Abstract

The physical properties of AHfO₃ (A = Ca, Ba) are revealed using the density functional theory (DFT) based FP-LAPW+lo approach. The existing work investigates the pressure dependence of mechanical, electronic characteristics for specifying the optical and thermoelectric device applications of alkaline rare-earth hafnate perovskites. The PBEsol-GGA functional has been applied for the dealing of the exchange-correlation energy. The lattice constants of the stable cubic phases are extracted by structural optimization, which is similar to the existing experimental and theoretical literature. The bulk moduli (B) and cubic elastic constants are computed for evaluating the mechanical strength against external pressure up to 15 GPa. The electronic properties reveal that Hf-3d states primarily construct conduction band minima, while O–2p states construct valence band maxima at 0 GPa, exhibiting an indirect bandgap (Γ–M), which has been transformed to direct bandgap (Γ–Γ) at 15 GPa. Investigations of the optical properties illustrate that change in pressure can tune the optical parameters of these materials within ultraviolet (UV) energies suggesting commercial optoelectronic utilities. Our analysis shows that BAHfO₃ exhibits better thermoelectric properties than CAHfO₃ at room temperature whereas, thermoelectric performance both the compounds become comparable at a higher temperature.

Graphical abstract

中文翻译：

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通过从头算计算系统研究了在不同压力下AHfO 3（A = Ca，Ba）钙钛矿的光电和热电性质

摘要

使用基于密度泛函理论（DFT）的FP-LAPW + lo方法揭示了AHfO ₃（A = Ca，Ba）的物理性质。现有工作研究了机械，电子特性对压力的依赖性，以规定碱性稀土重晶铁酸盐钙钛矿的光学和热电器件应用。PBEsol-GGA功能已用于交换相关能量的处理。通过结构优化来提取稳定立方相的晶格常数，这与现有的实验和理论文献相似。计算总模量（B）和立方弹性常数，以评估在高达15 GPa的外部压力下的机械强度。电子性能表明Hf-3 d态主要构造导带的最小值，而O–2 p态则构造在0 GPa的价带最大值，表现出间接带隙（Γ– M），在15 GPa时已转变为直接带隙（Γ – Γ）。对光学性能的研究表明，压力变化可以在紫外线（UV）能量范围内调整这些材料的光学参数，这表明商业上的光电实用性。我们的分析表明，在室温下，BAHfO ₃表现出比CAHfO ₃更好的热电性能，而两种化合物的热电性能在更高的温度下变得可比。

图形概要