Effect of Ba substitution on the microstructure and electrical conductivity of Ba_xSr_1-xRuO₃ thin films prepared by laser ablation

Ba_xSr_1-xRuO₃ (BSRO) thin films were prepared by laser ablation on quartz substrates at a substrate temperature (T_sub) of 973 K and an oxygen pressure (Po₂) of 13 Pa. The effect of Ba substitution for Sr on the microstructure and electrical conductivity (σ) was investigated. (110) -oriented pseudo-cubic BSRO thin films were obtained at a Ba substitution ratio (x) below 0.5. The thin films prepared at x = 0.6 to 0.8 had the 4H-type BaRuO₃ (BRO) structure, whereas 9R BRO thin films were obtained at x = 1.0. The BSRO thin films consisted of well-crystallized fine grains. The pseudo-cubic lattice parameter of the BSRO thin films increased linearly from 0.393 to 0.407 with increasing x. The BSRO thin films showed metallic conduction, and the σ decreased due to lattice expansion with increasing χ.