用攀枝花钛矿和云南钛矿冶炼钛渣工业试验研究

通过磁性测量和X-射线衍射研究了Gd2(Co，Al)17化合物的结构和磁晶各向异性。当x≤4时，样品具有菱方Th2znl7型结构，x=5时，具有六方CaCu5型结构。随着Al浓度增加，晶格常数和单胞体积单调增大，而居里温度和自发磁化强度近似线性地减小；在x≥l时，观察到Co亚点阵的磁晶各向异性变号，室温易磁化方向由易面转变为易轴，且易轴各向异性场和各向异性常数随Al原子浓度增加出现极大值；基于补偿温度(65K)下自由粉末颗粒的磁化曲线，导出了亚点阵间的分子场系数和Gd-co交换耦合常数，结果表明，Al原子对Gd-Co交换耦合作用的影响较小。根据Al原子在Co亚点阵4种晶位的择优占位，分析了磁晶各向异性的演变。     

Ce、Gd、Ce/Tb、Gd/Tb单双掺杂ZCB基质光致发光性质

采用高温固相法在弱还原气氛下,分别合成了单掺Ce3+、Gd3+和双掺Ce3+/Tb3+、Gd3+/Tb3+的ZnO-CdO-B2O3(ZCB)基质系列荧光体.光谱分析表明:Ce3+的5d→4f(2F7/2,2F5/2)和Gd3+的8P7/2→8S7/2跃迁的强发射分别对应于427 nm和574 nm,而Ce3+/Tb3+和Gd3+/Tb3+的强发射分别对应于546 nm和548 nm.双掺Ce3+/Tb3+、Gd3+/Tb3+的荧光体比单掺Tb3+的发射强度显著增强,这表明存在Ce3+→Tb3+、Gd3+→Tb3+的能量传递,且Ce3+和Gd3+都是Tb3+的优异敏化剂.     

钆内嵌金属富勒烯的制备、分离及质谱表征

利用自制的电弧炉,通过电弧放电法合成了内嵌金属富勒烯Gd@C82,研究并获得了制备钆金属富勒烯的最佳工艺条件：摩尔比Gd：C=1：15,电流I=90～100A,氦气压力0．08MPa;探讨并获得了Gd@C82新的萃取分离条件：常温下以DMF为溶剂,抽真空至压强为0．01MPa下萃取;讨论了内嵌金属富勒烯的生成和分离机理。     

Synthesis of Polycrystalline Yb:Gd_3Ga_5O_(12) Nanopowders by Homogeneous Precipitation Method

The Ytterbium doped gadolinium gallium garnet [Yb3+:Gd3Ga5O12, Yb:GGG] precursor powders were synthesized via homogeneous precipitation method using Yb2O3, Ga2O3, Gd2O3 and ammonium bicarbonate [NH4HCO3] as precipitator, and ammonium sulfate [(NH4)2SO4] as additive. The evolution of phase composition and micro-structure of the powders were characterized by TG- DTA, XRD, IR, and TEM. The results indicate that all precursor powders completely transform to Yb:GGG phase by calcining at 900 ℃ for 8 h, the resultant powders are well dispersed and have smaller particle size approximately 80 nm owing to the electrostatic effect.     

中温固体电解质Ce_(0.8)Gd_(0.2-x)Y_xO_(2-δ)(x=0,0.05,0.10)的制备与性能研究

用溶胶-凝胶法合成了固体电解质Ce0.8Gd0.2-xYxO2-δ(x=0,0.05,0.10).用X射线衍射谱、拉曼光谱分析了样品的微观结构,用交流复阻抗谱研究了样品的电学性能.结果表明:800℃焙烧的所有样品均为具有氧缺位的单相立方萤石结构,晶胞参数随钇(Y)掺杂量增加而减小.钇掺杂量x=0.05的样品Ce0.8Gd0.15Y0.05O2-δ的电导率最高,导电活化能最小,(σ700℃=5.58×10-3S·cm-1,Eα=0.92 eV),高于未掺杂Y的Ce0.8Gd0.2O2-δ样品的电导率(σ700℃=5.38×10-3S·cm-1Eα=1.09 eV).说明适量双掺杂Y提高了Ce0.8Gd0.2-xYxO2-δ的电导率并且降低了其活化能.     

Mg-6Al-1Nd-1.5Gd合金的高温蠕变机制

采用高温蠕变装置,研究了Mg-6Al-1Nd-1.5Gd合金在150、175、200℃以及50、70、90 MPa条件下的高温压缩蠕变行为,分析合金在高温蠕变过程中的蠕变机制。结果表明,Mg-6Al-1Nd-1.5Gd合金的平均应力指数及蠕变激活能分别为4.64和73.87kJ/mol,其主要蠕变机制是由位错攀移和晶界扩散共同作用,合金的蠕变本构方程为:ε=1.877×10-8σ4.641exp[-73 865/(RT)];合金在高温蠕变过程中,微观组织中的位错密度逐渐增大,出现位错缠结及位错堆积,合金蠕变后的晶粒变得粗大,金属间化合物Al3Nd和Al3Gd在晶界上出现偏聚。     

Ag-Pd-5Ru-Gd四元系部分相图的700℃等温截面

在Ag Pd Gd ,Ag Pd Ru ,Ag Ru Gd和Pd Ru Gd三元系合金相图的基础上 ,采用X射线衍射 ,差热分析、扫描电镜和显微金相分析等方法研究了Ag Pd Ru Gd(x(Ru) =5 % ,x(Gd) <2 5 % )四元系相图的 70 0℃等温截面。结果表明 :该截面上包含有 2个单相区 ,即Pd(Ag)和Pd3 Gd ;4个两相区 ,即Pd(Ag) (Ru) ,Pd(Ag) Pd3 Gd ,(Ru) Ag51Gd14 ,(Ru) Pd3 Gd ;3个三相区 ,即Pd(Ag) Pd3 Gd (Ru) ,Pd(Ag) Ag51Gd14 (Ru) ,Pd3 Gd Ag51Gd14 (Ru) ;1个四相区 ,即Pd(Ag) Pd3 Gd Ag51Gd14 (Ru)。未发现新的四元中间相     

Phase equilibria and microstructure development in Mg-rich Mg-Gd-Sr alloys: Experiments and CALPHAD assessment

Mg-Sr alloys are promising to fabricate orthopedic implants. The alloying of rare earth elements such as Gd may improve the comprehensive mechanical properties of Mg-Sr alloys. The information on the phase diagram and the microstructure development are required to design chemical composition and microstructure of Gd alloyed Mg-Sr alloys. The phase equilibria and the microstructure development in Mg-rich Mg-Gd-Sr alloys (Gd, Sr < 30 at. %) are experimentally investigated via phase identification, chemical analysis, and microstructure observation with respect to the annealed ternary alloys. The onset temperatures of liquid formation are measured by differential scanning calorimetry. A thermodynamic database of the Mg-rich Mg–Gd–Sr ternary system is developed for the first time via CALPHAD (CALculation of PHAse Diagram) approach assisted by First-Principles calculations. The thermodynamic calculations with the developed database enable a well reproduction of the experimental findings and the physical-metallurgical understanding of the microstructure formation in solidification and annealing.     

(Gd,Y)相对GW103K时效合金局部腐蚀的影响

对Mg-10Gd-3Y-0.4Zr(GW103K)合金进行193 h时效处理,使用扫描电子显微镜(SEM)和透射电子显微镜(TEM)观测块状和链状相的微观结构和腐蚀形貌,使用扫描开尔文探针显微镜(SKPFM)测试块状相和链状相与基体之间的相对电势差,研究了这些相对GW103K合金局部腐蚀的影响。结果表明：分布在晶内和晶界的单独块状相为Mg₂(Gd, Y)相,(Gd, Y)固溶体与Mg₂(Gd, Y)相交替排列形成链状相。(Gd, Y)固溶体和Mg₂(Gd, Y)相的相对电势均高于基体,与相邻基体形成微电池,(Gd, Y)固溶体和Mg₂(Gd, Y)相作为阴极促进了周围基体的腐蚀。尽管(Gd,Y)固溶体与基体之间的相对电势差更大,但是与基体的相界面为共格界面,界面能低、化学稳定性高,因此对基体腐蚀没有更强烈的影响。     

Synthesis and Characterization of Sm_xGd_yCe_(1-x-y)O_(2-δ) Nanopowders

SmxGdyCe1-x-yO2-δ (x+y=0.2 and x=0, 0.04, 0.08, 0.12, 0.16, 0.2) nanopowders were prepared by a copre-cipitation method. The zeta potential and sedimentation volume of Ce(OH)4 aqueous dispersions at different pH values were measured. The isoelectric point (IEP) of Ce(OH)4 suspensions is 7.0. The maximum potential value of -18.5 mV and maximum sedimentation volume of 19 ml are reached at pH=10. The evolution behaviors of the xSm(OH)3·yGd(OH)3·(1-x-y)Ce(OH)4 dried powders in the heating process was characterized by DTA/TG and XRO. The powders decompose to ceria based solid solution at a temperature below 300℃ and forms cubic fluorite structure ceria at about 650℃. The properties of SmxGdyCe1-x-yO2-δ solid solutions were characterized by XRD, TEM and BET. The lattice parameter of doped Ce02 increases linearly with increasing Sm3+ substitution (or decreasing Gd3+ substitution). The particle size of the doped ceria powders is from 5 nm to 10 nm.