Crystal chemistry of mixed framework. Principles of their formation

This work is devoted to consideration of the main principles of the mixed frames formation. General formula is given in the paper, it provides sufficiently complete reflection of the basic rules of crystallic structure formation. General formulae of the threedimensional bonds, flat layers and other mixed type radicals were determined. Main microunits, taking part in the mixed radical formation were indentified. Using general rules the reverce problem can be solved: namely fixing the frame charge and the types of polyhedrons determine whether this crystal structure is stable or not and for which stoichiometry of its polyhedrons. Preliminary calculation of the frame holls allow to select optimum cation-compensator. In the class of phosphates, arsenites and other compounds neutral frame exists only with m:n=1:2 ratio which is realized in ZrP2O7, SiP2O7 compounds