The synthesis and crystal structure of new compound K6CrNb15O42

Abstract

Abstract A new compound was found in the ternary system K2O–Cr2O3–Nb2O5, Chemical analyses show that the compound formula is K6CrNb15O42. The structure was solved using direct method and Fourier techniques; it crystallizes in the hexagonal system with unit cell parameters a = 9.126(3) Å, c = 12.068(3) Å, V = 870.4(5) Å3, and space group P63/mcm, Z = 1. Of the 829 unique reflections measured by counter techniques 448 with I > 3σ(I) were used in the least-square refinement of the model to R = 0.034 (Rw = 0.044). The structure of K6CrNb15O42 may be described as consisting of corner-shared and edge-shared octahedra the ring units composed of six octahedra share corners along the c-axis to form a kind of hexagonal column octahedra chain, which is the first one discovered in niobates.