Thermal expansion of phases formed in the system Nb2O5-MoO3

Studies on thermal expansion of phases formed in the system Nb2O5 - MoO3 (WO3) have been carried out in the high-temperature X-ray diffraction attachment. In the case of Nb14Mo3O44, Nb12MoO33 and Nb12WO33 the structure that consists of ReO3 type blocks, the direction of minimal thermal expansion is consistent with direction in which the chains of corner-sharing polyhedra spread to infinity. On the contrary, for Nb2Mo3O14, the structure of which resembles the structure of tetragonal tungsten bronzes, the maximal thermal expansion direction is consistent with above mentioned direction.