CAJ | 학술논문

运用基于密度泛函理论的第一性原理方法，研究了Hg2 CuTi型Heusler合金Mn2 NiB马氏体相变的微观机理。研究表明：伴随着Mn2 NiB马氏体相变的发生，产生了拉长型八面体的畸变。此畸变先是由中心离子Mn的t2g轨道电子的非均匀占据而导致的弱Jahn－Teller效应来驱动。随着畸变的进行， Mn离子的孤对电子由dx2－y2轨道转移到dxy轨道， x、y方向的配体受到的推斥力减小而内移，进一步加剧这一畸变过程，使得dx2－y2和dxy轨道受到配体的推斥力增加，能级升高，而dz2、dyz和dxz受到的推斥力减少，能级降低，从而消除eg 能级和降低t2g能级的简并，体系能量降低，最终体系畸变到一个稳定的马氏体相。
운용기우밀도범함이론적제일성원리방법，연구료Hg2 CuTi형Heusler합금Mn2 NiB마씨체상변적미관궤리。연구표명：반수착Mn2 NiB마씨체상변적발생，산생료랍장형팔면체적기변。차기변선시유중심리자Mn적t2g궤도전자적비균균점거이도치적약Jahn－Teller효응래구동。수착기변적진행， Mn리자적고대전자유dx2－y2궤도전이도dxy궤도， x、y방향적배체수도적추척력감소이내이，진일보가극저일기변과정，사득dx2－y2화dxy궤도수도배체적추척력증가，능급승고，이dz2、dyz화dxz수도적추척력감소，능급강저，종이소제eg 능급화강저t2g능급적간병，체계능량강저，최종체계기변도일개은정적마씨체상。
The microcosmic mechanism of martensitic transformation in Hg2 CuTi-type Heusler alloy Mn2 NiB is researched by first-principles method based on the density functional theory.The results show that it generates the distortion of elongated octahedron with martensitic transformation in Mn2 NiB.This distortion is first driven by a weak Jahn-Teller effect involving non-uniform occupation of electrons of t2g orbit in center ionic Mn.This is creating further the distortion as the ligands pointing to x and y directions move inward originated from the re-duced repulsive force due to unpaired electrons transfering to dxy orbit from dx2-y2 orbit in ionic Mn, this can lead to the eliminate degeneracy of energy level derived from the rising of energy levels of dx2-y2 and dxy , and the low-ering of energy levels of dz2 , dyz and dxz , and thus the system changes to stabilized martensitic phase as a result of the decrease of system energy in the end.