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A setup and approach for simultaneous measurement of the inverse and direct transverse piezoelectric coefficients of piezoelectric films was constructed. A longitudinal vibration mode resonator with a hydrothermally synthesized (K,Na)NbO 3 film deposited on a SrRuO 3 /SrTiO 3 substrate was investigated. The fabricated vibrator consists of two upper electrodes, one for actuation and the other for sensing. A driving voltage was applied to the actuator electrode to generate mechanical vibration at its resonance frequency. The vibration velocity was measured with a laser Doppler vibrometer, and the output current from the shorted sensing electrode was also measured to simultaneously evaluate the inverse and direct piezoelectric responses. The obtained inverse piezoelectric coefficient e 31 ̅ was −3.60 C/m2, while the direct piezoelectric coefficient e 31 ̅ was almost same at −3.69 C/m2. From these values, the inverse and direct piezoelectric coefficients e 31 , f were −4.93 and −5.05 C/m2, respectively. [Display omitted] • Measurement method establishment of the inverse and direct transverse piezoelectric coefficients for piezoelectric films simultaneously. • Use longitudinal vibration mode resonator using a hydrothermally synthesized (K,Na)NbO 3 film deposited on SrRuO 3 /SrTiO 3 substrate • Almost similar inverse and direct piezoelectric coefficients ( e 31 ̅) value of −3.60 and −3.69 C/m2, respectively. [ABSTRACT FROM AUTHOR]

Stacks are among the most important devices for influencing the energy-conversion efficiency of work flow to heat flow during thermoacoustic phenomena. An optimal stack design is indispensable for the practical application of thermoacoustic systems. To this end, it is necessary to estimate the heat flow generated in the stack. This study proposes to estimate this quantity based on the sound generated by a thermoacoustic phenomenon in a stack without any temperature gradient. The heat flow caused by a standing-wave component generated by this thermoacoustic phenomenon is successfully measured. [ABSTRACT FROM AUTHOR]

This paper proposes a novel system for three dimensional – position and velocity measurements with echolocation. It is improved from the former systems, based on low computational one-bit signal processing, to have wider detectability from one and two dimensions to three dimensions with the rearrangement of the ultrasonic receiver positions. The proposed method can measure the object location from non-linear equations without using iterative methods. This method can concurrently measure position and velocity in three dimensional spaces with one-time measurement. The sound radiation and reflection studies using echolocation are also included in this paper. The additive noise: White Gaussian Noise, Colored Gaussian Noise, General Gaussian Noise, Laplacian Noise, and Gaussian Mixture Noise, is considered for the performance study. The system consists of one sound transmitter and three receivers. These devices are simple sound packages to support low-cost applications. In addition, to satisfy the requirement for a low-computation cost, an echo is converted into a one-bit signal by a three-channel delta–sigma-modulation board. Then, FPGA is used to determine recursive cross correlation based on one-bit computation. The object location is then defined with x – y – z coordinates. The object’s velocity is computed using linear-period-modulated signals. The validity and repeatability of experimental results are evaluated using statistics. [ABSTRACT FROM AUTHOR]

Using a hydrothermal method, (K0.88Na0.12)NbO3 films were deposited at 240 °C on (100) cSrRuO3//(100)SrTiO3 substrates. Moreover, without any poling treatment, direct and inverse transverse piezoelectric coefficients, e31,f, near 0 kV/cm were approximately −5.0 C/m2 for the as-deposited film. This value was nearly unchanged following the application of an electric field and poling treatment, suggesting that as-deposited films are almost in a fully self-polarized state without the application of an electric field. As-deposited films with a thickness of up to 22 μm showed constant piezoelectricity without any poling treatment. The films did not crack or peel because of substrates due to the small thermal strain originating from the low deposition temperature. The figures of merit (FOM) for the vibration energy harvester [FOM = e31,f2/(ε0εr)] and sensor [FOM = e31,f/(ε0εr)] were estimated to be good at 32.8 GPa and –5.9 GV/m, respectively, primarily because of the low relative dielectric constant of ∼110. Furthermore, the piezoelectric voltage coefficient g31 [= d31/(ε0εr)] was estimated and demonstrated a high value of 0.073 Vm/N. [ABSTRACT FROM AUTHOR]

Highlights • Epitaxial (K 0.88 Na 0.12)NbO 3 films were prepared by hydrothermal method. • Effect of crystallinity of Nb 2 O 5 source to deposition behavior was investigated. • Deposition thickness increased by suppression of powder formation. • Efficiency of source to film can increased. Abstract Epitaxial (K 0.88 Na 0.12)NbO 3 films were deposited at 240 °C onto (1 0 0) c SrRuO 3 //(1 0 0)SrTiO 3 substrates utilizing a hydrothermal method. Both crystalline and amorphous niobium oxide powders were utilized as starting niobium sources with KOH and NaOH as potassium and sodium sources, respectively. Film thickness increased with deposition time, but eventually became saturated. The saturated film thickness of (K 0.88 Na 0.12)NbO 3 films prepared from the amorphous niobium source was greater than that from the crystalline source for mixtures of 6 and 7 mol/L KOH-NaOH solutions. This is found to be due to the suppression of the (K,Na)NbO 3 powder simultaneously prepared with films by selecting amorphous niobium source. Their electrical and piezoelectric properties were nearly identical after following heat treatment at 600 °C for 10 min in an atmospheric O 2 flow irrespective of the starting niobium sources; The average values of remanent polarization and effective longitudinal piezoelectric constant, d 33 , were 5–6 μC/cm2 and 45 pm/V, respectively. [ABSTRACT FROM AUTHOR]