Insertion of boron in tectosilicate frameworks in the presence of large alkali cations

Borosilicates of rubidium and cesium with the analcime structure can be formed under mild hydrothermal conditions. The formation of a solid solution is possible for any intermediate composition between borosilicate and aluminosilicate pollucite. K-danburite is obtained in the presence of potassium. The easy formation of borosilicates in the presence of the largest alkali cations is related to the organic-templated synthesis of borosilicate zeolites and confirms the relevance of a hydrophobic effect in the insertion of boron in tetrahedral lattice sites.