Subjects: Materials Science >> Materials Mechanics submitted time 2022-10-19 Cooperative journals: 《桂林电子科技大学学报》
Abstract： For exploring the effect of bimetallic co-doping on the hydrogen storage performance of MgH2 hydrogen storage materials, the thermodynamic stability and bonding mechanism of (Fe+Co) co-doping MgH2 hydrogen storage materials system were systematically studied by using first-principles calculations based on density functional theory.The lattice structure of the co-doped system was investigated,and found that the volume of Mg12Fe2Co4H36 and M-g12Fe4Co2H36 cell structure shrank by 16% and 17.5% respectively after (Fe+Co) co-doping .The formation enthalpy of the (Fe+Co) co-doping system was calculated, the calculated results reveal that the formation enthalpy of the system decreases after doping, which is more conducive to the resolution of hydrogen. The charge transfer of Fe and Co before and after doping and the bonding orbital between the metal atom and the hydrogen atom were investigated by calculating the Bader charge and electron density of states of the doping system, the analysis of the electronic structure proved that the electron transfer from the hydrogen atom to the magnesium atom after doping, which is beneficial to the weakening of the Mg—H bond. The (Fe+Co) bimetallic co-doping has a positive effect on the improvement of thermodynamic properties of MgH2 hydrogen storage materials, which provides theoretical guidance for the development of high-performance hydrogen storage materials.
Subjects: Materials Science >> Materials Mechanics submitted time 2019-02-01
Abstract：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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