Synthesis, Structure and Bonding Feature of New Metallic Zintl Phases RE 3Cu 3Sb 4(RE=Nd, Sm, Tb, Dy, Ho)

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High quality thin film phosphors of Y2O3:Eu3+ deposited via chemical bath deposition

High transparency in visible region was required for red-light-emitting Y2O3:Eu3+ thin film phosphors. Such films were obtained via chemical bath deposition on bare SiO2 glass substrates through heterogeneous nucleation with further heat treatment. Thin amorphous yttrium basic carbonate films could be completely transformed to crystalline Y2O3 at 650 °C. X-ray diffraction and field-emission scanning electron microscopy were used to characterize these products. The deposition temperature and the post-anneali...     

Li、Eu掺杂NaY（WO4）2荧光粉的合成与红色发光

利用固相法合成了Li+、Eu3+掺杂的NaY(WO4)2红色荧光粉,并且用X射线粉末衍射仪和紫外-可见光谱仪进行了表征。研究发现纯相产物可以在1100℃下制备,然而稳定存在的温度区间仅约100℃。和已报道的燃烧法产物不同,Eu3+掺杂产物的发光性质证实了浓度猝灭现象的存在,掺杂9mol%时发光最强,有效激发波长是393 nm,发射光谱体现为高选择性的Eu3+的5D0→7F2电偶极跃迁,因此适合于解决白光LED中缺乏红光成分的问题。Li+掺杂既没有改变Eu3+红光发射的择优性,又能够调节发光强度。研究发现合适的Li+浓度可以增强发光,但是浓度过大或过小对发光不利,掺杂30mol%时发光最强。这种变化规律可以归因于点阵缺陷增加和Y原子格位不对称性增强对发光强度的不同影响之间竞争的结果。     

Synthesis, characterization and luminescent properties of needle-like lanthanide-doped orthorhombic Y5O4F7

Thermal annealing of YOH1.1F1.9 and YOH1.1F1.9:Ln3+(Ln3+=Eu3+,Tb3+ and Gd3+) precursors in air gave access to synthesize yttrium oxyfluoride phosphors with well-preserved needle-like morphologies. The phase purities of samples strongly depended on the thermal annealing temperature. At 600 °C, pure Y5O4F7 with orthorhombic structure were obtained, as evidenced by powder X-ray diffraction measurement and chemical analysis. The interesting microstructure evolution of the annealed sample from well-organized nanoparticles on curly slices to microrod-bundle structure had been aroused by raising annealing temperature. The multicolor fluorescent emissions of Y5O4F7:Ln3+ phosphors were observed, e.g. ultraviolet emission for Gd3+ , green emission for Tb3+ and red emission for Eu3+ , which resulted from characteristic transitions of different lanthanide ions.     

通过等价和异价元素掺杂促进YbMg2Sb2热电性能提升（英文）

由于其电热输运性能便于调控,锑基Zintl相化合物AM2Sb2(A=Ca,Sr,Ba,Yb,Eu;M=Mg,Zn,Cd,Mn)被认为是一类重要的热电材料.本文通过在YbMg2Sb2中掺入等价的元素Zn和异价元素Ag,实现了声子和载流子的输运性能优化.首先,体系YbMg2-xZnxSb2室温热导率从1.96 W m^-1K^-1降低至1.15 W m^-1K^-1,这是由于形成YbMg2Sb2-YbZn2Sb2的固溶体带来的合金化散射效应.其次,掺杂Ag可以增加载流子浓度,其数值在室温下从0.42×10^19cm^-3提升至7.72×10^19cm^-3,从而有效地提高了电导率和功率因子.通过综合两方面的协同效应使得体系zT在703 K时达到0.48,比纯样品YbMgZnSb2高60%.     

Syntheses and Crystal Structure Characterizations of New Rare Earth Copper Bismuth Compounds RE CuBi2 （RE = La, Gd and Dy）

The tide new compounds with chemical formula RE CuBi2 were synthesized by arc melting method followed by annealing. The crystal structures refined using Rietveld method and X-ray powder diffraction data show to be isotypic to CaMnBi2 structure type with space group P4/nmm (No. 129). The unit cell parameters are a=0.457946(4)nm,c =0. 98858(2) nm, V =0. 207319(8) nm^3 for LaCuBi2, a = 0.449279(9) nm, c = 0. 95958(4) nm, V = 0. 19369(2) nm^3 for GdCuBi2 and a =0. 447680(7) nm, c =0. 95124( 3 ) nm, V = 0. 190644(5 )nm^3 for DyCuBi2 respectively, showing lanthanide contraction. The structure is characterized by layers of edge-shearing CuBi4 tetrahedron and covalently bonded Bi square net separated by rare earth atoms.     

Synthesis and Characterizations of Rare Earth Compounds RE(HCO 2) 3(HNO 2)(H 2CO 2)(RE=Y, Tb, Dy, Ho, Er, Yb, Tm)

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v-PrBO3的晶体结构、相变和光学性质

采用高温固相合成法分别在1200和1500℃合成了λ-PrBO₃和ν-PrBO₃样品, 并通过单晶X射线衍射确定了ν-PrBO3的晶体结构。结果表明该结构为三斜晶系, 空间群为P1, 晶胞参数为a = 0.6302 (4) nm, b = 0.6521 (4) nm, c = 0.6525 (4) nm,α = 94.312(7)°,β = 107.335(7)°,γ = 106.455(7)°, V = 0.2417(2) nm³, Z = 4。同时研究了从λ-PrBO₃到ν-PrBO₃的相变过程, 并从漫反射光谱得出λ-PrBO3和?-PrBO3的光学带隙均为4.96 eV。在X射线和紫外激发下,均未观测到λ-PrBO3和?-PrBO3样品在紫外可见波长范围内的Pr³⁺特征发光。     

Synthesis,structure and luminescent properties of a new Vernier phase Lu7O6F9 doped by Eu^3＋ as potential scintillator with unique lath tube architecture

To explore novel nano-scintillator with a controllable architecture, pure and Eu3+ doped lutetium oxyfluoride(Lu7O6F9) powder were synthesized by combining mild hydrothermal method and solid state calcination approach. The products were all pure orthorhombic Vernier phase demonstrated by X-ray powder diffraction(XRD). The detailed crystal structure was also studied by Reitveld refinement. Lath-like microcrystals composed of nanoparticles with unique hollow tube of the products were supported by the images of scanning electron microscopy(SEM) and transmission electron microscopy(TEM). Excited by X-ray with W as the target, the pure product showed intense broad emission with the peak at about 400 nm suitable for modern photoelectric multiplier tube(PMT), while the Eu3+ doped sample transferred the incident energy to Eu3+ ions and gave strong 5D0→7Fj(j=0, 1, 2 and 4) emission, which fitted for imaging and labeling measurements. From the luminescent properties, both pure and Eu3+-doped products are potential excellent scintillator for X-ray imaging and other high energy detectors, and the pure product is also a good host candidate for rare earth doping.     

极具潜力的金属间化合物功能材料

现代文明生活的各个方面,无不与能源联系在一起,但当前作为主要能源的天然气、石油和煤炭因长期大量开采而面临枯竭的危险。对于新清洁能源中取之不尽用之不竭的氢,还存在着一个很大的难题即氢气的贮存及运输。为此科学家们进行了艰苦的探索,最终将目光投向了一种崭露头角的化合物——金属间化合物。