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1.
A series of new compounds Ln(GaM2+)O4 and Ln(AlMn2+)O4 having a layer structure were successfully prepared [Ln = Lu, Yb, Tm, Er, Ho, and Y, and M = Mg, Mn, Co, Cu, and Zn]. The synthesis conditions and the unit cell parameters for 23 compounds have been determined. These compounds are isostructural with YbFe2O4 (space group Å, and c = 25.109(2) Å). 相似文献
2.
The phase relations in the Yb2O3Ga2O3CoO system at 1300 and 1200°C, the Yb2O3Ga2O3NiO system at 1300 and 1200°C, the Yb2O3Ga2O3CuO system at 1000°C and the Yb2O3Ga2O3ZnO system at 1350 and 1200°C, the Yb2O3Cr2O3CoO system at 1300 and 1200°C, the Yb2O3Cr2O3NiO system at 1300 and 1200°C, the Yb2O3Cr2O3CuO system at 1000°C, and the Yb2O3Cr2O3ZnO system at 1300 and 1200°C were determined in air by means of a classical quenching method. YbGaCoO4 (a = 3.4165(1) and c = 25.081(2) Å), YbGaCuO4 (a = 3.4601(4) and c = 24.172(6) Å), and YbGaZnO4 (a = 3.4153(5) and c = 25.093(7) Å), which are isostructural with YbFe2O4 (space group: and c = 25.109(2) Å, were obtained as stable phases. In the Yb2O3Ga2O3NiO system and the Yb2O3Cr2O3MO system (M: Co, Ni, Cu, and Zn), no ternary stable phases existed. 相似文献
3.
Triple orthovanadates, SrLaTh(VO4)3 and PbLaTh(VO4)3 are found to be dimorphic, the crystalline form depending upon the firing temperature. The low-temperature form has zircon structure and the corresponding high-temperature form exhibits its well-known monoclinic modification. The X-ray powder diffractograms and infrared spectra are recorded and discussed in comparison with those of structurally related compounds. 相似文献
4.
Measurement of the magnetic hyperfine interaction in paramagnetic Fe2+ in ZnF2 and MgF2 by Mössbauer spectroscopy is reported. The results, ?275 ± 3 kOe and ?270 ± 3 kOe for ZnF2:Fe2+ and MgF2:Fe2+ respectively are compared with a previous analysis of hyperfine interactions in the rutile fluorides. 相似文献
5.
The magnetic susceptibilities of powder samples of the polymeric compounds M(dmp)SO4 (M = Mn, Fe, Co, Ni, Cu; dmp = 2,9-di-CH3-1,10-phenanthroline) have now been studied at temperatures between 1.5 and 305 K. There is clear evidence of one-dimensional, antiferromagnetic interactions in the Mn, Fe, Co, and Ni compounds: from , the magnetic moment decreases steadily from a value that is approximately the spin-only moment of the high-spin configuration to a value that is ~20% of the spin-only moment, and the susceptibility-vs-temperature curve contains a broad maximum atT ≤ 30 K. Cu(dmp)SO4, however, exhibits almost perfect Curie-Weiss paramagnetism. These results when combined with the results of various spectroscopic studies lead to proposed molecular structures (chainlike polymers of cis-MN2O4 chromophores and bridging-chelating sulfates) and estimated energies of intrachain antiferromagnetic exchange (). 相似文献
6.
M. Gasperin M.C. Saine A. Kahn F. Laville A.M. Lejus 《Journal of solid state chemistry》1984,54(1):61-69
A series of compounds with the initial composition LaMxAl11O18+x has been studied with x ranging from 0 to 1, and M = Mn, Co, Cu. They exhibit a more or less distorted and defective magnetoplumbite arrangement. Their effective compositions have been determined by X-ray structure refinement. The smaller the content of M2+, the higher the disorder in the crystal lattice, the worse the crystal growth, and more intense the diffuse scattering in (001) planes. The role of M2+ is compared to that of M2+ stabilizing γ-Al2O3 to give MAl2O4 spinels. 相似文献
7.
In the Sc2O3---Ga2O3---CuO, Sc2O3---Ga2O3---ZnO, and Sc2O3---Al2O3---CuO systems, ScGaCuO4, ScGaZnO4, and ScAlCuO4 with the YbFe2O4-type structure and Sc2Ga2CuO7 with the Yb2Fe3O7-type structure were obtained. In the In2O3---A2O3---BO systems (A: Fe, Ga, or Al; B: Mg, Mn, Fe, Ni, or Zn), InGaFeO4, InGaNiO4, and InFe3+MgO4 with the spinel structure, InGaZnO4, InGaMgO4, and InAlCuO4 with the YbFe2O4-type structure, and In2Ga2MnO7 and In2Ga2ZnO7 with the Yb2Fe3O7-type structure were obtained. InGaMnO4 and InFe2O4 had both the YbFe2O4-type and spinel-type structures. The revised classification for the crystal structures of AB2O4 compounds is presented, based upon the coordination numbers of constituent A and B cations. 相似文献
8.
Profile analysis of constant-wavelength powder neutron diffraction data has been used to refine the crystal structure of the ordered perovskite Ca2YRuO6. The material is monoclinic (space group ) with a disordered arrangement of calcium and yttrium on the A site and one of the B sites, such that the formula is best written as Ca1.43Y0.57[(Ca0.57Y0.43)Ru]O6. Low-temperature neutron diffraction experiments showed that the material is a Type I antiferromagnet at 2.5 K with an ordered magnetic moment of 1.2(1)μB per Ru5+. It is suggested that the dominant factor in determining the electronic properties of the series M2+2X3+Ru5+O6 (M = Ca, Sr, Ba; X = La, Y) is the Ru-Ru separation distance. 相似文献
9.
The phase relations in the In2O3A2O3BO systems at elevated temperatures [A: Fe or Ga, B: Cu or Co]
The phase relations in the In2O3Fe2O3CuO system at 1000°C, the In2O3Ga2O3CuO system at 1000°C, the In2O3Fe2O3CoO system at 1300°C, and the In2O3Ga2O3CoO system at 1300°C were determined by means of a classical quenching method. InFeCuO4 (a = 3.3743(4) Å, c = 24.841(5) Å), InGaCuO4 (a = 3.3497(2) Å, c = 24.822(3) Å), and InGaCoO4 (a = 3.3091(2) Å, c = 25.859(4) Å) having the YbFe2O4 crystal structure, In2Fe2CuO7 (a = 3.3515(2) Å, c = 28.871(3) Å), In2Ga2CuO7 (a = 3.3319(1) Å, c = 28.697(2) Å), and In2FeGaCuO7 (a = 3.3421(2) Å, c = 28.817(3) Å) having the Yb2Fe3O7 crystal structure, and In3Fe3CuO10 (a = 3.3432(3) Å, c = 61.806(6) Å) having the Yb3Fe4O10 crystal structure were found as the stable ternary phases. There is a continuous series of solid solutions between InFeCoO4 and Fe2CoO4 which have the spinel structure at 1300°C. The crystal chemical roles of Fe3+ and Ga3+ in the present ternary systems were qualitatively compared. 相似文献
10.
Cyclic transport of Fe3+ as H[FeX4], where X is Cl or Br, across solvent-type liquid membranes has been demonstrated. H[FeCl4] was transported from HCl into HBr across a dibutyl ether—benzene mixture. In HBr the transported species reacted to H[FeBr4], which moved out to the HCl side against the concentration gradient of Fe3+. On the HCl side it was reconverted into H[FeCl4]. This continued till equilibrium was achieved. Likewise, Fe3+, present as H[FeBr4] in HBr, migrated from HBr into HCl and then back to HBr across the same membrane. 相似文献
11.
The crystal structure of dicyclooctatetraenedinickel, [(COT)Ni]2, has been determined from three-dimensional, single crystal X-ray data collected by counter methods. Crystals of [(COT)Ni]2, belong to the monoclinic system with a = 8.2906(3), b = 11.4185(5), c = 7.2340(3) Å, β = 115.978(2)°, d(calc) = 1.757 gcm?3, Z = 2. The space group is C22h-P21/a. The structure was refined anisotropically (hydrogen atoms and a nickel atom fragment isotropically) by fullmatrix least-squares techniques. Final values of R and Rw were 0.046 and 0.079, respectively, for the 1055 unique, absorption and extinction corrected reflections with I > 2σ(I). Crystals of [(COT)Ni]2 consists of discrete molecules with crystallographic Ci () symmetry. The compound possesses a sandwich structure with both metal atoms between the COT rings. Each nickel atom forms π-allyl type bonds to three carbon atoms of each COT ring. The nickel atoms are disordered over three sites. The effect of this disorder on the interpretation of the derived structural parameters is discussed. 相似文献
12.
Perovskites of the type A2+3B2+M5+2O9, where A2+ = Ba, Sr; B2+ = Mn, Co, Ni, Zn; M5+ = Nb, Ta, show order-disorder phenomena. At lower temperatures a thermodynamically unstable disordered cubic perovskite is formed ( formula unit——in the cell), which transforms irreversibly into a 1: 2 ordered high-temperature form with 3L structure (sequence (c)3). For A2+ = Ba this lattice is hexagonal (space group ; one formula unit in the cell); with A2+ = Sr a triclinic distortion is observed. For Ba3CoNb2O9 a second transformation into a cubic disordered perovskite takes place at 1500°C. This transition is reversible and of the order-disorder type. The vibrational and diffuse reflectance spectra are discussed. 相似文献
13.
14.
G. Collin J.P. Boilot A. Kahn J. Thery R. Comes 《Journal of solid state chemistry》1977,21(4):283-292
Structures of K+ and Tl+ aluminas were investigated by single-crystal X-ray diffraction. In the final refinements, corresponding to R values of 0.034 and 0.058, respectively, the distribution of conducting ions was found to be similar to that of Na β-alumina. In K+ β-alumina clear evidence of additional electronic density in the spinel-like blocks is obtained and is interpreted as due to a Frenkel defect. 相似文献
15.
In the isomorphous hydrates MSO4 · H2O (M = Mn, Co, Ni, Zn), where M-OW distance is the only variable, the frequencies of the wagging, rocking and bending modes of water and of metal-oxygen stretching have been shown to correlate smoothly with the distance r(M-OW). Quantitative relations have been found for νW and ν(M-OW) which vary linearly, while νR and νC2 vary non-linearly with r(M-OW). 相似文献
16.
The O? center in CaF2 is investigated by performing multiple scattering Xα calculations on the (OF6)7? cluster. In agreement with experiment, a strong Jahn-Teller distortion of tetragonal symmetry is predicted. Finally the ground state electronic structure of the cluster is discussed. 相似文献
17.
J. M. Gonzlez-Calbet M. Vallet-Regí M. A. Alario-Franco 《Journal of solid state chemistry》1985,60(3):320-331
The reduction of Ca2LaFe3O8+z in the electron microscope shows this solid to decompose into Ca2 Fe2O5 and LaFeO3, two perovskite-related line-phases which, under these conditions, appear to be thermodynamically more stable. In kinetic terms, the decomposition appears to be of the nucleation and growth type. Microdomains appear to be an essential characteristic of the system since they are present in both the reactants and the reaction products. Up to nine sets of structurally-related microdomains can simultaneously be present within the same crystal. This leads to quite elaborate electron diffraction patterns which can be interpreted in terms of perovskite superstructures. These results are discussed in terms of diffusion data on perovskite-like ferrites. 相似文献
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19.
Kinetics of polymerization of acrylonitrile initiated by the redox system Mn3+/citric acid were investigated in aqueous sulphuric acid in the range of 20–25°; initial rates of polymerization and Mn3+ disappearance etc. were measured. The effects of certain water miscible organic solvents and certain cationic and anionic detergents on the rate of polymerization have been examined. A mechanism has been suggested involving formation of a complex between Mn3+ and citric acid, decomposition of which yields the initiating free radical and with polymerization being terminated by mutual interaction of growing radicals. 相似文献