Crystal chemistry of silver borates with salt-inclusion structures

A review of structural studies of silver borates with salt-inclusion structures is presented. Data on the first halogen-containing silver borates are provided, along with the structural and physicochemical characterization of the Ag4B4O7X2 (X = Br, I), Ag3B6O10X (X = Br, I, NO3), Ag4B7O12X (X = Cl, Br, I) families, as well as Ag4(B3O6)(NO3) and Ag3B4O6(OH)2(NO3). The crystal structures of these compounds are framework-type, layered, or composed of isolated boron-oxygen groups. In almost all cases, silver atoms exhibit pronounced anharmonicity in thermal displacements, which was investigated using X-ray structural analysis, including extensive temperature-dependent studies. The reasons for the low stability of chlorine-containing silver borates are discussed, along with the relationship between the anharmonicity of thermal displacements and other properties, such as the high ionic conductivity of Ag3B6O10I.