Structural degradation behavior of Mg2-xPrxNi4 upon hydrogenation
Sakaki, Kouji 1Terashita, Naoyoshi 2Kim, Hyunjeong 1Tsunokake, Shigeru 2Majzoub, Eric H. 3Nakamura, Yumiko 1Akiba, Etsuo4
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作者信息
1. Natl Inst Adv Ind Sci & Technol
2. Japan Met & Chem Co Ltd
3. Univ Missouri
4. Kyushu Univ
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Abstract
Hydrogenation properties of Mg2-xPrxNi4 (x = 1.0, 1.2 and 1.4) and their structural degradation (amorphization) upon hydrogenation have been investigated using in-situ X-ray diffraction. In Mg1.0Pr1.0Ni4, the crystalline phase was stable up to a temperature of 573 K under 3 MPa of hydrogen pressure and amorphization did not take place. Mg0.6Pr1.4Ni4 was directly transformed to an amorphous hydride, Mg0.6Pr1.4Ni4H~7.2, while Mg0.8Pr1.2Ni4 transformed to amorphous Mg0.8Pr1.2Ni4H~6 through the formation of Mg0.8Pr1.2Ni4H~4 having an orthorhombic structure. While reversible hydrogen absorption and desorption was observed in the first plateau region between Mg0.8Pr1.2Ni4 and Mg0.8Pr1.2Ni4H~4. First principles calculation indicate that the elastic modulus and bulk modulus decreased with increase of the Pr content and hydrogen content in Mg2-xPrxNi4 suggesting that decrease of bulk modulus induce amorphization upon hydrogen absorption. These results clearly indicate that the hydrogenation properties, the stability of crystalline hydride and amorphization behavior strongly depend on the chemical composition of Mg2-xPrxNi4 and their hydrogen content. (C)& nbsp;2022 Elsevier B.V. All rights reserved.
NSTL
Elsevier