分类： 材料科学 >> 材料力学 提交时间： 2022-10-19 合作期刊: 《桂林电子科技大学学报》
摘要： 为探索双金属共掺杂对MgH2 储氢材料储氢性能的影响,运用基于密度泛函理论的第一性原理对(Fe+Co)共掺杂MgH2 储氢材料体系的热力学稳定性、键合机理进行系统研究。对共掺杂体系的晶格结构进行考察,发现(Fe+Co)共掺杂后,Mg12Fe2Co4H36 和Mg12Fe4Co2H36 晶胞的体积分别收缩了16%和17.5%。对(Fe+Co)共掺杂体系的生成焓进行计算,结果表明掺杂后体系的生成焓减少,更有利于氢气的解析。通过对掺杂体系Bader电荷和电子态密度的计算,探索Fe、Co金属掺杂前后的电荷转移情况和金属原子与氢原子之间的成键轨道,电子结构分析表明掺杂后电子从氢原子转移到了镁原子,有利于MgH键的弱化。(Fe+Co)双金属共掺杂对MgH2 储氢材料热力学性能的改善有积极影响,为发展高性能储氢材料提供了理论指导。
分类： 材料科学 >> 材料力学 提交时间： 2019-02-01
摘要： Magnetorheological (MR) materials are a type of magnetoactive smart materials, whose physical or mechanical properties can be altered by applying a magnetic field. In usual, MR materials can be prepared by mixing magnetic particles into non-magnetic matrices. In this work, the electromagnet-induced (or non-uniform magnetic field-induced) normal stress of MR materials is studied. It shows that the stress does not vary monotonically along with the enhancement of the applied magnetic field. There exists a field-dependent reversal effect of the variation of the stress. The reversal effect is thought resulting from that the ratio of interparticle repellent of parallel magnetic particles to the particle-electromagnet attraction gets enlarged along with the enhancement of the field.
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