Synthesis and Properties of Highly Oriented (Sr, Ba)(Nb, Ta)2O6 Thin Films by Chemical Solution Deposition

Abstract

Transparent and highly oriented (Sr, Ba)(Nb, Ta)2O6 (SBNT) thin films have been synthesized by a chemical solution deposition method. A homogeneous and stable SBNT precursor solution was prepared by controlling the reaction of metal alkoxides in solution and by optimizing the additive as a stabilizing agent. Tantalum-substituted (Sr0.5Ba0.5)Nb2O6 powders and thin films, such as (Sr0.5Ba0.5)(Nb0.5Ta0.5)2O6 (SBNT50/50) and (Sr0.5Ba0.5)(Nb0.8Ta0.2)2O6 (SBNT50/80), directly crystallized into the tetragonal tungsten bronze phase at 700°C. The synthesized SBNT thin films on MgO(100) and Pt(100)/MgO(100) had a prominent c-axis-preferred orientation. Two crystal lattice planes of SBNT were found to intergrow at an orientation of 18.5° on MgO(100) and Pt(100)/MgO(100) substrates by X-ray pole figure measurement. The SBNT50/80 and SBNT50/50 thin films on Pt(100)/MgO(100) were paraelectric at room temperature and showed diffuse phase transition of the ε-T curves.