Role of additives in LiBH4-MgH2 reactive hydride composites for sorption kinetics
Role of additives in LiBH4-MgH2 reactive hydride composites for sorption kinetics
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DOI：
10.1016/j.actamat.2010.02.012
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发表时间：
2010-05-01
期刊：
影响因子：
9.4
通讯作者：
Dornheim, M.
中科院分区：
文献类型：
--
作者：
Boesenberg, U.;Kim, J. W.;Dornheim, M.
详细研究了添加剂对LiBH 4-MgH 2复合材料的反应动力学和组织细化的影响。通过比较测量的反应动力学与模拟一个特定的限速过程的反应过程中的限速过程的指示。吸附反应的动力学来自体积测量以及从原位X-射线衍射测量。在脱附过程中，氢以恒定速率释放，这可能与MgB 2片晶的一维生长有关。相反，吸收反应的动力学曲线表现出典型的收缩体积控制动力学形状。动力学测量的显微镜解释的支持下，通过透射电子显微镜图像确认添加剂的纳米结构的形成在循环时的晶界。本研究强调了添加剂作为成核基质的重要性以及微观结构对反应动力学的影响。(C)2010 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
The influence of additives on the reaction kinetics and microstructure refinement in LiBH4-MgH2 composites is investigated in detail. Indications of the rate-limiting processes during the reactions are obtained by comparison of the measured reaction kinetics with simulations with one specific rate-limiting process. The kinetics of the sorption reactions are derived from volumetric measurements as well as from in situ X-ray diffraction measurements. During desorption, the hydrogen is released at a constant rate, which is possibly correlated with the one-dimensional growth of MgB2 platelets. In contrast, the kinetic curves of the absorption reactions exhibit the typical shape of contracting-volume controlled kinetics. The microscopical interpretation of kinetic measurements are supported by transmission electron microscopy images confirming the formation of additive-nanostructures in the grain boundaries upon cycling. The present investigations underline the importance of the additives as nucleation substrates and the influence of microstructure on the reaction kinetics. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.