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) 2 O 6 (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 (Sr 0.5 Ba 0.5 )Nb 2 O 6 powders and thin films, such as (Sr 0.5 Ba 0.5 )(Nb 0.5 Ta 0.5 ) 2 O 6 (SBNT50/50) and (Sr 0.5 Ba 0.5 )(Nb 0.8 Ta 0.2 ) 2 O 6 (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.