铝合金化对LaNi5-xAlx电子结构的影响

在全电子水平上,基于广义梯度近似密度泛函和全势能线性缀加平面波方法,计算了不同Al含量LaNi5-xAlx(x＝0,0.5,1.0)的晶体结构、能带结构、状态密度等特征.对LaNi5的计算表明:GGA Perdew96的计算结果可信,自旋极化对优化结构和能量的影响不明显;对LaNi4Al的研究表明Al原子最可能取代3g位的Ni原子;对LaNi4 5Al0.5的优化结构与实验结果一致.随着Al含量的升高,晶胞能量、费米面能量升高,如从LaNi5,LaN45Al05到LaNi4Al,费米面能量从-10.591、-10.134 eV升高到-9.441 eV,而Ef上的态密度和材料对应的低温比热容则急剧下降,态密度从11.81、8.86急剧降低到1.61 eV/f.u..并计算给出了LaNi4.5Al0.5的能带结构、状态密度图.

Alloying effects on electronic structures of LaNi5-xAlx

Based on the generalized gradient approximation (GGA) of density of function and the full potential linearized augmented wave (FLAPW), the equilibrium structure , energy bands and density of states were calculated for (LaNi_(5-x)Al_x). The results show that, For (LaNi_5), the calculation by GGA perdew96 is better than those of other methods, and the spin-polarization have no obvious effect on the optimized structure and energy. For (LaNi_4Al), the result indicates that nickel is most likely substituted by aluminum on the 3g site, and the optimized structure for (LaNi_(4.5)Al_(0.5)) exactly agrees with the experimental results. With the increasing content of aluminum, the Fermi energy and density of states sharply decrease in the order from LaNi_5 to LaNi_(4.5)Al_(0.5)and LaNi_4Al, the Fermi Energy increases from (-10.591), (-10.134) eV to (-9.441) eV, and the density of states (DOS) of E_f decreases from 11.81, 8.86 to (1.61) eV/f.u.. The energy band structure and density of states for LaNi_(4.5)Al_(0.5) were firstly calculated.