Study On Absorb-Hydrogen Mechanism And Functions Of Substitute Element In AB₂ Type Laves Phase Hydrogen Storage Alloys

In this paper, absorb-hydrogen mechanism and the functions of substitute element in AB2 type Laves phase hydrogen storage alloys have been investigated. The following aspects are included in this thesis:The effect factors of C14, C15 structure in AB2 type Laves phase hydrogen storage alloys are analyzed by Partial Least Square(PLS) method, and some criteria for forming of C14, C15 structure are obtained; the electronic structures of ZrMn2, ZrMnM(M=Mn, Co, V, Fe), TiMn2, TiMnM(M=V, Cr, Fe, Co) and those hydrides, which were applied to analyze the bonding styles between hydrogen and alloying elements in hydrogen storage alloy and roles of hydride forming and non-forming elements, were investigated by the SCC-DV-Xa (Self-Consistent-Charge Discrete Variational Xa ) method. In addition, the functions of substitute element in AB2 type Laves phase hydrogen storage alloys are also analyzed. These results show that:1. RA/RB, ANOE( the Averaged Number of Outer Electrons) and have influence on forming of AB2 type Laves phase hydrogen storage alloys.RA/RB is the most important factor effecting forming of C14 and C15 structure.2. Hydrogen atom makes a strong chemical bond with Mn atom rather than Zr atom and Ti atom in ZrMn2 and TiMn2 hydrides; The c axis of ZrMn2 unit cell can be changed easier than a axis when hydrogen atom is absorbed.3. The change of 3d electron of substitute element is an important factor which affects the hydrogen storage properties of ZrMnM alloys, and the charge population of 3p orbit in substitute element can be taken as a criterion for comparing stabilization among ZrMnM hydrides.4. In TiMnCoH and TiMnVH alloy, hydrogen atom make a strong chemical bond with Mn atom rather than with Co and V atom; The 3p orbit bond peak in substitute elements atom become low, which is a mainly character that decreases the hysteresis effect in TiMnM(M=V, Cr, Fe, Co).