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971.
报道了两个典型掺杂的镍氧化物Nd_2-xSr_xNiO_4(x =0.33,1.35)的低温热导率、电阻率和低场交流磁化率,测试温区为77—300K. 在Nd_2-xSr_xNiO_4 (x=0.33)样品的热导率-温度曲线上在电荷有序转 变温度(T_CO)和自旋有序转变温度(T_SO)附近分别观测到反常, 电荷有序使热导率在T_CO以下有所增加,反铁磁自旋有序使热导率在T_SO附近被压制. 在低场交流磁化率-温度曲线上也分别观测到对电荷有序和自旋有 序的响应,而在其电阻率-温度曲线上仅观测到电荷有序. 作为比较,Nd_1.67Sr0.33NiO_4样品中没有观测到输运性质和磁性质上的反常. 两个样品中声子热导占 主导地位. Nd_1.67Sr0.33NiO_4样品中电荷有序和自旋有序导致的热导 率的反常表明样品中存在强的电荷-声子和自旋-声子相互作用.
关键词:
热导率
电荷有序
自旋有序 相似文献
972.
Agglomeration behaviour of nano-particle aluminium (nano-Al) in normal incident shock waves is investigated by our devised shock tube technology. The morphology, particle size, agglomeration process of nano-Al studied in normal incident shock waves are comprehensible evaluated by x-ray diffraction, transmission electron microscopy and scanning electron microscopy. The above-mentioned techniques show that the high strength and temperature of incident shock wave give a chance for activity of nano-Al in the reactions and decrease the agglomeration, and the morphology of agglomeration is affected by the temperature of nano-Al reaction region. The dynamic temperature of reaction region determined by the intensity ratio of two A10 bands is 2602K, which is closer to nano-Al actual reacted temperature than the determined temperature of ordinary methods (i.e. six channel instantaneous optical pyrometer; plank black body radiation law, etc.) 相似文献
973.
Huang Shi-Zhong Zhang Peng-Fei Ruan Tu-Nan Zhu Yu-Can Zheng Zhi-Peng 《The European Physical Journal C - Particles and Fields》2005,42(3):375-389
Based on the solution to the Rarita-Schwinger equations, a direct derivation of the projection operator and propagator for a particle with arbitrary spin is worked out. The projection operator constructed by Behrends and Fronsdal is re-deduced and confirmed, and simplified in the case of half-integral spin; the general commutation rules and Feynman propagator for a free particle of any spin are derived, and explicit expressions for the propagators for spins 3/2, 2, 5/2, 3, 7/2, 4 are provided.Received: 13 March 2003, Revised: 24 April 2005, Published online: 6 July 2005 相似文献
974.
LU Xing-Qianga PI Xiang-Dongb SU Cheng-Yonga a 《结构化学》2005,24(10):1176-1180
1 INTRODUCTION N,N?-4-aminomethyl-pyromellitic diimide (4-pmpmdwas firstly obtained[1] in 1989 as one of the bypro-ducts by refluxing equimolar quantities of pyrome-llitic anhydride, n-hexylamine and 4-aminomethyl py-ridine in dry DMF to assemble electronic donor-spa-cer-acceptor systems, but its structure and coordina-tion chemistry did not receive attention at that time.For 4-pmpmd, the entity of two methylene groups(-CH2-) between the rigid pyromellitic diimide (PMDcore and two fre… 相似文献
975.
976.
Hao Jinbo Ruan Liming Tan Heping 《Journal of Quantitative Spectroscopy & Radiative Transfer》2003,78(2):151-161
Effect of scattering on radiative heat transfer in two-dimensional rectangular media by the finite-volume method has been studied. Compared with the existing solutions, it shows that the result obtained by the finite-volume method is reliable. Furthermore, relative errors caused by the approximation that linear and nonlinear anisotropic scattering media is simplified to isotropic scattering media have been studied. 相似文献
977.
X. H. Chen T. F. Li M. Yu K. Q. Ruan C. Y. Wang L. Z. Cao 《Physica C: Superconductivity and its Applications》1997,290(3-4):317-322
Samples of Bi2Sr2Ca1−xPrxCu2Oy have been characterized by resistivity and thermoelectric power measurements. All metallic samples show superconductivity with a maximum Tc = 90 K at X = 0.2. The sample of x = 0.6 shows a crossover from hopping conduction at low temperature above Tc to metallic conduction at high temperature. For the metallic samples below x = 0.6, the results of thermoelectric power are well fitted by both of a phenomenological band spectrum model and the Nagaosa and Lee model. 相似文献
978.
The surface modes in the plasma circular cylindrical waveguide in a lossy material are analyzed, particularly for the variations
of their propagation properties with plasma parameters and surrounding material. The characteristic equations of surface modes
are derived, and their relevant approximate solutions are given. The limit results of this paper are consistent with that
given in literature’s. The analysis show that it can be used to improve the properties of mode suppressors and fabricat cut-off
attenuators. 相似文献
979.
980.