共查询到20条相似文献,搜索用时 500 毫秒
1.
2.
3.
4.
采用基于单电子晶体场机制的对角化能量矩阵方法, 计算了Gd3+在钼酸盐AMoO4 (A=Ca, Sr, Ba, Pb)晶体中的自旋哈密顿参量(g因子g//, g⊥和零场分裂b20, b40, b44, b60, b64). 矩阵中的晶体场参量采用重叠模型计算. 计算结果显示, 应用三个合理的可调参量[即重叠模型中的内禀参量A2 (R0), A4 (R0)和A6 (R0)], 计算的七个自旋哈密顿参量与实验结果符合甚好, 表明该方法可用于计算或解释Gd3+在晶体中的自旋哈密顿参量.
关键词:
AMoO4 (A=Ca,Sr,Ba,Pb):Gd3+晶体')" href="#">AMoO4 (A=Ca,Sr,Ba,Pb):Gd3+晶体
自旋哈密顿参量
晶体场理论
对角化能量矩阵 相似文献
5.
6.
在八个(111)面磁泡膜上,观察了施加面内(in-plane)磁场后在不同晶轴方向上条状畴的消失过程,测量了条畴消失场Hs*和磁畴消失场Hk*与面内磁场的方向的关系。本文计及立方磁晶各向异性,完善了面内磁场中条畴的稳定性理论。用该理论定性地解释了实验结果的主要特点。导出了Hs*与立方各向异性及面内场方向的两种近似的理论关系,它们分别适用于面内场方向靠近和不十分靠近〈110〉晶轴的情形。它们和实验结果是大致符合的。在〈110〉晶轴上,理论关系具有下列简单的形式:Hk*<110>=Hs*<110>=Hk{1+(k1/2Ku)-[al/h(4πMs/Hk)2]2/3},此式与实验结果符合得相当好。
关键词: 相似文献
7.
8.
9.
报道了Ni(C3H10N2)2NO2(ClO4)晶体在T=1.5K温度和W波段的ESR实验.建立了d8离子基态3A2(F)的零场分裂参量D,E,和g因子与斜方对称晶场势参量间的关系,并应用于Ni(C3H10N2)2NO2(ClO4)晶体.计算值与实验数据符合很好,表明所给关系式是合理的. 相似文献
10.
11.
Using the Mössbauer effect of 155Gd, the quadrupole interaction in GdRh4B4 has been measured, which yields the A02 term in the crystalline electric field Hamiltonian to be 1165 ± 100 K/a.u. Using this, the B02 terms for the other RERh4B4 (RE = Gd to Tm) have been deduced, and the physical properties predicted by the resulting Hamiltonian are compared with the experimental results. 相似文献
12.
In this paper we report the modified solid state synthesis of Ce3+ activated Sr6B5AlO15, Ca6B5AlO15 Ba6B5AlO15 and mixed host aluminoborate phosphors. The prepared phosphors were characterized by photoluminescence technique. The PL excitation spectra showed the excitation peaks ranging from 300 to 400 nm and emission spectra are observed in UV-blue region of spectrum and it varied for different hosts. This kind of emission is due to 4f65d → 4f7 transition of Ce3+ ion. Further PLE and PL emission spectra for various compositions Ca5Sr1B5AlO15, Ca4Sr2B5AlO15, Ca3Sr3B5AlO15, Ca2Sr4B5AlO15, CaSr5B5AlO15 are also taken which shows Ce3+ emission at 428 nm, 425 nm, 432 nm, 427 nm, 438 nm respectively. The calculated 2FJ (J = 7/2, 5/2) energy gap of Ce3+ in all hosts have been calculated and obtained values for Sr6B5AlO15, Ba6B5AlO15 phosphors are 1888 cm−1 and 1330 cm−1 respectively. PL emission spectra of mixed host aluminoborates have shown slight variations in positions of emission peaks. 相似文献
13.
The magnetic hyperfine fields for 119Sn impurity atoms, localized in Ga sites of ferromagnetic intermetallic compounds RGa (R=Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm), were measured by the Mössbauer spectroscopy technique. At T=5 K, the hyperfine field value (Bhf) varies from 3.3 T in TmGa to 28.0 T in GdGa. Huge deviation from the proportionality between Bhf and the projection of the R3+ ion spin (Sz=(g−1)J) was found. As the atomic number of the R element increases, the Bhf/Sz ratio drastically decreases from 12.6 T for PrGa to 3.3 T for TmGa. This unexpected result can be explained by the strong dependency of Bhf value on the relationship between the Sn-R atomic separation (Rnn) and the radius of the magnetic 4f shell (R4f). In the framework of this concept, the available experimental data for Sn atom in the rare-earth compounds with non-magnetic sp elements were considered. The data may be described by the universal dependency on the single parameter, λ=Rnn/R4f. 相似文献
14.
R. Reschke A. Trautwein J.P. Desclaux 《Journal of Physics and Chemistry of Solids》1977,38(8):837-841
For fifteen iron-oxygen compounds we carry out semi-empirical MO cluster calculations. The derived electronic structure is used to calculate electron charge densities ρ(0) and electric field gradients Vpq at the iron nucleus. The ρ(0)-values correlate with experimental isomer shifts δ, however, extreme cases like the Fe(VI)-compound BaFeO4 are beyond the scope of accuracy of our method. We discuss variations of our calculational method, with one of them leading to ρ(0)-values for all fifteen compounds (including BaFeO4) which satisfy the relation Δδ = αΔρ(0). The isomer shift calibration constant is in the range -0.195 mms?1a03 to -0.25 mms?1a03. Calculated quadrupole splittings are comparable with experimental data. 相似文献
15.
Dieter Kuse 《Zeitschrift für Physik A Hadrons and Nuclei》1967,203(1):49-58
The optical absorption spectra of trivalent erbium in isostructural single crystals of YPO4 and YVO4 have been obtained between 14000 and 29000 cm?1. The observed crystal field splittings are interpreted in terms of crystal potentials of symmetryD 2d. From the positions of 33 Stark components the five crystal field parametersB 0 2 , B 0 4 , B 0 6 , B 4 4 andB 4 6 have been determined. The values of the parameters for Er3+:YPO4 are significantly different from those of Er3+:YVO4. 相似文献
16.
17.
Using the level crossing technique the ratios and absolute values of the hyperfine structure (hfs) constants of the levelsz 4F9/2 andz 4F7/2 of the configuration 3d 74s4p of Co I were measured:z 4 F 9/2: ¦A¦=(811±12)MHz; ¦B¦=(48±93) MHz;B/A=?0.06±0.11 A>0; B<0z 4 F 7/2: ¦A¦ = (659 ±11)MHz; ¦B¦=(33±84)MHz;B/A=?0.05±0.13 A>0; B<0. In addition the hfs constants of three other excited levels of Co I could be determined by optical methods:z 4 F 9/2:A=525±26 MHz;B=200 MHzy 4 F 9/2:A=300±30 MHz;B=?500 MHzy 4 G 11/2:A=315±20 MHz;B=400 MHz. The experimental results are compared with known experimental and also with theoretical values which where calculated using the parametric potential method. 相似文献
18.
A tensor-charge model is developed for the lattice dynamics of the ternary compounds A2B4C
2
5
and A1B3C
2
6
. The long-wavelength phonon frequencies are calculated for ZnGeP2 and AgGaS2 crystals. The tensor-charge parameters are determined by comparing the theoretical and experimental values of the infrared intensities of active frequencies. In the crystal ZnGeP2, the tensor charges of the zinc and phosphorus are found to be close to the isotropic charges of the point-ion model, while the tensor charge of germanium is very different from the point-ion charge. In the AgGaS2 crystal, the tensor charges of all the atoms differ appreciably from the point-ion charges. The results are discussed from the point of view of the chemical bond.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 40–44, September, 1980. 相似文献
19.
Tarek Ben Salah Hatem Garrab Sami Ghedira Bruno Allard Damien Risaletto Christophe Raynaud Kamel Besbes Herv Morel 《Superlattices and Microstructures》2006,40(4-6):580
The paper evaluates the optimal design of the low-doped base region inside power diodes and other bipolar devices. It is demonstrated theoretically that a low-doped base region of P+N−N+ diodes can provide a high breakdown voltage and an optimal on-resistance . A simple, accurate and CPU timesaving approach is presented to extract an optimal value for the base region width, WB, and its doping concentration, ND. The paper details an analytical relation between WB and ND, and gives a method for quantifying the trade-off between their values for a given breakdown voltage and for obtaining the minimal on-resistance. Analytical results are confronted with experimental results for 4H-SiC- and 6H-SiC-based diodes. 相似文献
20.
The results of the energy band structure calculations of A2B4C25 compounds are reviewed, and the differences in the energy spectra passing from A3B5 semiconductors to their closest ternary analogs are described. The origin of the lowest conduction band minima of A2B4C25 compounds was determined from the slopes of the fundamental absorption edge and the pressure coefficients of the energy gap. The investigations of the valence band structure from electroreflectance (ER), thermoreflectance (TR) and wavelength modulated absorption (WMA) spectra are reviewed. In the higher energy region the ER and TR spectra of A2B4C25 compounds were found to be more complicated in comparison with those of their binary analogs. A model of an assignment of the structures in optical spectra of A2B4C25 compounds is discussed. 相似文献