STRUCTURES OF SrSiO₃ AND SrGeO_3. Fumito Nishi, Saitama Institute of Technology, Fusaiji 1690, Okabe-machi, Ohsato-gun, Saitama-ken, Japan

I succeeded in synthesizing SrSiO₃ and SrGeO₃ single crystals The space group is C2/c and the crystal data are: a=12.305(4), 12.533(3)Å; b=7.129(2), 7.262(1)Å; c=10.861(2), 11.259(3)Å; [[beta]] =111.60(2), 111.30(2)deg. for SrSiO₃ and SrGeO₃, respectively. Hilmer(1962) studied the crystal structure of SrGeO₃ by Weissenberg method and Nadezhina, Pobedimskaya, Ilyukhin, Nikishina and Belov (1977) studied it by four-circle diffractometer. According to my results, it may be said that Hilmer's crystal is same polymorph as mine but he misunderstood its unit cell. On the contrary, it is certain that Nadezhina's one is another polymorph having SrGeO₃ contents. I can summarized: ( 1 ) Both structures include the layers comprised by SiO₄ or GeO₄ three-membered rings and the layers comprised by SrO₈ polyhedra. ( 2 ) They are piled up along c direction alternately. ( 3 ) In viewpoint of the polytipic consideration, my crystals are classified into the 6-layers group which are studied by Yamanaka and Mori (1981).

Hilmer, W. Kristallografiya 7, 704 (1962).

Nadezhina, T. N., Pobedimskaya, E. A., Ilyukhin, V. V., Nikishina, N. N. & Belov, N. V. Dokl. Akad. Nauk SSSR, 233, 1086 (1977).

Yamanaka, T.and Mori, H. Acta Cryst. B37, 1010 (1981).