Electrical transport and magnetic properties of the misfit layer compound (LaS)1.14NbS2

(LaS)1.14NbS2 is a misfit layer compound built of alternate double layers of LaS with La in square pyramidal coordination with sulphur and sandwiched with NbS2 as occurs in 2H-NbS2. The electrical transport properties and magnetic properties were determined using single crystals and powder compacts. The compound is a p-type metal (Hall coefficient RH and Seebeck coefficient positive) with a strong anisotropy of the electrical resistivity: rho perpendicular to c/ rho /sub //c/=5*10-5. The electrical transport properties are interpreted as being due to holes in 4d(z2) band of the NbS2 part of the structure. The 4d(z2) band which is half-filled in the case of 2H-NbS2 contains 0.12 hole/Nb atom. This corresponds to a donation of 0.88 electron/Nb atom from the LaS part, the charge of La being +2.8. The magnetic properties are interpreted as being due to the LaS part. In the temperature region 40-300 K the curve of reciprocal magnetic susceptibility (not corrected) against T is linear with a Curie constant C of 1.4*10-6 m3 K (mol La)-1 corresponding to 0.14 4f electron at La, 0.86 electron being donated to the 4d(z2) band of the NbS2 part. Down to 4 K there are no signs of superconductivity

Beitrag zur Beschichtung von Kernbrennstoffteilchen im Fließbett

In a fluidized bed of a conical 3 inch coating furnace temperature gradients, zones of deposition and the composition of the gas mixture in and above the bed were studied. Measurements with thermo-couples as well as theoretical co siderations led to defining the temperature distribution regarding the particles and the gas composition across the bed. Thermal equilibrium was found to exist between the incoming gas and the bed of particles beyond a short heating-up stage above the nozzle system. No significant axial temperature gradients were detected here; radial temperature gradients remain small (<20 °C). Zones of deposition were defined by thickness measurements carried out on the pyrocarbon deposits obtained on small fixed rods mounted in the bed. Comparison of plasma-oxidized pyrocarbon deposits on particles and fixed rods demonstrates the strong influence of particle movement and gas velocity on the structure of the pyrocarbon. Gas was sampled in the zone of reaction by a suction method using small graphites tubes. The samples were analyzed by gas chromatography and mass spectrometry. Measurement results compared with calculated gas composition for the thermodynamical equilibrium case rendered the composition to approach that of equilibrium above the heating-up stage

The formation of 1T and 2H titanium disulfide by deintercalation of NaxTiS2

The topochemical reaction of NaxTiS2 solid phases with I2 in acetonitrile leads to several modifications of TiS2. The 1T-TiS2 modification, Cd(OH)2 type, is found by deintercalation of the rhombohedral phases 3R(I)-NaxTiS2 and 3R(II)-NaxTiS2. Deintercalation of the hexagonal phase 2H(I)-NaxTiS2 leads to a strongly disordered 2H-TiS2 phase with a chch stacking of sulfur. The structure is in agreement with a mechanism of deintercalation consisting of parallel displacements of TiS2 sandwiches. The observed magnetic susceptibility of powder 2H-TiS2 is discussed in terms of a nearly temperature-independent intrinsic contribution of about 14 × 10−6 emu per mole and a Curie-like tail contribution due to about 3 × 10−4 mole of localized paramagnetic Ti2+ (3d2)