Structure change in strontium oxide-doped dicalcium silicates

A series of strontium-bearing dicalcium silicate (Ca2SiO4) solid solutions (C2S(ss)), (SrxCa1-x)(2)SiO4 with 0.02 less than or equal to x less than or equal to 0.10, was prepared and examined by powder X-ray diffractometry. These crystals, heated in the stable temperature region of the alpha phase and then quenched in water, mere composed of the beta phase, with x less than or equal to 0.08, and like alpha'(L) and beta phases, with x = 0.10, With increasing x, the unit-cell axes of the beta phase expanded and the beta angle became small with eventual increase in the unit-cell volume. The Rietveld analysis of the beta-C2S(ss) with x = 0.08 showed that the Sr2+ ions preferentially occupied the seven-coordinated site rather than the eight-coordinated site, This site preference, which was originally established in the parent alpha-phase structure, seemed to cause the systematic change in the cell dimensions.