocations.

  9. Elastic properties determination of CuInSe2 polycrystalline thin films via a dynamic method

    NASA Astrophysics Data System (ADS)

    Hadjoub, Z.; Merdes, S.; Hadjoub, I.; Doghmane, A.

    2010-11-01

    Developing and using a simulation program based on the spectrum angular model, we first determine reflectance functions and acoustic signatures for bulk as well as for different thickness of CuInSe2 films. For bulk material, it is found that the longitudinal and Rayleigh modes are excited at incidence angles of 23.4° and 47°, respectively. This result reveals the great difficulties to characterize CuInSe2 with a conventional scanning acoustic microscope that uses a lens half- opening angle of 50° and water as a coupling liquid. Hence, Freon is used as alternative coupling liquid. Consequently, the effect of thickness on reflection coefficient and acoustic signature variations are quantified for both bulk and thin material. It is shown that as the thickness increases: (i) the critical angle of mode excitation increases, (ii) the periods of acoustic signature curves decrease and (iii) the Rayleigh velocity, VR, mode shifts towards lower values. Hence, a velocity dispersion curve is established in terms of VR as a function of film thickness; it decreases initially from the velocity value of the glass substrate then saturates when it reaches that of CuInSe2. The importance of such curve lies in the possibility of velocity determination by just knowing the thickness, and vice versa. Moreover, elastic constants are straight forward deduced from such a velocity.

  10. Depositing bulk or micro-scale electrodes

    DOEpatents

    Shah, Kedar G.; Pannu, Satinderpall S.; Tolosa, Vanessa; Tooker, Angela C.; Sheth, Heeral J.; Felix, Sarah H.; Delima, Terri L.

    2016-11-01

    Thicker electrodes are provided on microelectronic device using thermo-compression bonding. A thin-film electrical conducting layer forms electrical conduits and bulk depositing provides an electrode layer on the thin-film electrical conducting layer. An insulating polymer layer encapsulates the electrically thin-film electrical conducting layer and the electrode layer. Some of the insulating layer is removed to expose the electrode layer.

  11. 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.

  12. Effect of annealing in reduced oxygen pressure on the structure and magnetic properties of M-type hexaferrite bulk and film

    NASA Astrophysics Data System (ADS)

    Moon, Kyoung-Seok; Yang, Dae-Jin; Lee, Sang-Eui; Kim, Dong Hun; Kang, Young-Min

    2017-06-01

    The Ca-La-Co-doped M-type Sr-hexaferrite (Sr0.1Ca0.45La0.45Fe11.7Co0.3O19) decomposed into three different phases of orthorhombic, spinel, and hexagonal structures after annealing at 1200 °C in nitrogen atmosphere while the non-substituted SrFe12O19 maintained the hexagonal structure after annealing at the same condition. It is suggested that the charge-imbalance substitution of La3+/Co2+ = 1.5 induces phase instability of the M-type structure and it causes the phase transformation during the N2 annealing. In film experiment, polycrystalline Sr-hexaferrite films (SrFe12O19) have been prepared by pulsed laser deposition and post-annealing processes. When the film was annealed in vacuum at 500 °C, the magnetization value at the magnetic field H = 15 kOe increased by ∼80% and the coercivity decreased significantly without microstructural change.

  13. 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.

  14. Dependence of Device Characteristics of Bulk-Heterojunction Organic Thin-Film Solar Cells on Concentration of Glycerol and Sorbitol Addition in Pedot:. PSS Solutions for Fabricating Buffer Layers

    NASA Astrophysics Data System (ADS)

    Yamaki, Yusuke; Marumoto, Kazuhiro; Fujimori, Takuya; Mori, Tatsuo

    We have investigated the dependence of device characteristics of bulk-heterojunction organic thin-film solar cells on the concentration of glycerol and sorbitol addition in poly(3,4-ethylenedioxy thiophene):poly(4-styrene sulfonate) (PEDOT:PSS) solutions for fabricating buffer layers. The device structure is ITO/buffer/regioregular poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C61-butyric acid methylester (PCBM)/Al. Glycerol addition is effective for increasing power conversion efficiency (PCE) from 1.25 to 1.41% because of the increase in short-circuit current density (Jsc) without decreasing open-circuit voltage (Voc). On the other hand, sorbitol addition decreases PCE from 1.25 to 1.04%, owing to the decrease in Voc. This difference in Voc behavior is ascribed to different work function of PEDOT:PSS with glycerol and sorbitol treatment.

  15. 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 ...

  16. Applications of bulk high-temperature superconductors

    SciTech Connect

    Hull, J.R.

    1995-06-01

    The development of high-temperature superconductors (HTSs) can be broadly generalized into thin-film electronics, wire applications, and bulk applications. We consider bulk HTSs to include sintered or crystallized forms that do not take the geometry of filaments or tapes, and we discuss major applications for these materials. For the most part applications may be realized with the HTSs cooled to 77 K, and the properties of the bulk HTSs are often already sufficient for commercial use. A non-exhaustive list of applications for bulk HTSs includes trapped field magnets, hysteresis motors, magnetic shielding, current leads, and magnetic bearings. These applications are briefly discussed in this paper.

  17. Applications of bulk high-temperature superconductors

    NASA Astrophysics Data System (ADS)

    Hull, J. R.

    The development of high-temperature superconductors (HTS's) can be broadly generalized into thin-film electronics, wire applications, and bulk applications. We consider bulk HTS's to include sintered or crystallized forms that do not take the geometry of filaments or tapes, and we discuss major applications for these materials. For the most part applications may be realized with the HTS's cooled to 77 K, and the properties of the bulk HTS's are often already sufficient for commercial use. A non-exhaustive list of applications for bulk HTS's includes trapped field magnets, hysteresis motors, magnetic shielding, current leads, and magnetic bearings. These applications are briefly discussed in this paper.

  18. Acoustic Seaglider

    DTIC Science & Technology

    2008-03-07

    a national naval responsibility. Acoustic sensors on mobile, autonomous platforms will enable basic research topics on temporal and spatial...problem and acoustic navigation and communications within the context of distributed autonomous persistent undersea surveillance sensor networks...Acoustic sensors on mobile, autonomous platforms will enable basic research topics on temporal and spatial coherence and the description of ambient

  19. 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.

  20. 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.

  1. 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.

  2. Lattice-Latching Effect in Metalorganic Vapor Phase Epitaxy Growth of InGaAsN Film Lattice-Matched to Bulk InGaAs Substrate

    NASA Astrophysics Data System (ADS)

    Sanorpim, Sakuntam; Katayama, Ryuji; Onabe, Kentaro; Usami, Noritaka; Nakajima, Kazuo

    2010-04-01

    The effects of lattice mismatch between an InzGa1-zAs bulk substrate and an InxGa1-xAs1-yNy epilayer on the incorporation kinetics of N (y) and In (x) were investigated. Compositions (x,y) were revealed to be pinned by the substrate to those satisfying lattice-matching conditions. With decreasing In (z) content in the substrate, the incorporation of N is spontaneously enhanced. On the other hand, the In content of the layer is reduced to decrese the deformation energy due to the lattice mismatch. On the basis of our results, thick InxGa1-xAs1-yNy (0.289 < x < 0.312 and 0.009 < y < 0.014) layers exhibiting photoluminescence in the wavelength range of 1.3-1.55 µm were observed to grow owing to the “lattice-latching” effect.

  3. Using volatile additives to alter the morphology and performance of active layers in thin-film molecular photovoltaic devices incorporating bulk heterojunctions.

    PubMed

    Dang, Minh Trung; Wuest, James D

    2013-12-07

    Thin-film photovoltaic devices composed of polymers or small molecules have an exciting future as sources of renewable energy because they can be made in large sizes on flexible surfaces by inexpensive techniques of fabrication. Significant progress in developing new molecular photovoltaic materials and device architectures has been achieved in the last decade. The identity of molecular components in active layers and their individual optoelectronic properties obviously help determine the properties of devices; in addition, however, the behavior of devices depends critically on the nature of the local organization of the components. Recent studies have shown that the morphology of active layers can be tuned by adjusting various parameters, including the solvent used to cast the layer, thermal annealing, and special processing additives. In this review, we summarize the effect of volatile additives on the nanoscale morphology of molecular blends, and we show how these effects can improve the performance of devices. Although we focus on the behavior of mixtures of the type used in current molecular thin-film photovoltaic devices, the subject of our review will interest researchers in all areas of science and technology requiring materials in which separate phases must form intimate long-lived intermixtures with defined structures.

  4. Magnetic and structural properties of sintered bulk pucks and aerosol deposited films of Ti-doped barium hexaferrite for microwave absorption applications

    NASA Astrophysics Data System (ADS)

    Johnson, Scooter D.; Gonzalez, Christopher M.; Anderson, Virginia; Robinson, Zachary; Newman, Harvey S.; Shin, Sanghoon; Qadri, Syed B.

    2017-07-01

    We report structural, compositional, and magnetic properties for a commercially available doped barium hexaferrite material produced by Temex Ceramics. The material is designed to absorb electromagnetic radiation near the upper edge of the Ku frequency band ( ˜18 GHz) and may serve as an important component to microwave circuitry. To aid in the development of such circuits that may utilize this or similar materials, we present results of the material properties of the raw starting powder, sintered pucks, and in the form of a film deposited by aerosol deposition. We find that the structural and magnetic properties are consistent with the parent compound, barium hexaferrite. Samples sintered at 1250 °C show some degree of preferred magnetic and structural orientation. Chemical analysis indicates that a titanium dopant has been added and that the material demonstrates broad absorption above 13 GHz that improves with sintering temperature. To our knowledge, this is the first report on the properties of this commercially available material.

  5. 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.

  6. Microfluidic device for acoustic cell lysis

    SciTech Connect

    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.

  7. 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.

  8. Study of surface plasmons with a scanning acoustic microscope

    SciTech Connect

    Bereiter-Hahn, J; Blase, C; Lozovik, Yurii E; Nazarov, Maksim M; Shkurinov, A P

    2003-05-31

    A new technique for investigating the surface plasmons by means of a scanning acoustic microscope is proposed. Within this technique, the surface electromagnetic wave (plasmon polariton) is excited by laser radiation on one side of a metal film, while a scanning acoustic microscope excites surface acoustic waves on the other side of the film. Obtained for the first time, the acoustic images of plasmons, propagating on the grating surface, demonstrate the possibility of studying the plasmon wave field distribution by means of a scanning acoustic microscope. (nonlinear optical phenomena)

  9. A spherically-shaped PZT thin film ultrasonic transducer with an acoustic impedance gradient matching layer based on a micromachined periodically structured flexible substrate.

    PubMed

    Feng, Guo-Hua; Liu, Wei-Fan

    2013-10-09

    This paper presents the microfabrication of an acoustic impedance gradient matching layer on a spherically-shaped piezoelectric ultrasonic transducer. The acoustic matching layer can be designed to achieve higher acoustic energy transmission and operating bandwidth. Also included in this paper are a theoretical analysis of the device design and a micromachining technique to produce the novel transducer. Based on a design of a lead titanium zirconium (PZT) micropillar array, the constructed gradient acoustic matching layer has much better acoustic transmission efficiency within a 20-50 MHz operation range compared to a matching layer with a conventional quarter-wavelength thickness Parylene deposition. To construct the transducer, periodic microcavities are built on a flexible copper sheet, and then the sheet forms a designed curvature with a ball shaping. After PZT slurry deposition, the constructed PZT micropillar array is released onto a curved thin PZT layer. Following Parylene conformal coating on the processed PZT micropillars, the PZT micropillars and the surrounding Parylene comprise a matching layer with gradient acoustic impedance. By using the proposed technique, the fabricated transducer achieves a center frequency of 26 MHz and a -6 dB bandwidth of approximately 65%.

  10. A Spherically-Shaped PZT Thin Film Ultrasonic Transducer with an Acoustic Impedance Gradient Matching Layer Based on a Micromachined Periodically Structured Flexible Substrate

    PubMed Central

    Feng, Guo-Hua; Liu, Wei-Fan

    2013-01-01

    This paper presents the microfabrication of an acoustic impedance gradient matching layer on a spherically-shaped piezoelectric ultrasonic transducer. The acoustic matching layer can be designed to achieve higher acoustic energy transmission and operating bandwidth. Also included in this paper are a theoretical analysis of the device design and a micromachining technique to produce the novel transducer. Based on a design of a lead titanium zirconium (PZT) micropillar array, the constructed gradient acoustic matching layer has much better acoustic transmission efficiency within a 20–50 MHz operation range compared to a matching layer with a conventional quarter-wavelength thickness Parylene deposition. To construct the transducer, periodic microcavities are built on a flexible copper sheet, and then the sheet forms a designed curvature with a ball shaping. After PZT slurry deposition, the constructed PZT micropillar array is released onto a curved thin PZT layer. Following Parylene conformal coating on the processed PZT micropillars, the PZT micropillars and the surrounding Parylene comprise a matching layer with gradient acoustic impedance. By using the proposed technique, the fabricated transducer achieves a center frequency of 26 MHz and a −6 dB bandwidth of approximately 65%. PMID:24113683

  11. 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.

  12. Undersea acoustic research

    NASA Astrophysics Data System (ADS)

    Spindel, R. C.

    1984-01-01

    This is the final report of Contract N00014-77-C-0196 between the Woods Hole Oceanographic Institution and the Office of Naval Research for the contract period 1 January 1977 to 28 February 1983. This contract supported a broad program of research and development in underwater acoustics related to present and future Navy systems and requirements. The bulk of this contract research was conducted from 1977 to 1981, during which time the categories outlined below were all areas of active research. (Between 1981 and 1983 the contract remained in effect, although only in the area of bottom acoustics and at a reduced level.) The primary contract products are the published technical reports and papers listed below. These reports give detailed descriptions of the research work and the specialized techniques, methods, and instrumentation developed to support this research program. The final report contains a brief review of the program highlights and a bibliography of associated reports.

  13. 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.

  14. Acoustical oceanography

    NASA Astrophysics Data System (ADS)

    The Acoustical Society of America has formed a Technical Specialty Group on Acoustical Oceanography. At ASA meetings the new group will have special sessions where they will give invited and contributed papers and have panel discussions about ocean parameters that are measured effectively by acoustical techniques.The first special sessions will be May 22-23, 1990, at the ASA meeting at Pennsylvania State University, University Park. The focus on May 22 will be acoustical techniques for detection and measurement of internal waves and turbulence; conveners are Robert Pinkel of Scripps Institution of Oceanography, La Jolla, Calif., and Herman Medwin of the Naval Postgraduate School, Monterey, Calif. Acoustical studies of the physical and biological characteristics of ocean mass boundaries are the discussion topic on May 23. The convener is C. S. Clay, University of Wisconsin, Madison.

  15. Acoustic Climb to Cruise Test

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Flight test film footage of three different aircraft testing the acoustical noise levels during take-off, climb, maneuvers, and touch and go landings are described. These sound tests were conducted on two fighter aircraft and one cargo aircraft. Results from mobile test vehicle are shown.

  16. 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

  17. Acoustic waves in medical imaging and diagnostics.

    PubMed

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

    2013-07-01

    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. Beginning in the 1990s, there started to emerge numerous acoustic imaging modalities based on the use of a different mode of acoustic wave: shear waves. Imaging with these waves was shown to provide very useful and very different information about the biological tissue being examined. We discuss the 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 is presented. We discuss the potential for future shear wave imaging applications. Copyright © 2013 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  18. 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.

  19. 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.

  20. Glancing angle deposited nanostructured film Fabry-Perot etalons for optical detection of ultrasound.

    PubMed

    Hajireza, Parsin; Krause, Kathleen; Brett, Michael; Zemp, Roger

    2013-03-11

    In this paper a new class of optical Fabry-Perot-based ultrasound detectors using low acoustic impedance glancing angle deposited (GLAD) films is demonstrated. GLAD is a single-step physical vapor-deposition (PVD) technique used to fabricate porous nanostructured thin films. Using titanium dioxide (TiO(2)), a transparent semiconductor with a high refractive index (n = 2.4), the GLAD technique can be employed to fabricate samples with tailored nano-porosity, refractive index periodicities, and high Q-factor reflectance spectra. The average acoustic impedance of the porous films is lower than bulk materials which will improve acoustic coupling, especially for high acoustic frequencies. For this work, two filters with high reflection in the C-band range and high transparency in the visible range (~80%) using GLAD films were fabricated. A 23 µm Parylene C layer was sandwiched between these two GLAD films in order to form a GLAD Fabry Perot Interferometer (GLAD-FPI). A high speed tunable continuous wavelength C-band laser was focused at the FPI and the reflection was measured using a high speed photodiode. The ultrasound pressure modulated the optical thickness of the FPI and hence its reflectivity. The fabricated sensor was tested using a 10 MHz unfocused transducer. The ultrasound transducer was calibrated using a hydrophone. The minimum detectable acoustic pressure was measured as 80 ± 20 Pa and the -3dB bandwidth was measured to be 18 MHz. This ultra-sensitive sensor can be an alternative to piezoelectric ultrasound transducers for any techniques in which ultrasound waves need to be detected including ultrasonic and photoacoustic imaging modalities. We demonstrate our GLAD-FPI for photoacoustic signal detection in optical-resolution photoacoustic microscopy (OR-PAM). To the best of our knowledge, this is the first time that a FPI fabricated using the GLAD method has been used for ultra-sensitive ultrasound detection.

  1. Setup for high-temperature surface Brillouin light scattering: Application to opaque thin films and coatings

    NASA Astrophysics Data System (ADS)

    Faurie, D.; Girodon-Boulandet, N.; Kaladjian, A.; Challali, F.; Abadias, G.; Djemia, P.

    2017-02-01

    A setup combining surface Brillouin light scattering with a high-temperature chamber has been developed. The temperature of the sample is controlled with a Bühler HDK chamber for optical measurements (maximum temperature of 1600 °C), in controlled atmospheres or high vacuum (10-6 mbar). This setup allows the study of sound velocity of surface acoustic waves and of the elastic constants of opaque thin films and coatings in situ as a function of temperature from surface Brillouin light scattering, by analyzing the backscattered light from the sample at a fixed angle of incidence. In this paper, we will demonstrate the applications of this setup for metallic glass thin films devitrification study and evaluation of high temperature elastic properties of hard nitride coatings. This kind of study using surface acoustic waves is rare, in contrast to those made on transparent bulk materials.

  2. 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.

  3. 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.

  4. 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.

  5. Integrated Model for the Acoustics of Sediments

    DTIC Science & Technology

    2014-09-30

    743-750. [published] 3. N. P. Chotiros, M. J. Isakson, J. N. Piper , and A. R. McNeese, "Sea floor roughness measured by a laser profiler on a ROV...135, p. 2298, 2014. [published] 7. N. P. Chotiros, M. J. Isakson, J. N. Piper , and A. R. McNeese, "Spatial variation of seabed acoustic bulk properties," J. Acoust. Soc. Am., vol. 135, p. 2231, 2014. [published

  6. 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.

  7. Prototype acoustic resonance spectroscopy monitor

    SciTech Connect

    Sinha, D.N.; Olinger, C.T.

    1996-03-01

    This report reports on work performed for the International Atomic Energy Agency (IAEA) through the Program Office for Technical Assistance (POTAS). In this work, we investigate possible applications of nondestructive acoustics measurements to facilitate IAEA safeguards at bulk processing facilities. Two different acoustic techniques for verifying the internal structure of a processing tank were investigated. During this effort we also examined two acoustic techniques for assessing the fill level within a processing tank. The fill-level measurements could be made highly portable and have an added safeguards advantage that they can also detect stratification of fill material. This later application may be particularly useful in confirming the absence of stratification in plutonium processing tanks before accountability samples are withdrawn.

  8. 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.

  9. 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.

  10. 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.

  11. Acoustically enhanced heat transport

    SciTech Connect

    Ang, Kar M.; Hung, Yew Mun; Tan, Ming K.; Yeo, Leslie Y.

    2016-01-15

    We investigate the enhancement of heat transfer in the nucleate boiling regime by inducing high frequency acoustic waves (f ∼ 10{sup 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 (ξ{sub s} ∼ 10{sup −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 (ξ{sub s} ∼ 10{sup −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{sup −8} m with 10{sup 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.

  12. 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.

  13. Effect of crystallinity on acoustic behaviors of biocompatible silk studied by Brillouin spectroscopy

    NASA Astrophysics Data System (ADS)

    Lee, Jeong Woo; Lee, Byoung Wan; Yeon, Yeung Kyu; Lee, Ok Joo; Park, Chan Hum; Park, Jaehoon; Ko, Jae-Hyeon

    2017-08-01

    Temperature dependences of thermal, thermogravimetric, and acoustic properties were investigated for the crystalline silk fibroin films crystallized by methanol exposure. The crystallization peak in the thermal flow at 225 ◦ C, which was prominent in the amorphous silk film, disappeared in the crystalline silk film. The heat-treatment at 100 ◦ C for 1 h reduced the weight by 5.5% due to the release of water molecules. The formation of beta-sheets in the film did not have any substantial effect on the acoustic properties of the longitudinal acoustic mode in the crystalline film. However, the heat treatment of the methanol-exposed silk film induced clear anomalies in the acoustic mode behaviors in a specific temperature range between -20 30 ◦ C. The existence of water molecules has more profound effect than the crystallinity does on the acoustic properties of silk fibroin films.

  14. Donor–acceptor stacking arrangements in bulk and thin-film high-mobility conjugated polymers characterized using molecular modelling and MAS and surface-enhanced solid-state NMR spectroscopy† †Electronic supplementary information (ESI) available: Additional computational and experimental details, including the DNP sample preparation. See DOI: 10.1039/c7sc00053g Click here for additional data file.

    PubMed Central

    Chaudhari, Sachin R.; Broch, Katharina; Lesage, Anne; Lemaur, Vincent; Dudenko, Dmytro; Olivier, Yoann; Sirringhaus, Henning; Emsley, Lyndon; Grey, Clare P.

    2017-01-01

    Conjugated polymers show promising properties as cheap, sustainable and solution-processable semiconductors. A key challenge in the development of these materials is to determine the polymer chain structure, conformation and packing in both the bulk polymer and in thin films typically used in devices. However, many characterisation techniques are unable to provide atomic-level structural information owing to the presence of disorder. Here, we use molecular modelling, magic-angle spinning (MAS) and dynamic nuclear polarisation surface-enhanced NMR spectroscopy (DNP SENS) to characterise the polymer backbone group conformations and packing arrangement in the high-mobility donor–acceptor copolymer diketopyrrolo-pyrrole-dithienylthieno[3,2-b]thiophene (DPP-DTT). Using conventional 1H and 13C solid-state MAS NMR coupled with density functional theory calculations and molecular dynamics simulations, we find that the bulk polymer adopts a highly planar backbone conformation with a laterally-shifted donor-on-acceptor stacking arrangement. DNP SENS enables acquisition of 13C NMR data for polymer films, where sensitivity is limiting owing to small sample volumes. The DNP signal enhancement enables a two-dimensional 1H–13C HETCOR spectrum to be recorded for a drop-cast polymer film, and a 13C CPMAS NMR spectrum to be recorded for a spin-coated thin-film with a thickness of only 400 nm. The results show that the same planar backbone structure and intermolecular stacking arrangement is preserved in the films following solution processing and annealing, thereby rationalizing the favourable device properties of DPP-DTT, and providing a protocol for the study of other thin film materials. PMID:28507688

  15. Sediment Acoustics: Wideband Model, Reflection Loss and Ambient Noise Inversion

    DTIC Science & Technology

    2011-09-01

    grain contact in water- saturated sand," J. Acoust. Soc. Am., vol. 124, pp. EL296-301, (2008). N. P. Chotiros, and M. J. Isakson. "Shear and...34Frame bulk modulus of porous granular marine sediments," J. Acoust. Soc. Am. 120, 699-710, (2006). B. J. Kraft and C. P. de Moustier, "Detailed

  16. Acoustofluidics 14: Applications of acoustic streaming in microfluidic devices.

    PubMed

    Wiklund, Martin; Green, Roy; Ohlin, Mathias

    2012-07-21

    In part 14 of the tutorial series "Acoustofluidics--exploiting ultrasonic standing wave forces and acoustic streaming in microfluidic systems for cell and particle manipulation", we provide a qualitative description of acoustic streaming and review its applications in lab-on-a-chip devices. The paper covers boundary layer driven streaming, including Schlichting and Rayleigh streaming, Eckart streaming in the bulk fluid, cavitation microstreaming and surface-acoustic-wave-driven streaming.

  17. Acoustic Pump

    NASA Technical Reports Server (NTRS)

    Heyman, Joseph S.

    1993-01-01

    Pump uses acoustic-radiation forces. Momentum transferred from sound waves to sound-propagating material in way resulting in net pumping action on material. Acoustic pump is solid-state pump. Requires no moving parts, entirely miniaturized, and does not invade pumped environment. Silent, with no conventional vibration. Used as pump for liquid, suspension, gas, or any other medium interacting with radiation pressure. Also used where solid-state pump needed for reliability and controllability. In microgravity environment, device offers unusual control for low flow rates. For medical or other applications in which contamination cannot be allowed, offers noninvasive pumping force.

  18. Bulk Nanostructured Materials

    NASA Astrophysics Data System (ADS)

    Koch, C. C.; Langdon, T. G.; Lavernia, E. J.

    2017-09-01

    This paper will address three topics of importance to bulk nanostructured materials. Bulk nanostructured materials are defined as bulk solids with nanoscale or partly nanoscale microstructures. This category of nanostructured materials has historical roots going back many decades but has relatively recent focus due to new discoveries of unique properties of some nanoscale materials. Bulk nanostructured materials are prepared by a variety of severe plastic deformation methods, and these will be reviewed. Powder processing to prepare bulk nanostructured materials requires that the powders be consolidated by typical combinations of pressure and temperature, the latter leading to coarsening of the microstructure. The thermal stability of nanostructured materials will also be discussed. An example of bringing nanostructured materials to applications as structural materials will be described in terms of the cryomilling of powders and their consolidation.

  19. 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.

  20. Laser Measurement of SAM Bulk and Surface Wave Amplitudes for Material Microstructure Analysis

    SciTech Connect

    Ken L. Telschow; Chiaki Miyasaka; David L. Cottle

    2005-07-01

    Scanning Acoustic Microscopy (SAM) at ultra high frequencies has proven to be a useful tool for investigating materials on the scale of individual grains. This technique is normally performed in a reflection mode from one side of a sample surface. Information about the generation and transmission of bulk acoustic waves into the material is inferred from the reflection signal amplitude. We present an adaptation to the SAM method whereby the acoustic bulk waves are directly visualized through laser acoustic detection. Ultrasonic waves were emitted from a nominal 200 MHz point focus acoustic lens into a thin silicon plate (thickness 75ìm) coupled with distilled water. A scanned laser beam detected the bulk and surface acoustic waves at the opposite surface of the thin silicon plate. Distinct amplitude patterns exhibiting the expected symmetry for Silicon were observed that alter in predictable ways as the acoustic focal point was moved throughout the plate. Predictions of the acoustic wave fields generated by the acoustic lens within and at the surface of the Silicon are being investigated through the angular spectrum of plane waves approach. Results shall be presented for plates with (100) and (111) orientations followed by discussion of applications of the technique for material microstructure analysis.

  1. Large area bulk superconductors

    DOEpatents

    Miller, Dean J.; Field, Michael B.

    2002-01-01

    A bulk superconductor having a thickness of not less than about 100 microns is carried by a polycrystalline textured substrate having misorientation angles at the surface thereof not greater than about 15.degree.; the bulk superconductor may have a thickness of not less than about 100 microns and a surface area of not less than about 50 cm.sup.2. The textured substrate may have a thickness not less than about 10 microns and misorientation angles at the surface thereof not greater than about 15.degree.. Also disclosed is a process of manufacturing the bulk superconductor and the polycrystalline biaxially textured substrate material.

  2. Multifunctional Parylene-C Microfibrous Thin Films

    NASA Astrophysics Data System (ADS)

    Chindam, Chandraprakash

    columnar muFTFs and bulk films. The static hydrophobicity of columnar muFTFs was found to be anisotropic and can be maximized by a proper choice of monomer deposition angle. In contrast, the hydrophobicity of bulk film is isotropic. 2. Mechanical properties: Dynamic storage and loss moduli of columnar muFTFs were determined in the 1 to 80 Hz frequency range for temperatures between -40 °C and 125 °C in one of two orthogonal directions lying wholly in the substrate plane: either (i) normal or (ii) parallel to the morphologically significant plane of the muFTF. The storage and loss moduli for normal loading did not exceed their counterparts for parallel loading. All columnar muFTFs were found to be softer than a bulk film. In both bulk and columnar forms, Parylene C was found to be rheologically not simple. 3. Relative permittivity: The charge-storage and absorption properties measured for the columnar muFTFs in the 100 Hz-1 MHz frequency range over temperatures between -40 °C and 125 °C were lower than the bulk film. Internal surfaces of the columnar muFTFs were found to increase the charge-storage capacity. The lower charge-storage capability of columnar muFTFs suggests their possible applications as interlayer dielectrics. The frequency dependence of the relative permittivity of the columnar muFTFs was identified in terms of the Hashin-Shrtikmann model. The elastodynamic bandgaps of Parylene-C muFTFs as phononic crystals were computationally determined for the columnar, chevronic, and chiral muFTFs. Microfibers were arranged either on a square or a hexagonal lattice with the host medium as either water or air. Following are the significant findings: 1. All bandgaps were observed to lie in the 0.01-162.9-MHz regime. The upper limit of the frequency of bandgaps was the highest for the columnar muFTFs and the lowest for the chiral muFTFs. More bandgaps were found to exist when the host medium is water than air. The presence of complete bandgaps suggests their use as bulk-acoustic

  3. Utilization of polymer viscoelastic properties in acoustic wave sensor applications

    NASA Astrophysics Data System (ADS)

    Martin, Stephen J.; Ricco, Antonio J.; Frye, G. C.

    The changes which occur in polymer viscoelastic properties in response to cross-linking reactions and due to absorption of gas phase species were used advantageously in several acoustic wave-based sensor applications. When a polymer film is present on the surface of an acoustic wave device, changes in the visoelastic properties of the film induce changes in wave porpagation velocity and attenuation, providing two sensor responses. Film changes which occur polymer cross-linking allow photopolymerization to be monitored in real time using acoustic devices. A photoaction spectrum of photoresist reveals the cross-linking wavelength with maximum quantum yield. Changes in the viscoelastic properties of a polysiloxane film induces by vapor absorption are found to be unique for each of several species, enabling differentiation of species with a single film. A Maxwell model for polymer viscoelasticity, in combination with mass loading effects, provides a sound theoretical basis for explaining observed results for both polysiloxane and polybytadiene/polystyrene copolymer films.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. An acoustic glucose sensor.

    PubMed

    Hu, Ruifen; Stevenson, Adrian C; Lowe, Christopher R

    2012-05-15

    In vivo glucose monitoring is required for tighter glycaemic control. This report describes a new approach to construct a miniature implantable device based on a magnetic acoustic resonance sensor (MARS). A ≈ 600-800 nm thick glucose-responsive poly(acrylamide-co-3-acrylamidophenylboronic acid) (poly(acrylamide-co-3-APB)) film was polymerised on the quartz disc (12 mm in diameter and 0.25 mm thick) of the MARS. The swelling/shrinking of the polymer film induced by the glucose binding to the phenylboronate caused changes in the resonance amplitude of the quartz disc in the MARS. A linear relationship between the response of the MARS and the glucose concentration in the range ≈ 0-15 mM was observed, with the optimum response of the MARS sensor being obtained when the polymer films contained ≈ 20 mol% 3-APB. The MARS glucose sensor also functioned under flow conditions (9 μl/min) with a response almost identical to the sensor under static or non-flow conditions. The results suggest that the MARS could offer a promising strategy for developing a small subcutaneously implanted continuous glucose monitor.

  11. 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.}

  12. Medical Acoustics

    NASA Astrophysics Data System (ADS)

    Beach, Kirk W.; 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.

  13. Bulk viscosity effects on ultrasonic thermoacoustic instability

    NASA Astrophysics Data System (ADS)

    Lin, Jeffrey; Scalo, Carlo; Hesselink, Lambertus

    2016-11-01

    We have carried out unstructured fully-compressible Navier-Stokes simulations of a minimal-unit traveling-wave ultrasonic thermoacoustic device in looped configuration. The model comprises a thermoacoustic stack with 85% porosity and a tapered area change to suppress the fundamental standing-wave mode. A bulk viscosity model, which accounts for vibrational and rotational molecular relaxation effects, is derived and implemented via direct modification of the viscous stress tensor, τij ≡ 2 μSij +λ/2 μ ∂uk/∂xk δij , where the bulk viscosity is defined by μb ≡ λ +2/3 μ . The effective bulk viscosity coefficient accurately captures acoustic absorption from low to high ultrasonic frequencies and matches experimental wave attenuation rates across five decades. Using pressure-based similitude, the model was downscaled from total length L = 2 . 58 m to 0 . 0258 m, corresponding to the frequency range f = 242 - 24200 Hz, revealing the effects of bulk viscosity and direct modification of the thermodynamic pressure. Simulations are carried out to limit cycle and exhibit growth rates consistent with linear stability analyses, based on Rott's theory.

  14. Acoustic dose and acoustic dose-rate.

    PubMed

    Duck, Francis

    2009-10-01

    Acoustic dose is defined as the energy deposited by absorption of an acoustic wave per unit mass of the medium supporting the wave. Expressions for acoustic dose and acoustic dose-rate are given for plane-wave conditions, including temporal and frequency dependencies of energy deposition. The relationship between the acoustic dose-rate and the resulting temperature increase is explored, as is the relationship between acoustic dose-rate and radiation force. Energy transfer from the wave to the medium by means of acoustic cavitation is considered, and an approach is proposed in principle that could allow cavitation to be included within the proposed definitions of acoustic dose and acoustic dose-rate.

  15. 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.

  16. Gigahertz scanning acoustic microscopy analysis of voids in Cu-Sn micro-connects

    NASA Astrophysics Data System (ADS)

    Ross, G.; Vuorinen, V.; Petzold, M.; Paulasto-Kröckel, M.; Brand, S.

    2017-01-01

    Gigahertz scanning acoustic microscopy (GHz-SAM) is applied to the characterization of bulk voids in the Cu-Sn material system, often used in micro-connects. An increased demand for the development of miniaturized interconnect technologies, such as micro-connects, means that fast characterization methods are required for the assessment and detection of reliability impacting defects. This study attempts to formulate an analytical technique aimed at detecting micro-structural defects in Cu-Sn micro-connects, such as micro-bumps for 1st level interconnects and solid-liquid interdiffusion bonds for nano- and microelectromechanical systems. To study the potential of the analytical method, a specific electroplating chemistry was used that increases the probability of defect formation in the electroplated Cu film. The chemistry is known under certain electroplating overpotentials to promote hydrogen bubble induced voids within the Cu. The samples containing voids were inspected by GHz-SAM with a highly focused acoustic lens operating at 1.12 GHz. To validate the results, GHz-SAM micrographs were compared with focused ion beam prepared cross-sections of the selected samples. Advances in acoustic transducer technology operating in the GHz frequency band allow for micron sized defect examination of materials with enhanced lateral resolution and sub-surface sensitivity.

  17. Validation of a Phase-Mass Characterization Concept and Interface for Acoustic Biosensors

    PubMed Central

    Montagut, Yeison; García, José V.; Jiménez, Yolanda; March, Carmen; Montoya, Ángel; 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/mL, where mL 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

  18. 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.

  19. 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.

  20. Sputtered SiO2 as low acoustic impedance material for Bragg mirror fabrication in BAW resonators.

    PubMed

    Olivares, Jimena; Wegmann, Enrique; Capilla, José; Iborra, Enrique; Clement, Marta; Vergara, Lucía; Aigner, Robert

    2010-01-01

    In this paper we describe the procedure to sputter low acoustic impedance SiO(2) films to be used as a low acoustic impedance layer in Bragg mirrors for BAW resonators. The composition and structure of the material are assessed through infrared absorption spectroscopy. The acoustic properties of the films (mass density and sound velocity) are assessed through X-ray reflectometry and picosecond acoustic spectroscopy. A second measurement of the sound velocity is achieved through the analysis of the longitudinal lambda/2 resonance that appears in these silicon oxide films when used as uppermost layer of an acoustic reflector placed under an AlN-based resonator.

  1. Bulk acoustic wave resonators made of amorphous materials

    NASA Astrophysics Data System (ADS)

    Breuzet, Michel

    1990-08-01

    The investigation of plates vibrating at radio frequency and made of amorphous conductive or insulating materials is carried out. Capacitive excitation was employed for this type of resonator made of non piezoelectric material. The advantage of using contour vibration modes is demonstrated, with particular reference to the Lame mode. The optimization of mountings designed to minimize resonator/mounting coupling is investigated. The finite element computing method was applied. The results obtained on resonators made of AU4G and vitreous silica (SiO2) are discussed.

  2. Wireless actuation of bulk acoustic modes in micromechanical resonators

    NASA Astrophysics Data System (ADS)

    Mateen, Farrukh; Brown, Benjamin; Erramilli, Shyamsunder; Mohanty, Pritiraj

    2016-08-01

    We report wireless actuation of a Lamb wave micromechanical resonator from a distance of over 1 m with an efficiency of over 15%. Wireless actuation of conventional micromechanical resonators can have broad impact in a number of applications from wireless communication and implantable biomedical devices to distributed sensor networks.

  3. 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.

  4. 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.

  5. Seesaw in the Bulk

    NASA Astrophysics Data System (ADS)

    Watanabe, A.; Yoshioka, K.

    2011-01-01

    A five-dimensional seesaw framework is analyzed with the lepton-number-violating propagator of bulk right-handed neutrinos. That can bypass summing up the effects of heavy Majorana particles whose masses and wavefunctions are not exactly known. The propagator method makes it easier to evaluate the seesaw-induced neutrino mass for various boundary conditions of bulk neutrinos and in a general background geometry, including the warped extra dimension. It is also found that the higher-dimensional seesaw gives a natural framework for the inverse seesaw suppression of low-energy neutrino masses.

  6. Soap film vibration: origin of the dissipation.

    PubMed

    Acharige, Sébastien Kosgodagan; Elias, Florence; Derec, Caroline

    2014-11-07

    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.

  7. 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.

  8. 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.

  9. 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…

  10. 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…

  11. 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.

  12. 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.

  13. Acoustic iridescence.

    PubMed

    Cox, Trevor J

    2011-03-01

    An investigation has been undertaken into acoustic iridescence, exploring how a device can be constructed which alter sound waves, in a similar way to structures in nature that act on light to produce optical iridescence. The main construction had many thin perforated sheets spaced half a wavelength apart for a specified design frequency. The sheets create the necessary impedance discontinuities to create backscattered waves, which then interfere to create strongly reflected sound at certain frequencies. Predictions and measurements show a set of harmonics, evenly spaced in frequency, for which sound is reflected strongly. And the frequency of these harmonics increases as the angle of observation gets larger, mimicking the iridescence seen in natural optical systems. Similar to optical systems, the reflections become weaker for oblique angles of reflection. A second construction was briefly examined which exploited a metamaterial made from elements and inclusions which were much smaller than the wavelength. Boundary element method predictions confirmed the potential for creating acoustic iridescence from layers of such a material.

  14. Acoustic hologram formation with a frequency shifted reference beam.

    PubMed

    Whitman, R L

    1970-06-01

    This paper discusses an interference technique that makes it possible to directly observe and record the usually very weak light diffracted by an acoustical surface perturbation. This is accomplished by using spatial filtering techniques in combination with a frequency shifted reference beam. It is shown that the acoustically diffracted light may be visualized even in the presence of statically scattered light of much higher intensity. An experiment is described in which this technique is used to view the surface perturbations of piezoelectric ceramic material caused by acoustic surface waves. The application of this system to acoustic holography is discussed in detail. This application makes use of the fact that bulk acoustic waves in a material, upon striking the surface at some acute angle, cause surface ripple patterns which form a dynamic hologram of the acoustic field. A photographic image of this hologram frozen in time may then be recorded using the process discussed above.

  15. Tunable acoustic double negativity metamaterial.

    PubMed

    Liang, Z; Willatzen, M; Li, J; Christensen, J

    2012-01-01

    Man-made composite materials called "metamaterials" allow for the creation of unusual wave propagation behavior. Acoustic and elastic metamaterials in particular, can pave the way for the full control of sound in realizing cloaks of invisibility, perfect lenses and much more. In this work we design acousto-elastic surface modes that are similar to surface plasmons in metals and on highly conducting surfaces perforated by holes. We combine a structure hosting these modes together with a gap material supporting negative modulus and collectively producing negative dispersion. By analytical techniques and full-wave simulations we attribute the observed behavior to the mass density and bulk modulus being simultaneously negative.

  16. 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.

  17. 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...

  18. 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...

  19. 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...

  20. 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...