Presentation Information
[9p-N107-7]Control of optical, electrical and thermal properties of the thin films by metal-semiconductor phase-change caused by hydro-/dehydrogenation reactions (2):
Reaction kinetics on SmH2 films.
〇Kaiwen Zhu1, Minseok Kim1, Tadashi Suzuki1, Yuzo Shigesato1 (1.Aoyama Univ.)
Keywords:
rare-earth hydrides,hydro-/dehydrogenation kinetics,Johnson-Mehl-Avrami (JMA) model
Samarium (Sm) hydrides undergo a reversible phase transformation between metallic SmH2 and semiconducting SmH3, accompanied by significant changes in transmittance as well as electrical and thermal conductivities. This study aims to clarify the reaction mechanism by analyzing the kinetics of hydrogenation and dehydrogenation processes and estimating the corresponding activation parameters. The hydrogenation kinetics were analyzed using the Johnson-Mehl-Avrami (JMA) model to determine the reaction rate constant k. Based on the obtained Avrami exponent, the dimensionality of SmH3 crystal growth and nucleation behavior was discussed. The dehydrogenation process was analyzed using the diffusion equation derived from Fick's second law, based on transmittance changes. Furthermore, activation energy and activation entropy for both hydrogenation and dehydrogenation reactions were estimated using Arrhenius and Eyring plots.