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利用密度泛函理论的平面波赝势方法研究了IrTi合金的晶格动力学行为. 声子谱计算表明四方(L10)结构动力学不稳定,通过冷冻不稳定声子模式, 发现IrTi会发生从四方(L10)到正交的结构相变.进一步分析软模对应的原子振动, 得到了具有正交对称性,空间群为Cmmm,相对于四方(L10)相能量更低、更稳定的结构. 这种正交新相(Cmmm)弹性稳定和动力学稳定,而且其结构参数与实验上观察到的低温结构有限的晶格参数相符合,表明IrTi合金的低温相是正交结构(Cmmm). 从理论上肯定了IrTi合金立方到四方再到正交的相变机制, 解决了实验上关于相变机制和低温相结构形式的争议.
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关键词:
- 马氏体相变 /
- 晶体点阵中的声子和振动 /
- 密度泛函理论
The structural behaviors of IrTi are studied using first-principles density-functional theory with pseudopotentials and a plane-wave basis. Phonon calculations indicate that the tetragonal (L10) structure is dynamically unstable. We obtain the orthorhombic structure (Cmmm) which is shown to be a global energy minimum by the frozen phonon method. The resulting structure is mechanically and dynamically stable and its lattice constant is similar to the experimentally observed lattice constant of low-temperature structure, which demonstrates that the low-temperature phase of IrTi is the orthorhombic structure (Cmmm). Thus, we put an end to the experimental debate regarding the low-temperature phase: whether it is orthorhombic or monoclinic, and demonstrate theoretically that the IrTi alloys will undergo a cubic→tetragonal→orthorhombic transformation.-
Keywords:
- Martensitic transformations /
- phonons and vibrations in crystal lattices /
- density functional theory
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[7] Huang X, Rabe K M, Ackland G J 2003 Phys. Rev. B 67 024101
[8] Yuan P F, Zhu W J, Xu J A, Liu S J, Jing F Q 2010 Acta Phys. Sin. 59 8755 (in Chinese) [原鹏飞, 祝文军, 徐济安, 刘绍军, 经福谦 2010 59 8755]
[9] Liu Z M, Cui T, Ma Y M, Liu B B, Zou G T 2007 Acta Phys. Sin. 56 4877 (in Chinese) [刘志明, 崔田, 马琰铭, 刘冰冰, 邹广田 2007 56 4877]
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[14] Monkhorst H J, Pack J D 1976 Phys. Rev. B 13 5188
[15] Methfessel M, Paxton A T 1989 Phys. Rev. B 40 3616
[16] Li Y, Zhang L J, Cui T, Ma Y M, Zou G T 2006 Phys. Rev. B 74 054102
[17] Zhang J Y, Zhang L J, Cui T, Li Y, He Z, Ma Y M, Zou G T 2007 Phys. Rev. B 75 104115
[18] Zhang L J, Wang Y C, Cui T, Li Y, Li Y W, He Z, Ma Y M, Zou G T 2007 Phys. Rev. B 75 144109
[19] Li Y, Ma Y M, Cui T, Yan Y M, Zou G T 2008 Appl. Phys. Lett. 92 101907
[20] Li Z W, Wang H B, Li Y, Ma Y M, Cui T, Zou G T 2010 New J. Phys. 12 043058
[21] Li Z W, Xu Y, Gao G Y, Cui T, Ma Y M 2009 Phys. Rev. B 79 193201
[22] Li Y, Li Y W, Ma Y M, Cui T, Zou G T 2010 Phys. Rev. B 81 052101
[23] Chen C B, Liu Z M, Ma Y M, Cui T, Liu B B, Zou G T 2007 Acta Phys. Sin. 56 2828 (in Chinese) [陈长波, 刘志明, 马琰铭, 崔田, 刘冰冰, 邹广田 2007 56 2828]
[24] Beckstein O, Klepeis J E, Hart G L W, Pankratov O 2001 Phys. Rev. B 63 134112
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[1] Gong C W, Wang Y N, Yang D Z 2006 Acta Phys. Sin. 55 2877 (in Chinese) [宫长伟, 王轶农, 杨大智 2006 55 2877]
[2] Murray J L 1982 J. Phase Equilib. 3 205
[3] Raman A, Schubert K 1964 Z. Metallkd. 55 704
[4] Chen B H, Franzen H F 1990 J. Less-Common Met. 158 11
[5] Okamoto H 1992 J. Phase Equilib. 13 329
[6] Huang X, Bungaro C, Godlevsky V, Rabe K M 2001 Phys. Rev. B 65 014108
[7] Huang X, Rabe K M, Ackland G J 2003 Phys. Rev. B 67 024101
[8] Yuan P F, Zhu W J, Xu J A, Liu S J, Jing F Q 2010 Acta Phys. Sin. 59 8755 (in Chinese) [原鹏飞, 祝文军, 徐济安, 刘绍军, 经福谦 2010 59 8755]
[9] Liu Z M, Cui T, Ma Y M, Liu B B, Zou G T 2007 Acta Phys. Sin. 56 4877 (in Chinese) [刘志明, 崔田, 马琰铭, 刘冰冰, 邹广田 2007 56 4877]
[10] Kresse G, Hafner J 1993 Phys. Rev. B 48 13115
[11] Kresse G, Furthmuller J 1996 Phys. Rev. B 54 11169
[12] Perdew J P, Burke K, Ernzerhof M 1996 Phys. Rev. Lett. 77 3865
[13] Kresse G, Joubert D 1990 Phys. Rev. B 59 1758
[14] Monkhorst H J, Pack J D 1976 Phys. Rev. B 13 5188
[15] Methfessel M, Paxton A T 1989 Phys. Rev. B 40 3616
[16] Li Y, Zhang L J, Cui T, Ma Y M, Zou G T 2006 Phys. Rev. B 74 054102
[17] Zhang J Y, Zhang L J, Cui T, Li Y, He Z, Ma Y M, Zou G T 2007 Phys. Rev. B 75 104115
[18] Zhang L J, Wang Y C, Cui T, Li Y, Li Y W, He Z, Ma Y M, Zou G T 2007 Phys. Rev. B 75 144109
[19] Li Y, Ma Y M, Cui T, Yan Y M, Zou G T 2008 Appl. Phys. Lett. 92 101907
[20] Li Z W, Wang H B, Li Y, Ma Y M, Cui T, Zou G T 2010 New J. Phys. 12 043058
[21] Li Z W, Xu Y, Gao G Y, Cui T, Ma Y M 2009 Phys. Rev. B 79 193201
[22] Li Y, Li Y W, Ma Y M, Cui T, Zou G T 2010 Phys. Rev. B 81 052101
[23] Chen C B, Liu Z M, Ma Y M, Cui T, Liu B B, Zou G T 2007 Acta Phys. Sin. 56 2828 (in Chinese) [陈长波, 刘志明, 马琰铭, 崔田, 刘冰冰, 邹广田 2007 56 2828]
[24] Beckstein O, Klepeis J E, Hart G L W, Pankratov O 2001 Phys. Rev. B 63 134112
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