Piezoelectric Properties of (K,Na)NbO₃ Thin Films Deposited on (001)SrRuO₃/Pt/MgO Substrates

ABSTRACT (K_x,Na_1-x)NbO₃ (KNN) thin films were deposited on (001)SrRuO₃/(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 ε_r was 270∼ 320. The piezoelectric properties were measured from the tip displacement of the KNN/MgO unimorph cantilevers; the transverse piezoelectric coefficient e₃₁^∗ (= d₃₁/s₁₁^E) of KNN (x = 0) thin films was calculated to be -0.9 C/m². 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 e₃₁^∗ = -2.4 C/m².

Digital Object Identifier 10.1109/TUFFC.2007.577

© 2007, by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved.

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