Investigation into polytantalates of yttrium and europium

The series Eu2O3xnTa2O5 (n = 5-9) is investigated by X-ray, luminescence and microstructural methods, and the region of the EuTa7O19 phase homogeneity is determined. The existence of a succession of solid solutions with a hexagonal structure in Eusub(x)Ysub(1-x)Tasub(7)Osub(19) has been established, and changes of roentgenographic parameters in cross section are presented. It has been found that melting of yttrium and europium polytantalates is of an incongruent nature. The interaction reactions of polytantalates with rare-earth elements and tantalum oxides, as well as with other tantalates, have been studied. The spectra of luminescence excitation in europium poly- and metatantalate are described, the dependence of cathode luminescence intensity on the composition in the series Eu2O3xnTa2O5 is given