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《Solid State Communications》1986,60(4):331-335
The absorption spectra of NH4MnCl3 and NH4MnF3 crystals have been measured down to 10 K in the 250 to 600 nm region. The observed bands are assigned to electronic transitions from the 6A1g(S) ground state to various excited levels of Mn2+ ions in an octahedral crystalline field. The position of the bands have been fitted within the strong crystal field scheme. Resulting parameters at room temperature are B=741, C=2990 and Dq=520 cm−1 for NH4MnCl3 and B=800, C=3139 and Dq=694 cm−1 for NH4MnF3. At low temperature some bands show a rich fine structure in which some phonon progressions have been identified. 相似文献
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I. M. Batyaev F. M. Kishalov S. B. Sukhanov L. V. Khrol 《Journal of Applied Spectroscopy》1991,54(1):38-40
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 1, pp. 51–54, January, 1991. 相似文献
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A. N. Vasiliev E. A. Popova L. N. Bezmaternykh V. L. Temerov Z. Hiroi 《Journal of Experimental and Theoretical Physics》2006,102(2):262-265
The specific heat was measured in the range 0.4–300 K in YFe3(BO3)4, Y0.5Gd0.5Fe3(BO3)4, and GdFe3(BO3)4 single crystals. Sharp anomalies were found at temperatures of first-order structural, second-order antiferromagnetic, and
first-order spin-reorientational transitions. A Néel temperature of about 37 K was found to be virtually independent of presence
of rare-earth ions, indicating rather weak coupling of Gd and Fe subsystems. The contribution of the magnetic system to specific
heat was separated through the scaling procedure allowing determination of the magnetic entropy of Fe and Gd subsystems. At
the lowest temperatures, the specific heat in GdFe3(BO3)4 exhibits a Schottky-type anomaly, which is due to Gd3+ eightfold degenerate ground-level splitting by the internal magnetic field of the Fe subsystem of about 7 T.
The text was submitted by the authors in English. 相似文献
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Abstract The high-pressure crystal structures of Th3P4 and U3X4, where X = P, As and Sb, have been studied by means of synchrotron x-ray diffraction in the pressure range up to 50 GPa. The cubic phase of these compounds is retained in the whole pressure range. The bulk modulus B0 and its pressure derivative B0’ have been determined for each compound. A log-log plot of B0 versus unit-cell volume gives a straight line for the uranium pnictides, with a slope about -5/3. 相似文献
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Ashok Kumar 《Molecular physics》2013,111(10):1657-1663
Experimental and theoretical photoabsorption cross sections combined with constraints provided by the Kuhn–Reiche–Thomas sum rule, the high-energy behaviour of the dipole oscillator strength density, static dipole polarisabilities, and molar refractivity data when available are used to construct dipole oscillator strength distributions for PH3, PF3, PF5, PCl3, SiCl4, GeCl4, and SnCl4. The distributions are used to predict dipole sum rules S(k), mean excitation energies I(k), and van der Waals C6 coefficients. 相似文献
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We have studied the stability of mixed 3He/4He clusters in L = 0 and L = 1 states by the diffusion Monte Carlo method, employing the Tang-Toennies-Yiu (TTY) He-He potential. The clusters 3He4HeM (
) and 3He24HeM (L = 0, S = 0) are stable for M > 1, while to bind two 3He in a triplet state the minimum number of 4He is four. Considering clusters with three 3He, 3He34He4 is the smallest stable system in the L = 1 state, while 3He34He8 is the smallest stable system in the L = 0 state. 相似文献
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Nuclear quadrupole resonance (NQR) of209Bi has been studied in Bi4 (GeO4)3 and Bi4 (SiO4)3 using a wide band coherence-controlled superregenerative oscillator-detector. All the four allowed (ΔM
I=±1) transitions are observed. In both cases the electric field gradient (EFG) tensor is axially symmetric (η=0.0). The quadrupole
coupling constante
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qQ is measured to be 490.8±1 MHz and 470.4±1 MHz respectively. It is pointed out that the purely ionic model is inadequate to
understand these results. With the available experimental accuracy and the strength of the applied electric field (∼ 6 KV/cm),
no field-induced effects on the NQR spectrum could be observed in the case of Bi4 (SiO4)3. 相似文献
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《Journal of magnetism and magnetic materials》2001,231(1):23-28
We report the results of low-temperature magnetic properties of newly synthesized samples of TbPd3S4 and YbPd3S4, which indicate that they merely exhibit antiferromagnetism below 2.9 and 1.8 K, respectively, without showing any other transitions above 0.4 K. From the powder neutron diffraction experiments, we determined the magnetic structure of these rare-earth palladium bronzes. 相似文献
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研究了Sr3Gd(PO4)3 : Tm3 和GdPO4 : Tm3 样品的结构特性、光谱特性.GdPO4 : Tm3 为单斜晶系,基质掺入铥离子后结构没有明显变化.GdPO4:Tm3 在164和210 nm附近有强烈的吸收峰.位于164 nm附近的强烈的吸收峰是归因于基质的吸收引起,210 nm附近的吸收峰则归因于Gd 的8S7/2-6GJ的能级跃迁.在164 nm真空紫外光激发下,样品于453及363 nm处有较强的发射峰,发射主峰位于453nm,属于Tm3 的1D2→3H4(22,123 cm-1)跃迁的典型发射.由于阳离子质量的不同,Sr3Gd(PO4)3:Tm3 在166 nm附近的激发峰高于GdPO4: Tm3 的同位置的激发峰,其在363 nm处的发射有明显减弱,而在453 nm处的蓝色发射有显著的增强. 相似文献
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Jang H Lee JS Ko KT Noh WS Koo TY Kim JY Lee KB Park JH Zhang CL Kim SB Cheong SW 《Physical review letters》2011,106(4):047203
Based on the detailed Mn L(2,3)-edge x-ray resonant scattering results, we report a new complexity in the magnetic order of multiferroic orthomangnites, which has been considered as the simple A-type cycloid order inducing ferroelectricity. The Dzyaloshinskii-Moriya interaction involved in the orthorhombic distortion brings on F-type canting from the A type, and the ordering type becomes the off-phase synchronized bc cycloid in TbMnO(3) or the tilted antiphase ab cycloid in Eu(3/4)Y(1/4)MnO(3). The F-type canting is responsible for the magnetic field-driven multiferroicity to weak ferromagnetism transition. 相似文献
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The spin-lattice relaxation timesT 1 were measured for protons and deuterons in polycrystalline NH4NO3 and ND4NO3. The investigation was carried out at temperatures between about 80°K and 430°K using the NMR pulse method. From the measured values ofT 1 the activation energies for the reorientation motions of NH 4 + and ND 4 + ions below 200°K were calculated to be 2.07±0.11 kcal/mole and 2.56±0.23 kcal/mole, respectively. The quadrupole coupling constante 2 Qq/h of the deuteron in ND 4 + ion was found to be 194±30 kc/s. 相似文献
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Direct ultrasonic-assisted synthesis of sphere-like nanocrystals of spinel Co3O4 and Mn3O4 总被引:1,自引:0,他引:1
A simple sonochemical method was developed to synthesize uniform sphere-like or cubic Co(3)O(4) and Mn(3)O(4) nanocrystals by using acetate salts and sodium hydroxide or tetramethylammonium hydroxide (TMAH) as precursors. Influence of some parameters such as time of reaction, alkali salts, and power of the ultrasound and the molar ratio of the starting materials on the size, morphology and degree of crystallinity of the products was studied. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), FTIR spectroscopy, Thermal gravimetry analysis and differential thermal analysis (TGA/DTA) were used to characterize the nanocrystals. 相似文献
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The magnetic properties of an antiferromagnet with trigonal symmetry, namely, HoFe3(BO3)4, have been investigated theoretically. The calculations have been performed in the molecular field approximation and in the framework of the crystal field model for the rare-earth subsystem. Extensive experimental data on the magnetic properties of HoFe3(BO3)4 have been interpreted and good agreement between theory and experiment has been achieved using the obtained theoretical dependences. The spontaneous spin-reorientation transition and the spin-reorientation transition induced by a magnetic field B ‖ a from the easy-axis to easy-plane state, as well as the spin-flop transition in a magnetic field B ‖ c, have been described. It has been shown that the spontaneous spin-reorientation transition is a magnetic analog of the Jahn-Teller effect. The temperature dependences of the initial magnetic susceptibility at temperatures ranging from 2 to 300 K, the nonlinear curves of magnetization for B ‖ c and B ⊥ c in a magnetic field up to 1.2 T (which indicate the occurrence of first-order phase transitions), and their evolution with variations in the temperature have been described, as well as the temperature and field dependences of the magnetization in a magnetic field up to 9 T. The parameters of the trigonal crystal field for the rare-earth ion Ho3+ and the parameters of the Fe-Fe and Ho-Fe exchange interactions have been determined in the course of interpretation of the experimental data. 相似文献
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研究了Si3N4层在ZrN/Si3N4纳米多层膜中的晶化现象及其对多层膜微结构与力学性能的影响.一系列不同Si3N4层厚度的ZrN/Si3N4纳米多层膜通过反应磁控溅射法制备.利用X射线衍射仪、高分辨透射电子显微镜和微力学探针表征了多层膜的微结构和力学性能.结果表明,由于受到ZrN调制层晶体结构的模板作用,溅射条件下以非晶态存在的Si3N4层在其厚度小于0.9 nm时被强制晶化为NaCl结构的赝晶体,ZrN/Si3N4纳米多层膜形成共格外延生长的柱状晶,并相应地产生硬度升高的超硬效应.Si3N4随层厚的进一步增加又转变为非晶态,多层膜的共格生长结构因而受到破坏,其硬度也随之降低. 相似文献