Effect of film thickness on piezoelectric vibrator using hydrothermally synthesized epitaxial (K_0.88Na_0.12)NbO₃ film

Abstract

Two types of vibrators using hydrothermally synthesized ferroelectric (K, Na)NbO3 films were fabricated on SrTiO3 substrates. Cantilever piezoelectric vibrators with film thicknesses of 3.5- 22.3 µm were used under low-frequency and no resonance drive. The obtained output displacement increased almost linearly as the film thickness increased under both unipolar and bipolar drives. The obtained transverse piezoelectric coefficient, e 31,f , was almost independent of film thickness, ≈−5 C/m2. On the other hand, a longitudinal piezoelectric vibrator was used under the resonance of half-length longitudinal vibration. The electromechanical coupling factor, K 2, and the mechanical quality factor, Q m, were evaluated. K2 and Q m respectively increased from 0.14% to 1.23% and decreased from 556 to 224 as the film thickness increased from 2.5 to 26 μm. By applying a large voltage of 50 V0-p, a large vibration velocity of 1.5 m/s was obtained for the vibrator with a film thickness of 26 μm.

Achieving High Piezoelectric Performance across a Wide Composition Range in Tetragonal (Bi,Na)TiO3–BaTiO3 Films for Micro-electromechanical Systems

“…Finally, the transverse piezoelectric coefficients, e 31,f , which are widely used to characterize the piezoelectric properties of thin films, were measured to compare the piezoelectric properties of films prepared on other substrates and films of other materials with x = 0.2. The e 31,f were calculated from the curvature of the cantilever, owing to the actuation of the piezoelectric film on the beam. , …”

“…The e 31,f were calculated from the curvature of the cantilever, owing to the actuation of the piezoelectric film on the beam. 48 , 49 …”

“…The e 31,f were calculated from the curvature of the cantilever, owing to the actuation of the piezoelectric film on the beam. 48,49 Figure 6 15 In contrast, the films on the Si substrate exhibited a high e 31,f value of 19 C/m 2 for both film compositions. 35,50 No clear "two-step increase" was detected in the dependence of e 31,f on an applied electric field.…”

Effect of film thickness on output power of a piezoelectric vibration energy harvester using hydrothermally synthesized (K,Na)NbO3 film

“…[36][37][38] In the previous paper, we characterize the cantilever consisting of (K,Na)NbO 3 film for DC voltage driving, and the quantitative evaluation of high-frequency vibration for the ultrasonic transducer applications using inverse piezoelectric effect. 39) Contrary to the previous study, present paper reports on the quantitatively evaluation of the effect of film thickness for (K,Na)NbO 3 films for an energy harvester applications using the direct piezoelectric effect, although the material of the (K,Na)NbO 3 film is the same. We employed orientation-controlled epitaxial film to investigate the effect purely of film thickness on output power.…”

Preparation of {100}-oriented (1−x)(Bi,K)TiO3−xCaTiO3 solid-solution epitaxial films by the hydrothermal method and their ferroelectric and piezoelectric properties

“…Ferroelectric materials have various properties including pyroelectric, piezoelectric and dielectric. [1][2][3][4] They have been widely applied for various devices including sensors, actuators, energy harvesters and capacitors. [5][6][7] For practical use, film form is often favorable due to its capabilities of high integration, small heat capacity, low power consumption, etc.…”