共查询到20条相似文献,搜索用时 62 毫秒
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研究了晶场二级效应在PrF3晶体中的作用,发现该效应可使Pr3+离子的晶场单态与其他态混合,对PrF3晶体磁化率产生明显影响.进一步研究了晶体内的交换作用有效场,其形式为Hin=(1.9-0.02556T)×10-5M,在100—300 K的温度范围内,以此计算的PrF3晶体的倒数磁化率和Verdet常数的倒数与实验值符合较好.结果表明,在PrF3晶体中,晶场二级效应与离子间的交换作用都不能忽略.
关键词:
晶场二级效应
交换作用有效场
Verdet常数
3晶体')" href="#">PrF3晶体 相似文献
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针对低温下各向同性Pr2Fe14B永磁材料的最小形核场问题,用数值 计算法和近似解 析解研究了第二磁晶各向异性常数K2对最小形核场的影响.研究发现,尽管对于 Nd2 Fe14B永磁材料一级近似的解析解与数值计算结果很接近,但是对于低温下各向 同性P r2Fe14B永磁材料则至少要用二级近似下的解析解才能与数值计算 结果相接近.用有 关最小形核场的计算结果很好地解释了低温时各向同性Pr2Fe14B永 磁材料的矫顽力与最小形核场的关系.
关键词:
第二磁晶各向异性常数
形核场
矫顽力 相似文献
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在一些磁性材料内, 磁性离子间交换作用和磁性离子的自旋涨落对材料磁性有影响. 本文根据磁比热实验值确定了晶场参数后, 利用包含自旋涨落的交换作用有效场Hm= n0 (1 + γ T + β eω T)M, 计算了PrNi2晶体晶场能级的Zeeman劈裂. 在温度为3.8 K ≤T≤ 30 K范围内, 计算了该晶体多晶磁矩随外磁场的变化, 以及外磁场H=5000 Oe时磁化率倒数随温度的变化, 计算结果和实验值符合较好. 当外磁场在0–50000 Oe时, 计算的该晶体的磁熵变与已有文献的理论结果相似. 计算结果说明, 提出的包含自旋涨落的交换作用有效场不仅适合亚铁磁性晶体, 而且也适合顺磁性晶体.
关键词:
2')" href="#">PrNi2
磁比热
交换作用有效场
磁矩
磁熵变 相似文献
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P. Allenspach A. Furrer R. Osborn A. D. Taylor 《Zeitschrift für Physik B Condensed Matter》1991,85(2):301-305
Neutron spectroscopy has been employed to study the crystal-field excitations in Pr2CuO4. The energetic ordering of the crystal-field levels and the crystal-field parameters are determined from the observed transitions. Our results are consistent with the large magnetic anisotropy observed in single-crystal susceptibility data. 相似文献
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Inelastic neutron scattering experiments have been performed in UBr3 in order to determine the crystal-field levels. Four transitions between the ground state and all excited states have been observed, thus the crystal-field level scheme could be unambigously assigned. The Russell-Saunders coupling scheme has been used to derive the crystal-field parameters which cannot be accounted for by a simple point charge calculation. 相似文献
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The crystal-field model is applied to a series of scheelites crystals (CaWO4, SrWO4, PbWO4, BaWO4, CdMoO4, CaMoO4, SrMoO4 and PbMoO4) doped with the Yb3+ ion. The calculated crystal-field parameters present a general trend of variation with M2+ ionic radius of the host cation. The maximum splitting ΔE of the 2F7/2 manifold of the Yb3+ ion is then obtained as a function of NV crystal-field strength parameters. The agreement between experimental results and theoretical predictions for all investigated systems is very satisfactory. The crystal-field effects are very important for the prediction of emission energies of the Yb3+ ion in different scheelites. 相似文献
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Structural analysis and crystal-field calculations of Nd^3+ in Gdx Lu1-x TaO4(x = 0.85) polycrytalline 下载免费PDF全文
The crystal structural parameters of Nd 3+-doped rare earth orthotantalate Gd x Lu 1 x TaO 4(x = 0.85) are determined by applying the Rietveld refinement to its X-ray diffraction,and its emission and excitation spectra at 77 K are analysed.The relativistic model of ab initio self-consistent DV-Xα method,which is applied to the cluster NdO 8 in Gd x Lu 1 x TaO 4,and the effective Hamiltonian model are used to investigate its spin-orbit and crystal-field parameters.The free-ions and crystal-field parameters are fitted to the experimental energy levels at 77 K with a root-mean-square deviation of 14.92 cm 1.According to the crystal-field calculations,96 levels of Nd 3+ are assigned.Finally,the fitting results of free-ions and crystal-field parameters are compared with those already reported for Nd 3+:YAlO 3.The results indicate that the free-ion parameters are similar to those of the Nd3+ in Gdx Lu1-x TaO4 and YAlO 3 hosts,and the crystal-field interaction of Nd3+ in Gdx Lu1-x TaO4 is stronger than that in YAlO 3. 相似文献
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B. Stroka A. Schröder T. Trappmann H. v. Löhneysen M. Loewenhaupt A. Severing 《Zeitschrift für Physik B Condensed Matter》1993,90(2):155-160
The specific heat of CeCu6–x
Au
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withx=0,0.3, and 0.9, and of the corresponding La homologues has been measured between 1.5 K and 150 K. With increasingx we find progressively better-defined Schottky anomalies arising from the crystal-field splitting, which is attributed to the decrease of the Kondo temperature. Both observations are in line with the results of inelastic neutron-scattering data performed on samples withx=0.5. Overall, the crystal-field splitting does not change very much upon alloying with Au. A detailed analysis shows that forx=0.5 the quasielastic line width is smaller and the inelastic crystal-field transitions are better resolved compared to CeCu6. 相似文献
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G. Riou S. Jandl M. Poirier V. Nekvasil M. Diviš P. Fournier R.L. Greene D.I. Zhigunov S.N. Barilo 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,23(2):179-182
We present an infrared crystal-field study of Pr2CuO4 single crystals and thin films. Excitations from the ground state multiplet 3H4 to the 3H5, 3H6, 3F2 and 3F3 excited multiplets are observed in both single crystals and thin films. A precise set of crystal-field parameters, that reproduces
the energy and the symmetry of the levels, is determined.
Received 25 April 2001 相似文献
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The optical isotropy of the cubic garnet was overcome by crystal-site selective excitation and fluorescence spectroscopy. Thus the symmetries of the crystal-field states of the free ion levels7F
J
and5D4 could be determined. On this basis a crystal field analysis was performed to derive the crystal-field parameters for the Tb3+ ions replacing the Y3+ ions on the D2 sites. 相似文献
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The g factor of Cr4+ in Y2SiO5 crystal is calculated from a completed high-order perturbation formula, in which not only the conventional contribution to the g-shift Δg(=g−ge) from the crystal-field mechanism, but also the contribution from the charge-transfer mechanism (which is neglected in the crystal-field theory) are considered. The calculated result shows good agreement with the observed value. It is found that the calculated Δg due to the charge-transfer mechanism is opposite in sign and about 38% in magnitude, compared with that due to the crystal-field mechanism. So, in the studies of the g factor for a 3dn ion having high valence state in crystals, the contribution due to the charge-transfer mechanism should be taken into account. 相似文献
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Using a crystal-field calculation within a point charge model, we interpret the rare-earth magnetic moment direction in the equiatomic rare earth-silicon compounds of CrB type. We showed that the 2nd order crystal-field parameter V22 is predominant and implies the magnetic moment to the perpendicular to the two-fold quantization axis i.e. b-axis. The calculated magnetic moment direction are in good agreement with neutron diffraction results. 相似文献
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Ab initio calculations using an extended set of gaussian-type orbitals have been performed for the CoO6 10- cluster in the Hartree-Fock approximation and with a limited configuration interaction. The results have been compared with those of crystal-field theory. CoO is found to be a very ionic system with localized d-electrons. The excited d-states may be described using a simple configuration interaction scheme, which is found to be almost equivalent to a crystal-field parameterized configuration interaction built on Hartree-Fock results. Localization and delocalization phenomena in openshell systems have been discussed. 相似文献