Synthesis and X-ray diffraction study of K2.92Nb2.58Ti1.42P2.5O17 single crystals

Single crystals of the composition K2.92Nb2.58Ti1.42P2.5O17 possessing ioni c conductivity sigma = 10(3) Omega (-1) cm(-1) at 300 degreesC were grown b y the method of spontaneous crystallization from flux in the quaternary K2O -TiO2-Nb2O5-P2O5 system. The X-ray diffraction study of the single crystals grown showed that they are monoclinic with the unit-cell parameters a = 13 .800(1), b = 6.412(2), c = 16.893(3) Angstrom, beta = 83.33(1)degrees, Z = 16, sp. gr. P2/n and provided the determination of the structure of this ne w compound. The Nb and Ti atoms statistically (with different probabilities ) occupy four crystallographically independent octahedra. The (Nb,Ti) and P -tetrahedra form the three-dimensional framework with the channels along th e diagonal [101] direction occupied by potassium atoms. (C) 2001 MAIK "Nauk a/Interperiodica".