Effect of electron localization in theoretical design of Ni-Mn-Ga based magnetic shape memory alloys
Effect of electron localization in theoretical design of Ni-Mn-Ga based magnetic shape memory alloys
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DOI：
10.1016/j.matdes.2021.109917
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发表时间：
2021-11
影响因子：
8.4
通讯作者：
M. Zelený;P. Sedlák;O. Heczko;H. Seiner;P. Veřtát;Masao Obata;T. Kotani;T. Oda;L. Straka
中科院分区：
文献类型：
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作者：
M. Zelený;P. Sedlák;O. Heczko;H. Seiner;P. Veřtát;Masao Obata;T. Kotani;T. Oda;L. Straka
准确确定不同马氏体相的稳定性是成功设计(磁性)形状记忆合金的一项重要任务。我们评估了电子离域修正对磁性形状记忆化合物原型Ni-Mn-Ga的密度泛函理论预测能力的影响。利用修正的基于Hubbard模型的广义梯度近似(GGA+U)，我们将库仑排斥参数U从0 eV改变到3 eV，以揭示预测的材料参数的演化。化学计量比Ni2MnGa中10M调制结构的稳定化程度与实验一致，而未修正的GGA和Meta-GGA泛函分别为4O调制结构和非调制结构提供了最低的能量。GGA+U计算表明，对于U>；1.2 eV，10M结构比其他马氏体结构更稳定。用改进的准粒子自洽GW(QSGW)方法计算的态密度(DOS)对特定马氏体相的稳定或失稳也有重要作用，这支持Hubbard修正的物理背景。此外，当U=1.8 eV时，计算得到的化学计量比和非化学计量比合金的晶格参数与实验数据符合得最好。
The precise determination of the stability of different martensitic phases is an essential task in the successful design of (magnetic) shape memory alloys. We evaluate the effect of electron delocalization correction on the predictive power of density functional theory for Ni-Mn-Ga, the prototype magnetic shape memory compound. Using the corrected Hubbard-model-based generalized gradient approximation (GGA+U), we varied the Coulomb repulsion parameter U from 0 eV to 3 eV to reveal the evolution of predicted material parameters. The increasing localization on Mn sites results in the increasing stabilization of 10M modulated structure in stoichiometric Ni2MnGa in agreement with experiment whereas uncorrected GGA and meta-GGA functional provide the lowest energy for 4O modulated structure and non-modulated structure, respectively. GGA+U calculations indicate that 10M structure is more stable than other martensitic structures for U > 1.2 eV. The key features of density of states (DOS) responsible for the stabilization or destabilization of particular martensitic phases calculated with GGA+U are found also in DOS calculated with advanced quasi-particle self-consistent GW (QSGW) method, which support the physical background of Hubbard correction. Moreover, the calculations with U = 1.8 eV provide the best agreement with experimental data for lattice parameters of stoichiometric and off-stoichiometric alloys.