Tomonori Nambu1, Hisakazu Ezaki1, Hiroshi Yukawa2 and Masahiko Morinaga2
1Department of Materials Science and Engineering, Suzuka National College of Technology, Suzuka 510-0294
The local lattice distortion and the chemical bond change in the course of hydrogenation in niobium metal were simulated using the pseudopotential method and the DV-Xα molecular orbital method. The calculated enthalpy changes, Δ H, of hydrogen solution into niobium indicated that hydrogen could be dissolved readily into niobium up to the hydrogen content (H/M) of about 0.7 at 673 K, but further dissolution became difficult, in agreement with the experiment. The local lattice distortion appeared to occur in the niobium lattice so as to suppress the large decrease in the Nb-Nb covalent interaction during hydrogen dissolution, while enhancing the Nb-H interaction.
pseudopotential method, DV-Xα cluster method, enthalpy of hydrogen solution, niobium, niobium hydride
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