Piezoelectric Properties of Epitaxial NaNbO₃ Thin Films Deposited on (001)SrRuO₃/Pt/MgO Substrates

Abstract

Sodium niobate (NaNbO 3 , NN) thin films were deposited on (001)SrRuO 3 /Pt/MgO substrates by rf magnetron sputter deposition. The X-ray diffraction (XRD) pattern of the sputtered NN thin films showed epitaxial growth with a (001)-oriented perovskite structure. From the reciprocal space maps, the lattice parameters of the in-plane and out-of-plane directions were a ¼ 0:392 nm and c ¼ 0:395 nm, respectively. The relative dielectric constant " r and the range of the dielectric loss tan were about 270 and 0.05 -0.13 at 1 kHz, respectively. The P-E hysteresis loop showed clear ferroelectricity with spontaneous polarization P s of 20 mC/cm 2 and coercive electric field E c of 50 kV/cm. The transverse piezoelectric properties were evaluated from the tip displacement of NN/MgO unimorph cantilevers. The transverse piezoelectric coefficient e à 31 (¼ d 31 =s E 11 ) was À0:9 C/m 2 , which is almost compatible with that of the bulk NN ceramics. The tip deflection showed typical butterfly curves owing to the polarization reversal, indicating that the sputtered NN thin films had a high piezoelectric performance.

Unstable state in epitaxial films of sodium niobate

“…Experimental phase analysis of epitaxial NNO films is limited to the demonstration of the room-temperature FE and piezoelectric behavior. 6,7 In bulk NNO, phase identification is dramatically complicated by the coexistence of several phases at the same temperature and the structural instability. In thin films of NNO, also possible presence of a pyrochlore-type phase, 6 expansion of the perovskite unit cell, 7 and technological imperfections ͑such as e.g., nonstoichiometric phase at grain boundaries͒ make this task even more difficult.…”

Fabrication and Characterization of PZT Fibered-Epitaxial Thin Film on Si for Piezoelectric Micromachined Ultrasound Transducer

“…For the simulation, the pattern of the Au topside electrode with a thickness of 0.15 µm was considered, while the buffer layers were ignored. The e 31, f of P-5A were calculated to be −16 C/m 2 from the following expression [36] $e_{31,f}=e_{31}-\frac{C_{13}}{C_{33}}{e}_{33}$ where e and c correspond to the piezoelectric and stiffness coefficients, respectively. Figure 9d plots the dependencies of the static displacements on the driving voltages for the simulation and measurement results.…”

Ferroelectric Properties of (Na0.5K0.5)NbO3-Based Thin Films Deposited on Pt/(001)MgO Substrate by Pulsed Laser Deposition with NaNbO3Buffer Layer

“…The average lattice constant of NN buffer layer is 3.905 Å which is smaller than that of the NKLNTS. 4,[24][25][26]29) The ionic radium of K þ (1.64 Å ) is larger than that of Na þ (1.39 Å ). 32) To decrease the lattice mismatch between the NN buffer layer and the growing NKLNTS film, the K concentration in the NKLNTS film decreases near the interface between the NN buffer layer and the film.…”