Piezoelectric, Dielectric, and Structural Properties of Ternary (K0.5Na0.5)Nb0.95O3–BaTiO3–BaZrO3 Thin Films Prepared on Pt/TiOx/SiO2/Si Substrates by the Chemical Solution Deposition Method

Abstract

Well-controlled polycrystalline (1-x-y)(K0.5Na0.5)Nb0.95O3–xBaTiO3–yBaZrO3 (KNN–BTO–BZO; 0≤x,y ≤0.1) thin films were systematically synthesized on Pt/TiOx/SiO2/Si substrates by the chemical solution deposition (CSD) method in order to improve the piezoelectric properties by the formation of the morphotropic phase boundary (MPB). The synthesized thin films exhibited excellent insulated resistance and ferroelectric properties. Experimental results indicated that the tetragonal structure was fabricated in the range of at least 0.05≤x ≤0.1 in (1-x)KNN–xBTO, whereas the rhombohedral structure was not formed at room temperature in the range of 0≤y ≤0.1 in (1-y)KNN–yBZO thin films. Therefore, the desired MPB between tetragonal and rhombohedral structures was not formed in the fabricated KNN–BTO–BZO thin films, which hinders the improvement in the piezoelectric property of d33* from that of (K0.5Na0.5)Nb0.95O3. This finding demonstrates that the original composition control with the consideration of the effects of the strain from substrate and the small grain size is indispensable for further improvement in the piezoelectric properties of KNN thin films.