A combined experimental and theoretical study of enthalpy of phase transition and fusion of yttria above 2000 °C using “drop-n-catch” calorimetry and first-principles calculation

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• 作者：D. Kapush^a ; S.V. Ushakov^a ; A. Navrotsky^a ; ^{anavrotsky@ucdavis.edu} ; Q.-J. Hong^b ; H. Liu^b ; A. van de Walle^b
• 关键词：Aerodynamic levitation ; Enthalpy ; First-principles calculation ; Thermodynamics ; Yttria
• 刊名：Acta Materialia
• 出版年：2017
• 出版时间：1 February 2017
• 年：2017
• 卷：124
• 期：Complete
• 页码：204-209
• 全文大小：996 K
• 卷排序：124

文摘

“Drop-n-catch” calorimetry was performed on Y2O3 spheroids of 2–3 mm in diameter, prepared by laser melting of powders. Samples were aerodynamically levitated in a splittable nozzle levitator in air or argon flow, laser heated from ∼2200 to 3000 °C and dropped into a calorimeter at 25 °C, thus measuring their enthalpy as a function of temperature. The fusion enthalpy of cubic Y2O3 was derived from the step in the temperature–enthalpy curve as 119 ± 10 kJ/mol. Calculations performed using density functional theory and molecular dynamics techniques produced the value 127 ± 3 kJ/mol Y2O3. This combined methodology enables accurate determination of the enthalpies of fusion and phase transition of refractory oxides, including those containing lanthanides and actinides.