Preparation and Properties of the Sulfides of Thorium and Uranium²

Abstract

Since lattice energy calculations have indicated that the most stable sulfides of the periodic system could be expected in the neighborhood of the elements of the rare earth and actinide series, a thorough study of the sulfides of typical representatives of these elements was made. This paper describes the results of the study of the sulfides of thorium and uranium.The earliest careful study of thorium and uranium sulfides is that of Picon4r6sB who studied methods of preparation of ThS2 and US2 and the properties and reactions of these compounds. Strotzer and Zumbusch7 and Strotzer, Schneider and Biltz8 extended the study to polysulfides above the MS2 compounds and to oxidation states below the four plus state. However, due to very extensive oxygen contamination during preparation, the compositions and composition ranges given for the various phases below MS2 were greatly in error.In the present work both uranium and thorium were found to have compounds of the 2f oxidation state, US and ThS, which have the NaCl crystal structure. No compounds below the 2+ oxidation state were found. The solid solution ranges for these compounds appear to be relatively small. The next phase found above the MS phase was a M& phase corresponding to the 3f oxidation state. Both U2S3 and Th&s were found to have the same orthorhombic structure with apparently relatively small solid solution ranges. Th83 is an unusual thorium compound as i t is the only definitely established compound observed to date which contains thorium in the 3+ oxidation state. ThSz prepared by conversion of the oxide by H2S in a graphite container had the orthorhombic PbCt structure. US2 was prepared in a similar manner. Upon heating under reduced pressures, both lost sulfur through a solid solution range. US2 was less stable than ThSz and lost sulfur a t lower temperatures. A compound, Th&, of hexagonal structure, has been prepared by heating liquid ThS2 above 1950' under reduced pressures. It has a homogeneity range of approximately ThS1.71--1.,6. Because of the ready loss of sulfur, the study of the uranium sulfide range down (1) This work was performed under Manhattan District Contract to a composition corresponding to Th&2 did not give definite results. Experimental I. Preparation of the Sulfides of Uranium and Thorium.-Four different methods of preparation will be described below. The first three methods were also used for the preparation of the cerium sulfides and the apparatus used and details of the procedures may be obtained from the paper by Eastman, Brewer, Bromley, Gilles and Lofgreno on the cerium sulfides.Method 1.-This method is suited only for ThS2 and US2 since it involves the treatment of the oxides with excess H2S in a carbon system. Thus one obtains the highest sulfide stable at the temperature of the preparation. The temperature of the reaction should be varied between 1200-1300°; the rate of reaction a t these temperatures is fairly rapid. During the course of the reaction, the oxysulfides ThOS and UOS are first formed at lower temperature ...

Electronic properties of mixed uranium-thorium monosulphides (U xTh1-x)S

“…Introduction. -Uranium and thorium monosulphides (US and ThS) have at room temperature the NaCI crystalline structure [1] and a metallic electrical conductivity [2]. While ThS shows a small temperature independent paramagnetism [3], US is ferromagnetic below 178 K [4].…”

Synthesis and Studies of Some New Dioxouranium (VI) Complexes with Azoester Ligands

“…The magnetic susceptibilities are independent of field strength and temperature. In the present studies complexes are weakly diamagnetic as observed [22][23][24] .…”

Hydrolysis of Thorium Nitrides and Carbonitrides

“…The predominant reaction equation for the hydrolysis was found to be T~C I --, N , S~ HzO =ThOz+(l-z)CH&x N&+X/2 H2, and side reactions such as lead to the formation of amines were far less prominent. (2) The absence of higher nitrides through the hydrolysis of ThN was explained by the lattice relation between ThN and the higher nitrides, Th3N4 and Th2N20. A calculation showed that the movement of thorium atoms by 2 a a t least is necessary for the formation of ThsN4 or ThzNzO lattices starting from the ThN lattice.…”