Activities of FexO in Na2O-Al2O3-SiO2-FexO Homogeneous Liquid Slags at 1673 K

Electrochemical measurements of the solid-oxide galvanic cell of the type Mo/Mo + MoO[2]/ZrO[2] (MgO)/Fe + {Na[2]O-Al[2]O[3]-SiO[2]-FexO} slag/Ag/Fe were conducted at 1673 K in order to obtain the activities of FexO in Na[2]O-Al[2]O[3]-SiO[2]-FexO system. The iso-activity curves for FexO at 1673 K were determined for Na[2]O-(Al[2]O[3] + SiO[2])-FexO pseudo-ternary slags with an Al[2]O[3]/SiO[2] molar ratio of 33/67

Sulphur potential measurements with a two-phase sulphideoxide electrolyte

The open circuit potentials of the galvanic cell,Pt (or Au)|(Ar + H2S + H2)'||CaS + ZrO2(CaO)|| (Ar + H2S+ H2)"|Pt (or Au) has been measured in the temperature range 1000 to 1660 K and PH2S:PH 2 ratios from 1.73×10-5 to 2.65×10-1. The solid electrolyte consists of a dispersion of calcium sulphide in a matrix of calcia-stabilized zirconia. The surface of the electrolyte is coated with a thin layer of calcium sulphide to prevent the formation of water vapour by reaction of hydrogen sulphide with calcium oxide or zirconia present in the electrolyte. The use of a point electrode with a catalytically active tip was necessary to obtain steady emfs. At low temperatures and high sulphur potentials the emfs agreed with the Nernst equation. Deviations were observed at high temperatures and low sulphur potentials, probably due to the onset of significant electronic conduction in the oxide matrix of the electrolyte. The values of oxygen and sulphur potentials at which the electronic conductivity is equal to ionic conductivity in the two-phase electrolyte have been evaluated from the emf response of the cell. The sulphide-oxide electrolyte is unsuitable for sulphur potential measurements in atmospheres with high oxygen potentials, where oxidation of calcium sulphide may be expected

13C NMR study of the magnetic properties of the quasi-one-dimensional conductor, (TMTTF)2SbF6

Magnetic properties in the quasi-one-dimensional organic salt (TMTTF)2SbF6 are investigated by 13C NMR under pressures. Antiferromagnetic phase transition at ambient pressure (AFI) is confirmed. Charge-ordering is suppressed by pressure and is not observed under 8 kbar. For 5 < P < 20 kbar, a sharp spectrum and the rapid decrease of the spin-lattice relaxation rate 1/T1 were observed below about 4 K, attributed to a spin-gap transition. Above 20 kbar, extremely broadened spectrum and critical increase of 1/T1 were observed. This indicates that the system enters into another antiferromagnetic phase (AFII) under pressure. The slope of the antiferromagnetic phase transition temperature T_AFII, dT_AFII/dP, is positive, while T_AFI decreases with pressure. The magnetic moment is weakly incommensurate with the lattice at 30 kbar.Comment: 8 pages, 9 figures, to appear in Phys. Rev.

Quantum Monte Carlo Simulation of the Trellis Lattice Heisenberg Model for SrCu2_2O3_3 and CaV2_2O5_5

We study the spin-1/2 trellis lattice Heisenberg model, a coupled spin ladder system, both by perturbation around the dimer limit and by quantum Monte Carlo simulations. We discuss the influence of the inter-ladder coupling on the spin gap and the dispersion, and present results for the temperature dependence of the uniform susceptibility. The latter was found to be parameterized well by a mean-field type scaling ansatz. Finally we discuss fits of experimental measurements on SrCu$_2$O$_3$ and CaV$_2$O$_5$ to our results.Comment: 7 pages, 8 figure