Mössbauer study of properties and phase transitions of Cd2Nb2–2xSn2xO7–2xF2x

With the aid of Mossbauer spectroscopy the solid solution series Cd2Nb2–2xSn2xO7–2xF2x are investigated in the temperature range 4.2 to 400 K. The crystal structure belongs to the cubic pyrochlore type. The BY6 octahedra (B = Nb, Sn; Y = O, F) are linked three-dimensionally through their corners, forming groups of four octahedra which are extended or compressed in the (111)-direction for x ≤ 0.375 or x ≥ 0.400 respectively. The dependence of the quadrupole splitting ΔEQ on x shows a small but significant discontinuity in the region 0.375 < x < 0.400. This can be attributed to a first order phase-transition which depends on concentration, but not on temperature over the temperature region st…

Poster contributions