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<p>Two series of single-phase five-component aluminate perovskites with the composition (Y<sub>0.2</sub>Nd<sub>0.2</sub>Sm<sub>0.2</sub>Eu<sub>0.2</sub>Er<sub>0.2</sub>)AlO<sub>3</sub> were obtained for the first time using the sol-gel citrate method and the solution combustion technique. In both these cases, single-phase perovskite materials with average crystallite sizes of 38 and 76&#xa0;nm, respectively, are formed after heat treatment of the synthesis products in air at 1000&#xa0;°C. These materials remain stable after additional annealing for 4&#xa0;h at 1100&#xa0;°C; however, further heat treatment at 1200&#xa0;°C leads to the partial decomposition of both materials with the precipitation of a garnet phase, the relative fraction of which gradually increases with rising annealing temperature up to 1500&#xa0;°C. Complete sets of structural parameters for the high-entropy perovskite (Y<sub>0.2</sub>Nd<sub>0.2</sub>Sm<sub>0.2</sub>Eu<sub>0.2</sub>Er<sub>0.2</sub>)AlO<sub>3</sub> were obtained for the first time based on experimental X-ray powder diffraction data using full-profile Rietveld refinement. The evolution of the (Y<sub>0.2</sub>Nd<sub>0.2</sub>Sm<sub>0.2</sub>Eu<sub>0.2</sub>Er<sub>0.2</sub>)AlO<sub>3</sub> perovskite structure in the temperature range from RT to 773&#xa0;K was studied using in situ temperature-dependent X-ray powder diffraction. It was found that this HE perovskite shows strongly anisotropic thermal expansion with relative elongation along the [010] direction <i>ca.</i> 2 times weaker compared with [100] and [001] directions. Comprehensive crystal chemical analysis of five-component HE perovskite (Y<sub>0.2</sub>Nd<sub>0.2</sub>Sm<sub>0.2</sub>Eu<sub>0.2</sub>Er<sub>0.2</sub>)AlO<sub>3</sub> in comparison with the reference data for the single RE compounds REAlO<sub>3</sub> revealed that its crystal structure follows well the empirical relations earlier established for the rare-earth aluminate series, indicating that the structure of HE perovskite materials is mainly governed by the geometrical factor.</p>

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Crystal structure and thermal expansion behaviour of high-entropy perovskite (Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3

  • 期刊论文

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  • 发表日期：

    2026年7月23日

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  • Leonid Vasylechko,
  • Vasyl Hreb,
  • Vitalii Stadnik,
  • Iryna Lutsyuk,
  • Yurii Hirskyi,
  • Oleh Buryy,
  • Yaroslav Zhydachevskyy

摘要

Two series of single-phase five-component aluminate perovskites with the composition (Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3 were obtained for the first time using the sol-gel citrate method and the solution combustion technique. In both these cases, single-phase perovskite materials with average crystallite sizes of 38 and 76 nm, respectively, are formed after heat treatment of the synthesis products in air at 1000 °C. These materials remain stable after additional annealing for 4 h at 1100 °C; however, further heat treatment at 1200 °C leads to the partial decomposition of both materials with the precipitation of a garnet phase, the relative fraction of which gradually increases with rising annealing temperature up to 1500 °C. Complete sets of structural parameters for the high-entropy perovskite (Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3 were obtained for the first time based on experimental X-ray powder diffraction data using full-profile Rietveld refinement. The evolution of the (Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3 perovskite structure in the temperature range from RT to 773 K was studied using in situ temperature-dependent X-ray powder diffraction. It was found that this HE perovskite shows strongly anisotropic thermal expansion with relative elongation along the [010] direction ca. 2 times weaker compared with [100] and [001] directions. Comprehensive crystal chemical analysis of five-component HE perovskite (Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3 in comparison with the reference data for the single RE compounds REAlO3 revealed that its crystal structure follows well the empirical relations earlier established for the rare-earth aluminate series, indicating that the structure of HE perovskite materials is mainly governed by the geometrical factor.