Temperature dependent study of the crystal structure of NaCdZn2F7 pyrochlore

NaCdZn2F7 pyrochlore (Fd3¯m, Z=8), in which the Na and Cd cations are completely disordered, is shown to be structurally stable in the temperature range 100-643 K using X-ray diffraction and Raman scattering at atmospheric pressure. X-ray single-crystal measurements indicate that the (Na, Cd)F8 cubes become more regular, while the ZnF6 octahedra become more distorted in this structure upon cooling. The anomalous temperature-dependence of one of the Raman-active mode has been observed.