scholarly journals Fabrication and Characterization of High-Frequency Ultrasound Transducers Based on Lead-Free BNT-BT Tape-Casting Thick Film

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3166 ◽  
Author(s):  
Junshan Zhang ◽  
Wei Ren ◽  
Yantao Liu ◽  
Xiaoqing Wu ◽  
Chunlong Fei ◽  
...  
Keyword(s):  
Thick Film ◽  
High Frequency ◽  
Electromechanical Coupling ◽  
Ultrasonic Transducer ◽  
Tape Casting ◽  
Lead Free ◽  
Center Frequency ◽  
Electromechanical Coupling Coefficient ◽  
High Frequency Ultrasound ◽  
Casting Method

A lead-free 0.94(Na0.5Bi0.5) TiO3-0.06 BaTiO3 (BNT-BT) thick film, with a thickness of 60 μm, has been fabricated using a tape-casting method. The longitudinal piezoelectric constant, clamped dielectric permittivity constant, remnant polarization and coercive field of the BNT-BT thick film were measured to be 150 pC/N, 1928, 13.6 μC/cm2, and 33.6 kV/cm, respectively. The electromechanical coupling coefficient kt was calculated to be 0.55 according to the measured electrical impedance spectrum. A high-frequency plane ultrasound transducer was successfully fabricated using a BNT-BT thick film. The performance of the transducer was characterized and evaluated by the pulse-echo testing and wire phantom imaging operations. The BNT-BT thick film transducer exhibits a center frequency of 34 MHz, a −6 dB bandwidth of 26%, an axial resolution of 77 μm and a lateral resolution of 484 μm. The results suggest that lead-free BNT-BT thick film fabricated by tape-casting method is a promising lead-free candidate for high-frequency ultrasonic transducer applications.

Fabrication of a 40 MHz Single Element Ultrasonic Transducer Using a PMN-PT Single Crystal

2006 ◽  
Vol 321-323 ◽  
pp. 978-983 ◽  
Author(s):  
Dong Guk Paeng ◽  
Hyung Ham Kim ◽  
Sang Goo Lee ◽  
Sung Min Rhim ◽  
Min Joo Choi
Keyword(s):  
Single Crystal ◽  
High Frequency ◽  
Electromechanical Coupling ◽  
Ultrasonic Transducer ◽  
Electromechanical Coupling Coefficient ◽  
Single Element ◽  
Transducer Arrays ◽  
High Dielectric ◽  
Pulse Echo ◽  
Piezoelectric Constants

PMN-PT, a piezoelectric single crystal, has been known to be a better material for transducer arrays due to its high electromechanical coupling coefficient (k33) and high dielectric and piezoelectric constants. It may also be good even for high frequency single element transducers using relatively high kt and low attenuation and velocity dispersion. However, it’s challenging to fabricate high frequency transducers using PMN-PT since it is easily breakable and requires small area and thickness of the transducer. A KLM model was used to simulate a 40 MHz single element transducer including 2 matching layers and a conductive backing. The simulation showed that the PMN-PT transducer turned out to be better in sensitivity and bandwidth than a 40 MHz LiNbO3 transducer. A 40 MHz PMN-29%PT transducer was fabricated and the pulse echo signals were obtained and analyzed. Its sensitivity was found to be –48 dB and –6dB bandwidth was about 48 %.

scholarly journals Fabrication of AlGaN High Frequency Bulk Acoustic Resonator by Reactive RF Magnetron Co-sputtering System

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7377
Author(s):  
Yu-Chen Chang ◽  
Ying-Chung Chen ◽  
Chien-Chuan Cheng
Keyword(s):  
Aluminum Gallium Nitride ◽  
High Frequency ◽  
Electromechanical Coupling ◽  
Acoustic Resonator ◽  
Bragg Reflector ◽  
Center Frequency ◽  
Electromechanical Coupling Coefficient ◽  
Axis Orientation ◽  
Sputtering Power ◽  
Sputtering System

In this study, aluminum gallium nitride (AlGaN) thin films are used as the piezoelectric layers to fabricate solidly mounted resonators (SMR) for high frequency acoustic wave devices. AlGaN film is deposited on a Bragg reflector, composed of three pairs of Mo and SiO2 films, through a reactive radio frequency (RF) magnetron co-sputtering system at room temperature. The optimized deposition parameters of AlGaN film have a sputtering power of 175 W for Al target, sputtering power of 25 W for GaN target, N2 flow ratio (N2/Ar + N2) of 60%, and sputtering pressure of 10 mTorr. The obtained AlGaN film has a smooth surface, uniform crystal grains, and strong c-axis orientation. The contents of Al and Ga in the AlGaN film, analyzed by energy dispersive X-ray spectroscopy (EDS) are 81% and 19%, respectively. Finally, the frequency response S11 of the obtained SMR device shows that the center frequency is 3.60 GHz, the return loss is about −8.62 dB, the electromechanical coupling coefficient (kt2) is 2.33%, the quality factor (Q) value is 96.93 and the figure of merit (FoM) value is 2.26.

Design and Experiment of Capacitive Micromachined Ultrasonic Transducer Array for High-Frequency Underwater Imaging

2020 ◽  
Vol 13 ◽  
Author(s):  
Yuanyu Yu ◽  
Jiujiang Wang ◽  
Xin Liu ◽  
Sio Hang Pun ◽  
Weibao Qiu ◽  
...  
Keyword(s):  
Ultrasound Imaging ◽  
High Frequency ◽  
Ultrasonic Transducer ◽  
Center Frequency ◽  
Design Parameters ◽  
Underwater Imaging ◽  
Release Process ◽  
Steel Wires ◽  
Capacitive Micromachined Ultrasonic Transducer ◽  
Frequency Ultrasound

Background:: Ultrasound is widely used in the applications of underwater imaging. Capacitive micromachined ultrasonic transducer (CMUT) is a promising candidate to the traditional piezoelectric ultrasonic transducer. In underwater ultrasound imaging, better resolutions can be achieved with a higher frequency ultrasound. Therefore, a CMUT array for high-frequency ultrasound imaging is proposed in this work. Methods:: Analytical methods are used to calculate the center frequency in water and the pull-in voltage for determining the operating point of CMUT. Finite element method model was developed to finalize the design parameters. The CMUT array was fabricated with a five-mask sacrificial release process. Results:: The CMUT array owned an immersed center frequency of 2.6 MHz with a 6 dB fractional bandwidth of 123 %. The pull-in voltage of the CMUT array was 85 V. An underwater imaging experiment was carried out with the target of three steel wires. Conclusion:: In this study, we have developed CMUT for high-frequency underwater imaging. The experiment showed that the CMUT can detect the steel wires with the diameter of 100 μm and the axial resolution was 0.582 mm, which is close to one wavelength of ultrasound in 2.6 MHz.

Surface acoustic wave resonator from thick MOVPE-grown layers of GaN(0001) on sapphire

2002 ◽  
Vol 743 ◽  
Author(s):  
Sverre V. Pettersen ◽  
Thomas Tybell ◽  
Arne Rønnekleiv ◽  
Stig Rooth ◽  
Veit Schwegler ◽  
...  
Keyword(s):  
Acoustic Wave ◽  
Surface Acoustic Wave ◽  
Electromechanical Coupling ◽  
Film Surface ◽  
Center Frequency ◽  
Electromechanical Coupling Coefficient ◽  
Nitride Film ◽  
Wave Resonator ◽  
Lift Off ◽  
Definition Of

ABSTRACTWe report on fabrication and measurement of a surface acoustic wave resonator prepared on ∼10m thick GaN(0001) films. The films were grown by metal-organic vapor phase epitaxy on a c-plane sapphire substrate. The surface morphology of the films were examined with scanning electron and atomic force microscopy. A metallic bilayer of Al/Ti was subsequently evaporated on the nitride film surface. Definition of the resonator interdigital transducers, designed for a wavelength of λ=7.76m, was accomplished with standard UV lithography and lift-off. S-parameter measurements showed a resonator center frequency f0=495MHz at room temperature, corresponding to a surface acoustic wave velocity of 3844m/s. The insertion loss at center frequency was measured at 8.2dB, and the loaded Q-factor was estimated at 2200. Finally, measurements of the resonator center frequency for temperatures in the range 25–155°C showed a temperature coefficient of -18ppm/°C. The intrinsic GaN SAW velocity and electromechanical coupling coefficient were estimated at νSAW=383 1m/s and K2=1.8±0.4·10−3.

Improved Frequency Responses of Saw Filters with Interdigitated Interdigital Transducers on ZnO/Diamond/Si Layered Structure

2007 ◽  
Vol 23 (3) ◽  
pp. 253-260 ◽  
Author(s):  
C.-M. Lin ◽  
T.-T. Wu ◽  
Y.-Y. Chen ◽  
T.-T. Chou
Keyword(s):  
Layered Structure ◽  
Electromechanical Coupling ◽  
Effective Permittivity ◽  
Local Maximum ◽  
Side Lobe ◽  
Center Frequency ◽  
Electromechanical Coupling Coefficient ◽  
Side Lobe Level ◽  
Pass Band ◽  
Frequency Responses

AbstractThere are many investigations on surface acoustic wave (SAW) filters with interdigitated interdigital transducers (IIDT) in the last two decades; however, the same is not true for the case of IIDT SAW filters fabricated on layered piezoelectric substrates. Therefore, the aim of this study is to explore the characteristics of the IIDT structures on layered piezoelectric media and further, to improve the frequency response of layered IIDT SAW filters with the unique dispersive properties of a layered piezoelectric structure. A method based on the effective permittivity approach, the coupling of modes (COM) model, and the H-matrix is utilized to analyze the characteristics of IIDT on the ZnO/Diamond/Si layered structure. In this study, it is shown that by optimizing the ratio of input to output IDT pairs, the side-lobe level of frequency responses on the ZnO/Diamond/Si layered structure could be suppressed, similar to that on the half-space substrate. In addition, it is also proved that the notched pass-band could be flattened out by designing the center frequency on the local maximum of the electromechanical coupling coefficient dispersion curve.

New KNN-based lead-free piezoelectric ceramic for high-frequency ultrasound transducer applications

2015 ◽  
Vol 118 (4) ◽  
pp. 1177-1181 ◽  
Author(s):  
Jun Ou-Yang ◽  
Benpeng Zhu ◽  
Yue Zhang ◽  
Shi Chen ◽  
Xiaofei Yang ◽  
...  
Keyword(s):  
High Frequency ◽  
Piezoelectric Ceramic ◽  
Lead Free ◽  
Ultrasound Transducer ◽  
High Frequency Ultrasound ◽  
Frequency Ultrasound
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