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[en] Samples of (UAs)_x (ThSe)_1-x solid solutions with 1.00 ≤ x ≥ 0.30 were measured in constant high magnetic fields up to 14 T within the temperature range 4.2-200 K and, additionally, for samples with x ≥ 0.70; in pulsed magnetic fields up to 40 T at 4.2 and 77 K. In samples containing more than 20 mol% of ThSe, the stable magnetic ordering becomes ferromagnetic and the effect of diamagnetic dilution is observed

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[en] The phase transition pressures, equation of state and volume collapse have been computed for ThS and ThSe by means of a modified three-body potential (MTBP) model which includes the covalency effects. These compounds are found to undergo phase transition from NaCl (B1) structure to CsCl (B2) structure at high pressure. The values of the phase transition pressure, computed from the present model, show good agreement with their corresponding experimental data. These compounds show a compression of 8.9% and 10.3%. (author)

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[en] Single crystals of MnThTe₃ (1) and MgThTe₃ (2) grow as small black plates from the stoichiometric reaction of the elements, the former at 1,000 C and the latter at 900 C with the aid of a Sn flux. Both compounds crystallize in the space group Cmcm of the orthorhombic system with four formula units in cells of dimensions a = 4.2783(6) angstrom, b = 13.8618(11) angstrom, and c = 9.9568(15) angstrom for 1 and a = 4.2854(6) angstrom, b = 14.042(2) angstrom, and c = 9.9450(14) angstrom for 2 at T - 153(2) K. KCuThSe₃ (3) forms as red blocks from a stoichiometric mixture of K₂Se, Cu, Th, and Se at 800 C, and CsCuThSe₃ (4) forms as yellow blocks from a stoichiometric mixture of Cs₂Se₃, Cu, Th, and Se at 850 C. Compounds 3 and 4 also crystallize in the space group Cmcm of the orthorhombic system with four formula units in cells of dimensions a + 4.1832(8)angstrom, b = 14,335(3)angstrom, and c = 10.859(2)angstrom for 3 and 1 = 4.2105(7)angstrom, b = 15.715(3)angstrom, and c = 10.897(2)angstrom for 4 at 153(2) K. Compounds 1 and 2 are isostructural with each other as well as with several uranium analogues and comprise pseudolayered structures with slabs of corner-shared MTe₆ octahedra alternating with slabs of cap- and edge-shared ThTe₈ bicapped trigonal prisms. the slabs are bonded together through the sharing of edges and vertices of the various polyhedra to form three-dimensional structures. Compounds 3 and 4 are two-dimensional layered structures that are closely related to 1 and 2. In 3 and 4, ThSe₆ octahedra form the same slabs as MTe₆ in 1 and 2 and Cu atoms occupy the tetrahedralholes in the layers. Alkali metal cations occupy bicapped trigonal prismatic sites between the layers. Neither structure type has short Q-Q interactions, and therefore the oxidation states of all atoms are straightforwardly assigned on the assumption of Th⁴⁺. Magnetic susceptibility measurements on compound 1 show a ferromagnetic translation at 70 K and a magnetic moment of 5.9(2) μ_Β per Mn ion, indicating low-spin Mn²⁺

[en] The magnetic studies of solid solutions of the U/sub x/Th/sub 1-x/Se system have been carried out over the whole range of composition. The dependence of lattice parameters, of Curie and Weiss temperatures, and of the paramagnetic moment on the composition is presented and discussed. The magnetization curves of some ferromagnetic samples as a function of temperature are given. It was found that ferromagnetic interaction exists for solid solutions containing up to 50% ThSe and that replacing of U by Th decreases linearly the Curie and Weiss temperatures

[en] The high-pressure crystal structures of the members of the ThX series, where X = S, Se and Te, have been studied using synchrotron X-ray diffraction in the pressure range up to about 60 GPa. A distorted fcc structure is observed for ThS above 20 GPa. These transforms to the CsCl structure at 15 GPa. has the CsCl structure already at atmospheric pressure and no further phase transition has been observed. A log-log plot of bulk modulus versus specific volume gives a straight line with slope -1.85. (orig.)