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Wen-Yan Tian Xiao-Yu Kuang Mei-Ling Duan Rui-Peng Chai Cai-Xia Zhang 《Physica B: Condensed Matter》2009,404(21):3114-4336
A theoretical method for studying the inter-relation between electronic and molecular structure has been proposed based on the complete energy matrices for a d3 configuration ion in a tetragonal ligand-field. By means of this method, the local structure for Cr3+ ion doped in oxides TiO2 (anatase) and MgO has been determined. The calculated results indicate that the local structure of the (CrO6)9− cluster in TiO2:Cr3+ and MgO:Cr3+ systems exists as a compressed distortion relative to the regular octahedron. Meanwhile, the dependence of the EPR zero-field splitting parameter D on the local structure parameter ΔR (ΔR=R1−R2) has been revealed. In addition, the relation between the EPR g-factors (g,g,Δg) and the orbit reduction factor k has been discussed for the two systems, suggesting that the orbit reduction factor k is very important to understand the EPR g-factors. 相似文献
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利用Keating模型计算了Si(1-χ)Geχ合金中Si-Si,Ge-Ge和Si-Ge三种振动模态的拉曼频移,计算分别获得Ge浓度为0.1,0.5和0.9时,Si-Ge的振动拉曼频移分别为402.75,413.39和388.15 cm-1,这些结果与文献的实验结果符合,证明了Keating模型建立的关于原子振动模型是有效的,并可以利用拉伸压缩和相邻原子键之间弹性系数变化获得处于应变状态的拉曼光谱频率.利用Keating模型首次计算得到了非晶硅材料的单声子散射峰为477.029 cm-1,与文献实验结果480.0 cm-1相近,说明了非晶硅中原子的总体效果与晶体硅相比处于拉伸状态. 相似文献
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F. Wang T. Liu C.L. Xie Y. Liu N.S. Ma J. Duan J.R. He B. Li B.L. Ou Y. Ou J.J. Cheng Q. Liu L.F. Liu W. Wang 《Physics letters. A》2019,383(24):2933-2937
The Multicaloric effect in the PbZr0.8Ti0.2O3 thin films is investigated with the application of sine wave electric field, dc electric field and stress using a phase field method combined with the thermodynamic analysis. The simulation results show that the adiabatic temperature change-electric field curve presents a shape of butterfly in the presence of the sine wave electric field. In order to detect the effect of the sine wave electric field, the multicaloric effect and the domain structures under the direct electric field and the sine wave electric field are compared. It is found that the domain switching behaviors are quite different under the different applied electric fields. And the negative multicaloric effect in the PbZr0.8Ti0.2O3 thin film is attribute to the domain switching under the external field. 相似文献
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The intrinsic transport properties of zigzag graphene nanoribbons (ZGNRs) are investigated using first-principles calculations. It is found that although all ZGNRs have similar metallic band structure, they show distinctly different transport behaviors under bias voltages, depending on whether they are mirror symmetric with respect to the midplane between two edges. Asymmetric ZGNRs behave as conventional conductors with linear current-voltage dependence, while symmetric ZGNRs exhibit unexpected very small currents with the presence of a conductance gap around the Fermi level. This difference is revealed to arise from different coupling between the conducting subbands around the Fermi level, which is dependent on the symmetry of the systems. 相似文献
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Hongxia Wang Wei Zhang Faling Zhang Yuan Cao Wenhui Su 《Journal of magnetism and magnetic materials》2008
NiFe2O4/SiO2 nanocomposites were prepared using a sol–gel method with the addition of 3-aminopropyltrimethoxysilane (APS). Different phases and morphologies of NiFe2O4/SiO2 nanocomposites were obtained when different amounts of APS were used. The structural properties of the products were examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Sheet-like morphology was observed at higher molar ratio of APS to NiFe2O4, while spherical NiFe2O4/SiO2 nanoparticles separated from each other were formed at lower molar ratio of APS to NiFe2O4. The magnetic properties of the nanocomposites were also investigated, indicating that the interparticle interactions exhibit strong dependence on the molar ratio of APS to NiFe2O4. 相似文献
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高级加密标准(AES)是信息安全中实现数据加密、认证和密钥管理的核心分组密码算法,其安全性分析是密码学的重要课题之一.本文利用AES独立的相关密钥差分,构造了3轮biclique;基于该biclique,使用重计算技术,针对8~10轮AES-128给出新攻击.研究结果表明,攻击8轮AES-128所需的数据复杂度为264选择密文,时间复杂度为2125.29次加密;攻击9轮AES-128所需的数据复杂度为264选择密文,时间复杂度为2125.80次加密;攻击10轮AES-128所需的数据复杂度为264选择密文,时间复杂度为2126.25次加密.与已有的同轮攻击结果相比,新分析所需要的时间复杂度或数据复杂度降低. 相似文献
50.
研究力学系统Birkhoff动力学函数的构造方法.Santilli第二方法是目前构造Birkhoff动力学函数时常用的方法之一,但研究发现其计算公式存在冗余项.通过具体的证明得到了简化的Santilli第二方法,从而为自伴随系统Birkhoff动力学函数的构造提供了更为简洁的计算公式.举例说明结果的应用. 相似文献