التفاصيل البيبلوغرافية
| العنوان: |
Deep insight of unique phase transition behaviors and mechanism in Zr2Co-H isotope system with ultra-low equilibrium pressure. |
| المؤلفون: |
Liu, Yang, Zhou, Pan-Pan, Xiao, Xue-Zhang, Qi, Jia-Cheng, Bi, Jia-Peng, Ying, Tiao, Feng, Xing-Wen, Shi, Yan, Luo, Wen-Hua, Chen, Li-Xin |
| المصدر: |
Rare Metals; Jan2024, Vol. 43 Issue 1, p212-224, 13p |
| Abstract (English): |
Efficient capture, safe storage and release of tritium from the international thermonuclear experimental reactor (ITER) reaction exhaust gas is a perplexing problem, and the development of an efficient tritium-getter material with ultra-low hydrogenation equilibrium pressure is considered as a reliable way. In this work, Zr2Co alloy was selected as a tritium-getter material and prepared through induction levitation melting. Fundamental performance test results show that Zr2Co exhibits an ultra-low hydrogenation equilibrium pressure of 3.22 × 10–6 Pa at 25 °C and excellent hydriding kinetics under a low hydrogen pressure of 0.005 MPa. Interestingly, unique phase transition behaviors were presented in Zr2Co-H system. Specifically, Zr2CoH5 formed by Zr2Co hydrogenated at room temperature is initially decomposed into ZrH2 and ZrCoH3 at 200 °C. With the temperature increasing to 350 °C, ZrCoH3 is dehydrogenated to ZrCo, and then ZrCo further reacts with ZrH2 at 650 °C to reform Zr2Co and hydrogen. Among the staged phase transition pathways during dehydrogenation, the decomposition of Zr2CoH5 occurs preferentially, which is well accordance with both the smallest reaction energy barrier and the maximum reaction spontaneity that are determined respectively from kinetics activation energy and thermodynamics Gibbs free energy. Furthermore, first principles calculation results indicate that the stronger binding of hydrogen in interstitial environments of ZrCoH3 and ZrH2 triggers the hydrogen-stabilized phase transformation of Zr2CoH5. The unique phase transition mechanisms in Zr2Co-H system can shed light on the further exploration and regulation of analogous staged phase transition of hydrogen storage materials. [ABSTRACT FROM AUTHOR] |
| Abstract (Chinese): |
摘要: 如何从热核实验堆的反应排放气中有效捕获和回收氚仍是目前的一个难题。研究人员认为，开发具有超低吸氢平衡压的高效吸氚材料是一种可行途径。本文采用磁悬浮感应熔炼制备Zr2Co合金，详细研究了其低平衡氢压下的吸放氢性能。结果表明，Zr2Co在25 oC时具有3.22×10-6 Pa的超低吸氢平衡压力，在5000 Pa低氢压力下表现出优异的吸氢动力学。尤其值得关注的是，Zr2Co-H体系呈现出独特的吸放氢相变行为。Zr2Co合金在室温下吸氢直接生成Zr2CoH5。但在升温脱氢过程中，Zr2CoH5会在200 oC时首先歧化分解为ZrH2和ZrCoH3；随着放氢温度进一步升高，在350 oC时ZrCoH3会放氢生成ZrCo，在650 oC时ZrCo又会与ZrH2反应生成Zr2Co和氢气。通过动力学活化能和热力学吉布斯自由能的分析比较可知，Zr2CoH5的歧化分解反应具有最小反应能垒和最大反应自发性，因此，在脱氢过程中Zr2CoH5会首先发生歧化分解。此外，第一性原理计算结果表明，位于ZrCoH3和ZrH2间隙中的氢原子具有更强的结合能力，这是触发Zr2CoH5氢稳定诱导相变的主要因素。Zr2Co-H体系中独特的吸放氢相变机制可以为其它储氢材料的类似相变行为机制研究提供指导。 [ABSTRACT FROM AUTHOR] |
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