Crystal Chemistry of Silver Borates with Salt Inclusion Structure

A review of structural studies of silver borates with a salt inclusion structure is presented. Besides the presentation of the first halogen-containing silver borates, we discuss the structural and physicochemical characterization of the Ag4B4O7X2 (X = Br, I), Ag3B6O10X (X = Br, I, NO3), and Ag4B7O12X (X = Cl, Br, I) families, as well as the Ag4(B3O6)(NO3) and Ag3B4O6(OH)2(NO3). The dimensionality of their crystal structures varies from three to two or zero. In the majority of cases, the silver atoms exhibit strong anharmonicity of thermal displacements, which was studied by X-ray structural analysis, including polythermic. We discuss the reasons for the low stability of chlorine-containing silver borates, as well as the relationships between the anharmonicity of thermal displacements and other properties, including the high ionic conductivity of Ag3B6O10I.