The Study of the Interac tion between Uranium Monosulphide and Nitrogen

The study of the process of interaction between nitrogen and nearly stoichiometric uranium monosulphide reveals at least three distinct stages. The first one (200-580° C) is characterized by limited interstitial dissolution of nitrogen in th e lattice. At approximately 580° C , US starts to react with N 2 yielding uranium sulphonitride of the composition U 2S 2Ny. Above 1200° C U2S 2N y decomposes into US and U 2S2 _ xNy. The X-ray powder diffraction m ethod was used in order to derive the most probable atomic positions in the crystal structure of U2S2N

The Crystal Structure of TiCuHg2

X-Ray studies in the ternary system Ti-Cu-Hg revealed the existence of a new phase of the composition TiCuHg2. The cubic unit cell has a lattice parameter a = 6.155 A and conta ins appr. 3 formula units. The crystal structure was determined from x-ray powder diffraction data and found to belong to the ordered B 32 structure type. The density measurements indicate that the structure is only 710/o filled

The Crystal Structure of TiCuHg2

X-Ray studies in the ternary system Ti-Cu-Hg revealed the existence of a new phase of the composition TiCuHg2. The cubic unit cell has a lattice parameter a = 6.155 A and conta ins appr. 3 formula units. The crystal structure was determined from x-ray powder diffraction data and found to belong to the ordered B 32 structure type. The density measurements indicate that the structure is only 710/o filled

The Homogeneity Range in the System UP(O)

A large number of samples of uranium monorphosphide were prepared by direct reaction between uranium filings and red phosphor us, followed by homogenization in a high temperature furnace (Degussa) at 1200-1300 °c and a pres,sure of 10-4 Torr (1 Torr = 101.325/760 kPa). Samples were analyzed for uranium, phosphorus and nitrogen, assuming that the difference is oxygen. The oxygen content wa.s found to vary from sample to sample, ranging from 0.54 (min.) up to 7.10 wt. O/o (max.). X-ray analysis did not indicate the presence of U02• The amount of oxygen or nitrogen was not controled in advance, but final results ensured the working hypothesis, since the analytical data were in acordance with the X-ray powder diagrams

On the Existence of the FCC Uranium

Diffusion studies in the system U - S, employing the couples U - US, U - US2 and U -- U3S5 revealed the existence of new FCC phase with the composition ranging from approx. U20S to U8S. The lattice parameter of the phase as obta ~ned in the diffusion couple is 4.95 ± 0.01 A. The same phase can be also obtained by the arc melting of the mixtures of U and US or U and S in the appropriate proportions, if followed by the heat treatment at 1900 °c during at least four hours. It is believed that this is a crystal structure modification of uranium stabilized by the addition of a small quantity of nonmetal atoms, where S and N play a mayor role. The same phase has been obtained through the addition of approximately 9 a/o of Se, Te, P, As, Sb, Bi, C and Si. Although the effect of the stabilization is not yet completely understood all samples contain a FCC phase and posess virtually the same lattice parameter as the phase containing sulphur. The experimental density amounts 14.21 g cm·:i. The calculated density is 13.21 g cm-3

A Press for Electric Resistivity Measurements of Powders

In research work on semiconductors, the electric resistivity measurements are very important. In most cases it is impossible to obtain a compact sample and the measurements have to be done on the powdered material. For this purpose the resistivity is measured on a sample which is obtained by pressing the powder to a definite pressure between two electrodes