Synthesis and Stabilization of Crystal Hydrate Modification SrSO4•0.5H2O

A method has been developed for the synthesis of the metastable trigonal modification SrSO4 center dot 0.5H(2)O, isostructural to the well-known CaSO4 center dot 0.5H(2)O modification (space group P3(1)21). Frozen solutions of NaCl in water have been proposed as a precursor in the crystallization of SrSO4 center dot 0.5H(2)O. The SrSO4 center dot 0.5H(2)O structure can be stabilized by isovalent substitution of calcium ions for strontium ions or by aliovalent substitution of potassium and lanthanum ions for strontium ions. The compound of composition K0.25La0.25Sr0.5(SO4)center dot 0.5H(2)O has been synthesized as an example of the stabilized SrSO4 center dot 0.5H(2)O modification. The unit cell parameters have been determined and refined. A model of the structure of SrSO4 center dot 0.5H(2)O with a statistical distribution of potassium, lanthanum, and strontium atoms over the positions of Ca atoms in the well-known SO4 center dot 0.5H(2)O structure has been proposed.

Automated summary

A method has been developed to synthesize the metastable trigonal modification SrSO4·0.5H(2)O, and its structure can be stabilized by isovalent or aliovalent substitution. The compound K0.25La0.25Sr0.5(SO4)·0.5H(2)O has been synthesized as an example of the stabilized SrSO4·0.5H(2)O modification.