材料期刊网

BOND STRUCTURE OF HYDROGENATED DIAMOND LIKE CARBON FILMS DEPOSITED BY PLASMA BASED ION IMPLANTATION

G.Li , L.F.Xia , X.X.Ma , Y.Sun and Z.J.Zhan Schoolof Materials Science and Engineering , Harbin Institute of Technology , Harbin 150001 , China

金属学报(英文版)

The bondstructureofhydrogenated diamond likecarbon( DLC) filmsdeposited with plasmabased ionimplantation ( PBII) wascharacterized by Raman spectroscopy andcore level band and valenceband spectrum of XPS. Theresultsshow thatthe hydrogenated carbon filmspre pared with lower pulse bias, especially zero bias, display polymer like feature. The DLCfilms deposited with 15 kVpulsebiascontainsthehighestdensityofsp3 bonds. Thecore lev elband ( C1s) spectra of allfilmsshifttowardlow bindingenergy after4kVAr+ ion bom barding. The valenceband spectra of hydrogenated DLCfilmsarequite differentfrom thatof diamond and graphite. However, afterion bombarding, besidetwosingle peaksatabout17 0 eVand 12 5 eV(similarto graphite) ,two new sharp peaksappearatabout21 3 eVand 8 0 eV,respectively. Thepeak at8 0 eVcan beconsidertothecontribution duetothe actingofimplanted argon on C Cbondsand C Hbondsin thefilms.

关键词: hydrogenated DLCfilms , null , null , null , null

Theoretical studies of g factors and defect structures for cubic, tetragonal, and orthorhombic Fe+ Centers in alkali halides MX (M = Li, Na; X = F, Cl)

Communications in Theoretical Physics

The EPR g factors for cubic, tetragonal and orthorhombic Fe+ centers in alkali halides MX (M = Li, Na; X = F, Cl) are calculated from second-order perturbation formulas of g factors based on cluster approach for 3d(7) ions in three symmetries. From calculations, the g factors of these Fe+ centers in MX crystals are reasonably explained and the defect structural data for the tetragonal and orthorhombic Fe+ centers are estimated. The results are discussed.

关键词: crystal;and ligand-field theory;electron paramagnetic resonance;defect structure;atomic screening constants;spin-orbit interaction;superposition model;resonance-spectra;epr parameters;crystal-field;scf functions;ions;co2+

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

(Sr0.98-xMx)Al2O4(M=Ba,Ca)∶0.02Eu3+,yG(G=Li+,Na+,K+)红色荧光粉的制备及性能的研究

阎峰云 , 刘兰 , 夏心俊 , 何玲

功能材料 doi:10.3969/j.issn.1001-9731.2017.02.032

采用化学共沉淀法制备出SrAl2O4∶Eu3+红色荧光粉,尝试向粉体中添加辅助激活剂(Li+、Na+、K+),改变粉体中基质元素相对比例,并对粉体进行XRD、荧光光谱分析.结果表明,样品中加入相同摩尔的Li+、Na+、K+辅助激活剂,掺入Li+的粉体发光强度最好.改变Li+的掺入量,当Li+的量为0.04 mol时,粉体发光强度最好.改变粉体中基质Sr2+的含量,当掺入Ba2+时,荧光粉发射峰出现"蓝移"现象;当掺入Ca2+时,荧光粉发射峰出现"红移"现象.

关键词: 共沉淀 , 红色荧光粉 , 辅助激活剂 , 基质

LaF3表面修饰Li[Li0.2Mn0.54Ni0.13Co0.13]O2的制备及其电化学性能

李成冬 , 姚志垒 , 李举 , 徐进 , 熊新

材料研究学报 doi:10.11901/1005.3093.2016.468

分别以Na2CO3和NH3·H2O为沉淀剂和络合剂,用共沉淀法和950℃高温烧结制备Li[Li0.2Mn0.54Ni0.13Co0.1力O2,并用湿化学法将LaF3包覆在Li[Li0.2Mn054Ni0.13Co013]O2正极材料表层.用XRD,SEM,TEM等手段表征了LaF3包覆前后Li[Li0.2Mn0..Ni0.13Co0.13]O2颗粒的微观结构和表面形貌,用电化学测试仪检测样品的充放电性能.结果表明,包覆前后材料的结构没有变化,已经成功地将LaF3包覆在Li[Li02Mn054Ni0.13Co0.13]O2表面;LaF3包覆使Li[Li.2Mn054Ni0』3Co0.13]O2的电化学综合性能明显提高.在5C高倍率下,LaF3-Li[Li0.2Mn10.54Ni013Co0.13]O2的放电比容量比原始Li[Li0.2Mn0.54Ni0.13Co0.13]O2超过了20.3 mAh·g-1.经过100次循环后LaF3-Li[Li0.2Mn054Ni0.13Co0.13]O2的容量保持率高达94.8％,循环稳定性更佳.这些结果表明,LaF3包覆改性是提高Li[Li02Mn0.54Ni0.13Co0.13]Oz电化学性能切实可行的方法.

关键词: 材料合成与加工工艺 , 锂离子电池 , 共沉淀法 , Li[Li0.2Mn0.54Ni0.13Co0.13]O2 , LaF3

Li1-xCrxFePO4的微波合成研究

徐徽 , 刘卫平 , 苏元智 , 石西昌 , 杨喜云

材料导报

采用机械球磨结合微波法合成了Cr3+掺杂锂离子电池正极材料Li1-xCrx FePO4.通过X射线衍射(XRD)、扫描电镜(SEM)和恒电流充放电测试研究了Cr3+掺杂方式和掺杂量对样品的物相结构、形貌和电化学性能的影响.实验结果表明,微波法可以快速合成Li1-xCrx FePO4正极材料；以共沉淀掺杂方式合成的样品Li0.99 Cr0.01FePO4具有最好的电化学性能,在室温下以20mA/g进行充放电测试,其首次放电容量为153.59mAh/g,10次循环之后还有149.29mAh/g,容量保持率为97.20%.

关键词: LiFePO4 , 正极材料 , Cr3+掺杂 , 微波 , 锂离子电池

Studies of EPR parameters for Mn5+-doped Li3PO4 and Li3VO4 crystals

Spectrochimica Acta Part a-Molecular and Biomolecular Spectroscopy

The EPR parameters (zero-field splitting D and g factors g(vertical bar vertical bar), g(perpendicular to)) of Mn5+-doped Li3PO4 and Li3VO4 crystals are calculated from the complete high-order perturbation formulas based on a molecular orbital scheme for a 3d(2) ion in tetragonal MX4 clusters. These formulas include not only the contribution coming from crystal-field excitations, but also that arising from charge-transfer excitations (which is discarded in crystal field theory). The calculated results are in reasonable agreement with the observed values. The contributions to EPR parameters coming from the charge-transfer excitations are comparable with those arising from the crystal-field excitations. It appears that for a high valence state 3d(n) ion in crystals, the reasonable explanations of EPR parameters should take the contributions due to both crystal-field and charge-transfer excitations into account. (c) 2006 Elsevier B.V. All rights reserved.

关键词: electron paramagnetic resonance (EPR);crystal;and ligand-field theory;charge transfer mechanism;Mn5+;Li3PO4;Li3VO4;atomic screening constants;oxo coordination;phase-transition;scf;functions;laser action;complexes;pressure;forsterite;covalency;ions

Oxygen Deficient Li4Ti5O12 for High-rate Lithium Storage

Journal of the Chinese Chemical Society

An oxygen deficient Li4Ti5O12 was investigated for lithium ion batteries (LIBs) in this work. Compared with nitrogen doping and pristine Li4Ti5O12, the oxygen deficient Li4Ti5O12 exhibits significant improvement of electrochemical performance, it could deliver a specific capacity of 75 mAh/g even at a high charge/discharge rate of 10C and exhibit excellent cycling performance. The results revealed in this work show that oxygen deficient control can be a promising way to improve high rate performance of the LIBs electrode materials.

关键词: Lithium ion batteries;Oxygen deficient;Li4Ti5O12;visible-light photocatalysis;li-ion batteries;electrochemical;performance;titanium-oxides;anode materials;insertion;electrode;powders

Co2+掺杂对Li2FeSiO4/C电化学性能的影响

刘兴亮 , 鲁道荣 , 桂宏亮

金属功能材料

采用溶胶-凝胶法,合成纳米复合材料硅酸亚铁锂(Li2FeSiO4/C).用XRD、TEM和电化学方法,研究了Co2+掺杂对Li2FeSiO4/C的影响.结果表明,掺杂适量的Co2+不会改变Li2FeSiO4的正交晶系结构,可稳定材料结构,改善高倍率充放电性能.室温下,Li2Fe0.97Co0.03SiO4/C以0.1C放电的首次放电比容量为151.8 (mA· h)/g,20次充放电循环后放电比容量为131.2 (mA·h)/g;Li2FeSiO4/C的首次放电比容量为122.0 (mA·h)/g,20次循环后,比容量衰减率为20.3％.交流阻抗测试表明:Li2Fe0.97Co0.03SiO4/C在1.5～4.5V下充放电的可逆性优于Li2FeSiO4/C.

关键词: 溶胶-凝胶法 , 正极材料 , 硅酸亚铁锂 , 掺杂Co2+ , 电化学性能

冷轧复合工艺制备超轻Mg-Li合金复铝板

祖国胤 , 姚广春 , 李红斌

功能材料

研究了采用冷轧复合法制备Mg-Li合金复铝板的工艺,得到了适宜的轧制制度与退火热处理参数,结果表明轧制压下率在60%～65%时复合效果最佳.退火时Mg-Li合金内的α相发生了明显的球化转变,300℃退火1 h后Mg-Li合金的再结晶过程基本完成.Mg-Li合金复铝板的密度为1.6～1.7 g/cm3,具有显著的轻质特点、而耐蚀性较单一Mg-Li合金显著提高.

关键词: Mg-Li合金复铝板 , 冷轧复合 , 退火 , 密度