Effect of thermal transformations of constituent polyhedra of the crystal structure on the properties of Cd2V2O7

Analysis of variations in the linear and angular parameters of constituent polyhedra of the cadmium pyrovanadate Cd 2 V 2 O 7 structure, namely, VO 4 tetrahedra and CdO 6 octahedra, as calculated from the results of in situ high-temperature X-ray diffraction experiments in the range from 25 to 900°C, showed that, in the range from 600 to 720°C, the thermal expansion coefficient (tec) of CdO 6 polyhedra is near zero, whereas VO 4 tetrahedra increase in volume, although less strongly than in other temperature ranges. A structural interpretation is given to anomalous temperature dependences of cadmium ion emission and electrical conductivity on the basis of different thermal behavior patterns of the constituent polyhedra of the Cd 2 V 2 O 7 structure.