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arXiv 2403.00705cond-mat.mtrl-sci
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CrNbO4和CrTaO4的温度依赖热力学性质的首原理计算

Temperature-dependent thermodynamic properties of CrNbO4 and CrTaO4 by first-principles calculations

The Pennsylvania State University(宾夕法尼亚州立大学)

Shuang Lin, Shun-Li Shang, Allison M. Beese, Zi-Kui Liu

AI总结:

通过PBE+U方法和准谐phonon方法,研究CrNbO4和CrTaO4等氧化物的温度依赖热力学性质,验证其热力学稳定性及热膨胀系数,并分析其对铬挥发的影响。

摘要:

本文采用Perdew、Burke和Ernzerhof(PBE)+U方法,即PBE+U方法,通过准谐phonon方法(QHA)预测 rutile型氧化物CrNbO4和CrTaO4以及二元氧化物Cr2O3、Nb2O5和Ta2O5的温度依赖热力学性质。计算的二元氧化物热力学性质与实验数据对比,显示高精度,除了Nb2O5的负热膨胀(NTE)归因于其多形复杂性。通过结合DFT预测的形成能与现有的SGTE物质数据库(SSUB5),发现CrNbO4和CrTaO4在1706 K和1926 K时热力学稳定,并分别分解为Cr2O3和Nb2O5或Ta2O5。预测了CrNbO4和CrTaO4的线性热膨胀系数温度依赖性,其从500 K到2000 K的平均值分别为6.0×10-6/K和5.04×10-6/K,与文献中的实验观测一致。计算了气相物种及其蒸气压,表明CrTaO4和CrNbO4的形成可减少铬挥发,这对设计具有增强氧化阻力的增强型耐火高熵合金(RHEAs)至关重要。

英文摘要:

In the present work, the density functional theory (DFT) in the generalized-gradient approximation developed by Perdew, Burke, and Ernzerhof (PBE) +U method, i.e., PBE+U, was employed to predict temperature-dependent thermodynamic properties of the rutile-type oxides CrNbO4 and CrTaO4 as well as the binary oxides Cr2O3, Nb2O5, and Ta2O5 via the quasiharmonic phonon approach (QHA). Calculated thermodynamic properties of the binary oxides were benchmarked with experimental data, showing high accuracy except for the negative thermal expansion (NTE) of Nb2O5, attributed to its polymorphic complexity. By combining the formation energy predicted by DFT with the existing SGTE Substances Database (SSUB5), the CrNbO4 and CrTaO4 are found to be thermodynamic stable up to 1706 K and 1926 K and decompose into Cr2O3 and Nb2O5 or Ta2O5 at those temperatures, respectively. The temperature dependence of linear thermal expansion coefficients for CrNbO4 and CrTaO4 are predicted, and their mean values from 500 K to 2000 K are found to be 6.0*10-6/K and 5.04*10-6/K, respectively, in agreement with experimental observations in the literature. The gas-phase species and their vapor pressure are calculated, indicating that the formation of CrTaO4 and CrNbO4 reduces chromium volatilization, which is critically important to design enhanced Refractory high entropy alloys (RHEAs) with enhanced oxidation resistance.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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