Blue luminescence of nanocrystalline CaZrO3:Tm phosphors synthesized by a modified Pechini sol-gel method

This paper reports the photoluminescence (PL) properties of nanocrystalline CaZrO₃:Tm phosphor synthesized by the polymerizable complex method based on the Pechini-type reaction. Nanosized phosphors with paving stone morphology were prepared at a relatively low temperature about 800 °C with the particle size being about 30 nm. The transmission electron microscope (TEM) images showed that further heat treatment at higher temperature could increase the particle size to 50 nm, but its morphology remained unchanged. The luminescence spectra indicated that the blue emission of CaZrO₃:Tm could be produced by four kinds of excitation energies, i.e. the charge transfer (CTS) between Tm³⁺-O²⁻, band-band absorption of host, the absorption defects in the host and the ³H₆-¹D₂ transition. The luminescent mechanism of CaZrO₃:Tm was deduced tentatively based on the luminescence spectra.     

Surface plasmon resonance sensors based on Ag-metalized nanolayer in microstructured optical fibers

Surface plasmon resonance sensors based on Ag-metalized nanolayer in microstructured optical fibers are theoretically analyzed by using finite element method (FEM). In our simulations we use Drude-Lorentz model to describe the metal dielectric constant. The numerical results show that the sensitivity of Ag-metalized SPR sensor could reach 1167 nm/RIU and corresponding resolution is 8.57×10⁻⁵ RIU. Compared to conventional Au-metalized SPR sensors the performance of our device is obviously better.     

Energy theorems for solving equations of deflections

In this paper the unit-dummy-load method is generalized on the basis of Castigliano’s Theorem. On these grounds the general eguations of deflection surfaces of the structures, such as a kind of beams,plates and shells, are directly derived by the force method.We derived the eguations of the deflection surfaces of the rectangular thin plates and thick plates considering the effect of transverse shearing deformations with the inhomogeneous displacement boundary conditions. At the same time we give the equations of deflection axes of the corresponding straight beams.The applications of the reciprocal theorem are also generalized.Three simple calculated examples are given.     

基于流函数模型的矢量海流生成方法

提出了一种基于海洋流函数模型的双站高频地波雷达径向流生成矢量流算法.该算法避免了传统矢量合成法将径向流进行插值带来的误差,而且符合海洋动力学原理,生成的流场更接近实际分布.通过计算机仿真发现,流函数算法的容错、容差能力比矢量合成法更强.在径向流探测标准误差为10 cm.s-1时,新算法反演结果的均方根误差减小了约5 cm.s-1.应用到雷达实测数据中,与海流计实测结果比较表明,新算法比传统算法的平均误差减小了2 cm.s-1.     

Lipschitz局部严格伪压缩映象的迭代逼近

设Ｋ是一致光滑Ｂａｎａｃｈ空间Ｋ的非空子集，Ｔ：Ｋ→Ｘ是Ｌｉｐｓｃｈｉｔｚ局部严格伪压缩映象。本文给出一个迭代序列强收敛到Ｔ的唯一不动点，并给出一个涉及Ｌｉｐｓｃｈｉｔｚ局部强增殖映象Ｔ的非线性方程Ｔｘ＝ｆ的解的迭代逼近。     

标量场与电磁场相互作用体系中的Gasimir效应

摘要本文用Feynmann路径积分方法,研究了一种U(1)规范场理论中的Casimir效应。在一圈图近似下,计算了带电标量场在两个平行的理想金属板之间的Casimir能,并对低维情况进行了讨论。     

The structural,electronic and magnetic properties of Ag4M and Ag4MCO (M = Sc–Zn) clusters

The structures, spectra and electronic and magnetic properties of Ag₄M and Ag₄MCO (M?=?Sc–Zn) clusters have been studied using density functional theory and CALYPSO structure searching method. Structural searches show that M atoms except Zn tend to occupy the highest coordination position in the ground state Ag₄M and Ag₄MCO clusters. Carbon monoxide is most easily adsorbed on Ag atom of Ag₄Zn and M atom of other Ag₄M. Infrared and Raman spectra, photoabsorption spectra and photoelectron spectra of Ag₄M and Ag₄MCO clusters are forecasted and can be used to identify these clusters from experiment. Analysis of electronic properties indicates that the adsorption of CO on Ag₄M clusters changes the zero vibrational energy (ZPVE) and increases stability of the host clusters. Dopant atoms except for Zn improve the stability of silver cluster. The Ag₄Ni cluster shows high chemical activity and maximum adsorption energy for carbon monoxide. Magnetism calculations reveal that the magnetic moment of Ag₄M (M?=?Mn–Ni) cluster adsorbed by carbon monoxide is decreased by 2 μ_B. The change of magnetic moment makes it possible to be used as a nanomaterial for carbon monoxide detection. Simultaneously, it is found that the adsorption of CO on Ag₄Cu cluster is a physical adsorption.     

Friedel-like oscillations from interstitial iron in superconducting Fe(1+y)Te0.62Se0.38

Using polarized and unpolarized neutron scattering, we show that interstitial Fe in superconducting Fe(1+y)Te(1-x)Se(x) induces a magnetic Friedel-like oscillation that diffracts at Q⊥=(1/2 0) and involves >50 neighboring Fe sites. The interstitial >2μ(B) moment is surrounded by compensating ferromagnetic four-spin clusters that may seed double stripe ordering in Fe(1+y)Te. A semimetallic five-band model with (1/2 1/2) Fermi surface nesting and fourfold symmetric superexchange between interstitial Fe and two in-plane nearest neighbors largely accounts for the observed diffraction.