Systematics of Phase Transition and Mixing Energetics in Rare Earth, Yttrium, and Scandium Stabilized Zirconia and Hafnia
Systematics of Phase Transition and Mixing Energetics in Rare Earth, Yttrium, and Scandium Stabilized Zirconia and Hafnia
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DOI：
10.1111/j.1551-2916.2007.01678.x
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发表时间：
2007-07
影响因子：
3.9
通讯作者：
P. Simoncic;A. Navrotsky
中科院分区：
文献类型：
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作者：
P. Simoncic;A. Navrotsky
用氧化物熔体热法系统地研究了稀土、钇和钪稳定氧化锆和铪的能量学。同时将氧化端分子的生成焓拟合为二次函数，以提取相互作用参数和氧化端分子向萤石结构的转变焓。zro2 - smo1.5和HfO 2 - smo1.5的放热生成焓和相互作用参数最大，而zro2 -ScO 1.5的放热生成焓和相互作用参数最小。这表明，在所有被研究的体系中，zro2 -ScO 1.5体系表现出最小的短程有序，与其高离子电导率一致。外推的稀土氧化物端元向立方萤石结构的转变焓随着阳离子尺寸的减小而增大。用差示扫描量热法（DSC）研究了zro2 -ScO 1.5中γ-立方萤石的相变。相变是可逆的，发生在1000°-1200°C，并表现出滞后（~ 100°C）。转变焓是吸热的，从1.7±0.1 kJ/mol （22 mol% ScO 1.5）增加到2.9±0.2 kJ/mol （30 mol% ScO 1.5）。
Energetics of rare earth, yttrium, and scandium stabilized zirconia and hafnia have been systematically investigated by oxide melt solution calorimetry. The enthalpies of formation with respect to the oxide end members were simultaneously fit to a quadratic function to extract interaction parameters and enthalpies of transition of the oxide end members to the fluorite structure. ZrO 2 -SmO 1.5 and HfO 2 -SmO 1.5 show the most exothermic enthalpies of formation and interaction parameters, whereas ZrO 2 -ScO 1.5 has the least exothermic enthalpy of formation and interaction parameter. This suggests that the ZrO 2 -ScO 1.5 system shows the least short range order among all investigated systems, consistent with its high ionic conductivity. The extrapolated enthalpy of transition of the rare earth oxide end members to the cubic fluorite structure increase to more endothermic values with decreasing cation size. The γ-cubic fluorite phase transition in ZrO 2 -ScO 1.5 was investigated by differential scanning calorimetry (DSC). The phase transition is reversible, occurs at 1000°-1200'C and shows hysteresis (∼100°C). The enthalpy of transition is endothermic on heating and increases from 1.7±0.1 kJ/mol (22 mol% ScO 1.5 ) to 2.9±0.2 kJ/mol (30 mol% ScO 1.5 ).