THE CRYSTAL STRUCTURE OF RARE EARTH COMPLEX WITH AMINO ACIDS Ⅱ The Crystal Structure of Gtutamate Comptex of Erbium Perchtorate

The crystat structure of {[Er;（L—Glu）;（H;O）;]（ClO;）;·3H;O);has been studied by X-ray diffraction. The crystal is monoctinic with space group P2;and cell parameters a=19.987（3） , b=16.505（3） , c=11.040（2） , β=104.69（1）;, V=3538（1） , Z=2, Dc=2.29 g. cm;, μ=53.2 cm;, F（000）=2384. The asymmetric unit contains two complex motecules and four centre ions. Each erbium （Ⅲ） is coordinated by five oxygen donors from four different glutamates and four oxygen donors from the aqua ligand to form a nine coordination potyhedron. The mean distances of Er—0 （carboxylate） and Er—Ow are 2.439 and 2.41 respectivety. The finat R and Rw are 0.043 and 0. 058, respectivety.

Crystal Structure of Tris(m-nitrobenzoato) Samarium Dihydrate

The crystal structure of [Sm(m-NO2C6H4CO2)3(H2O)2] was determined.Mr=684. 66,triclinic,space group P1.α=11. 408(6),b=12.990(6).c=9.469(3) A,α=104. 84(3),β=92.84,γ=65.31(3)°,V=1229.9(9)A3.Z=2,Dc=1.85g/cm3, F(000)=674,μ=25.1 cm-1,R=0.67.The coordination number of samarium ion is eight.The metal ions are bridged by carboxylato groups to form a polymeric chain structure.The crystal data of [Ho (m-NO2C6H4CO2)3 (H2O)2] were measured:triclinic,space group P1,α=11.368(3) .b=12. 943(3),c=9.443(1) A α=104.92(1),β=92.80(3),γ=65.07(2)°,V=1214.7(4)A 3,Z=2,Dc=1.91 g/cm3.These show that the samarium and holmium cornpounds are isomorphous.

Phase Behavior of BaLn_2Mn_2O_7 (Ln=Rare Earth) with a Layered Perovskite Structure

Many phases appear in BaLn 2Mn 2O 7 family (Ln=rare earth) belonging to one of the Ruddlesden-Popper type compounds, depending upon the experimental conditions such as heating conditions when prepared and composition. Some of these phases were characterized by powder X-ray diffraction method using Rietveld analysis. These phases have only a little difference in crystal structure which has fundamentally K 2NiF 4 type structure, although the X-ray diffraction patterns are clearly different: a little deformation or tilting of the oxygen octahedron surrounding a central manganese ion composing the main frame of this structure induce these different diffraction patterns. Phase behavior of these compounds, mainly the detailed relation between various phases in BaTb 2Mn 2O 7, was refined including the data of high temperature X-ray diffractometry.

SYNTHESIS AND STRUCTURE OF A NEW TYPE OF COORDINA-TION COMPOUND OF Gd(Ⅲ) WITH H_2 CCH_2CH_2C(^+NH_2)C-HCOO-

The crystal structure of gadolinium L-proline (Pro) complex [Gd2-(C5H9NO2)6 (H2O)6] (ClO4)6 has been determined. The complex crystallizes in the triclinic space group PI with following crystal data: a = 9. 906(3), b=13. 052(5), c = 13.703(5) A. α=109. 63(3), β=110.31(2), γ=100. 73(3)°, V=1470.3(9) A3.Mr=1710. 1, F(000) = 854,μ=26. 30 cm-1, Dc = 1. 931 g/cm3, Z=1.The structure was refined to the final R of 0. 048 for 3804 reflections. The structure is of one-dimensional chain, in which each gadolinium ion lies at the center of a distorted square antiprism of the eight oxygen atoms provided by four bridging carboxylate groups from four Pro ligands, a terminal carboxylate group from one terminal Pro ligand and three water molecules and the two neighbouring gadolinium ions are linked to each other through the two bridging carboxylate groups from the two Pro ligands. The prolines exist in the form of H2 CCH2CH2(+NH2)CHCOO-, and the complexions in the crystal are linked together by the net of hydrogen bonds between theClO4- , NH2+ and the coordinated water molecules.

New Advances in Structural Studies of Barium Rare-Earth Fluor-Carbonate Minerals

This paper summarizes the new developments in the study of barium rare-earth fluor-carbonate mineral structures .The second order superstructure of cebaite -(Ce ) was solved by using high power X-ray single crystal diffractometer . Five kinds of coordination forms were found . All atoms in the cell , including C and F , were properly located . In the process of study in a cordylite-(Ce ), a new mineral was discovered , whose chemical formula is (Ca0.5□0.5) BaCe2 (CO3)4F . It is isostructural with baiyuneboite - (Ce ), but different in composition (Na in baiyuneboite- (Ce ) is substituted by Ca disorderly ) . On the basis of the studies a proposal to re-define cordylite-(Ce )as a mineral group name is put forth by the authors . Finally a new type of twinning of huanghoite-(Ce ) was found on the systematical absence of diffraction data by means of a single crystal diffractometer .

Rietveld Refinement of New Solid Solution Al_xSb_ ( 3-x)Y_5 (0≤x≤2.16)

The X-ray diffraction analyses show that the existence of a continuous solid solution of Al_xSb_ 3-xY_5 (0≤x≤216). Al_xSb_ 3-xY_5 crystallizes in the hexagonal system with the space group P6_3/mcm (193) and Mn_5Si_3 structure type. The cell parameters for Al_2SbY_5 compound at 25 ℃ are a=0.88086 (2) nm, c=0.64662 (2) nm.

Synergistic effect of crystal structure and concentration quenching on photoluminescence of Er^(3+) doped upconversion nanocrystals

YbF（2.357, YbF3, Ba2 YbF7, and Ba 2 upconversion nanocrystals doped with emitter Er^3＋ ion were synthesized in the same solvent system just with changing the molar ratio of Ba^2＋ to Yb^3＋ in the precursor, which corresponed to the crystal phases of rhombohedral, orthorhombic, tetragonal, and cubic, respectively. All the samples emitted both 660 nm red light and 543/523 nm green light which originated from Er^3＋-4f^n electronic transitions ~4F（9/2-~4I（15/2 and ~4S（3/2/~2H（11/2-~4I（15/2, respectively. It was worth mentioning that YbF 3：Er^3＋, Ba2 YbF7：Er^3＋, and BaF2：Er^3＋ could emit dazzlingly bright light even under the excitation of a 980 nm CW laser with output power of 0.1 W. Upconversion emission mechanism analysis indicated that the intensity ratio of red to green light highly depended on the synergistic effect of crystal structure, concentration quenching, and particle size, but were not sensitive to crystallinity as previously reported for NaL nF4（Ln=lanthanide.

Growth, structural, spectral and high-power continuous-wave laser operation of Yb0.11Gd0.89COB crystal

A Yb_（0.11）Gd_（0.89）Ca_4O（BO_3）_3 crystal with new composition was grown by the Czochralski method. The crystal structure was measured and analyzed. The unit-cell parameters of the Yb_（0.11）Gd_（0.89）COB were calculated to be a=0.8089（7） nm, b=1.5987（6） nm, c=0.3545（8） nm, β=101.22o. The absorption and fluorescence spectra were measured. The maximum absorption cross-section of Yb_（0.11）Gd_（0.89） COB crystal was 0.79×10^（–20）cm^2, which occurred at 976 nm with Y polarization. The emission cross-section at 1027 nm was calculated to be 0.33×10^（–20） cm^2. The radiative lifetime trad was calculated to be 2.74 ms. The Stark energy-level diagram of Yb^（3＋）in the Yb_（0.11）Gd_（0.89）COB crystal field at room temperature was determined. The ground-state energy level ~2F_（7/2） splitting was calculated to be as large as 1004 cm^（–1） and the zero-line energy was 10246 cm^（–1）. A maximum output power of 9.35 W was achieved in continuous-wave（CW） mode, with the slope efficiency being 42.1%. Chemical etching experiment revealed that the dominating imperfections in the studied Yb_（0.11）Gd_（0.89） COB crystal were dislocations and sub-grain boundaries. The existence of crystal defects could cause light scattering, and degrade laser output efficiency. The influence of crystal defects on laser properties was discussed.