A CORRELATION BETWEEN THE STRUCTURE AND SOME PHYSICAL-PROPERTIES OF BINARY MOLYBDATES (TUNGSTATES) OF UNIVALENT AND BIVALENT METALS

General principles of arrangement are discussed and analyzed for 13 kn own structural types (families) of binary molybdates and tungstates of uni- and bivalent metals, which were classified according to the degr ee of condensation of M(2+)O(n) polyhedral and MoO4 tetrahedral constr uctions. The structural features of some phases correlate with their f erroelectric, ion-conducting, and luminescent (laser) properties. We s uggest crystallochemical criteria and mechanisms of distortion (ferroe lectric) phase transitions in palmierites, langbeinites, and Rb4Mn(MoO 4)(3) and show the paths of ionic transport in phases with NaCo231(MoO 4)(3), alluaudite, and Na2Mg5(MoO4)(6) structures. On the basis of the analysis performed we outlined the compounds that are the most promis ing for the development of inorganic materials with efficient physical properties.