Structural, optical and ionic transport properties of Dy^sub 2-x^La^sub x^Zr^sub 2^O^sub 7^ nanoceramics

This study deals with how the oxide-ion ordering due to the La3+ substitution affects the structural, optical and ionic transport properties of Dy2Zr2O7. A series of nanoceramics, Dy2-xLaxZr2O7 (x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) are prepared through the modified combustion technique. Structure of the materials is studied using X-ray diffraction and vibrational spectroscopy. A combination of these two studies indicates the gradual change from the defect fluorite to the pyrochlore structure due to the oxide-ion ordering. Optical properties of the nanoceramics are studied using UV–visible spectroscopy and photoluminescence spectroscopy. Disc shaped compacts prepared from the nano materials achieve a higher density (>95%) during the sintering process. The electrical conductivity of the dense ceramics are investigated by the impedance spectroscopic analysis. Higher concentration (x > 0.1) of La content in the series considerably decreases the grain size of the materials. The electrical conductivity measurements obey the Arrhenius relation. The increase of oxide-ion ordering in the 8b site of pyrochlore structure is the major cause of increase of electrical conductivity.