Piezoelectric properties of (K,Na)NbO ₃ thin films deposited on (001)SrRuO ₃/Pt/MgO substrates

Abstract

(K(x),Na(1-x))NbO(3) (KNN) thin films were deposited on (001)SrRuO(3)/(001)Pt/(001)MgO substrates by RF-magnetron sputtering, and their piezoelectric properties were investigated. The x-ray diffraction measurements indicated that the KNN thin films were epitaxially grown with the c-axis orientation in the perovskite tetragonal system. The lattice constant of the c-axis increased with increasing concentrations of potassium. The KNN thin films showed typical ferroelectric behavior; the relative dielectric constant epsilon(r) was 270 to approximately 320. The piezoelectric properties were measured from the tip displacement of the KNN/MgO unimorph cantilevers; the transverse piezoelectric coefficient epsilon*(31) (= d(31)/s(E)(11)) of KNN (x = 0) thin films was calculated to be -0.9 C/m(2). On the other hand, doping of potassium caused an increase in the piezoelectric properties, and the KNN (x = 0.16) films showed a relatively large transverse piezoelectricity of epsilon*(31) = -2.4 C/m(2).

Improvement of Piezoelectric Properties of (K,Na)NbO3 Films Deposited by Sputtering

“…This indicates that the lattice parameter of the KNN crystal decreases with increasing Na=ðK þ NaÞ ratio, which is the same tendency as described in a previous report. 15) …”

“…In this study, to eliminate the ambiguity of the mechanical properties of the KNN thin films such as s 11,p , we define the transverse piezoelectric coefficient e à 31 as follows: 15) …”

Outstanding Piezoelectric Performance in Lead‐Free 0.95(K,Na)(Sb,Nb)O3‐0.05(Bi,Na,K)ZrO3 Thick Films with Oriented Nanophase Coexistence

“…[17,[26][27][28][29] Substrates with lattice match favor epitaxial films with preferred crystallographic orientation. [30,31] However, growing high-performance piezoelectric films with perovskite structure on silicon substrates without the appropriate lattice match is often required for device applications. In the nucleation stage of films with strong anisotropy, nucleation dominates along the plane with lower surface energy [32] ; whereas in the grain growth process, strong crystallographic texture is favored along the plane with the lowest surface energy to minimize the free energy of the films.…”

Composition dependency of crystal structure, electrical and piezoelectric properties for hydrothermally-synthesized 3 µm-thickness (K<i>_x</i>Na₁₋<i>_x</i>)NbO₃ films

“…Kanno et al reported the continuous change of the lattice parameter with x value for epitaxial (K x Na 1¹x )NbO 3 films deposited by sputtering method. 17) However, the peak from (K x Na 1¹x )NbO 3 was only one on their XRD chart within the 2ª = 4448°for all composition range that is different from the present results of two series of peaks labeled as [2] and [3]. One possibility for the two series of XRD peaks in the present study is the existence of the two orientations derived from the single phase, such as (100), (010) and (001) orientations of the orthorhombic phase.…”