GdAlO_3∶Tb,RE中Tb,RE的能量传递研究

采用柠檬酸盐硝酸盐燃烧法制备了GdAlO3∶Tb,RE荧光粉体.在紫外激发下(254nm),GdAlO3∶Tb发射绿色荧光(5D4→7F5,544nm),Dy共掺杂对绿色发光有增强作用,Ce共掺杂对GdAlO3∶Tb绿色发光有降低作用.激发谱和能谱研究表明:Dy能级嵌入Tb主发射能级5D4(绿色发光能级)、5D3(蓝色发光能级)能级之间,Ce能级嵌入Tb主发射能级5D4、5D3能级上方.这种能级嵌入方式,使得稀土离子之间存在声子支持的共振能量传递,但Tb→Dy→Tb能量传递使Tb绿色发射(5D4→7FJ(J=3,4,5,6))增强,蓝色发射(5D3→7FJ(J=3,4,5,6))减弱;而Ce→Tb能量传递使Tb蓝色发射增强,绿色发射减弱.     

RE2CuO4的热力学稳定性（RE=La,Nd,Sm,Eu）

构筑了ＭｇＯ部分稳定的ＺｒＯ２基固体电解质电化学电池测量ＥＡＦ的实验装置，测定了Ｓｍ２ＣｕＯ４的标准Ｇｉｂｂｓ生成自由能。结果表明化合物ＲＥ２ＣｕＯ２３（ＲＥ＝Ｌａ，Ｎｄ，Ｓｍ，Ｅｕ）随着镧系元素离子半径减小，热力学稳定性下降，并用晶体场理论解释了这一规律。     

High-temperature calorimetric measurements on RE2TeO6 (RE = Gd,Er)

Journal of Thermal Analysis and Calorimetry - The ternary compounds of Gd2TeO6 (s) and Er2TeO6 (s) were prepared by solid-state route and characterized by XRD, ICP-AES and ICP-MS...     

CaBPO5∶RE(RE=Eu,Tb)的水热合成及其发光特性

利用水热法合成了CaBPO5∶RE(RE=Eu,Tb)荧光体并测试了其结构和光谱, 讨论了其发光性质, 并与高温固相法合成的产物作了对比. 结果表明, 由于电子转移, Eu3+, Tb3+和Eu2+共存于同一体系中, 而且Eu2+的发射位置从402 nm移至428 nm. 在双掺杂体系中引入Ce3+, Eu3+, Tb3+和Eu2+的发光强度均有所增强, 这可能是Ce3+与Eu3+之间的电子转移及各种稀土离子之间能量传递相互竞争的结果.     

RE1—xBxF3—y（RE=Y,La,Ce,Gd;B=Ca,Ba）的敏感性质的研究

LaF_3作为离子选择性电极和对气体的敏感性质已进行了一定的研究,但其他稀土氟化物的敏感性质却未见报道。本文合成了RE_(1-x)B_xF_(3-y),研究了它们的结构、电学性质及敏感性质,得到有可能在150℃使用的固体电解质氧敏材料。 (一) RE_(1-x)B_xF_(3-y)的结构分析 结构分析表明,Ca、Ba置换RE的含量少时,如La_(0.95)Ba_(0.05)F_(3-y)、Ce_(0.95)Ca_(0.05)F_(3-y)的X射线衍射分析结果与LaF_3、CeF_3相似,说明它们是固溶体。而Ca置换RE含量较多时,如Y_(0.71)Ca_(0.29)F_(3-y)、Gd_(0.85)Ca_(0.15)F_(3-主)的X射线衍射分析结果却与相应的YF_3和GdF_3完全不     

Tin-rich Phases RE2Au3Sn6 with RE = La,Ce, Pr,Nd, Sm – Synthesis,Structure, Magnetic Properties,and 119Sn Mössbauer Spectra

The stannides RE₂Au₃Sn₆ (RE = La, Ce, Pr, Nd, Sm) were synthesized from the elements by arc-melting. Small single crystals were grown by annealing samples in sealed tantalum tubes in an induction furnace with a special annealing sequence. The polycrystalline phases were characterized through their X-ray powder diffraction pattern. The structures of Ce₂Au₃Sn₆, Pr₂Au₃Sn₆, and Nd₂Au₃Sn₆ were refined from single-crystal X-ray diffractometer data. The RE₂Au₃Sn₆ stannides crystallize with the orthorhombic La₂Zn₃Ge₆ type, space group Cmcm. The basic structural building units are Au1@Sn₄ tetrahedra and Au2@Sn₅ square pyramids. These units are condensed to layers and the structure can be described by a simple stacking of tetrahedral and pyramidal layers with the rare earth cations in between. Temperature dependent susceptibility studies indicate that all rare earth atoms are in the trivalent oxidation state, as their effective magnetic moments match the expected values of the free RE³⁺ ions. Pr₂Au₃Sn₆ and Nd₂Au₃Sn₆ exhibit antiferromagnetic ordering at T_N = 6.3(1) and 6.7(1) K. Investigations of the electrical resistivity of La₂Au₃Sn₆ and Ce₂Au₃Sn₆ confirmed that these compounds are metallic, for La₂Au₃Sn₆ a lower resistivity was observed, in line with the absence of screening unpaired electrons. ¹¹⁹Sn Mössbauer spectra for La₂Au₃Sn₆, Ce₂Au₃Sn₆, Pr₂Au₃Sn₆ and Nd₂Au₃Sn₆ show a complex superposition of three sub-spectra which can be differentiated through their distinctly different quadrupole splitting parameters. The isomer shifts (1.87 to 2.22 mm · s^–1) indicate significant s electron density at the tin nuclei.     

Superstructure in RE2-xFe4Si14-y (RE = Y, Gd-Lu) characterized by diffraction, electron microscopy, and Mössbauer spectroscopy

Ternary rare-earth iron silicides RE(2-x)Fe4Si(14-y) (RE = Y, Gd-Lu; x approximately equal to 0.8; y approximately equal to 4.1) crystallize in the hexagonal system with a approximately equal to 3.9 A, c approximately equal to 15.3 A, Pearson symbol hP20-4.9. Their structures involve rare-earth silicide planes with approximate compositions of "RE1.2Si1.9" alternating with beta-FeSi2-derived slabs and are part of a growing class of rare-earth/transition-metal/main-group compounds based on rare-earth/main-group element planes interspersed with (distorted) fluorite-type transition-metal/main-group element layers. The rare-earth silicide planes in the crystallographic unit cells show partial occupancies of both the RE and Si sites because of interatomic distance constraints. Transmission electron microscopy reveals a 4a x 4b x c superstructure for these compounds, whereas further X-ray diffraction experiments suggest ordering within the ab planes but disordered stacking along the c direction. A 4a x 4b structural model for the rare-earth silicide plane is proposed, which provides good agreement with the electron microscopy results and creates two distinct Fe environments in a 15:1 ratio. Fe-57 M?ssbauer spectra confirm these two different iron environments in the powder samples. Magnetic susceptibilities suggest weak (essentially no) magnetic coupling between rare-earth elements, and resistivity measurements indicate poor metallic behavior with a large residual resistivity at low temperatures, which is consistent with disorder. First-principles electronic-structure calculations on model structures identify a pseudogap in the densities of states for specific valence-electron counts that provides a basis for a useful electron-counting scheme for this class of rare-earth/transition-metal/main-group compounds.     

RE（Ⅲ）—ADP,RE（Ⅲ）—AMP配合物的合成及物性研究

首次合成了具有生物活性的系列配合物RE(Ⅲ)-ADP(稀土-腺苷二磷酸)和RE(Ⅲ)-AMP(稀土-腺苷-磷酸)(RE=Y,La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu),根据红外、紫外、荧光、X射线衍射、元素分析、络合滴定等分析结果,研究了[RE(Ⅲ)(ADP)(H_2O)_3]和[RE(Ⅲ)(AMP)_2(H_2O)_4]H两个系列配合物的化学组成和性质。     

Li2O～SiO2～RE2O3(RE=Y,La,Nd)体系的锂快离子导体

快离子导体的组成决定了它的性能, 为提高离子电导率可在硅酸锂体系快离子导体中加入稀土元素等第三组分. 运用混料均匀设计方法, 在Li2O～SiO2～RE2O3 (RE=Y, La, Nd)三元体系中, 设计了一系列均匀试验点, 用高温固相法合成了快离子导体. 继而通过对实验数据的多元回归分析, 以离子电导率为评价标准, 找出三元体系中离子电导率最好的区域, 其中选取的验证点的实测值与预测值相当. 这说明均匀设计法可用于快离子导体研究. 实验中所得的快离子导体室温电导率最高为LSLa: 1.15×10-6 S·cm-1.     

Thermal decomposition of RE(C2H5CO2)3·H2O (RE = Dy,Tb, Gd,Eu and Sm)

The thermal decomposition of Dy(III), Tb(III), Gd(III), Eu(III), and Sm(III) propionate monohydrates was studied in argon by means of simultaneous differential thermal analysis and thermogravimetry, infrared-spectroscopy, X-ray diffraction, and optical microscopy. After dehydration, which takes place below 120 °C, all salts decompose into dioxycarbonates with simultaneous release of CO₂ and C₂H₅COC₂H₅ (3-pentanone) between 250 and 460 °C. However, whereas the anhydrous Dy-, Tb-, and Gd-propionates appear to transform into RE₂O₂CO₃ (rare earth [RE] = Dy, Tb, Gd) in a single step, an intermediate stage involving a RE₂O(C₂H₅CO₂)₄ composition was evidenced in the case of the Eu- and Sm-propionates. For all compounds, further decomposition of RE₂O₂CO₃ into the corresponding sesquioxides (RE₂O₃) is accompanied by the release of CO₂. The thermal decomposition of Dy- and Tb-propionates occurs entirely in the solid state. In contrast the dehydrated Gd-, Eu-, and Sm-propionates melt at increasingly higher temperatures. Evidence for recrystallization was found in conjunction with the onset of decomposition of these three propionates.     

Ternary Germanides RE 2Ge2Mg (REY, La–Nd, Sm, Gd, Tb)

Summary. The ternary rare earth metal-magnesium-germanides RE₂Ge₂Mg (RE=Y, La–Nd, Sm, Gd, Tb) were synthesized by reaction of the elements in sealed tantalum tubes in a water-cooled sample chamber of an induction furnace. The germanides were characterized through their X-ray powder patterns. The structures of Ce₂Ge₂Mg and Pr₂Ge₂Mg were refined from X-ray single crystal diffractometer data: Mo₂FeB₂ type, P4/mbm, a=750.6(1), c=442.4(1)pm, wR2=0.0378, 386 F² values, 12 variable parameters for Ce₂Ge₂Mg, and a=745.7(1), c=439.2(1)pm, wR2=0.0462, 448 F² values, 12 variable parameters for Pr₂Ge₂Mg. The lanthanum compound shows a homogeneity range La_2+xGe₂Mg_1–x. The structure of a single crystal with x=0.249(5) was refined from X-ray data: a=770.52(7), c=447.4(1)pm, wR2=0.0481, 322 F² values, 13 variable parameters. The RE₂Ge₂Mg structures can be considered as a 1:1 intergrowth of CsCl and AlB₂ related slabs of compositions REMg and REGe₂.     

(Ce,RE)-Fe-B永磁材料的研究开发新进展

中国Nd-Fe-B磁体产业的连年高速发展,造成稀土Ce的大量积压。为解决高丰度稀土资源Ce的平衡利用和高质化利用问题,同时也为了降低磁体原材料成本,提高市场竞争力,近年来围绕低成本(Ce,RE)-Fe-B磁体展开了一系列研究开发工作。对Ce-Fe-B磁体的内秉磁性和相组成,(Ce,RE)_2Fe_(14)B化合物中Ce的价态、原子占位等研究结果进行综述分析;对快淬和烧结(Ce,RE)-Fe-B磁体的研究进展,对烧结(Ce,RE)-Fe-B磁体的制备新技术及产业化开发现状进行报道,并展望其未来的发展趋势。     

GdAl03：Tb，RE中Tb，RE的能量传递研究

采用柠檬酸盐硝酸盐燃烧法制备了GdAl03：Tb,RE荧光粉体,在紫外激发下（254nm）,GdAl03：Tb发射绿色荧光（^5D4→^7F5,544nm）,Dy共掺杂对绿色发光有增强作用,Ce共掺杂对GdAl03：Tb绿色发光有降低作用,激发谱和能谱研究表明：Dy能级嵌入Tb主发射能级^5D4（绿色发光能级）、^5D3（蓝色发光能级）能级之间,欧能级嵌入Tb主发射能级^5D4、^5D3能级上方,这种能级嵌入方式,使得稀土离子之间存在声子支持的共振能量传递,但Tb→Dy→Tb能量传递使Tb绿色发射（^5D4→^7FJ（J=3,4,5,6））增强,蓝色发射（^5D3→^7FJ（J=3,4,5,6））减弱;而CPTb能量传递使Tb蓝色发射增强,绿色发射减弱。     

共沉淀法合成稀土正磷酸盐(La,Gd)PO4∶RE3+(RE=Eu,Tb)及其真空紫外光谱特性

采用共沉淀法制备了稀土正磷酸盐荧光粉(La,Gd)PO4∶RE3+(RE=Eu,Tb).红外光谱分析发现GdPO4的红外光谱吸收峰与LaPO4一致,只是峰位向高波数方向移动.(La,Gd)PO4∶RE3+的真空紫外光谱特性研究表明,Gd3+在能量传递过程中起中间体作用.XPS研究揭示,LaPO4的价带由O2-的2p能级构成,而GdPO4的价带则是由O2-的2p能级和Gd3+的4f能级共同构成.     

Preparation of the Phosphors BaAl_2O_4:Eu, RE (RE=Dy, Ho) by Microwave Heating Technique and Observation of Long Phosphorescence

TheMAI=O'fEu= (M=Ca,Sr,Ba)havebeenknowntobeexcelIentphosphorsunderultravioletandcath0de-rayexcitation'-'.Studies0ntheph0sphorswerem0stlypertbrmedinl960sandearlyl970smainlyf0rlampandcathode-raytubeapplicati0n.Inl990sthephosphorSrAl=O#fEu= hasbeenfoundtobeablet0maintainitsaftergl0wf0rafairlylongdurati0n'-'.lnthesereports.MAl=O'fEu' werepreparedmainl}byahightemperaturesolidstatemethod,whichexpendedquitel0ngreacti0ntime0f2-4hatahightemperature0fl20O~l500"Cinareducingatm0sphereandconsumedag…     

稀土叶绿素a配合物(RE=La,Ce,Eu,Y)的合成及表征

在丙酮溶液中分别合成了叶绿素a镧、叶绿素a铈、叶绿素a铕和叶绿素a钇等稀土叶绿素a配合物 ,并研究了它们的紫外可见光谱 (UV Vis)和Fourier红外光谱 (FT IR)。稀土叶绿素a配合物的UV Vis谱均呈现Soret带分裂 ,Oy( 0→ 0 ) 带紫移 ,其它Q带消失的特征。这类配合物的FT IR谱与叶绿素a(含镁 )的光谱性质极为相似 ,但与脱镁叶绿素a的光谱性质差异很大。证明了La3 ,Ce3 ,Eu3 ,Y3 均可以配位到脱镁叶绿素的卟啉环上 ,形成稀土叶绿素a的配合物。叶绿素a镧的MCD谱在Soret带有特殊峰 ,表明叶绿素a镧是三明治夹心配合物。     

Synthesis and Thermal Decomposition Mechanism of Rare Earth （RE=La, Y, Gd） Salicylates

The rare earth (RE=La, Y, Gd) salicylates were synthesized by the rheological phase reaction method. The complexes were characterized by elemental analysis, infrared spectra (IR), X-ray powder diffraction (XRD) and thermal gravity analysis (TG). They can be represented by general formula RE(HSal)3 (RE=La, Y, Gd; HSal=C6Ha(OH)COO). The crystals of them are monoclinic and have layered structure. The mechanism of thermal decomposition of rare earth salicylates was studied by using TG, DTA, IR and gas chromatography-mass spectrometry (GC-MS). The thermal decomposition of the rare earth salicylates in nitrogen gas proceeded in three stages: firstly, they were decomposed to form RE2(Sal)3 (Sal=C6H4OCOO) and salicylic acid; then, RE2(Sal)3 were decomposed further to form RE2O(CO3)2 and some organic compounds; finally, RE2O(CO3)2 were decomposed to form rare earth metal oxides (RE2O3) and carbon dioxide. The organic compounds obtained from the second step of the reaction are mainly dibenzofuran, xanthenone, 6H-benzo[c]chromen-6-one, 6-phenyl-6H-benzo[c]chromene, and 1,3-diphenyl-1, 3-dihydro-2-benzofuran.     

RE(C5H8NS2)3(C12H8N2)(RE=La,Pr,Nd,Sm)的标准摩尔生成焓测定研究

在无水乙醇中,使低水合氯化稀土(RE=La, Pr, Nd, Sm)与吡咯烷二硫代氨基甲酸铵(APDC)和1,10-邻二氮菲(σ-phen·H₂O)反应,制得其三元固态配合物.用化学分析和元素分析确定它们的组成为RE (C₅H₈NS₂)₃(C₁₂H₈N₂) (RE= La, Pr, Nd, Sm).IR光谱说明RE³⁺分别与3个PDC-的6个硫原子双齿配位,同时与σ-phen的2个氮原子双齿配位,配位数为8.用精密转动弹热量计测定了它们的恒容燃烧热Δ_cU,分别为-17776.94±7.72, -17810.41±7.93, -17762.71±7.91和-17482.42±9.35 kJ·mol^-1;并计算了它们的标准摩尔燃烧焓和标准摩尔生成焓,分别为-17792.43±7.72, -17825.90±7.93, -17778.20±7.91, -17497.91±9.35 kJ*mol^-1和-83.05±8.60, -64.70±9.40, -104.77±8.78, -388.70±10.13 kJ·mol^-1.估算出未研究的同类配合物Ce(C₅H₈NS₂)₃(C₁₂H₈N₂)和Pm(C₅H₈NS₂)₃(C₁₂H₈N₂)的和分别为-17815, -17660 kJ·mol^-1和-60, -217 kJ·mol^-1.     

Mg-20%(RE-Ni)(RE=La,Y,Mm)复合材料储放氢性能研究

通过磁悬浮熔炼和反应球磨相结合的方法成功制备出Mg-20wt%(RE-Ni)(RE=La,Y,Mm)复合储氢材料,主要研究了材料的物相结构和储放氢性能.结果表明.Mg-20wt%(RE-Ni)(RE=La,Y,Mm)复合储氢材料,具有相似的物相结构和吸放氢热力学性能,吸氢相均为MgH2和Mg2Ni,在同一温度下,合金只有一个放氢平台,表明两相具有良好的协同放氢效应.在复合体系中,Mg-20wt%(Y-Ni)具有最佳的综合储氢性能,表明Y具有最佳的催化效果,其在293 K,3.0 MPa H2,10 min的吸氢量和573 K,对0.1 MPa,15 min的放氢量可分别达到3.92%和4.75%,实现了室温快速大量吸氢和较温和条件下的快速放氢.