Dynamic characteristics of the γ→α phase transition of cerium at room temperature
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摘要: 通过试样组件尺寸匹配设计的被动围压SHPB实验，获得了99.8%纯铈在1.7GPa静水压内的、包含γ↔α相变和逆相变过渡区的室温动态静水压-体应变连续曲线。研究显示：室温铈γ→α相变是具有明显滞后现象的一级相变，而非以往研究认为的体积跃变的一级相变；相变过渡区的静水压范围是0.8~1.3GPa。逆相变过渡区的静水压范围是0.6~1.1GPa；逆相变过渡区的静水压-体应变曲线滞后于相变过渡区的静水压-体应变曲线0.15GPa静水压；在相变和逆相变过渡区内，静水压-体应变曲线按照约4.2GPa体积模量的线性关系演化；演化机制为γ和α两相均匀混合、静水压驱动两相组份转化。基于该演化机制，构建了描述相变前后和相变过程的静水压-体应变响应的三段线性模型。Abstract: The γ→α phase transition of 99.8% purity cerium was investigated using the passive confined split Hopkinson pressure bar experiment under a hydrostatic pressure up to 1.7GPa and at room temperature, the relationship of the hydrostatic pressure with the volume strain covering the whole process of γ↔α phase transformation was obtained, and the hysteresis loop was observed. The results show that the γ→α phase transition is the first-order with hysteresis rather than the first-order with volume discontinuity as recognized in previous researches. The γ →α phase transition occurs under the hydrostatic pressure ranging from 0.8 GPa to 1.3 GPa, whereas the inverse phase transition occurs under the hydrostatic pressure ranging from 1.1 to 0.6 GPa. The hysteresis loop shows a gap of 0.15 GPa hydrostatic pressure between the curve of hydrostatic pressure and volume strain during the γ→α phase transition and that during the inverse phase transition. The curves of the hydrostatic pressure and volume strain during the γ↔α phase transition were linear with the bulk modulus of 4.2 GPa. The mechanism behind the γ↔α phase transition is that the hydrostatic pressure drives the conversion between the phases of γ and α, which coexist during the γ↔α phase transition. Based on the mechanism of phase transition, a tri-segment linear model was constituted to describe the response of the hydrostatic pressure and volume strain in the process of γ→α phase transition. The modeled curve is found to be in good agree with the experimental curve.
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Key words:
- cerium /
- phase transition /
- hydrostatic pressure /
- phase transition model
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图 2 室温铈的静水压-体应变曲线
Figure 2. Curves of hydrostatic pressure and volume strain of cerium at room temperature
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[1] Nikolaev A V, Tsvyashchenko A V.The puzzle of the γ→α and other phase transitions in cerium[J].Physics-Uspekhi, 2012, 55(7):657-680. doi: 10.3367/UFNe.0182.201207b.0701 [2] Bridgman P W.The compression of 39 substances to 100, 000 kg/cm[J].Proceedings of American Academy of Arts and Sciences, 1927, 62:207. doi: 10.2307/25130122 [3] Koskenmaki D C and Gschneidner J K A.Handbook on the physics and chemistry of rare earths[M].Amsterdam:North-Holland Publishing Company, 1978. [4] Allen J W, Martin R W.Kondo volume collapse and the γ→α transition in cerium[J].Physical Review Letters, 1982, 49(15):1106-1110. doi: 10.1103/PhysRevLett.49.1106 [5] Voronov F F, Goncharova V A, Stal'gorava O V.Elastic properties of cerium at the pressures up to 84 kbar and the temperature of 293 K[J].Soviet Journal of Experimental and Theoretical Physics, 1979, 49:687. http://adsabs.harvard.edu/abs/1979JETP...49..687V [6] Johansson B, Abrikosov I A, Alden M, et al.Calculated phase diagram for the γα transition in Ce[J].Physical Review Letters, 1995, 74(12):2335-2338. doi: 10.1103/PhysRevLett.74.2335 [7] Amadon B, Biermann S, Georges A, et al.The γ-α transition of cerium is entropy driven[J].Physical Review Letters, 2006, 96(6):066402-1-4. doi: 10.1103/PhysRevLett.96.066402 [8] Held K, McMaham A K, Scalettar R J.Cerium volume collapse:Results from the merger of dynamical mean-field theory and local density approximation[J].Physical Review Letters, 2001, 87(27):276404. doi: 10.1103/PhysRevLett.87.276404 [9] Lipp M J, Jackson D, Cynn H, et al.Thermal signatures of the Kondo volume collapse in cerium[J].Physical Review Letters, 2008, 101(16):165703-1-4. doi: 10.1103/PhysRevLett.101.165703 [10] Decremps F, Belhadi L, Farber D L, et al.Diffusionless γ→α phase transition in polycrystalline and single-crystal cerium[J].Physical Review Letters, 2011, 106(6):065701. doi: 10.1103/PhysRevLett.106.065701 [11] Jeong I K, Darling T W, Graf M J, et al.Role of the lattice in the γ→α phase transition of ce:a high-pressure neutron and X-ray diffraction study[J].Physical Review Letters, 2004, 82(10):092102. http://adsabs.harvard.edu/abs/2004APS..MARW20012J [12] Wang Z, Bi Y, Xu L, et al.Elasticity of cerium up to 4.4 GPa by sound velocity measurements under hydrostatic pressure[J].Materials Research Express, 2014, 1(2):026501-1-9. doi: 10.1088/2053-1591/1/2/026501 [13] Rueff J P, Itie J P, Taguchi M, et al.Probing the γ-α transition in bulk Ce under pressure:a direct investigation by resonant inelastic X-ray scattering[J].Physical Review Letters, 2006, 96(3):237403-1-4. http://www.europepmc.org/abstract/MED/16803402 [14] Bassett W A.Diamond anvil cell, 50th birthday[J].High Pressure Research, 2009, 29(2):163-186. doi: 10.1080/08957950802597239 [15] Wang Z, Liu Y, Bi Y, et al.Hydrostatic pressure and temperature calibration based on phase diagram of bismuth[J].High Pressure Research, An International Journal, 2012, 32(2):167-175. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=b001199573d0370dd7e18015c949e475 [16] 李英雷, 叶想平, 张祖根, 等.一种适用于低体模量材料的被动围压SHPB实验设计[J].爆炸与冲击, 2014, 34(6):667-672. http://www.bzycj.cn/CN/abstract/abstract9400.shtmlLi Yinglei, Ye Xiangping, Zhang Zugen, et al.A design of passive confined SHPB experiment for materials with low bulk modulus[J].Explosion and Shcok Waves, 2014, 34(6):667-672. http://www.bzycj.cn/CN/abstract/abstract9400.shtml [17] 冯端.金属物理学(第2卷相变)[M].北京:科学出版社, 2000:9-10. -
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