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排序方式: 共有71条查询结果,搜索用时 15 毫秒
1.
Liqing Liu Kunquan Hong Xing Ge Mingxiang Xu 《Applied Physics A: Materials Science & Processing》2014,115(4):1147-1150
Copper oxide (CuO) is a p-type semiconductor with a band gap of 1.2 eV, which is well known in high-temperature superconductor and antiferromagnetic (AFM) materials through Cu–O–Cu super-exchange interaction. In this paper, we report the strong anisotropic ferromagnetism (FM) in aligned CuO nanorod arrays synthesized by a microwave-assisted hydrothermal method. The transmission electron microscopy (TEM) image shows that the CuO nanorod consists of a large number of smaller nanorods with almost the same growth direction. The X-ray diffraction (XRD) pattern indicates that the CuO nanorods are well crystallized with highly preferred orientation of the [020] direction. These CuO nanorod arrays show room-temperature ferromagnetism, with strong magnetic anisotropy when the magnetic field is applied perpendicular or parallel to the rod axis. This phenomenon of room-temperature ferromagnetism in those aligned CuO nanorods might originate from uncompensated surface spins and shape anisotropy of the nanorods. 相似文献
2.
Qingyu Xu Xiaohong Zheng Liaoyu Wang Yan Zhang Dunhui Wang Mingxiang Xu 《Physica B: Condensed Matter》2012,407(24):4793-4796
La and Co co-doped BiFeO3 ((Bi1−xLax)(Fe0.95Co0.05)O3 (x=0, 0.10, 0.20, 0.30)) ceramics were prepared by tartaric acid modified sol–gel method. The X-ray diffraction patterns indicate a transition from rhombohedral structure to tetragonal structure at x=0.20, which has been confirmed by the Raman measurements. The band gap increases with increasing x to 0.20, and then decreases with further increasing x to 0.30. The structural transition has significant effects on the multiferroic properties. The remnant magnetization and saturate ferromagnetic magnetization decrease abruptly with increasing x to 0.10, and then gradually increase with further increasing x up to 0.30. The coercivity is significantly reduced with increasing La doping concentration. The ferroelectricity has been improved by La doping, and the polarization increases with increasing x to 0.10, then decreases with further increasing x up to 0.30. The simultaneous coexistence of soft ferromagnetism and ferroelectricity at room temperature in tetragonal Bi0.70La0.30Fe0.95Co0.05O3 indicates the potential multiferroic applications. 相似文献
3.
Mingxiang Chen Dominic P. Clemence 《Journal of Difference Equations and Applications》2013,19(9):887-899
This paper considers a non-linear system of ordinary differential equations, which arises in the study of hantavirus epidemics. The system has the property that the total population obeys the logistic equation. For this system, we use linearization and the dynamical properties of the logistic equation to analyze the dynamics of the subpopulation system. In view of the usual numerical instabilities associated with standard finite difference methods used for simulating such systems, we construct non-standard finite difference (NSFD) schemes, which preserve the dynamic properties of the system, and may therefore be used for its simulation. 相似文献
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Mingxiang Chen 《力学学报》2010,42(2):228
针对各向同性材料,基于一组相互正交的基张量,建立了一套有
效的相关运算方法. 基张量中的两个分别是归一化的二阶单位张量和偏应力张量,另一个则
使用应力的各向同性二阶张量值函数经过归一化构造所得,三者共主轴. 根据张量函数表示
定理,本构方程和返回映射算法中所涉及到的应力的二阶、四阶张量值函数及其逆都由这组
基所表示. 推演结果表明:这些张量之间的运算,表现为对应系数矩阵之间的简单
关系. 其中,四阶张量求逆归结为对应的3\times3系数矩阵求逆,它对二阶张量的变换
则表现为该矩阵对3times 1列阵的变换. 最后,对这些变换关系应用于返回映
射算法的迭代格式进行了相关讨论. 相似文献
7.
Qingyu Xu Zheng WenJinlong Gao Di WuShaolong Tang Mingxiang Xu 《Physica B: Condensed Matter》2011,406(10):2025-2027
Bi(Fe0.95Co0.05)O3 films were prepared on conductive indium tin oxide (ITO)/glass substrates by chemical solution deposition. Well saturated polarization hysteresis loop has been observed with a remnant polarization value of about 22 μC/cm2 at room temperature. Weak ferromagnetism with saturation magnetization of about 3 emu/cm3 was observed at room temperature. The clear observation of both room temperature ferroelectric and ferromagnetic properties suggests the potential multiferroic applications of Bi(Fe0.95Co0.05)O3. 相似文献
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使用主值空间表示的各向同性塑性本构方程 总被引:1,自引:0,他引:1
针对各向同性材料,在内变量为标量的假定下,应用张量函数表示定理给出了其塑性应变增量的不变性表示.它的3个不可约基张量取决于应力张量、相互正交且共主轴.建立3个基张量构成的张量子空间与三维主值空间的对应关系,将共主轴的张量采用笛卡尔坐标系中的矢量描述,矢量在不同坐标系下的分量均为张量的一组不可约不变量.定义塑性应变增量对应的矢量为内变量增量,使用张量函数表示理论得到,内变量演化方程除取决于应力对应的矢量和内变量本身外,还取决于应力增量在张量子空间中的投影,该投影就是应力对应矢量的增量,因此,本构方程归结为确定主值空间中矢量之间的关系.最后表明,三维主值空间与张量子空间中的流动法则是等价的. 相似文献
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