Rare-earth tantalates present promise as thermal barrier coatings due to their favorable thermodynamic characteristics. To further diminish thermal conductivity, three high-entropy tantalate samples, namely (Ce_0.2Nd_0.2Sm_0.2Eu_0.2Lu_0.2)₃TaO₇, (Nd_0.2Sm_0.2Eu_0.2Gd_0.2Tm_0.2)₃TaO₇, and (Ce_0.2Nd_0.2Sm_0.2Eu_0.2Dy_0.2)₃TaO₇, denoted as HE-1, HE-2, and HE-3, respectively, were synthesized in this investigation. HE-1 exhibits a low thermal conductivity of 1.46 W/(m·K)^–1 at 1000°C. The rationale behind this reduced thermal conductivity is expounded via the phonon scattering mechanism. The introduction of atomic disparities and grain size inhomogeneity, attributable to high-entropy doping, collaborates to enhance phonon scattering, culminating in the lowest thermal conductivity. HE-3, on the other hand, possesses a notable thermal expansion coefficient of 11.6 × 10⁻⁶ K⁻¹ at 1200°C and manifests pronounced anisotropy in CTEs. All three high-entropy samples demonstrate commendable mechanical properties, with Young's modulus lower than that of single-component rare-earth tantalates, while simultaneously exhibiting high hardness values (>8.4 GPa). This work furnishes a valuable reference for the utilization of high entropy rare-earth tantalates in the realm of thermal barrier coatings.

中文翻译：

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高熵设计增强稀土钽酸盐的热力学性质

稀土钽酸盐由于其良好的热力学特性而有望作为热障涂层。为了进一步降低热导率，三个高熵钽酸盐样品，即(Ce _0.2 Nd _0.2 Sm _0.2 Eu _0.2 Lu _0.2 ) ₃ TaO ₇、(Nd _0.2 Sm _0.2 Eu _0.2 Gd _0.2 Tm _0.2 ) ₃ TaO ₇和(Ce _0.2本研究合成了Nd _0.2 Sm _0.2 Eu _0.2 Dy _0.2 ) ₃ TaO ₇，分别表示为HE-1、HE-2和HE-3。 HE-1在 1000°C 时表现出 1.46 W/(m·K) ^–1的低导热率。通过声子散射机制阐述了热导率降低背后的基本原理。由于高熵掺杂而引入的原子差异和晶粒尺寸不均匀性共同增强了声子散射，最终实现了最低的热导率。另一方面，HE-3 在 1200°C 时具有 11.6 × 10 ^-6 K ^-1的显着热膨胀系数，并且在 CTE 中表现出明显的各向异性。所有三个高熵样品都表现出值得称赞的机械性能，杨氏模量低于单组分稀土钽酸盐，同时表现出高硬度值（>8.4 GPa）。该工作为高熵稀土钽酸盐在热障涂层领域的应用提供了有价值的参考。