The cyclic degradation of TiCrV hydrogen storage alloy has been studied by using SEM and TEM. Microstructural analysis indicated that the accumulation of lattice defects such as dislocations and strain field occurred due to volume expansion and shrinkage during cycles, led to a loss of the effective storage capacity. Annealing with minute particles in order to suppress the development of lattice defects during cycles resulted in increase in plateau width during hydrogenation but nothing improved during de hydrogenation. This is probably due to beta hydrides formed during hydrogenation, which is stable with lattice defects and strain field. Fine particles less than several hundred nano meter in size could have a good degradation resistance due to less accumulation of lattice defects and during cycles.
In situ observation of the catalytic action of MgH 2 1 molNb 2 O 5 and MgH 2 10 molNb 2 O 5 was carried out by using transmission electron microscopy (TEM). In case of MgH 2 1 molNb 2 O 5 , TEM analysis indicated that MgH 2 started to decompose at 150°C and nano size particle of Mg formed. However, Nb 2 O 5 was not observed in the diffraction pattern and images. In case of MgH 2 10 molNb 2 O 5 , high resolution images, FFT and IFFT, revealed that the decomposition of MgH 2 started with the contact region in Nb 2 O 5 and Mg formed. The result suggested that the reaction of dehydration could proceed due to hydrogen diffusion to the Mg Nb 2 O 5 interface.
In order to clarify the reaction mechanism of the hydrogenation process in the Li 2 NH system, we have observed the partially hydrogenated samples by transmission electron microscopy (TEM). From the TEM images of partially hydrogenated samples, it was shown that the LiNH 2 phase was located between Li 2 NH phase, which was almost at the center of the particle, and LiH particles with the size of 100 nm. This result indicated that LiH was generated and grew up at the outside of the complex particle of Li 2 NH and LiNH 2 with Li moving from the center to the surface of the particle.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.