title: High-concentration Na doping of SrRuO3 and CaRuO3.
abstract: The Na-doped perovskite-structure ruthenates Sr(1-x)Na(x)RuO3 and Ca(1-y)Na(y)RuO3 were prepared by high-pressure synthesis, which enables us to go beyond the previously reported Na doping limits and substitute Na for over 50% of the Sr in SrRuO3 and the Ca in CaRuO3. Gradual and systematic changes in the crystal structures were observed, and the decreases in the Ru-O bond lengths confirmed the Na substitution at the A site caused hole doping to Ru(4+) at the B site. In contrast to what has been previously reported, Sr(1-x)Na(x)RuO3 showed metallic conductivity. Magnetic properties were influenced by the Na substitution, but no long-range antiferromagnetic behavior was observed in Ca(1-y)Na(y)RuO3.
authors.affiliation: Institute for Chemical Research, Kyoto University , Uji, Kyoto 611-0011, Japan.
authors.forename: Hayato
authors.initials: H
authors.lastname: Seki
authors.forename: Ryuta
authors.initials: R
authors.lastname: Yamada
authors.forename: Takashi
authors.initials: T
authors.lastname: Saito
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: Kennedy
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Shimakawa