共查询到20条相似文献,搜索用时 46 毫秒
1.
Yvonne Andersson Stig Rundqvist Roland Tellgren 《Journal of solid state chemistry》1984,52(3):327-329
The solid solutions Sr3?xLaxMn2O7 (0 ≤ x ≤ 1.50) and Sr3?xLnxMn2O7 (Ln = Nd, Sm, Gd; 0 ≤ x ≤ 1.40) with Sr3Ti2O7-type structure have been prepared. Their cell parameters and ratios are related to the size of the rare earths and to the Mn3+ ion concentration. 相似文献
2.
C. Boyer-CandalenJ. Derouet P. Porcher Y. MoëloA. Meerschaut 《Journal of solid state chemistry》2002,165(2):228-237
The optical properties of Ln2Ti2S2O5 compounds (Ln=Nd, Sm, Gd, Tb, Dy, Ho, Er, and Y) have been measured. Diffuse reflectance spectra revealed a strong absorption band above 2 eV, which explains the color of the compounds. Moreover, other bands, with a lower intensity, have been attributed to 4f-4f rare earth transitions. In the case of neodymium the derived energy level scheme is rich enough to determinate a set of phenomenological crystal field parameters that correctly reproduce the spectrum. These parameters were also calculated from the crystallographic structure, in a good agreement with the experiment. Finally, the paramagnetic susceptibility, well reproduced by the calculation, confirms that the rare earth is in a trivalent state. 相似文献
3.
O. M. Fedorova V. F. Balakirev Yu. V. Golikov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(6):1002-1004
XRD phase analysis of homogeneous phases and heterogeneous compositions of general formula Ln2?x MnxO3±δ (Ln = Nd, Sm, Eu; 0.90 ≤ x ≤ 1.20; Δx = 0.22) prepared by ceramic synthesis from oxides in air at 900–1400°C was used to determine the solubility boundaries for Ln2O3 oxides and maganese oxides in LnMnO3±δ. The results were represented as fragments of the phase diagrams for the Ln-Mn-O systems in air. It was assumed that the solubility of Ln2O3 oxides in LnMnO3±δ is determined by lattice defects, while that of manganese oxides, in addition to above mechanism, by the disproportionation reaction 2Mn3+ = Mn2+ + Mn4+ followed by the partial substitution of divalent magnesium for Ln3+ at cuboctahedral positions of the perovskitelike crystal lattice. 相似文献
4.
M. F. P. da Silva J. R. Matos P. C. Isolani 《Journal of Thermal Analysis and Calorimetry》2008,94(1):305-311
The synthesis and characterization of lanthanide(III) citrates with stoichiometries 1:1 and 2:3; [LnL·xH2O] and [Ln2(LH)3·2H2O], Ln=La, Ce, Pr, Nd, Sm and Eu are reported. L stands for (C6O7H5)3? and LH for (C6O7H6)2?. Infrared absorption spectra of both series evidence coordination of carboxylate groups through symmetric bridges or chelation. X-ray powder patterns show the amorphous character of [LnL·xH2O]. The compounds [Ln2LH3·2H2O] are crystalline and isomorphous. Emission spectra of Eu compounds suggest C 2v symmetry for the coordination polyhedron of [LnL·xH2O] and C 4v for [Ln2(LH)3·2H2O]. Thermal analyses (TG-DTG-DTA) were carried out for both series. The thermal analysis patterns of the two series are quite different and both fit in a 4-step model of thermal decomposition, with lanthanide oxides as final products. 相似文献
5.
By activation of the new host lattice Sr3La2W2O12 with the trivalent rare earth ions Nd, Eu, Ho, Er, Tm, Yb an intense emission in the visible and/or infrared region is obtained. Energy transfer from Er3+ to Tm3+ and Nd3+ to Yb3+ has been found to occur. The excitation, emission, and diffuse reflectance spectra are analyzed for Sr3La2W2O12: Ln3+ (Ln = Nd, Sm, Eu, Dy, Ho, Er, Tm, Yb). 相似文献
6.
C.E. Bamberger H.W. Dunn G.M. Begun S.A. Landry 《Journal of solid state chemistry》1985,58(1):114-118
The formation of solid solutions Ln2?xBixTi2O7, where Ln = La to Lu and Y, except Ce, Pm, and Eu, has been studied by Raman spectroscopy and to a lesser extent by X-ray diffraction. It has been established that the solubility of bismuth increases with decreasing ionic radius of the lanthanide element. No evidence was experimentally found in this work for the existence of Bi2Ti2O7. 相似文献
7.
L.Ya. Gavrilova 《Journal of solid state chemistry》2011,184(8):2083-2087
The phase equilibria in the Ln-Ba-Co-O (Ln=Nd, Sm) systems were systematically studied at 1100 °C in air. The homogeneity ranges and crystal structure of the solid solutions: Ln2−xBaxO3−δ (0<x≤0.1 for Ln=Nd and 0<x≤0.3 for Ln=Sm), Nd3−yBayCo2O7 (0.70≤y≤0.80), BaCo1−zSmzO3−δ (0.1≤z≤0.2) were determined by X-ray diffraction of quenched samples. The values of oxygen content (5+δ) for slowly cooled LnBaCo2O5+δ (Ln=Nd, Sm) samples were estimated as 5.73 for Ln=Nd, and 5.60 for Ln=Sm. The unit cell parameters were refined using Rietveld full-profile analysis. It was shown that NdBaCo2O5.73 possesses tetragonal structure and SmBaCo2O5.60 - orthorhombic structure. The projections of isothermal-isobaric phase diagrams for the Ln-Ba-Co-O (Ln=Nd, Sm) systems to the compositional triangle of metallic components were presented. 相似文献
8.
Bernadette Saubat Marcus Vlasse Claude Fouassier 《Journal of solid state chemistry》1980,34(3):271-277
To obtain rare earth luminescent materials with weak concentration quenching, the B2O3-rich portion of the ternary diagram Ln2O3MgOB2O3 (Ln = rare earth) has been investigated. A ternary phase of composition LnMgB5O10 has been found for Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Er. These compounds all crystallize in the monoclinic space group . The structure has been determined on a LaMgB5O10 crystal. A full-matrix least-squares refinement leads to R = 0.039. The structure can be described as being made of (B5O105?)n two-dimensional layers linked together by the lanthanum and magnesium ions. The rare earth atom coordination polyhedra form isolated chains. These borates are isostructural with some rare earth cobalt borates. 相似文献
9.
《Journal of Coordination Chemistry》2012,65(9):945-949
The synthesis, characterization and tg-dsc study of Ln(tfa)3?·?3aza where Ln?=?La, Pr, Nd, Sm, Eu, Gd, Tb and Er, tfa?=?trifluoroacetate and aza?=?2-azacyclononanone are reported. The obtained X-ray powder diffraction patterns show that the compounds are divided in two isomorphous groups: La, Pr, Nd and Eu, Sm, Gd, Tb and Er. For all compounds, the thermodegradation under nitrogen gave the respective oxifluorides (LnOF) as the final product. The melting temperature intervals are 105–110°C, 100–112°C, 90–95°C, 79–101°C, 65–70°C, 75–90°C, 64–76°C and 50–65°C for the La, Pr, Nd, Sm, Eu, Gd, Tb and Er compounds, respectively, and it is verified that the lanthanide contraction induces a weaker intermolecular interaction between adjacent molecules in the solid state. 相似文献
10.
The condition of thermal decomposition of La, Ce(III), Pr(III), Nd, Sm, Eu(III), Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu suberates were studied. The suberates of Ce(III), Sm, Eu(III), Ho, Tm, Yb and Lu heated lose crystallization water. Anhydrous Sm and Eu(III) suberates decompose to oxides with intermediate formation Ln2O2CO3, whereas suberates of other lanthanides decompose directly to oxides. Suberates of La, Pr(III), Nd, Gd, Tb, Dy and Er lose some water molecules and then decompose directly to oxides. Only La complex decomposes to La2O3 via the intermediate formation La2O2CO3.
Zusammenfassung Es wurden die UmstÄnde der thermischen Zersetzung von La-, Ce(III)-, Pr(III)-, Nd-, Sm-, Eu(III)-, Gd-, Tb-, Dy-, Ho-, Er-, Tm-, Yb- und Lu-suberat untersucht. Bei Erhitzen verlieren Ce(III)-, Sm-, Eu(III)-, Ho-, Tm-, Yb- und Lu-suberat Kristallwasser. Wasserfreies Sm-bzw. Eu(III)-suberat zersetzt sich über das Zwischenprodukt der Zusammensetzung Ln2O2CO3 zum Oxid, wÄhrend sich die Suberate der anderen Lanthanoide direkt zu den Oxiden zersetzen. La-, Pr(III)-, Nd-, Gd-, Tb-, Dy- und Er-suberat geben einige Moleküle Kristallwasser ab und zersetzen sich dann direkt zu den Oxiden. Nur der Lanthankomplex zersetzt sich zu La2O3 über das Zwischenprodukt La2O2CO3.相似文献
11.
The conditions of thermal decomposition of La, Ce(III), Pr(III), Nd, Sm(III), Eu, Gd, Tb(III), Dy, Ho, Er, Tm, Yb and Lu sebacates have been studied. When heated in air atmosphere, the sebacates of La and lanthanides with general formula Ln2(C10H16O4)3·nH2O, wheren=6?24, lose some crystallization water molecules in one or two steps at 323–343 K and are then dehydrated and decomposed simultaneously to the oxides Ln2O3, CeO2, Pr6O11 and Tb4O7. The oxides are formed over the range of temperature 783 K (CeO2)?1073 K (Nd2O3). 相似文献
12.
R. Pastorek 《Monatshefte für Chemie / Chemical Monthly》1972,103(3):831-839
Zusammenfassung Substanzen der ZusammensetzungLnCl3·3H2
Box
* (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Y) und LaBr3·3 H2
Box wurden isoliert und durch Thermoanalyse, IR-Absorptionsspektren und Röntgenstreuung charakterisiert.
Compounds of the rare earth elements with -benzoin oxime
Compounds of compositionLnCl3·3 H2 Box * (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Y) and LaBr3·3H2 Box were isolated and characterized by thermoanalysis, IR spectroscopy and X-ray diffraction.相似文献
13.
The phases SrLnMnO4 (Ln = La, Nd, Sm, Gd), BaLnMnO4 (Ln = La, Nd) and the solid solutions M1+xLa1?xMnO4 (M = Sr: 0 ? x ? 1; M = Ba: 0 ? x ? 0.50) have a K2NiF4-type structure. The ratio of the unit cell is related to the electronic configuration of the Mn3+ ions. 相似文献
14.
Nicolas Wartenberg Dr. Olivier Raccurt Prof. Elodie Bourgeat‐Lami Dr. Daniel Imbert Dr. Marinella Mazzanti 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(10):3477-3482
The bis‐tetrazolate‐pyridine ligand H2pytz sensitises efficiently the visible and/or near‐IR luminescence emission of ten lanthanide cations (Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb). The LnIII complexes present sizeable quantum yields in both domains with a single excitation source. The wide range of possible colour combinations in water, organic solvents and the solid state makes the complexes very attractive for labelling and encoding. 相似文献
15.
G.C. Lau B.D. Muegge T.M. McQueen E.L. Duncan R.J. Cava 《Journal of solid state chemistry》2006,179(10):3126-3135
Synthesis and crystal structures are described for the compounds Ln2(Ti2−xLnx)O7−x/2, where Ln=Tb, Dy, Ho, Er, Tm, Yb, Lu, and x ranges from 0 to 0.67. Rietveld refinements of X-ray powder diffraction data indicate that in the Tb and Dy titanate pyrochlores, the extra Ln3+ cations mix mainly on the Ti4+ site with little disorder on the original Ln3+ site. For the smaller rare earths (Ho-Lu), stuffing additional lanthanide ions results in a pyrochlore to defect fluorite transition, where the Ln3+ and Ti4+ ions become completely randomized at the maximum (x=0.67). Initial magnetic characterization for the fully stuffed x=0.67 samples for Ln=Tb-Yb shows no long range ordering down to 2 K, and only partial saturation of the full expected magnetic moment under applied fields up to 5 T. In all of these Ln-Ti-O pyrochlores, the addition of magnetic Ln3+ in place of non-magnetic Ti4+ adds edge sharing tetrahedral spin interactions to a normally corner sharing tetrahedral network of spins. The increase in spin connectivity in this family of solid solutions represents a new avenue for investigating geometrical magnetic frustration in the rare earth titanate pyrochlores. 相似文献
16.
A new series of solid solutions Ca2−xLnxMnO4 (Ln = Pr, Nd, Sm, Eu et Gd) in which manganese is found in both oxidation state of +III and +IV, have a structure derived from that of K2NiF4. The cationic distribution in sites of nine-fold coordination is random. 相似文献
17.
Zusammenfassung Die Oxide der Lanthanide und des Yttriums lösen sich beim Erhitzen in methanol. Ammoniumacetatlösungen. Aus den Lösungen konnten Verbindungen vom TypLn(OAc)3·3 NH4 OAc· ·1 H2O (Ln=La, Ce, Pr, Nd, Sm Eu, Gd, Tb, Dy, Ho) bzw. Ln(OAc)3 1 NH4OAc 1 H2O (Ln=Er, Yb, Y) isoliert werden.Die höheren Oxide PrO1,83 und TbO1,75 lösen sich nur unvollständig unter Valenzdisproportionierung. Der Löserückstand besteht aus PrO2 bzw. TbO2.
The oxides of the lanthanides and yttrium are dissolved in the heat by methanolic ammonium acetate solutions. From the obtained solutions compounds of the typeLn(OAc)3·3 NH4 OAc· ·1 H2O (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho) andLn(OAc)3·1 NH4OAc·1 H2O (Ln=Er, Yb, Y), respectively, could be isolated.The higher oxides PrO1,83 and TbO1,75 react incompletely and disproportionation of valence is observed. The residues consist of PrO2 and TbO2, respectively. *** DIRECT SUPPORT *** A3615112 00028相似文献
18.
The crystal structures of a series of compounds with the composition Ln3GaO6(Ln=Nd, Sm, Eu, Gd, Tb, Dy, Ho and Er) synthesized by solid-state reaction at 1400°C are investigated. X-ray diffraction shows that Ln3GaO6 has a non-centrosymmetric orthorhombic structure (space group Cmc21). Lattice parameters a,b,c and cell volume and the average distances between Ln(1)-O, Ln(2)-O of these compounds decrease with the decreasing of the radii of trivalent Ln ions, which accord with the expected lanthanide contraction behavior. There are two sites of seven-fold coordination for Ln atoms with oxygens, and Ga atoms are in oxygen tetrahedra which are distorted and elongated along the a-axis. Magnetization measurements indicate that the susceptibility χ changes with temperature in Curie-type manner. 相似文献
19.
V. N. Krasil’nikov O. I. Gyrdasova I. V. Baklanova L. Yu. Buldakova M. Yu. Yanchenko R. F. Samigullina O. V. Koryakova 《Russian Journal of Inorganic Chemistry》2013,58(2):120-126
Quasi-one-dimensional (1D) solid solutions Ti1 ? x Fe x (OCH2CH2O)2 ? x/2 (0 < x ≤ 0.1) with the structure of anatase were prepared by heating the glycolate Ti1 ? x Fe x (OCH2CH2O)2 ? x/2 in an atmosphere of air at a temperature of >450°C. The conditions of formation and the properties of the new glycolate Ti3Fe2(OCH2CH2O)9 were described. It was found that the synthesized Ti1 ? x Fe x O2 ? 2x/2 solid solutions exhibit photocatalytic activity in the reaction of hydroquinone oxidation in an aqueous solution on irradiation with UV light. A correlation between the rate of oxidation of hydroquinone and the concentration of iron in the catalyst was established. A procedure for the preparation of titanium dioxide with the structure of anatase doped with iron and carbon (Ti1 ? x Fe x O(2 ? x/2) ? yCy) and also composites on its basis, which contain an excess amount of carbon, was proposed. 相似文献
20.
M. Dabkowska 《Journal of Thermal Analysis and Calorimetry》1990,36(4):1319-1330
The multi-step dehydration and decomposition of trivalent lanthanum and lanthanide heptanediate polyhydrates were investigated by means of thermal analysis completed with infrared study. Further more, X-ray diffraction data for investigated heptanediate complexes of general stoichiometry Ln2(C7H10O4)3.nH2O (wheren=16 in the case of La, Ce, Pr, Nd and Sm pimelates,n=8 for Eu, Gd, Tb, Dy, Er and Tm pimelates,n=12 for Ho, Yb and Lu pimelates) were also reported.
Zusammenfassung Mittels TG, DTG, DTA wurde in Verbindung mit IR-Methoden der mehrstufige Dehydratations- und der Zersetzungsvorgang der Polyhydrate der PimelinsÄuresalze von dreiwertigem Lanthan und dreiwertigen Lanthanoiden untersucht. Röntgendiffraktionsdaten der untersuchten Heptandiat-Komplexe mit der allgemeinen Formel Ln2(C7H10O4)3 nH2O (mitn=16 für Ln=La, Ce, Pr, Nd und Sm,n=8 für Ln=Eu, Gd, Tb, Dy, Er und Tm sowien=12 für Ln=Ho, Yb und Lu) werden ebenfalls gegeben.相似文献