Influence of magnesia doping on structure and electrical conductivity of pyrochlore type GdSmZr207

摘要

Polycrystalline ceramic samples of magnesia doped GdSm_(1-x)Mg_xZr_2O_(7-x/2) have been prepared by conventional solid state reaction method using high purity oxides. The influence of magnesia dopant content on densification, microstructure and electrical properties of GdSm_(1-x)Mg_xZr_2O_(7-x/2) ceramics are investigated. Magnesia doping promotes the sintering densification behaviour of GdSm_(1-x)Mg_xZr_2O_(7-x/2) ceramics. GdSm_(1-x)Mg_xZr_2O_(7-x/2) (x=0, 0-05, 0-10) ceramics have a single phase of the pyrochlore type structure, while GdSm_(1-x)Mg_xZr_2O_(7-x/2) (x=0-15, 0-20) ceramics consist of the pyrochlore type structure and a small amount of magnesia as the second phase. The total conductivity of GdSm_(1-x)Mg_xZr_2O_(7-x/2) ceramics obeys the Arrhenius relation, and gradually increases with increasing temperature from 723 to 1173 K. GdSm_(1-x)Mg_xZr_2O_(7-x/2) ceramics are oxide-ion conductors in the oxygen partial pressure range of 1.0 x 10~(-4) to 1.0 atm at each test temperature. The maximum value of the total conductivity is 1.29 x 10~(-2) S cm~(-1) at 1173 K for the GdSm_(0.85)Mg_(0.15)Zr_2O_(6.925) ceramic.