La,Ce,Tb含量对(La,Ce,Tb) BO3发光性能的影响

采用高温固相法合成(La,Ce,Tb)BO3荧光粉,并对该荧光粉进行XRD和SEM分析。结果表明:(La,Ce,Tb)BO3的晶体结构和LaBO3相同,Ce3+,Tb3+的掺入没有改变晶体的结构,发光粉颗粒大小均匀,形貌规则,粒度在5μm左右。研究了(La,Ce,Tb)BO3的光谱性质,在(La,Ce,Tb)BO3的发射和激发光谱中除了有Tb3+的特征发射和激发峰外,还有Ce3+的特征发射和激发峰。     

Magnetic and electrical transport properties of RE9Ni24Sn49 compounds (RE=Y,Ce, Pr,Sm and Tb)

Magnetic and electrical transport properties of cubic phases RE₉Ni₂₄Sn₄₉ (RE=Y, Ce, Pr, Sm and Tb) have been investigated by means of magnetic susceptibility, magnetisation, electrical resistivity and Seebeck effect measurements. The Ce-, Pr- and Tb-based compounds order antiferromagnetically at T_N=3.1, 4.5 and 4.2 K, respectively, Sm₉Ni₂₄Sn₄₉ remains paramagnetic down to the lowest temperature studied, while Y₉Ni₂₄Sn₄₉ is a weak Pauli paramagnet. All the materials studied exhibit metallic character of their electrical conductivity and thermoelectric power.     

Application of Solid Electrolyte Cells to Study of Thermodynamic Properties of RE－O－F Systems

ＡｐｐｌｉｃａｔｉｏｎｏｆＳｏｌｉｄＥｌｅｃｔｒｏｌｙｔｅＣｅｌｌｓｔｏＳｔｕｄｙｏｆＴｈｅｒｍｏｄｙｎａｍｉｃＰｒｏｐｅｒｔｉｅｓｏｆＲＥ－Ｏ－ＦＳｙｓｔｅｍｓＨｏｎｇＹａｎｒｕｏａｎｄＬｉＬｉａｎｓｈｅｎｇ（洪彦若）（李联生）（Ｕｎｉｖｅｒｓｉｔ...     

稀土元素M(M=La,Ce,Pr)掺杂对LiNH2解氢性能的影响

采用基于密度泛函理论的第一性原理赝势平面波方法,研究了稀土元素M(M=La,Ce,Pr)对LiNH2解氢性能的影响.计算了合金形成热、H原子解离能和电子态密度,分析了结构稳定性.结果表明:稀土元素M替代LiNH2中部分Li时,费米能级附近能隙△EH-L变窄,使得N-H键间共价键特性减弱,系统结构稳定性降低,提高了LiNH2的解氢能力.     

RECl_3-CaCl_2-MgCl_2 TERNARY PHASE DIAGRAMS(RE:La,Ce,Pr,Nd)

Nine sub-binary phase diagrams of the RECl_3-CaCl_2,RECl_3-MgCl_2 and CaCl_2-MgCl_2 systems,andthermodynamic data for these systems are critically assessed and optimized.Using Hillert model and takingMgCl_2 as an asymmetric component,the ternary phase diagrams or the RECl_3-CaCl_2-MgCl_2 systems are predtcted.As well,the determination of asymmetric component in the asymmetric model is investigated.     

Fe/RE(Dy,Y)非晶多层膜的晶化方式及晶化温度

通过比较Ｆｅ／ＲＥ非晶多层膜中所有成分范围内非晶合金形成焓△Ｈ＾ａｍ与固溶体形成焓△Ｈ＾ＳＳ得出,在△Ｈ＾ａｍ〈△Ｈ＾ＳＳ成分范围内的非晶与在△Ｈ＾ａｍ〉△Ｈ＾ＳＳ成分范围内非晶的晶化方式及晶化温度不同。这从理论上系统地解释了多层膜晶化为一个缓慢过程,没有确定的晶化温度。     

BaMgSi_2O_6:RE~(3+)(RE=Tb,Ce)的真空紫外光谱特性

研究了MMgSi_2O_6:Tb~(3+) (M=Ca, Sr, Ba)样品的结构、发光特性.MMgSi_2O_6:Tb~(3+) (M=Ca,Sr , Ba)具有硅酸钙镁石结构,基质掺入铽离子后结构没有明显变化.结果表明:MMgSi_2O_6:Tb~(3+) (M=Ca, Sr ,Ba)在168、220和294 nm附近有强烈的吸收峰.在168 nm真空紫外激发下,546 nm是主发射峰.当材料BaMgSi_2O_6:Tb~(3+)中掺杂Ce~(3+)时,BaMgSi_2O_6:Tb~(3+)样品在168 nm真空紫外激发下的发射强度明显下降.     

Standard energies of combustion and standard enthalpies of formation for the complexes RE （Et2dtc）3（phen） （RE = Ho, Er, Tm, Yb, Lu）

The treatment of RECl3.xH2O （RE = Ho, Er, Tm, Yb, Lu; x = 3-4） with sodium diethyldithiocarbamate （NaEtEdtc-3H2O） and 1,10-phenanthroline hydrate （o-phen.H2O） in absolute ethanol yielded five ternary solid complexes RE（EtEdtC）a（phen）. IR spectra of the complexes showed that RE^3＋ coordinated to two sulfur atoms in NaEt2dtc and two nitrogen atoms in o-phen. The constant-volume energies of combustion of the complexes have been determined by a precise rotating-bomb calorimeter at 298.15 K. The standard enthalpies of combustion and standard enthalpies of formation were calculated.     

The effect of substitution of La for Tb on some physical properties of Tb1−xLaxNi2 solid solutions

The standard Gibbs energy of formation, , of MgLa in the temperature range from near absolute 0 to 525 K were determined by calorimetry. The heat capacities, C_p, from 2 K to 525 K were measured by the relaxation method and DSC. Also, a thermal anomaly at 5.9 K, which appeared to be a superconductive phase transition, was found in the obtained C_p values. The values were determined by combining the C_p data with the standard enthalpy of formation at 298 K which was measured by the Calvet-type calorimeter using hydrochloric acid solution. From 2 to 300 K, the increases gradually, and it can be evaluated as a linear function of temperature above 300 K as follows:

This result is expected to be useful as basic thermodynamic data of Mg-based alloys.     

Microwave Properties of RE(Nd, Tb)FeCoB Alloy System

采用熔炼、高能球磨、微氧化热处理工艺,制备RE(Nd,Tb)FeCoB粉体,借助X射线衍射仪和网络矢量分析仪等,研究不同B含量的NdFeCo粉体组织结构和微波吸收特性,以及用重稀土Tb取代NdFeCoB合金中的Nd后粉体的组织结构和微波吸收特性。结果发现:在Nd10.53Fe77.84Co11.63合金中加入B元素后会析出Nd2Fe14B相,而且,粉体中α-Fe相的相对含量随着B元素含量的增加而增加;用重稀土Tb取代NdFeCoB合金中的Nd后粉体主要由α-Fe、Tb2Fe14B、Tb2Fe17以及少量的Tb2O3相组成;(Nd10.53Fe77.84Co11.63)97B3粉体具有最低的吸收峰频率,其反射率最小值和吸收峰频率分别为–9.5 dB和4.5 GHz;用重稀土Tb取代(Nd10.53Fe77.84Co11.63)97B3合金中的Nd后,粉体的吸收峰频率升高到6.3 GHz,但反射率最小值降低到–11 dB。     

RE(Ni,Co,Mn,Ti)_5合金(RE=La,Ce,Pr,Nd)的单胞体积对电化学性能的影响

制备了Ｌａ（Ｎｉ,Ｃｏ,Ｍｎ,Ｔｉ）５,Ｃｅ（Ｎｉ,Ｃｏ,Ｍｎ,Ｔｉ）５,Ｐｒ（Ｎｉ,Ｃｏ,Ｍｎ,Ｔｉ）５和Ｎｄ（Ｎｉ,Ｃｏ,Ｍｎ,Ｔｉ）５四种单一稀土贮氢电极合金,分别测定了它们的单胞体积、氢化物生成焓和几个主要的电化学性能指标（包括活化循环次数、最大放电容量、高倍率放电率和容量衰退速率）,以分析不同稀土元素对合金电化学性能的影响.结果表明,在四种合金中,单胞体积对合金的热力学性质和电化学性能起了决定性作用,它与合金的氢化物生成焓呈简单的线性关系,对电化学性能有双重影响,使四个主要指标随单胞体积的变化均出现极大或极小值.单胞体积本身的变化与稀土元素的周期性有关．     

RE（Ni,Co,Mn,Ti）5合金（RE=La,Ce,Pr,Nd）的单胞体积对电化学性能的影响

制备了La(Ni,Co,Mn,Ti)5,Ce(Ni,Co,Mn,Ti)5,Pr(Ni,Co,Mn,Ti)5和（Nd(Ni,CO,Mn,Ti)5四种单一稀土贮氢电极合金,分别测定了它们的单胞体积,氢化物生成焓和几个主要的电化学性能（包括活化循环次数,最大放电容量,高倍率放电率和容量衰退速率）,以及析不同稀土地合金电化学性能的影响,结果表明,在四种合金中,单胞体积对合金的热力学性质和电化学性能起了决定性作用,它与合金的氢化物生成焓呈简单的线性关系,对电化学性能有双重影响,使四个主要指标随单胞体积的变化均出现极大极值,单胞体积本身的变化与稀土元素的周期有关。     

Thermodynamics of the rhombohedral-cubic phase transition of ROF with R Y, La, Pr, Nd, Sm---Er

The temperatures and enthalpies of the rhombohedral-cubic phase transition of stoichiometric ROF with R Y, La, Pr, Nd, Sm---Er, have been determined by differential scanning calorimetry. The temperatures of transition are found in the range 742–880 K in satisfactory agreement with literature data. The enthalpies and entropies of transition of LaOF, PrOF, NdOF and EuOF increase with decreasing cationic radius from 5135 ± 193 to 5504 ± 169 J mol⁻¹ and from 6.60 ± 0.25 to 6.908 ± 0.21 J mol⁻¹ K⁻¹ respectively, and for GdOF, TbOF, DyOF, HoOF, YOF and ErOF from 7085 ± 190 to 7903 ± 187 J mol⁻¹ and from 8.02 ± 0.24 to 9.04 ± 0.27 J mol⁻¹ K⁻¹. The transition mechanism and relations between the magnitude of the entropy of transition and the defect structure of fluorite-type α-ROF are tentatively discussed.     

金属氧(硫、碳、氮)化物单位体积标准生成自由能图

根据文献中的热力学数据及相关的密度数据,计算了金属氧化物（硫化物、碳化物、氮化物）的单位体积标准生成自由能变化,并绘制了相应的ΔＧＶ—Ｔ图。由于单位体积生成自由能变化是生成氧化物（包括硫化物、碳化物、氮化物）新相的唯一过程驱动力,在判断合金选择氧化（硫化、碳化、氮化）的可能性时,单位体积标准生成自由能变化将提供一项重要的基础性数据。     

冲天炉熔炼过程化学成分变化的热力学建模

冲天炉是熔炼铸铁最主要的设备,由于熔炼过程的机理复杂,影响因素繁多,对冲天炉熔炼过程中元素烧损率的定量计算以及铁液最终成分的预测一直是个难题.利用热力学的知识建立起了平衡常数法和最小自由能原理法这两种用于计算铸铁在冲天炉熔炼过程中成分变化的数学模型,总结了这两种模型各自的特点及适用范围,并给出了反求熔炼过程各种元素烧损率的方法.该热力学模型的建立,对扩大计算机模拟技术在铸造中的应用领域以及定量揭示冲天炉熔炼规律有着重要的意义.     

The thermochemistry of transition metal carbides

A general survey is made of the available data for the standard Gibbs energies of formation of solid carbides of transition metals. The results are plotted as standard Gibbs energy vs. temperature diagrams. The equations and the estimated accuracy when available are given for each substance.     

The thermochemistry of transition metal sulfides

A survey is made of the available data for the standard Gibbs energies of formation of solid and liquid sulfides of transition metals. The results are plotted as standard Gibbs energy vs temperature diagrams. The equations and estimated accuracy are quoted for each substance.Supported by a Glunz Fellowship from the Ohio State University.     

The magnetic structures of RMgSn compounds (R = Ce, Pr, Nd, Tb)

The synthesis of the new compounds RMgSn (R = La-Nd, Sm, Gd-Tm, Lu and Y) has been recently reported. The compounds formed by La and Ce crystallise in the TiNiSi structure type (oP12, Pnma), while from Nd they adopt the CeScSi-type (tI12, I4/mmm); PrMgSn is dimorphic: its high-temperature form (HT) is TiNiSi-type while the low-temperature one (LT) is CeScSi-type.In this paper we now report the results of a neutron diffraction investigation which has been performed in order to refine the crystal as well as the magnetic structures for the RMgSn compounds with R = Ce, Pr, Nd and Tb. All these compounds see at low temperature the establishment of long range magnetic ordering with a predominantly antiferromagnetic interaction; only PrMgSn-HT orders ferromagnetically. These results agree with those from magnetic measurements recently reported.The magnetic structure of CeMgSn is of the amplitude-modulated type, the value of the magnetic propagation vector refined at 2 K is τ = [0, 0.1886(4), 0.3384(8)]. The PrMgSn-HT phase below T = 52 K adopts first a purely ferromagnetic structure, then at about T = 15 K a second magnetic coupling leads to a spin-canted magnetic structure. Both PrMgSn-LT and NdMgSn have the same antiferromagnetic commensurate magnetic structure. The TbMgSn compound below T_N = 35 K orders antiferromagnetically with an equal moment cycloidal structure; however a second magnetic transition at a temperature corresponding to T_N2 = 65 K is likely also present.     

Crystal structures of R2Pd2Pb (R = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu) compounds

The crystal structures of the R₂Pd₂Pb (R=Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu) compounds were determined using X-ray powder diffraction. The investigated compounds crystallize with Mo₂FeB₂ structure type (space group P4/mbm, Pearson code tP10). The importance of stabilization by polar intermetallic R–Pd bonding is underscored by a bonding analysis derived from electronic band structure calculations.     

水溶液中电沉积非晶态Ni-RE-P（RE=Ce，Nd）稀土合金

报道了从水溶液中电沉积稀上含量高于30％的Ni-RE-P(RE=Ce，Nd)合金，其中Ni-P，Ni-Ce-P及Ni-Nd-P合金镀层均为非晶态结构，玻璃化温度约为385℃；用DTA测定了3种合金的晶化活化能分别为：523．3kJ／mol，574．4kJ／mol，558．9kJ／mol；利用二维Miedema坐标(△φ^*和△nws^-1.3)以及加入尺寸因素(△R/RA)构成的三维化学坐标分析了合金的非晶形成规律，探讨了实现稀土合金电沉积的途径，具体为：选择适当的络合剂、合适的电极材料及合适的共沉积元素。