[1Dp01-09] Surface Science(SS1) Physical Property

[1Dp05] Concentration dependence of Hydrogen diffusion in Platinum film

*Sudhansu Sekhar Das¹, Takahiro Ozawa¹, Hiroshi Nakanishi², Yuya Komatsu³, Ryota Shimizu^3,4, Taro Hitosugi^3,4, Katsuyuki Fukutani^1,5 (1. Institute of Industrial Science, University of Tokyo, 2. National Institute of Technology, Akashi College, 3. School of Materials and Chemical Technology, Tokyo Institute of Technology, 4. Department of Chemistry, University of Tokyo, 5. Advanced Science Research Center, Japan Atomic Energy Agency (JAEA))

Hydrogen diffusion in a polycrystalline Pt(25nm) film hydrogenated by the H⁺-ion implantation technique is studied through resistance relaxation experiments at different temperatures in the range 5 – 200K. The H-hopping rate which follows a linear Arrhenius behaviour in the classical regime (140 K < T < 200 K), transforms to a rather weak temperature-dependent quantum regime below 140 K. The activation energy E_A extracted from the Arrhenius slope from the thermal regime shows a decrease from 115 meV to 70 meV when x in the PtH_x rise from 0.23 to 0.45 H/Pt. This indicates that H-atomic levels at the metastable sites of PtHx are modified by the dominance of the repulsive H-H interaction at higher x.