共查询到20条相似文献,搜索用时 15 毫秒
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Rongjin Huang Laifeng Li Zhixiong Wu Xinxin Chu Xiangdong Xu Lihe Qian 《Solid State Communications》2010,150(35-36):1617-1620
Antiperovskite manganese nitrides (, 0.1, 0.15) were prepared and their negative thermal expansion, magnetic and specific heat properties were investigated. A frozen state with a freezing temperature was found at ~207 K in . This indicates that exhibits a spin glass state at low temperatures. We discussed the cause of spin glass behavior and correlated this spin glass behavior with broadening of the negative thermal expansion operation-temperature window of the manganese nitrides . 相似文献
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Magnetization and phase sensitive AC susceptibility was measured for the annealed and as-cast samples of ferromagnetic UCu2Ge2, . Special attention was paid to the low temperature range, , which is interesting due to the magnetization decrease and frozen AC response. The hysteresis loops showed a remanence of ≈87% and a fast, thermally activated decrease in the coercivity field. Thermoremanent magnetization at 4.3 K decayed with the relaxation time ≈11103 s. The strong increase of the with the amplitude of the driving field was observed. All these results point to a very large anisotropy of the compound at the lowest temperatures. Phase transition to the randomly canted ferromagnetic phase at was detected in the measurement of the third order non-linear susceptibility. It is concluded that the origin of the transition is the strong temperature dependence of magnetic anisotropy. 相似文献
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Negative thermal expansion materials can experience significant stresses when they are used in composites. Under ambient conditions Zr2(WO4)(PO4)2 displays anisotropic negative thermal expansion (NTE) (, , , at 0 GPa). The effect of hydrostatic pressure on its thermal expansion characteristics was investigated by neutron diffraction between 300 and 60 K at pressures up to 0.3 GPa. No phase transitions were observed in the pressure and temperature range examined. The material was found to have a bulk modulus, B0, of 61.3(8) GPa at ambient temperature, and unlike some other NTE materials, pressure had no detectable effect on thermal expansion (, , , at 0.3 GPa). 相似文献
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Manisha Bajpai Kusum Kumari Ritu Srivastava M.N. Kamalasanan R.S. Tiwari Suresh Chand 《Solid State Communications》2010,150(13-14):581-584
The current density–voltage () behavior of polymer PDY 132 thin films has been investigated in hole-only device configuration, viz., ITO/poly(ethylene-dioxthiophene):polystyrenesulphonate (PEDOT:PSS)/PDY 132/Au, as a function of polymer (PDY) film thickness (150 nm and 200 nm) and temperature (290–90 K). Hole current density was found to follow two distinct modes of conduction, (i) low electric field region I: ohmic conduction where slope , and (ii) intermediate and high electric field region II: non ohmic conduction where slope . Region I has been attributed to the transport of intrinsic background charge carriers while region II has been found to be governed by space charge limited currents (SCLC) with hole mobility strongly dependent on electric field and temperature. The respective hole transport parameters determined from the SCLC regime, is , is , and zero field activation energy () of 0.48 eV is obtained. 相似文献
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ZnO ceramics both with and without boric acid as a flux were sintered at and their luminescent characteristics were compared. In obtained samples UV as well as visible emission bands were observed. The addition of the flux was shown to cause the increase of grain size and the improvement of crystalline quality of the ceramics, which was ascribed to the creation of a liquid phase during the sintering process. It was found that the adding of 1 wt% of boric acid to ZnO powder allowed ceramics preparation without any pressing of the starting materials, in this case being enough to obtain firm and dense ceramics. This ceramics had higher intensity of UV emission and lower intensity of visible emission than ceramics sintered without the flux. 相似文献
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J.L. Izquierdo J.F. Montoya A. Gómez O. Arnache T. Wolf O. Morán 《Solid State Communications》2010,150(39-40):1951-1954
Single-crystals of the novel mixed valent cobaltite Y BaCo4O7+δ have been synthesized. Careful magnetization measurements gave evidence of a ferrimagnetic phase with a and a large coercive field of ~1 T at 5 K. As no substitution of a divalent cation for yttrium was realized, it is possible that the Co2+/Co3 ratio to be modified only by the presence of extra oxygen atoms in the tetrahedral network. 相似文献
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Jianwen Wei 《Solid State Communications》2010,150(15-16):777-781
The tunneling conductance in a normal metal/insulator/metal/ mixed wave superconductor (N/I/N/) junction is calculated, where the N/I/N region is a quantum wire. It is found in the single-mode case that the magnitude of the tunneling conductance near zero voltage is enhanced due to the Andreev bound state by quasiparticles with perpendicular and horizontal injection, and the zero-bias conductance varies with ( is the distance from insulating layer to the interface of N/ mixed wave superconductor). Splitting of the zero-bias conductance peak appears in the quantum point contact tunneling spectra for an N/I/N/ junction, and several subgap peaks can split at the same time. On increasing both and the magnitude ratio of the two components for the mixed wave, the subgap resonances exhibit an alternately high and low behavior inside the energy gap. These results are different from those in d-wave and p-wave superconductor junctions. 相似文献
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The 3d electronic states of transition-metal Mn dopants in have been investigated by Mn -edge X-ray absorption spectroscopy (XAS) measurements. Through the XAS analysis, the valence of the Mn ions is determined. With the increase of doping concentration, the integrated intensities of vary not monotonously, but increase first and then decrease. The relationship between the Mn doping concentration and the degree of p–d hybridization is discussed. 相似文献