Ren Yufang

Oxygen Permeating Properties of the Mixed Conducting Membranes without Cobalt

A new series of mixed conducting oxides, Sr10-n/2BinFe20Om (n = 4, 6, 8, 10), were synthesized by a solid state reaction method, and they have high oxygen permeability. The oxygen permeation rate at 1150 K is 0.41 ml(STD)/ cm(2).min for n = 6 and 0.90 ml(STD)/cm(2).min for n = 10, which is two times higher than that for Sr1-xBixFeO3 (x = 0.5). For the Sr1-xBixFeO3 (x = 0.1, 0.3, 0.5) series, the oxygen flux increases with increasing Bi content

THE SYNTHESIS AND PHYSICAL-PROPERTIES OF THE NEW LAYERED LANTHANIDE ALKALINE-EARTH COBALT OXIDES [LN2MCO2O7 (LN=SM,GD M=SR,BA)]

Three new oxides Sm[sub 2]SrCo[sub 2]O[sub 7], Sm[sub 2]BaCo[sub 2]O[sub 7] and Gd[sub 2]SrCo[sub 2]O[sub 7] have been successfully synthesized by a solid state reaction method. The x-ray diffraction spectra show that they are all isostructural with Sr[sub 8]Ti[sub 2]O[sub 7]. Ln[sub 2]SrCo[sub 2]O[sub 7] (Ln = Sm, Gd) crystallized in the tetragonal system, Sm[sub 2]BaCo[sub 2]O[sub 7] in the orthorhombic system. The Co-O bonds in CoO[sub 2] planes of Ln[sub 2]SrCo[sub 2]O[sub 7] are shorter than those of LnSrCoO[sub 4] (Ln = Sm, Gd), thus their d electrons are more delocalized and their electrical resistivities are smaller. The electrical resistivities versus temperature in the range 300--1100K showed that the five oxides represent weakly localized systems. In the lower temperature range, the magnetic behavior of Gd[sub 2]SrCo[sub 2]O[sub 7] and GdSrCoO[sub 4] fits the Curie-Weiss law well. The magnetic exchange reactions in the CoO sublattice of Gd[sub 2]SrCo[sub 2]O[sub 7] is ferromagnetic, but in GdSrCoO[sub 4] is antiferromagnetic. The other three oxides with Sm[sup +3] showed complex magnetic behavior which is perhaps related to the complexity of Sm[sup +3].

Preparation of periodatocuprate(III) and telluratocuprate(III) by electrochemical and ozone oxidation

Abstract In the cyclic voltammograms of complexes with periodate and tellurate, the anodic and cathodic peaks were observed evidently for CuIII/CuII couples in caustic potash aqueous solutions. Copper(III) complexes were obtained by utilizing ozone as oxidant, and two new copper(III) complexes Ba3K[Cu(HIO6)2](KOH)0.5(OH)2·8H2O and Ba4K [Cu(H2TeO6)2](OH)4·6H2O were isolated from solutions, which were investigated via magnetic measurements, electronic spectra and Cu2p XPS.

Valence and magnetic properties of YSr2−xCaxV3O9−y

Compounds YSr22-xCaxVO9-y have an orthorhombic symmetry. XPS results show that the vanadium ions exist in the mixing valence in the system. Temperature dependence of magnetic susceptibility represents the Curie-Weiss law. The valence state of vanadium obviously affects the magnetic properties of YSr2-xCaxV3O9-y. The system exhibits a paramagnetic behavior from 300K to 1073K.

A new hydrogen sensor with rare earth complex fluoride

A new type of solid-state galvanic cell for detecting a small amount of hydrogen in air at room temperature is proposed. The sensor cell is a potentiometric cell using Ce0.95Ca0.05F2.95 as solid-state electrolyte. The cell exhibits good sensing properties to hydrogen in air at room temperature.

The effect of doping with tantalum on the properties of YBa2Cu3O7-y

YBa2Cu3-xTaxO7-y (x=0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) superconductors have been prepared. X-ray diffraction shows that the system remains orthorhombic for all compositions studied but, for x>0.2, Ta2O5 was detected as an impurity phase. Substitution of Ta5+ for Cu2+ occurs in the Cu(2) sites on the Cu(2)-O planes. The introduction of the high-valence element tantalum produces extra free electrons. These electrons recombine with the positive carrier of the system, which causes the mobility and the Hall number of YBa2Cu3-xTaxO7-y to decrease and also results in a depression in Tc.

The electrical and magnetic properties of lanthanide alkaline-earth transition-metal oxides

Five Ln(2)SrMCuO(6.5) oxides (M = Co, Ln = Y and Ho; M = Fe, Ln = Y, Ho, and Dy) were synthesized, and their crystal structures, IR spectra, and physical properties were studied. They have almost the same structure and crystallize in orthorhombic systems. Below room temperature, Y2SrFeCuO6.5, a known layered oxide, shows antiferromagnetic behavior, but the four new oxides are paramagnetic. Y2SrFeCuO6.5 fits the Curie-Weiss law in the temperature range 300-100 K, but Y2SrCoCuO6.5 shows complex magnetic behavior because of the disproportion of some Co+3 to Co+2 and Co+4 The five oxides are all p-type semiconductors in the measured temperature range and have large electrical resistivities at room temperature.