Polycrystalline samples of samarium barium tungstate[Sm_(2)(Ba_(0.5)W_(0.5)T_(2)O_(7):(SBW)]pyrochlore structure type oxides have been prepared by a solid-state reaction technique.X-ray di®raction(XRD)patterns of...Polycrystalline samples of samarium barium tungstate[Sm_(2)(Ba_(0.5)W_(0.5)T_(2)O_(7):(SBW)]pyrochlore structure type oxides have been prepared by a solid-state reaction technique.X-ray di®raction(XRD)patterns of this compound at room temperature suggest the formation of a single phase compound with orthorhombic structure.Studies of the dielectric constant and dielectric loss of compound as a function of frequency(4 kHz-1MHz)at room temperature,and as a function of temperature(23-350℃)at 20 and 50 kHz frequencies suggest that the compound does not have dielectric anomaly.The variation of dc resistivity suggests the semiconductor characteristics of the material.The value of activation energy(E_(a)-0.43 at 20 kHz and E_(a)-0.29 at 50 kHz)of the above mentioned compound has been calculated from the slope of the ln-ac versus 1/T graph in the high temperature region(>240℃).The low value of activation energy supports the superionic nature of the compounds in the high temperature region.展开更多
文摘Polycrystalline samples of samarium barium tungstate[Sm_(2)(Ba_(0.5)W_(0.5)T_(2)O_(7):(SBW)]pyrochlore structure type oxides have been prepared by a solid-state reaction technique.X-ray di®raction(XRD)patterns of this compound at room temperature suggest the formation of a single phase compound with orthorhombic structure.Studies of the dielectric constant and dielectric loss of compound as a function of frequency(4 kHz-1MHz)at room temperature,and as a function of temperature(23-350℃)at 20 and 50 kHz frequencies suggest that the compound does not have dielectric anomaly.The variation of dc resistivity suggests the semiconductor characteristics of the material.The value of activation energy(E_(a)-0.43 at 20 kHz and E_(a)-0.29 at 50 kHz)of the above mentioned compound has been calculated from the slope of the ln-ac versus 1/T graph in the high temperature region(>240℃).The low value of activation energy supports the superionic nature of the compounds in the high temperature region.
