In situ U-Pb dating of xenotime by laser ablation （LA）-ICP-MS

Xenotime is an ideal mineral for U-Th-Pb isotopic dating because of its relatively high U and Th contents, but typically low concentration of common Pb. These characteristics, and the fact that it is widespread throughout various types of rocks, suggest that the U-Th-Pb dating of xenotime has broad applications. Studies of U-Pb dating on xenotime by ion microprobe (such as SHRIMP) have increased in recent years, whereas studies by laser ablation (LA)-ICP-MS are still rare. In this study, we developed a technique for U-Pb dating of xenotime using the 193 nm ArF laser-ablation system and Agilent 7500a Q-ICP-MS. To evaluate the reliability of our method, a xenotime standard, BS-1, was analyzed and calibrated against another xenotime standard, MG-1. The weighted mean 206 Pb/ 238 U ages of 510.1 ± 5.2 Ma (2 n = 21), 509.8 ± 4.3 Ma (2 n = 21) and 510.0 ± 4.6 Ma (2 n = 21) were obtained using beam diameters of 16, 24 and 32 m, respectively. These ages are identical to those determined by ID-TIMS method (weighted mean 206 Pb/ 238 U age of 508.8 ± 1.4 Ma), which supports the reliability of our LA-ICP-MS method. We also analyzed xenotimes in leucogranites from South Tibet and granites from Xihuashan in southern China, and obtained accurate and precise ages. Nevertheless, we observed systematic differences in Pb/U fractionation among xenotime, monazite and zircon. The matrix-effect resulted in either under-correction or over-correction of fractionation, and thus led to inaccurate ages. Thus, a matrix-matched material is required for U-Pb dating of xenotime by LA-ICP-MS.     

Theoretical study on photophysical property of C60M（CO）5 （M=Cr,Mo and W）

Configurations of three η2 models of transition-metal [60]fullerene derivatives C60M（CO）5（M=Cr, Mo and W） have been optimized at B3LYP/LanL2DZ level. On the basis of the optimized geometrical structures, their electronic spectra and the frequency dependence of third-order nonlinear optical polarizabilities γ in different optical processes of third-harmonic generation （THG）, electric-field-induced second-harmonic generation （EFISHG） and degenerate four-wave mixing （DFWM） are calculated by using TDB3LYP model based on LanL2DZ level coupled with the SOS （sum-over-state） method. The obtained results show that their electronic spectra have a red shift compared with that of [60]fullerene and different transition-metal functional groups added to C60 cage may result in different spectrum properties. For the three studied species, （η^2-C60）Mo（CO）5 has the largest third-order nonlinear optical polarizability.     

分子导体(PyH)[M(dmit)2]2(M=Pd,Ni)的晶体结构与能带结构

在配合物型分子导体(PyH)[Pd(dmit)2]2和(PyH)[Ni(dmit)2]2中,阴离子导电组元[M(dmit)2]^0．5-(M=Pd,Ni)的面对面堆积和肩并肩排列形成二维层状结构．采用推广休克尔紧束缚方法计算了二维导电层中相邻两阴离子的HOMO轨道的重叠积分,并进行了二维能带计算．计算结果表明它们是窄能隙半导体。与晶样的变温电导测试的结果一致.     

Hydrogen storage performances of the as-milled REMg11Ni (RE = Sm, Y) alloys catalyzed by CeO2

The addition of catalysts and rare earth elements is considered to be very effective methods to enhance the hydrogenation/dehydrogenation properties of Mg and Mg-based hydrides. In this paper, the REMg11 Ni+ 5 wt%CeO_2(RE = Sm, Y)(named REMg11 Ni-5 CeO_2(RE = Sm, Y)) alloys were fabricated through ball milling. The phase composition and structure of the as-milled alloys were investigated in detail. The isothermal hydrogen storage thermodynamics and kinetics of the as-milled alloys were measured by using an automatically Sievert apparatus. Non-isothermal dehydrogenation performance of the alloys was investigated by thermogravimetry(TG) and differential scanning calorimetry(DSC) at different heating rates. The results revealed that all the asmilled alloys were the nanocrystalline and amorphous structure. The RE = Y alloy had a faster hydriding rate and a lower onset hydrogen desorption temperature than the RE = Sm alloy. The superior property of the RE= Y alloy depended on the decrease of the dehydrogenation activation energy. By means of the measurement of Pressure-Composition-Isotherm(P-C-T) curves, the thermodynamic parameters of the REMg11 Ni-5 CeO_2(RE =Sm, Y) alloys were calculated, and the dehydrogenation enthalpy change was 74.86 k J/mol for the RE = Sm alloy and 73.75 k J/mol for the RE = Y alloy, respectively.     

Theoretical study on photophysical property of C_(60)M(CO)_5 (M=Cr,Mo and W)

Configurations of three η2 models of transition-metal 60 fullerene derivatives C60M(CO)5(M=Cr,Mo and W) have been optimized at B3LYP/LanL2DZ level.On the basis of the optimized geometrical structures,their electronic spectra and the frequency dependence of third-order nonlinear optical polarizabilities γ in different optical processes of third-harmonic generation(THG),electric-field-induced sec-ond-harmonic generation(EFISHG) and degenerate four-wave mixing(DFWM) are calculated by using TDB3LYP model based on LanL2DZ level coupled with the SOS(sum-over-state) method.The obtained results show that their electronic spectra have a red shift compared with that of 60 fullerene and dif-ferent transition-metal functional groups added to C60 cage may result in different spectrum properties.For the three studied species,(η2-C60)Mo(CO)5 has the largest third-order nonlinear optical polarizability.     

激光熔覆原位自生TiC增强Ni3(Si,Ti)金属间化合物复合涂层研究

运用激光熔覆技术在GH864镍基合金表面制备原位自生TiC颗粒,以增强Ni3(Si,Ti)金属间化合物复合涂层.实验结果表明:利用激光表面熔覆技术,可以在镍基合金表面直接原位合成TiC颗粒增强的Ni3(Si,Ti)金属间化合物复合涂层、涂层和基体呈良好的冶金结合,涂层宏观质量完好,无裂纹和气孔等缺陷.涂层组织由γ Ni、Ni3(Si,Ti)、Ni5Si2和TiC组成.涂层的显微硬度可达HV780,是基材显微硬度的2.5倍.     

尖晶石型MAl2O4(M=Ni、Mg)纳米粉体的溶胶凝胶法制备及表征

采用溶胶-凝胶法合成了MAl2O4（M=Ni、Mg）尖晶石纳米粉体，无水乙醇溶解摩尔比nM（NO3）2∶nM（NO3）3=1 ∶ 2，草酸作络合剂，加热搅拌得到湿凝胶，继续干燥得到干凝胶，随后对于凝胶在不同温度下进行焙烧，得到了粉体状产物．用TG、DSC技术对前躯体干凝胶进行热分析，对煅烧粉末进行了XRD、TEM表征，并考察了煅烧温度对MAl2O4晶化程度的影响．实验结果表明：该方法制备单相且晶化程度较高的尖晶石型MAl2O4纳米粉体所需温度为800℃，比微波反应法合成温度降低200℃，比铝单醇盐Sol-Gel法降低100℃．     

配合物[ML2]的合成及晶体结构(M=Ni2+,Cu2+;HL=C7H7NO)

标题化合物[ML2]（M=Ni^2-,Cu^2-;HL=C7H7NO,2-亚胺基甲基苯酚）由2-亚胺基甲基苯酚与NiCl2或CuCl2在无水乙醇中反应制得．用X射线衍射分析测定了两个化合物晶体结构．结果表明：它们均属单斜晶系,空间群为P2（1）／c,中心离子M（Ⅱ）的配位环境呈平面四方形．配合物[Ni（C7H6NO）2）]的晶体学参数：a=1．2918（3）nm,b=1．7512（4）nm,c=0．8110（2）nm,β=95．56（3）°,V=1．826（6）nm^3,Z=2,Dc=1．627Mg／m^3,Mr=298．97,μ=1．591mm^-1,F（000）=920,最终结构偏离因子R=0．0487,Ru=0．1199,S=1．018,最终差值电子云密度的最高峰和最低峰分别为1120nm^-3和-1226nm^-3配合物[Cu（C7H6NO）2）]的晶体学参数：a=1．2954（13）nm,b=0．5843（8）nm,c=0.8039（10）nm,β=94．69（3）°,V=0．6064（9）nm^3,Z=2,Dc=1．664Mg／m^3,Mr=303．80,μ=1．798mm^-1,F（000）=310,最终结构偏离因子R=0．0449,Rw=0．1196,S=1．077,最终差值电子云密度的最高峰和最低峰分别为484nm^-3和-388nm^-3．     

纳米金属酞菁MPc(M=Fe,Co,Ni,Cu和Zn)的合成与表征

采用溶剂热方法以邻苯二甲腈为原料、乙二醇为溶剂在反应釜中合成了各种形貌的Fe,Co,Ni,Cu和Zn纳米金属酞菁化合物,并对它们进行了电子扫描电镜、XRD、红外光谱及紫外-可见光谱表征.结果表明,产品纯度高,产率大,形貌独特.     

Polymerization of acrylonitrile catalyzed by lanthanide-sodium alkoxide clusters Lne（OCH2CH2NMe2）12（OH）eNas [Ln=Yb （1）, Nd （2） and Sm （3）]

Polymerization of acrylonitrile was carried out using,for the first time,the lanthanide-sodium alkoxide clusters Ln2(OCH2CH2NMe2)12(OH)2Na8 [Ln=Yb (1),Nd (2) and Sm (3)] as single component catalysts.These heterobimetallic complexes exhibit high activity and give atactic polyacrylonitriles with high molecular weight.The polymerization temperature can be varied over the range ?78 to 50°C.The solvent has a substantial effect on the polymerization activity.The order of activity for solvents is DMF>DME≈toluene≈...     

金属间化合物TM-Zn(TM=Ni,Pd,Pt,Cu,Ag,Au)四方变形结构稳定性的第一性原理研究

金属间化合物的结构和结构稳定性显著影响材料的性能. 本文基于第一性原理,利用“Exact Muffin-Tin Orbitals”(EMTO)方法及全电荷密度(Full Charge Density)处理技术,精确计算了TM10(Ni, Pd, Pt)-Zn和TM11(Cu, Ag, Au)-Zn两类金属间化合物体系能量,确定了体系的结构稳定性;使用“The Vienna ab initio package”(VASP)软件,采用投影缀加平面波赝势和PBE交换-关联泛函进行了全弛豫计算,模拟了TM-Zn金属间化合物的四方变形过程;通过分析金属间化合物在四方变形过程中电子态密度,揭示了其结构稳定性机理,并使用VESTA软件可视化了电子局域化函数,获得了金属键的特征;利用YPHON软件并结合线性响应理论计算了金属间化合物沿高对称点的声子色散曲线. 研究结果表明：TM10-Zn倾向于CuTi型结构稳定,而TM11-Zn倾向于CsCl型结构稳定;在费米能级附近的电子简并轨道劈裂,诱发TM10-Zn金属间化合物体系产生Jahn-Teller效应,Jahn-Teller效应使得其在四方变形过程中能量降低,因此其四方结构更加稳定,而在TM11-Zn金属间化合物体系并不存在Jahn-Teller效应,因此 CuTi型AgZn和AuZn结构不稳定;TM10-Zn的金属键强度大于TM11-Zn,且CsCl型结构的金属键强度大于CuTi型结构.     

锂离子电池负极材料M_2P_2S_6(M=Ni,Mn)的合成及电化学性能研究

通过室温固相法合成M2P2S6(M=Mn,Ni)层状结构材料,经XRD,SEM,EDS,IR和TG进行表征.结果表明,Mn2P2S6由粒径为40~50 nm的纳米球堆积而成,Ni2P2S6由不同大小粒子组成块状结构.将M2P2S6(M=Mn,Ni)作为锂离子电池负极材料进行电化学测试表明,M2P2S6(M=Mn,Ni)的首圈放电比容量分别高达800 m Ah/g和911 m Ah/g,说明M2P2S6化合物可能是一个潜在的锂离子电池负极材料.1     

Preparation of Ln_(3-x)Eu_xS_4 (Ln=Ce,Pr,and Nd) ceramics by pressureless sintering

The preparation of ternary rare earth sulfides of Ln3-xEuxS4 (Ln = Ce, Pr, and Nd) ceramics was investigated, and the effect of Eu substitution on Ln3-xEuxS4 ceramics was also studied. Ln3-xEuxS4 powders were synthesized by the sulfurization of their oxide powders using carbon disulfide gas. Ln3-xEuxS4 ceramics were sintered by pressure-less sintering method. All pressureless sintered Ln3-xEuxS4 ceramics crystallized in γ-phase. It was found that Eu substitution could improve the density of Ln3-xEuxS4 ceram...     

Down-conversion characteristics of Eu3+ doped M2Y2Si2O9 (M = Ba,Ca, Mg and Sr) nanomaterials for innovative solar panels

Down-conversion properties of Eu³⁺ doped M₂Y₂Si₂O₉ (M = Ba, Ca, Mg, Sr) phosphors have been investigated in detail. These phosphors were synthesized via the simple, fast and cost-effective sol-gel technique at a temperature of 950 °C. Color coordinates and emission color can be altered by the varying concentration of dopant ion in Ca₂Y₂Si₂O₉ phosphor. Optimum luminescence intensity was obtained when doping 0.03 mol of Eu³⁺ ion. Using the excitation wavelength of 395 nm, these silicates showed strong red color, pure and sharp spectral peaks in visible region due to ⁵D₀→⁷F_1-3 transitions of Eu³⁺ present in the lattice. Effect of reaction temperature on luminescence was also analyzed for these phosphors. The sharp peaks in the X-ray diffraction pattern indicated the high crystallinity of prepared phosphors. Ca₂Y₂Si₂O₉ has shown an orthorhombic crystal structure. The FTIR results confirmed the metal-oxygen vibrational modes available in the range of 400–1600 cm^?1. Transmission electron microscopy images have revealed that the variation of alkaline earth metal provided a very different crystal structure. Excellent down conversion response of these phosphor materials can provide a great significance in the application of the coming solar devices.     

包含平面四价碳的一个新家族

本文预测一类由碱土金属包围的含平面四价碳的新化合物,通过原子轨道分析和对键临界点的拓扑电子密度分析分别研究了其电荷稳定和成键情况。并且研究了分子的磁性质。这些包含平面四价碳的分子体系通过电子和力学性质得以稳定。D4hSi4B4H4还可以用来稳定平面四价氮离子。     

MnOx-M/AC(M=La,Ce,Co,Ni)氧还原催化材料的制备及性能

用热解法制备了掺杂La、Ce、Co、Ni等元素的氧还原催化材料MnOx/AC,并采用XRD和电化学方法对所制备材料的性质和电化学反应性能进行了表征。结果表明,掺杂适量的La、Ce、Co和Ni等元素可改善电极的氧还原反应性能。掺杂La和Co元素的MnOx/AC氧催化还原性能最好,其中,在50mA/cm2的电流条件下,使用这两种掺杂材料所制备的模拟锌-空气电池的放电电压分别为1.1236V和1.1246V。     

珠江三角洲全新统横栏组淤泥沉积中的有机碳、总氮和碳氮比值记录

对广州番禺区ZK5孔中全新统横栏组淤泥沉积进行了总有机碳，总氮含量和碳氮比值分析。根据其变化可划分2个不同的沉积环境阶段，阶段Ⅰ（15.8-9.0m)的总有机碳含量变化幅度较大，总氮含量很低，碳氮比值较高。表明其有机质以陆源为主，有机质生产力明显受气候的控制，阶段Ⅱ（9-1.4m)总有机碳和总氮含量上升，变化较小，而碳氮比值下降，表明其主要受海洋的影响，有机质主要来源于原地浮游生物。     

Preparation of Ln3-xEuxS4 （Ln=Ce,Pr, and Nd） ceramics by pressureless sintering

The preparation of ternary rare earth sulfides of Ln3-xEuxS4 （Ln = Ce, Pr, and Nd） ceramics was investigated, and the effect of Eu substitution on Ln3-xEuxS4 ceramics was also studied. Ln3-xEuxS4 powders were synthesized by the sulfurization of their oxide powders using carbon disulfide gas. Ln3-xEuxS4 ceramics were sintered by pressure-less sintering method. All pressureless sintered Ln3-xEuxS4 ceramics crystallized in y-phase. It was found that Eu substitution could improve the density of Ln3-xEuxS4 ceramics. Furthermore, Eu substitution might narrow the optical band gaps of Ln3-xEuxS4 ceramics.