Inverse-Heusler合金Ti_2Co_(1-x)Ni_xGa的磁性和半金属性

利用第一性原理计算了Inverse-Heusler合金Ti_2Co_(1-x)Ni_xGa的半金属性、磁性和电子性质.计算结果表明Ti_2Co_(1-x)Ni_xGa的原胞总磁矩和晶格常数随着x的增加而增加.由于过渡金属原子之间的直接杂化和sp电子的调节,原胞总磁矩和晶格常数随掺杂浓度x的改变而改变,并与Slater Pauling规则形成一定的差异.当Ni的掺杂浓度x=0.5时,Ti_2Co_(1-x)Ni_xGa合金的费米面在自旋向下带隙的中间位置,因而可以判定Ti2Co0.5Ni0.5Ga将具有最佳的半金属稳定性.     

SEPARABILITY OF SPECIFIC VOLUME IN THERMODYNAMIC EQUATION OF STATE

A type of system, in which the specific volume can be divided into several parts according to its Hamiltonian, has been obtained in a grand ensemble. The main character of such a system is that its Hamiltonian is absolutely separable. We also discuss the partial specific volume contributed by thermoelectrons in metals under a free-interaction approximation, and the corresponding Wu－Jing parameter is obtained as a simple example.     

Experimental implementation of a Wiener filter in a hybrid digital--optical correlator

We present the implementation of a clutter-tolerant filter in a hybrid correlator system. Wiener filters were mapped with a complex encoding technique onto a smectic A(*) liquid-crystal spatial light modulator (SLM). The technique overcomes the problem of representing high-dynamic-range data on SLM's that have limited modulation capabilities. It also provides a compact image recognition system that is robust enough for many real-world applications. Experimental results are presented.     

High pressure X-ray diffraction study on BaWO4-II

BaWO₄-II has been synthesized at 5 GPa and 610°C. Its high pressure behavior was studied by in situ synchrotron X-ray diffraction measurements at room temperature up to 17 GPa. BaWO₄-II retains its monoclinic structure. Bulk and axial moduli determined by fitting a third-order Birch–Murnaghan equation of state to lattice parameters are: K ₀=86.2±1.9 GPa, K ₀(a)=56.0±0.9 GPa, K ₀(b)=85.3±2.4 GPa, and K ₀(c)=146.1±3.2 GPa with a fixed K′=4. Analysis of axial compressible modulus shows that the a-axis is 2.61 times more compressible than the c-axis and 1.71 times more compressible than the b-axis. The beta angle decreases smoothly between room pressure and 17 GPa from 93.78° to 90.90°.     

Preconcentration and Separation of Gold(III) from Ore Samples by Solid-Phase Extraction Prior to Its Catalytic Fluorescent Determination

ABSTRACT

A new catalytic kinetic fluorescent quenching method for the determination of trace gold(III) was investigated. The method was based on the catalytic effect of gold on oxidation of 3-(3′-methylphenyl)-5- (2′-arsenoxylphenylazo) rhodanine by hydrogen peroxide in potassium hydrogen phthalate–hydrochloric acid (pH = 3.4). Under the optimum conditions, the great decrease of fluorescence intensity has a linear relationship against the concentration of gold in the range of 0 to 12.0 µg·L^?1 with a detection limit of 6.0 × 10^?10g·L^?1. The coexistent metal ions can be separated, and gold can be enriched by TBP resin of solid-phase extraction, which greatly improves the selectivity and sensitivity of the system. The method can be used to determine trace amounts of gold in ore samples successfully with satisfactory results.     

Effect of TiO2 addition on the crystallization of quenched glasses in the SiO2–Al2O3–ZrO2 system

The glass formation in the SiO₂-rich region of the ternary oxide system Al₂O₃–ZrO₂–SiO₂ with MgO, CaO, and TiO₂ as melting aids was analyzed. The crystallization of glasses with different content of TiO₂ and phase evolution with the temperature was studied by X-ray diffraction, infrared, laser Raman spectroscopy and transmission electron microscopy. The use of TiO₂ favored formation and crystallization of the glasses due to the decrease of the viscosity of melts and acting as a nucleating agent. The crystalline phase of t-ZrO₂ was developed at temperatures as low as 880°C whereas in as prepared specimens without TiO₂ its presence was not detected. For the specimens with TiO₂, t-ZrO₂ and mullite were the principal phases at 1000°C. TiO₂ addition did not change the crystallization sequence but decreased the formation temperature of the crystalline phases. Most of Ti⁴⁺ ions entered into t-ZrO₂ and only a small portion in mullite, but the surplus was detected in ZrTiO₄.     

Nd3+:Gd3Sc2Al3O12 晶场能级及拟合

Nd³⁺ :GSAG是性能优良的942 nm激光晶体.用提拉法成功生长Nd³⁺ :GSAG单晶,研究其室温透射光谱,辨认位置高达29967 cm^-1的68个Nd³⁺晶场能级.对这些能级拟合了自由离子及晶场Hamilton参量,拟合标准偏差为16.7 cm^-1,表明实验与计算能级符合很好.获得的Hamilton参量可用于计算Nd³⁺ :GSAG中Nd³⁺的     

The high squeezing and entanglement in regular loss modulated optical parametric amplifier

We investigate the quantum fluctuation characteristic for time dependent regular loss modulated optical parametric amplifier for below and above threshold regions.It is found that a high squeezing and entanglement can be achieved.     

代数迭代法用于傅里叶变换计算层析成像光谱仪数据重建

主要介绍代数迭代法在傅里叶变换计算层析成像光谱仪数据处理中的应用。根据4种不同投影数进行了光谱切片重建,并对光谱相似性进行了比较。针对ART算法可应用少数投影重建的特点,专门在45个投影数时,采用不同迭代系数进行了重建,并进行了比较。最后,对实际场景进行了光谱切片重建。     

光纤光热干涉气体检测技术研究进展

本文阐述光纤光热干涉气体检测的基本原理,从光纤光热相位调制的产生、动态过程、探测方法以及响应时间等方面出发,综述本研究组在光纤光热干涉气体检测方面的最新工作进展.光纤光热干涉技术具有灵敏度高、动态范围大、测量不受散射及其他损耗影响等优势,能够实现小型化、多点复用、组网及远程监测,在环境、医疗、安防等领域具有重要的应用.