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|Effect of Sintering Temperature on Structural Conducting and Thermal Properties of Pyrochlore Y2Ti2O7
|MECHANICAL ALLOYING;PYROCHLORE;IONIC CONDUCTIVITY;DISORDERED PYROCHLORE
|Yttrium titanate Y2Ti2O7, is isostructural with the mineral Pyrochlore. Samples have been prepared using high energy ball mill. Initial ingredients used in present study are TiO2, Ti2O3 with Y2O3. Two type of samples YTi (TiO2/Y2O3) and YTi2 (Ti2O3/Y2O3) are prepared. Pyrochlore phase Y2Ti2O7 has been prepared by ball milling the initial ingredients upto 40 hours. Both samples have been sintered at 1450°C for 12 hours. It has been observed that YTi has Pyrochlore Y2Ti2O7 phase whereas YTi2 has pyrochlore Y2Ti2O7 and TiO2 phase. Conductivity of YTi2 is found to be 2.23x10-6 S/cm which is an order higher than YTi. An exothermic peak has been observed at 850° C in both the samples. Lattice parameter of YTi and YTi2 are 9.90 Å and 9.97Å respectively. The relative density of YTi and YTi2 has been found to be 84% and 97% of theoretical density respectively. At high temperature range (T˃ 660°C); activation energy of YTi and YTi2 has been observed 0.61eV and 0.59eV respectively. Thermal expansion coefficient (TEC) of YTi and YTi2 has been found to be 8.389x10-6/K and 8.212x10-6/K respectively. During the second part our study we sintered both samples pellet at 800°C and 1000°C for 12 hours. Concentration of TiO2 in YTi2 sample is found to be higher than single sintered YTi 2. Conductivity of both double sintered samples is of the same order ( ̴ 2.99x10-4 S/cm) and greater than the conductivity single sintered sample. No exothermic peak was observed in differential thermal analysis. Density of double sintered samples is comparatively very low than single sintered samples. Lattice parameter of YTi and YTi2 is found to be 10.15Å and 10.02Å respectively. Thermal expansion coefficient (TEC) of YTi and YTi2 is found to be 8.343x10-6 /K and 8.405x10-6 /K respectively. Due to lower density of double sintered samples, activation energy is low in comparison of single sintered samples.
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