材料期刊网

EMISSION M■SSBAUER SPECTROSCOPY OF NiTi SHAPE MEMORY ALLOY

Y G. Li and CS. Xue (Institute of Semiconductor Research , Shandong Normal University , Jinan 250014 , China)G.L. Zhang(Shanghai Institute of Nuclear Research , The Chinese Academy of Sciences , Shanghai 201800 , China )

金属学报(英文版)

The emission Mssbauer Spectroscopy in cotnbination with transmission electron microscope was used to study NiTi shape memory alloy. The damage and the precipitated phase in NiTi alloy have heen discussed.

关键词: emission m■ssbauer spectroscopy , null

Investigations of the zero-field splittings and g factors for the rhombic Cr3+-Li+ and Cr3+-Na+ defect centers in Cs2CdCl4 crystals

Physica B-Condensed Matter

The high-order perturbation formulas for the zero-field splitting parameters D and E, and g factor g(x), g(y), g(z) for 3d(3) ions in rhombic symmetry are derived by using a two spin-orbit coupling parameter model, in which both the contributions from the spin-orbit coupling of central d(3) ion and that of the ligands are considered. From these formulas, spin Hamiltonian parameters for the rhombic defect centers Cr3+-Li+ and Cr3+-Na+ in Cs2CdC4, crystals are calculated by considering the suitable defect-induced lattice distortions. The results agree well with the observed values. The contributions to spin Hamiltonian parameters from the spin-orbit coupling of ligands are discussed. (C) 1999 Elsevier Science B.V. All rights reserved.

关键词: crystal- and ligand-field theory;electron paramagnetic resonance;spin-orbit coupling;Cr3+;Cs2CdCl4;superposition model;ions

Explanations of the EPR parameters for the rhombic Cr3+-V-M and Cr3+-Li+ centers in A(2)MF(4) (A = K, Rb, Cs; M = Mg, Zn, Cd) crystals

Radiation Effects and Defects in Solids

In this paper, we establish the high-order perturbation formulas of EPR zero-field splittings D, E and g factors, g(x), g(y) and g(z) for 3d(3) ions in a sort of rhombic symmetry where the symmetry axes and hence the crystal-field axes lie along the [001], [010] and [100] axes. From these formulas, the EPR parameters D, E, g(x), g(y) and g(z) for the rhombic Cr3+-V-M and Cr3+-Li+ defect centers in the tetragonal A(2)MF(4) (A = K, Rb, Cs; M = Mg, Zn, Cd) fluorides are calculated by considering the suitable defect-induced lattice distortions. The results are in reasonable agreement with the observed values.

关键词: electron paramagnetic resonance;crystal-field theory;superposition;model;lattice distortions;Cr3+;A(2)MF(4) (A = K, Rb, Cs;M = Mg, Zn,;Cd;spin-orbit coupling;electron-paramagnetic-res;superposition model;cr-3+ centers;ions;rb2znf4;spectra;k2mgf4;k2znf4

CS-MCM-48复合载体固定化脂肪酶催化苯乙酮-锅法还原转酯化拆分反应

薛屏 , 严祥辉

应用化学 doi:10.3969/j.issn.1000-0518.2007.03.002

将天然聚合物壳聚糖(CS)涂覆在介孔分子筛MCM-48表面制得CS-MCM-48复合载体,控制CS与介孔分子筛MCM-48质量比为1∶10时,CS-MCM-48的比表面积、平均孔径和孔容分别为408 m2/g、2.14 nm和0.38 cm3/g.在磷酸盐缓冲溶液-异辛烷混合溶剂中制备了固定化假单胞菌脂肪酶(Pseudomonas CepaciaLipase,PSL)PSL/CS-MCM-48,并用于潜手性苯乙酮一锅法还原转酯化手性拆分反应.结果表明,PSL/CS-MCM-48的催化活性和对映选择性均明显优于纯介孔分子筛MCM-48和壳聚糖制备的固定化酶PSL/MCM-48和PSL/CS.甲苯作溶剂,反应温度为40℃时,底物1-苯乙醇转化率达15.3%,产物(R)-乙酸苯乙酯和(S)-1-苯乙醇的对映体过量值分别为99%和18.0%,对映选择性参数E值达237,固定化酶PSL/CS-MCM-48显示出良好的手性拆分性能.

关键词: CS-MCM-48复合载体 , 固定化脂肪酶 , 一锅法 , 苯乙酮 , 拆分 , 对映选择性

Studies of the trigonal field parameters and g factors for magnetic semiconductor NaCrS2

Spectrochimica Acta Part a-Molecular and Biomolecular Spectroscopy

The trigonal field parameters v and v' of magnetic semiconductor NaCrS2 are calculated from the superposition model, and its g factors g(parallel to) and g(perpendicular to) are calculated from the high-order perturbation formulas of 3d(3) ions in trigonal symmetry obtained by the one and two spin-orbit coupling parameter models. These calculations are based on the structural data of NaCrS2 crystal. The calculated results suggest that the superposition model is effective to the analyses of the low-symmetry field parameters of 3d(n) ions in crystals and that the two spin-orbit coupling parameter model (where the contributions from both the spin-orbit coupling parameter of 3d(n) ion and that of ligand are considered) is preferable to the one spin-orbit coupling parameter model (in which the contribution from only the spin-orbit coupling parameter of 3d(n) ion is considered) in the explanations of g factors in the cases that ligands have large spin-orbit coupling parameter in 3d(n) clusters. (c) 2006 Elsevier B.V. All rights reserved.

关键词: electron paramagnetic resonance;crystal field;ligand field;optical;spectra;NaCrS2;Cr3+;atomic screening constants;chromium(iii) sulfides;superposition model;local-structure;scf functions;cr3+ ions;crystal;resonance;spin;selenides

G(f)/HA-CS复合材料的制备及性能研究

沈基显 , 黄剑锋 , 曹丽云 , 曾燮榕 , 熊信柏

稀有金属材料与工程

以羟基磷灰石-壳聚糖(HA-CS)为基体,玻璃纤维G(f)为增强相,采用原位杂化法制备短玻璃纤维增强HA-CS基生物复合材料.研究交联剂、羟基磷灰石含量和玻璃纤维含量对复合材料性能的影响.采用红外吸收光谱、扫描电子显微镜和万能材料试验机对材料的结构和性能进行表征.结果表明:原位杂化法能制备性能较好的复合材料;用戊二醛交联改性复合材料可以明显增加其韧性和弯曲强度,使复合材料抗弯曲强度提高16%;当CS/HA=10/1(质量比)和玻璃纤维含量为1.5%时复合材料抗折强度达到极大值84.47 MPa;随玻璃纤维含量的增加,复合材料的断裂面由平整向多层断裂变化,材料的韧性有所提高.

关键词: G(f)/HA-CS复合材料 , 玻璃纤维 , 交联剂 , 弯曲强度

CS-KPS复合体系引发S-g-PAM反相胶乳的研究

卢绍杰 , 刘瑞贤 , 孙希明 , 卫乃勤 , 杨光中

高分子材料科学与工程

以K2S2O8为引发剂,研究了在反相乳液中合成淀粉接枝聚丙烯酰胺共聚物(S-g-PAM),实验证明,加入少量铈离子组成复合体系,对提高反应速率、接枝率和接枝效率起到显著的促进作用.文中对硫酸铈-过硫酸钾(CS-KPS)体系的用量及反应影响因素进行了探讨.

关键词: 淀粉接枝 , 丙烯酰胺 , 复合引发体系 , 反相胶乳

Luoyang Institute of Refractories Research Ministry of Metallurgical Industry

ZHONG Xiangchong Luoyang Institute of Refractories Research , Luoyang , China.

材料科学技术（英文）

关键词:

CS-G催化剂小试研究及其在Novolen聚丙烯装置上的应用

孟永智 , 曾祥国 , 李磊

合成材料老化与应用

在神华宁煤500kt/a气相Novolen聚丙烯( PP)装置上进行了国产CS-G催化剂的工业化应用试验,并考察了该催化剂物理化学性能和催化活性。小试聚合实验结果表明,在相同的聚合条件下,国产催化剂CS-G比进口催化剂PTK4320活性高出49．4%,但其制备的聚丙烯的等规度和熔融指数略低。工业应用结果表明,CS-G催化剂的平均聚合活性较PTK4320催化剂高60%,硅烷用量基本相同,氢气的用量增加了25%。 CS-G催化剂在神华宁煤Novolen聚丙烯装置上生产的1102 K产品可以达到优等品的标准,产品性能与进口催化剂生产的产品没有明显差异。

关键词: 聚丙烯 , Novolen气相工艺 , CS-G催化剂 , 催化活性 , 工业应用

锂离子电池正极材料Li0.99Y0.01FePO4的制备

曲涛 , 田彦文 , 钟参云 , 翟玉春

功能材料

橄榄石型LiFePO4是近年发展起来的一种锂离子电池正极材料,它的理论容量为170mAh/g.具有价格便宜、环境友好、无毒、无吸湿性、热稳定性好等优点,越来越受到人们的重视.但是由于LiFePO4的室温电导率低,影响了它的实际应用,为改善其电导率低的问题,本文采用固相法掺杂稀土元素Y合成Li0.99Y0.01FePO4,结果表明,掺杂后材料具有良好的电化学性能,其室温初始放电容量为129.9mAh/g,循环15次后几乎没有衰减.

关键词: 锂离子电池 , 正极材料 , Li0.99Y0.01FePO4 , 稀土