Crystal Structure of Six-Layer Ba1―xSrxRuO3

• Published in: Journal of the Physical Society of Japan 2009, Vol.78 (9)
• Main Authors: KOBAYASHI, Yoshihiko, OHISHI, Tetsuji, KANEKO, Tetsuya, IWATA, Masatoshi, ASAI, Kichizo
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Crystalline state (including molecular motions in solids); Crystallographic aspects of phase transformations; pressure effects; Exact sciences and technology; Inorganic compounds; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids
• ISSN: 0031-9015; 1347-4073
• DOI: 10.1143/jpsj.78.094601

We have synthesized the polycrystalline Ba1-xSrxRuO3 for 0≤x≤1.0, and investigated the crystal structure by X-ray powder diffraction. The crystalline structure of Ba1-xSrxRuO3 of six-layer phase at around 0.4≤x≤0.8 is clarified to be six-layer monoclinic with C2/c symmetry. The high-temperature X-ray diffraction experiment revealed the structural transition between the six-layer monoclinic and six-layer hexagonal structure with P63/mmc around 580 K for x=0.5. For x=0.6 and 0.7, the monoclinic distortion decreases with increasing temperature though the transition was not observed below 623 K. The phase diagram of the crystalline structure against Sr content x of Ba1-xSrxRuO3 at the ambient temperature and pressure was established in the present experiment as the nine-layer hexagonal for x=0, the four-layer hexagonal for 0.1≤x≤0.3, the six-layer monoclinic for 0.5≤x≤0.7 and perovskite for x=1.0. The crystal is the mixture of the six-layer monoclinic and the four-layer hexagonal at around x=0.4, and the mixture of the six-layer monoclinic and the perovskite at around 0.8≤x≤0.9. At the phase boundaries, the volume per formula unit and the averaged interlayer distance show a discontinuous decrease with increasing Sr content. However, the changes within the phase are much smaller than those at the phase boundaries.