Facile In Situ Synthesis of Micro/Nano Structured MgH 2 Whiskers and Investigation of Their Growth Mechanisms

• Published in: Crystal research and technology (1979) Vol. 53; no. 10
• Main Authors: Zhang, Tonghuan, Song, Yanwei, Han, Zongying, Chen, Xin, Zhao, Xi, Zhou, Shixue, Yu, Hao
• Format: Journal Article
• Language: English
• Published: 01.10.2018
• ISSN: 0232-1300; 1521-4079
• DOI: 10.1002/crat.201800147

Abstract To improve hydrogen storage capacity, MgH 2 whiskers are produced directly from common Mg particles through hydrogenation at 420 °C under 2 MPa of H 2 for 72 h. The morphology, thermal stability, growth direction, and growth mechanism of the whiskers are investigated. Results show that the as‐prepared sample with whiskers has a hydrogen storage capacity of 7.14 wt.%, but features high thermal stability. Under SEM, the MgH 2 whiskers are 400–1000 nm in diameter and their lengths can reach to 150 µm. The long whiskers display, to some extent, flexibility like human hair. XRD test reveals that the preferred orientation for the whisker growth is along the [101] direction of β‐MgH 2 . Existence of liquid phase MgH 2 is demonstrated. Two growth pathways for the MgH 2 whiskers have been found according to their different morphologies. One is by vapor–liquid–solid mechanism from hydriding chemical vapor deposition and the other is by stress inducible recrystallization orientated growth from bulk MgH 2 particles. Besides, the addition of transition metal (Cu, Co) is found to suppress the growth of MgH 2 whiskers.