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。     

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.     

Preparation and characterization of single RE2O3–Mo secondary emission materials

La₂O₃–Mo, Y₂O₃–Mo, Gd₂O₃–Mo and Ce₂O₃–Mo were prepared by liquid–liquid doping combined with spark plasma sintering. The microstructure and surface behaviour of rare earth oxide of the cathode have been studied by microscope, Auger Electron Spectroscopy (AES) and X-ray Photoelectron Spectroscopy (XPS) methods. Among these four kinds of cathode, Y₂O₃–Mo cathode exhibits the best secondary emission property, i.e., the maximum secondary emission yield could reach 5.24. The penetration depth of primary electrons and escape depth of secondary electrons have been calculated and the energy distribution of primary electrons in the cathode has been simulated by Monte Carlo method. Y₂O₃–Mo cathode has the largest penetration depth and escape depth, which could be attributed to the highest secondary electron emission yield of the cathode.     

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...     

Electromagnetic properties and microwave absorption enhancement of Ba0.85RE0.15Co2Fe16O27-polyaniline composites: RE = Gd,Tb, Ho

The Gd-, Tb-, and Ho-doped W-type hexagonal ferrite Ba_0.85RE_0.15Co₂Fe₁₆O₂₇ was fabricated by a facile route of low-temperature sol–gel self-propagating combustion. Furthermore, a combination of dielectric loss phase polyaniline and magnetic loss phase Ba_0.85RE_0.15Co₂Fe₁₆O₂₇ as the microwave absorber in a core-shell architecture has been synthesized. The effect of different lanthanide ions Gd, Tb, and Ho on their microstructure, static magnetic properties, electromagnetic properties, and microwave reflection loss have been systematically studied. Our results show that the Ho-doped ferrite has the low microstructure parameters (a, c, and V) and high saturation magnetization (Ms) attributed to its ionic radius and magnetic moment. Moreover, it was found that the Ho-doped composite exhibited excellent microwave absorbing property with a minimum reflection loss (RL) of about ?15.1 dB at 9.4 GHz. The reflection loss of composite increases up to almost triple upon the combination of polyaniline and doped ferrite. Such lightweight and highly effective absorbers via combining the organic and inorganic phase into a core-shell architecture are highly desirable for microwave absorber in various applications. Figure

The synthesis and properties of the PANI/REBF composites     

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…     

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.     

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.     

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。Eu^3 ,Tb^3 和Eu^2 共存于同一体系中，而且Eu^2 的发射位置从402nm移至428nm,在双掺杂体系中引入Ce^3 ．Eu^3 ，Tb^3 和Eu^2 的发光强度均有所增强,这可能是Ce^3 与Eu^3 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。     

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.     

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。     

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对耐候钢溶质再分配的影响

为研究RE对耐候钢中各元素偏析的影响,进行了不同RE含量的耐候钢定向凝固实验,拉速为15μm.s-1,观察了RE对耐候钢定向凝固试样糊状区的影响,并用电子探针定量分析了耐候钢中各元素的溶质分配系数。结果表明,钢中加入RE可以抑制枝晶生长,细化枝晶,有利于二次枝晶的生长,可以促进等轴晶的生成。RE原子在晶界的富集可以抑制溶质元素在固液界面的析出,提高各元素的非平衡溶质分配系数,可以有效减轻耐候钢的宏观偏析。     

Magnetic and thermoelectric properties of REMoN3 (RE = La,Ce, Pr,Nd, and Sm): A first-principles study

We investigated the magnetic and thermoelectric properties of REMoN₃ (RE = La, Ce, Pr, Nd, Sm) perovskites using the full potential linearized augmented plane wave (FP-LAPW) method. To overcome the problem of underestimation of electronic interaction, we employed the DFT + U approach to accurately map the electronic structure of these compounds. Our study shows an increasing trend in the magnetic moments with the increasing number of unpaired electrons in RE. Among these compounds, SmMoN₃ possesses a large magnetic moment, which is suitable for applications such as memory devices and sensors. Interestingly, all these perovskites display ferromagnetic behavior except CeMoN₃, which exhibits an antiferromagnetic nature. Furthermore, our analysis indicates n-type thermoelectric behavior in all these materials. The compound, namely PrMoN₃, exhibits a high figure of merit among REMoN₃, which can be improved by modifying the lattice sites.     

Luminescence properties of sol-gel derived silica gels doped and undoped with RE-complexes(RE=Eu,Tb)

The luminescence properties of silica gels and silica gels doped with two rare earth complexes,Eu(TTA)3 and Tb(o-CBA)3 (TTA=thenoyltrifluocetate,o-CBA=o-chlorobenzoic acid) are reported and discussed.Pure silica gels show a blue luminescence,and the maximum excitation and emission wavelengths depend strongly on the solvents used.Both of the studied rare earth complexes exhibit the characteristic emissions of the rare earth ions in silica gels,i.e.,Eu3+5 Do→7 FJ(J=0,1,2,3,4),Tb3+5D4→7FJ(J=3,4,5,6) transitions.Compared with the pure RE-complexes powder,the silica gels doped with RE-complexes show fewer emission lines of the rare earth ions.Furthermore the rare earth ion (Tb3+) presents a longer lifetime (1346μs) in silica gel doped with Tb(o-CBA)3 than in pure Tb(o-CBA)3 powder (744μs).The reasons responsible for these results are discussed in the context.     

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。     

稀土纳米复合氧化物RE2O3：Eu（RE=Y，Gd）的制备及特性

以甘氨酸辅助的燃烧法和非晶态稀土DTPA配合物前驱体热分解法制备了Y2O3:Eu和Gd2O3:Eu纳米材料。X射线衍射表明燃烧法和配合物前驱体热分解法制备的纳米Y2O3：Eu均为立方相,而GdO3:Eu纳米材料则随制备条件不同可得到立方相或单斜相两种产物,发射光谱证实了这一结论。通过透射电子显微镜、扫描电子显微镜对不同方法制备的纳米材料的尺寸、形貌也进行了表征。