Fabrication of broadband poly(vinylidene difluoride-trifluroethylene) line-focus ultrasonic transducers for surface acoustic wave measurements of anisotropy of a (1 0 0) silicon wafer |
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| Institution: | 1. College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing, China;2. Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan, China;1. Emanuel Institute of Biochemical Physics Russian Academy of sciences, 4 Kosygin st., Moscow, 119334, Russia;2. Scientific and Technological Center of Unique Instrumentation, Russian Academy of sciences, 15 Butlerov st., Moscow, 117342, Russia;1. GW Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States;2. School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States;3. Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208, United States;1. College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing, China;2. School of Environment and Civil Engineering, Dongguan University of Technology, Dongguan 523808, China;3. School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Jungong Road 580, Shanghai 200093, China;1. School of Environment and Civil Engineering, Dongguan University of Technology, Dongguan 523808, China;2. State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi''an Jiaotong University, Xi''an 710049, China;3. School of Civil Engineering, Qinghai University, Xining 810016, China;4. College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing 100124, China;5. Key Laboratory of Nondestructive Testing of Ministry of Education, Nanchang Hangkong University, Nanchang 330063, China |
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| Abstract: | This paper investigates a new method for fabrication of broadband line-focus ultrasonic transducers by sol–gel spin-coating the poly(vinylidene difluoride-trifluroethylene) P(VDF-TrFE)] copolymer film on a concave fine-polished beryllium copper backing. The ferroelectric hysteresis loops of the P(VDF-TrFE) films spin-coated from different molar ratios of VDF/TrFE, 77/23 and 55/45, were measured to select the better mixture. Owing to the better acoustic matching to water, compared with lead zirconate titanate (PZT), the fabricated transducers show relatively wide bandwidth of approximately 50 MHz with high central frequency of 60 MHz obtained at the focal plane when a fused-quartz acts as a reflecting target. Each one of the two finished transducers has a focal length of 5 mm and a full aperture angle of 90°. After applying the specially developed digital signal processing algorithm to the defocusing experiment data, which is called V(f,z) analysis method based on two-dimensional fast Fourier transform (2-D FFT), the operating frequency can extend from several MHz to over 90 MHz. Surface acoustic wave (SAW) velocities of a typical (1 0 0) silicon wafer was measured along various directions between 1 0 0] and 0 1 0] to represent the anisotropic features. |
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| Keywords: | Broadband line-focus transducer P(VDF-TrFE) film Ferroelectric hysteresis loop Surface acoustic wave |
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