Site occupancy, magnetic moments, and elastic constants of off-stoichiometric Ni(2)MnGa from first-principles calculations

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	Site occupancy, magnetic moments, and elastic constants of off-stoichiometric Ni(2)MnGa from first-principles calculations
	Q. M. Hu; C. M. Li; R. Yang; S. E. Kulkova; D. I. Bazhanov; B. Johansson; L. Vitos
	2009
发表期刊	Physical Review B
ISSN	1098-0121
卷号	79 期号:14
摘要	The site occupancy and elastic modulus of off-stoichiometric Ni(2)MnGa alloys are investigated by the use of the first-principles exact muffin-tin orbital method in combination with coherent-potential approximation. The stable site occupancy at 300 K is determined by comparing the free energies of the alloys with different site-occupation configurations. It is shown that, for most of the off-stoichiometric Ni(2)MnGa, the "normal" site occupation is favorable, i.e., the excess atoms of the rich component occupy the sublattice(s) of the deficient one(s). Nevertheless, for the Ga-rich alloys, the excess Ga atoms have strong tendency to take the Mn sublattice no matter if Mn is deficient or not. Based on the determined site occupancy, the elastic moduli of the off-stoichiometric Ni(2)MnGa are calculated. We find that, in general, the bulk modulus increases with increasing e/a ratio (i.e., the number of valence electrons per atom). The shear moduli C(') and C(44) change oppositely with e/a ratio: C(') decreases but C(44) increases with increasing e/a. However, the Mn-rich Ga-deficient alloys deviate significantly from this general trend. The correlation of calculated elastic moduli and available experimental martensitic transformation temperatures (T(M)) demonstrates that the alloy with larger C(') than that of the perfect Ni(2)MnGa generally possesses lower T(M) except for Ni(2)Mn(1+x)Ga(1-x).
部门归属	[hu, qing-miao; li, chun-mei] chinese acad sci, inst met res, shenyang natl lab mat sci, shenyang 110016, peoples r china. [hu, qing-miao; johansson, borje; vitos, levente] royal inst technol, dept mat sci & engn, se-10044 stockholm, sweden. [kulkova, svetlana e.] russian acad sci, inst strength phys & mat sci, siberian branch, tomsk 634021, russia. [bazhanov, dmitry i.] moscow mv lomonosov state univ, fac phys, moscow 119992, russia. [johansson, borje; vitos, levente] uppsala univ, dept phys, condensed matter theory grp, se-75121 uppsala, sweden. [johansson, borje] dalian univ technol, sch phys & optoelect technol, dalian 116024, peoples r china. [johansson, borje] dalian univ technol, coll adv sci & technol, dalian 116024, peoples r china. [vitos, levente] res inst solid state phys & opt, h-1525 budapest, hungary.;hu, qm (reprint author), chinese acad sci, inst met res, shenyang natl lab mat sci, 72 wenhua rd, shenyang 110016, peoples r china;qmhu@imr.ac.cn
关键词	Density Functional Theory Elastic Constants Elastic Moduli Ferromagnetic Materials Gallium Alloys Linear Muffin-tin Orbital Method Magnetic Moments Magnetomechanical Effects Manganese Alloys Martensitic Transformations Nickel Alloys Shape Memory Effects Shear Modulus Stoichiometry Shape-memory Alloys Ni-mn-ga Martensitic-transformation Phase-transformations Potential Model Heusler Alloys Landau Theory Transition Metals Approximation
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文献类型	期刊论文
条目标识符	http://ir.imr.ac.cn/handle/321006/31971
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	Q. M. Hu,C. M. Li,R. Yang,et al. Site occupancy, magnetic moments, and elastic constants of off-stoichiometric Ni(2)MnGa from first-principles calculations[J]. Physical Review B,2009,79(14).
APA	Q. M. Hu.,C. M. Li.,R. Yang.,S. E. Kulkova.,D. I. Bazhanov.,...&L. Vitos.(2009).Site occupancy, magnetic moments, and elastic constants of off-stoichiometric Ni(2)MnGa from first-principles calculations.Physical Review B,79(14).
MLA	Q. M. Hu,et al."Site occupancy, magnetic moments, and elastic constants of off-stoichiometric Ni(2)MnGa from first-principles calculations".Physical Review B 79.14(2009).