Crystal chemistry of condensed phosphates of trivalent metals

An attempt was made to predict the possibility of formation of polymer anions with chain or cyclic structure and to establish a correlation between structural characteristics and luminescence properties in search of new materials on the basis of results of X-ray diffraction analysis of different classes of trivalent metal condensed phosphates. The following aspects of atomic structure of condensed phosphate crystals were considered to solve the problems mentioned: change in the form of polymer anions, depending on the size of M3+, M+ cations, ratio of their sizes, presence of hydrogen bonds; the influence of the structure peculiarities of double condensed phosphates of rare earths and alkali metals on radiating ability of cation; dependence of p-p bond length in rare earth hypophosphates on Ln3+ cation size