Kablov Eugene N, Stolyarova Valentina L, Vorozhtcov Viktor A, Lopatin Sergey I, Shugurov Sergey M, Shilov Andrey L, Karachevtsev Fedor N
All-Russian Scientific Research Institute of Aviation Materials, Moscow, Russia.
Saint Petersburg State University, Saint Petersburg, Russia.
Rapid Commun Mass Spectrom. 2022 Apr 15;36(7):e9238. doi: 10.1002/rcm.9238.
The Sm O -ZrO -HfO system is a promising base for the development of a wide spectrum of new refractory materials. Reliable data on thermodynamic properties in this system are of significant importance for planning the preparation and application of high-temperature ceramics. Especially, they can be useful for calculation of the unknown phase equilibria in this system.
The thermodynamic properties of the Sm O -ZrO -HfO system were studied by the high-temperature mass spectrometric method. The samples in the system under consideration synthesized by the solid-state method were vaporized from a tungsten twin effusion cell using a MS-1301 magnetic sector mass spectrometer. Ionization of the vapor species effusing from the cell was carried out by electrons at an energy of 25 eV.
It was shown that, at temperatures below 2500 K, the main vapor species over the ceramics based on the Sm O -ZrO -HfO system were SmO, Sm, and O corresponding to vapor composition over pure Sm O . The SmO, Sm, and O partial vapor pressures over the samples and the Sm O activities were obtained in the temperature range 2319-2530 K. This allowed the excess Gibbs energy values to be determined. For comparison, the excess Gibbs energies in the Sm O -ZrO -HfO system were also calculated by the semi-empirical Kohler, Toop, Redlich-Kister, and Wilson methods and optimized by the statistical thermodynamic Generalized Lattice Theory of Associated Solutions (GLTAS).
The thermodynamic data calculated by the semi-empirical approaches at 2423 K were shown to be lower than the experimental values. However, the Toop and Wilson methods were found to be useful for evaluation of the excess Gibbs energy values at the Sm O mole fraction less and higher than 0.32, respectively. The self-consistent thermodynamic description of the Sm O -ZrO -HfO system was derived at high temperatures by optimization of the experimental results using the GLTAS.
Sm₂O₃-ZrO₂-HfO₂体系是开发多种新型耐火材料的理想基础。该体系热力学性质的可靠数据对于规划高温陶瓷的制备和应用具有重要意义。特别是，它们可用于计算该体系中未知的相平衡。
采用高温质谱法研究Sm₂O₃-ZrO₂-HfO₂体系的热力学性质。通过固态法合成的该体系样品，使用MS-1301磁扇形质谱仪从钨双喷射池中蒸发。从池中流出的气相物种通过能量为25 eV的电子进行电离。
结果表明，在低于2500 K的温度下，基于Sm₂O₃-ZrO₂-HfO₂体系的陶瓷上方的主要气相物种是SmO、Sm和O，这与纯Sm₂O₃上方的气相组成相对应。在2319-2530 K的温度范围内获得了样品上方SmO、Sm和O的分压以及Sm₂O₃的活度。这使得能够确定过量吉布斯能值。为了进行比较，还通过半经验的科勒、图普、雷德利希-基斯特和威尔逊方法计算了Sm₂O₃-ZrO₂-HfO₂体系中的过量吉布斯能，并通过统计热力学关联溶液广义晶格理论（GLTAS）进行了优化。
结果表明，在2423 K时，通过半经验方法计算得到的热力学数据低于实验值。然而，发现图普和威尔逊方法分别对于评估Sm₂O₃摩尔分数小于和大于0.32时的过量吉布斯能值很有用。通过使用GLTAS对实验结果进行优化，在高温下得出了Sm₂O₃-ZrO₂-HfO₂体系自洽的热力学描述。
