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Formation of Calcium Lanthanum Sulfide by Carbonate Coprecipitation and CS 2 Sulfurization
Author(s) -
Tsai MingShyong,
Wang LiHsing,
Hon MinHsiung
Publication year - 1995
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1995.tb08467.x
Subject(s) - coprecipitation , sulfide , ammonium carbonate , inorganic chemistry , carbonate , precipitation , chemistry , lanthanum , nuclear chemistry , phase (matter) , organic chemistry , physics , meteorology
Pure calcium lanthanum sulfide (CLS) powders with various La/Ca ratios were prepared by a carbonate coprecipitation method and CS 2 sulfurization. Four coprecipitation processes were investigated by conventional titration, and a suitable means for coprecipitating CLS was found. By that process, a cation solution containing La 3+ and Ca 2+ ions was added to the precipitation medium (an anion solution of ammonium carbonate) with stirring. Precursors with various La/Ca ratios were synthesized and then sulfurized for 3 h using CS 2 as a sulfurizing agent. In the range of La/Ca ratios from 2 to 5, the intermediate phase of sulfide powder was LaS 2 , and the CLS formation temperature could be increased by increasing the La/Ca ratio. For powder with high La/Ca ratios (La/Ca = 10, 15), and LaS 2 intermediate phase formed at low temperature (700°C), a (β‐La 2 S 3 minor phase at 800°C, and a pure CLS phase after 950°C treatment. The resulting pure CLS powder was spherical, with slight necking in the submicrometer range.