Sodalite-type Na8Mg3Si9O24(OH)2 and Na8Mg3Si9O24(OH,Cl)2: novel framework magnesiosilicates

Abstract

Na₈Mg₃Si₉O₂₄(OH)₂ and Na₈Mg₃Si₉O₂₄(OH,Cl)₂ have been prepared by solid state reaction at ca. 700 °C in air. These new materials have the sodalite structure type with I-centred cubic unit cells of dimensions a= 9.059(2) and 8.989(1)Å, respectively. The magnesium and silicon atoms in the sodalite framework are disordered with the interstitial sodium ions being partially exchangeable at 85 °C. These materials represent only the second type of magnesiosilicate framework structure reported.