First-principles calculations on temperature-dependent elastic constants of rare-earth intermetallic compounds: YAg and YCu |
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Authors: | Rui Wang Shaofeng WangXiaozhi Wu Yin Yao |
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Institution: | Institute for Structure and Function and Department of Physics, Chongqing University, Chongqing 400044, People''s Republic of China |
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Abstract: | We present the temperature-dependent elastic constants of two ductile rare-earth intermetallic compounds YAg and YCu with CsCl-type B2 structure by using a first-principles approach. The elastic moduli as a function of temperature are predicted from the combination of static volume-dependent elastic constants obtained by the first-principles total-energy method with density-functional theory and the thermal expansion obtained by the first-principles phonon calculations with density-functional perturbation theory. The comparison between our calculated results and the available experimental data for Ag and Cu provides good agreements. In the calculated temperature 0-1000 K, the elastic constants of YAg and YCu follow a normal behavior with temperature that those decrease with increasing temperature, and satisfy the stability conditions for B2 structures. The Cauchy pressure for YAg and YCu as a function of temperature is also discussed, and our results mean that YAg and YCu become more ductile while increasing temperature. |
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Keywords: | Rare-earth intermetallics Temperature-dependent elastic constants First-principles calculations |
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