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Syntheses of MSn(OH) 6 by coprecipitation and of MSnO 3 by thermal decomposition (M = Mg, Co, Zn, Mn, Cd, Ca, Sr, Ba)

1985; Wiley; Volume: 527; Issue: 8 Linguagem: Inglês

10.1002/zaac.19855270822

1521-3749

M. Inagaki, Tadafumi Kuroishi, Y. Yamashita, Masayuki Urata,

ZnO doping and properties

Abstract MSn(OH) 6 (M = Mg, Co, Zn, Mn, Cd, Ca, Sr, and Ba) and their solid solutions were synthesized by coprecipitation from aqueous solutions of Na 2 Sn(OH) 6 complex and MCl 2 . MSnO 3 and their solid solutions were prepared by thermal decomposition of these MSn(OH) 6 precipitates. Coprecipitation procedures were established, and structures of MSn(OH) 6 and MSnO 3 were discussed in relation to mean radius of M 2+ ions. The morphology of particles of these hydroxides and oxides were also observed. In order to obtain a single phase precipitate MSn(OH) 6 , the concentration of both solutions of Na 2 Sn(OH) 6 and MCl 2 had to be as low as 0.1 mol/l. The pH‐value was kept above 11, and so acidic solution of MCl 2 was added slowly to basic solution of Na 2 Sn(OH) 6 . The structure of MSn(OH) 6 depended strongly of mean radius of M 2+ ions, being cubic with NaCl‐type arrangement of M 2+ and Sn 4+ cations below 1.26 Å and hexagonal above 1.26 Å. Crystalline MSnO 3 was obtained by the decomposition of MSn(OH) 6 precipitates above 500–600°C. The structure of MSnO 3 was also related with mean radius of M 2+ ions closely, ilmenite‐type below 1.09 Å and pervoskite‐type above 1.14 Å. In perovskite‐type structure, a gradual decrease in lattice distortion and rapid increase in crystal volume were observed with the increase in radius of M 2+ ions. An interesting morphology change was observed from CaSn(OH) 6 precipitates to CaSnO 3 , the particles with either cubic or flower‐like appearance in hydroxide becoming porous in oxide without appreciable change in particle appearance.