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摘要: 使用Bundy和Dunn发展起来的带有烧结金刚石砧的Drickamer型高压装置,用固定点测压法标定实验压力,在室温及0~43 GPa的压力范围内测量了稀土金属中Pr、Nd、Sm、Gd、Tb、Dy、Ho、Tm、Lu和Yb的电阻随压力的变化。在各稀土元素的电阻随压力变化的曲线上,观测到了若干凸起和斜率突变点,根据Jayaraman提出的三价稀土在压力作用下的相变顺序,得到了这些突(凸)变点分别对应着hcpSm-typedhcpfcc相变顺序中的某一类型的相变压力。此外还观测到了Pr、Gd、Tb的fcc相随着压力再增高而发生的相变,根据已报导的关于Pr的工作,推测Gd和Tb的这一相变应为fccdfcc相变,它们分别发生在22.0和24.5 GPa。在本工作所得结果基础上对Johansson的三价稀土总相图进行了修正。Abstract: The pressure equipment used in this investigation was a Drickamer-type apparatus with sintered diamond compacts. The pressure calibration was established by using p vs. (L. Go) calibration diagram. The electrical resistance behavior of ten rare-earth metals (Pr, Nd, Sm, Gd, Tb, Dy, Ho, Tm, Lu and Yb) was studied under high pressure up to 43 GPa and at room temperature. Some kinks and slope changes are found on the resistance vs. pressure curves and many of them are first experimentally discovered, which are perhaps related to the hcpSm-typedhcpfcc phase transitions. These new phase transition pressure are 14.0 GPa for Lu from hcp-Sm-type, 7.0 GPa for Gd, 12.0 GPa for Tb, 12.5 GPa for Dy, 13.0 GPa for Ho, 17.5 GPa for Tm, and 26.0 GPa for Lu from Sm-type to dhcp, 12.0 GPa for Sm, 17.5 GPa for Gd, 18.0 GPa for Tb, 22.0 GPa for Dy, 24.0 GPa for Ho, and 31.0 GPa for Tm from dhcp to fcc, respectively. For Gd and Tb there is a slope change on each R vs p curve at 22.0 and 24.5 GPa respectively. We believe that these two changes are associated with the phase transition from fcc to a new phase, dfcc, three slope changes at 14.5, 18.6 and 25.0 GPa are also found for Yb. The first change is related to valence change from divalent to trivalent, which is in agreement with the value calculated by Johansson et al. The second and the third changes should indicate hcp to Sm-type and Sm-type to dhcp transitions respectively.
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Jayaraman A, Sherwood R C. Phys Rev A, 1964, 134: 691. Stager R A, Drickamer H G. Phys Rev A, 1964, 133: 830. Johansson B, Rosengren A. Phys Rev B, 1975, 11: 2836. Bundy F P, Dunn K J. Rev Sci Instrum, 1980, 51: 753. Dunn K J, Bumdy F P. Rev Sci Instrum, 1978: 365. Mao H K, Hazen R M, Bell P M. J Appl Phys, 1980, 52: 4572. Dong W Y, Lin T H, Dunn K J, et al. Phys Rev B, 1987, 35: 966. Gschneider K A Jr. Solid State Phys, 1964, 16: 275.
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