Effect of Ba substitution on the microstructure and electrical conductivity of BaxSr1-xRuO3 thin films prepared by laser ablation

Abstract

Ba x Sr 1-x RuO 3 (BSRO) thin films were prepared by laser ablation on quartz substrates at a substrate temperature (T sub ) of 973 K and an oxygen pressure (PO 2 ) of 13 Pa. The effect of Ba substitution for Sr on the microstructure and electrical conductivity (s) 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 BaRuO 3 (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 s decreased due to lattice expansion with increasing x. 2008 The Ceramic Society of Japan. All rights reserved.Key-words : Laser ablation, Strontium ruthenate, Barium ruthenate, Thin films, substitution effect, Microstructure, Electrical conductivity [Received November 28, 2007; Accepted February 21, 2008] 1. Introduction SrRuO 3 (SRO) and BaRuO 3 (BRO) are useful materials as conductive paste and electrodes for micro devices because of their excellent high conductivity. 1)-3) Since the lattice parameter of pseudo-cubic perovskite SRO (a＝0.393 nm) is close to those of dielectric perovskites such as SrTiO 3 (Pm3m; a＝0.391 nm), BaTiO 3 (P4mm; a＝0.394 nm, c＝ 0.395 nm) and Pb(Zr 0.52 Ti 0.48 )O 3 (PZT, P4mm; a＝0.404 nm, c＝4.14 nm), SRO is a promising candidate for use as an alternative conductive oxide electrode replacing metal electrode such as Pt. 4),5) On the other hand, BRO is a hexagonal perovskite. The 9R-type BRO structure (R˜3m: a＝ 0.575 nm, c＝2.161 nm), 6),7) and the 4H-(P6 3 /mmc: a＝ 0.574, c＝0.950 nm) and 6H-type BRO structures (P6 3 / mmc: a＝0.574, c＝1.405 nm) 8) are constructed from three and two face-sharing RuO 6 octahedra combined with cornersharing RuO 6 octahedra, respectively. 9R BRO is commonly prepared under normal conditions, whereas 4H and 6H BRO might be prepared at high pressures.

Effect of Ba Substitution on the Microstructure and Electrical Conductivity of Ba<I><SUB>x</SUB></I>Ca<SUB>1&minus;<I>x</I></SUB>RuO<SUB>3</SUB> Thin Films Prepared by Laser Ablation

“…We have previously reported the effect of Ba substitution on the microstructure and characteristics of polycrystalline BSRO thin films prepared by laser ablation. 11) In the Ba x Ca 1Àx RuO 3 (BCRO) system, on the other hand, the crystal structure of the Ba 3 CaRu 2 O 9 single crystal 12) and the magnetic and electrical properties of the polycrystalline Ba 3 CaRu 2 O 9 body have been reported. 13) However, no report on the preparation of BCRO thin film and the effect of Ba addition to CRO has so far been published.…”