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根据Nd2Fe14B的冲击加载实验，计算了3.3–7.2 GPa压力范围内冲击波阵面上压力与温度的关系. 基于分子场理论，引入压力等效场，改进了双亚点阵理论模型，并分析了在不同温度和压力下Nd2Fe14B的磁性转变机理. 计算了压力对Nd2Fe14B 磁致伸缩系数、磁化率、磁化强度以及居里温度的影响，给出了Nd2Fe14B发生铁磁-顺磁相变的压力和温度判据. 计算结果表明：压力使Nd2Fe14B的居里温度逐渐向低温区转移，当压力从0 GPa 增加到1.15 GPa时，居里温度从584 K降至292 K; 随着压力的增加，Nd2Fe14B的磁化强度不断下降，且临界去磁压力随温度的升高呈下降趋势; 在3.3–7.2 GPa压力范围内，Nd2Fe14B 发生了铁磁-顺磁相变.According to the shock wave experiment on the Nd2Fe14B ferromagnet, the relationship between pressure and temperature on the shock front is calculated in a pressure range from 3.3 GPa to 7.2 GPa. In order to analyze the magnetic transition mechanism of Nd2Fe14B under different temperatures and applied pressures, the equivalent pressure field is introduced to improve the two-sublattice model based on the molecular field theory. The pressure dependence of magnetostriction coefficient, susceptibility, magnetization, and Curie temperature of Nd2Fe14B are calculated. The criteria of the ferromagnetic-paramagnetic phase transition occurring in Nd2Fe14B at different temperatures and pressures are obtained. The results indicate that the Curie temperature of Nd2Fe14B decreases as pressure increases. The Curie temperature reduces from 584 K at 0 GPa to 298 K at 1.142 GPa. With the increasing of pressure, the magnetization of Nd2Fe14B declines. The critical demagnetization pressure of Nd2Fe14B also decreases with the increasing of temperature. In a pressure region from 3.3 GPa to 7.2 GPa, there appears the pressure induced ferromagnetic-paramagnetic phase transition of Nd2Fe14B.
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Keywords:
- ferromagnetic-paramagnetic phase transition /
- Curie temperature /
- molecular field theory /
- Nd2Fe14B
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[10] Wang W, Xu H J, Xu X M, Zhang Y J, Li F 2013 J. Magn. Magn. Mater. 331 225
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[15] Wang H J 2007 Ph. D. Dissertation (Beijing: Central Iron and Steel Research Institute) (in Chinese) [王会杰 2007 博士学位论文 (北京: 钢铁研究总院)]
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[18] Li Y F, Zhu M G, Li W Zhou D, Lu F Chen L, Wu J Y, Qi Y, Du A 2013 Chin. Phys. Lett. 30 097501
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[1] Herbst J F, Croat J J 1982 J. Appl. Phys. 53 4304
[2] Zhang Z W, Zhang X M, Ren S W, Han L P, Ni Z C, Liu Z Y 2002 J. Magn. Magn. Mater. 248 158
[3] Zhang X M, Huang R W, Zhang Z W 2002 J. Magn. Magn. Mater. 241 131
[4] Zhang Z W, Huang R W 1992 J. Alloys Compd. 185 363
[5] Ren S W, Zhang Z W, Liu Y 1995 J. Magn. Magn. Mater. 139 175
[6] Hao Y M 2000 Chin. Phys. Lett. 17 444
[7] Wang X G, Pan S H, Yang G Z 2000 Chin. Phys. Lett. 17 132
[8] Guo G H 2001 Acta Phys. Sin. 50 313 (in Chinese) [郭光华 2001 50 313]
[9] Prasongkit J, Tang I M 2004 J. Magn. Magn. Mater. 284 376
[10] Wang W, Xu H J, Xu X M, Zhang Y J, Li F 2013 J. Magn. Magn. Mater. 331 225
[11] Hu T Li, Wang X, Han B, Li Y, Huang F X, Zhou Q, Zhang T 2013 Chin. Phys. B 22 120701
[12] Zhang B P, Zhang Q M, Huang F L 2001 Theory of Detonation Physics (Beijing: Weapon Industry Press) p402 (in Chinese) [张宝平, 张庆明, 黄风雷 2001 爆轰物理学 (北京: 兵器工业出版社) 第402页]
[13] Kaminski D A, Jiles D C, Biner S B, Sablik M J 1992 J. Magn. Magn. Mater. 104 382
[14] Bozorth R M 1951 Ferromagnetism (New York: D. Van Nostrand) p610
[15] Wang H J 2007 Ph. D. Dissertation (Beijing: Central Iron and Steel Research Institute) (in Chinese) [王会杰 2007 博士学位论文 (北京: 钢铁研究总院)]
[16] Hirosawa S, Matsuura Y, Yamamoto H, Fujimura S, Sagawa M 1986 J. Appl. Phys. 59 873
[17] Zhou S Z, Dong Q F 2004 Supermagnets: Rare-earth and Iron System Permanent Magnet (Beijing: Metallurgical Industry Press) p7 (in Chinese) [周寿增, 董清飞 2004 超强永磁体–稀土铁系永磁材料(北京: 冶金工业出版社)第7页]
[18] Li Y F, Zhu M G, Li W Zhou D, Lu F Chen L, Wu J Y, Qi Y, Du A 2013 Chin. Phys. Lett. 30 097501
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