Synthesis and Structural Studies of Strontium-Substituted Tricalcium Aluminate Ca3-xSrxAl2O6

Abstract

A series of 27 oxides of the type Ca_3–xSr_xAl₂O₆, 3 £ x £ 0, were prepared as polycrystalline powders. The compounds are isostructural with Ca₃Al₂O₆, space group Pa₃^–, and their structures were refined from powder neutron and/or X-ray diffraction data by using the Rietveld method. The evolution of Ca/Sr site occupancies, with x, was determined. It was found that the Ca and Sr cations display strong site selectivity, the smaller Ca ²⁺ cations preferentially occupying the six-coordinate sites. The relationship between the observed structures and the reactivity of Ca₃Al2O₆ in Portland cement is discussed.