Hydrogen insertion in Ti2AlC and its influence on the crystal structure and bonds

作者：Liu, Q.; Ding, H. M.^*; Du, B. Q.; Chu, K. Y.; Shi, Y.

来源：Journal of Ceramic Science and Technology, 2017, 8(2): 201-208.

DOI：10.4416/JCST2016-00082

• MAX phases
• Ti2AlC
• first-principles calculations

First-principles calculations have been performed to study hydrogen insertion in Ti2AlC and its influence on the crystal structure and bonds. It has been found that H insertion in interstitial sites of the Ti-Al layers is thermally favorable and H diffusion along the basal plane is feasible. When H is inserted into tetrahedral interstitial sites (I-tetr-2) surrounded by three Ti atoms and one Al atom, the surrounding Ti-Al bonds will be substituted by H-Al and H-Ti bonds. When H is inserted into hexagonal interstitial sites (I-hexa -5) surrounded by three Al and two Ti atoms, the Ti-Al a-5) bonds will be weakened while H-Ti bonds will be formed, at the same time, surrounding Al-Al bonds will be substituted by H-Al bonds, which will result in a change of part of the crystal structure of the Al layers. In comparison, H insertion into octahedral interstitial sites (I-oct -3) surrounded by three Ti and three Al atoms has the least influence on the Ti Al bonds. As a result, H insertion into I-tetr-2 will seriously weaken the bonding between the Ti and Al layers while H insertion into Ihexa-5 and Ioct-3 will enhance it. It is considered that the influence of H on the properties of Ti2AlC closely depends on its insertion position.

• 出版日期2017-6
• 单位华北电力大学