On the Polymorphism in Lanthanum Polysulfide (LaS2)

Sulfur Nonstoichiometry of PrS2: A Series of New Sulfur-Deficient Phases

“…The room-temperature Raman spectrum of the structure of the type, given in Fig. 3, spectrum 1, shows two resolved bands near 400 cm\, typical for the (S\ ) layer as expected according to the symmetry analysis (3,16). The single band of the PrS polysul"de ( Fig.…”

Comprehensive Uranium Thiophosphate Chemistry: Framework Compounds Based on Pseudotetrahedrally Coordinated Central Metal Atoms

“…Further refinements showed that only 50 % of the U(2) sites in the cell are occupied, resulting in a stoichiometry U 3 (PS 4 ) 4 with tetravalent metal atoms. All reported orthothiophosphates crystallizing in the PrPS 4 structure type [49][50][51] show this systematic discrepancy between the temperature factors of the atoms on the two metal sites, which might indicate a site disorder for these compounds. However, the structure does not show a lattice distortion due to the disorder, but a high symmetry tetragonal space group with statistically occupied M2 positions is formed.…”

Thermodynamic investigation of the phase formation processes in the systems LnSe2–LnSe1.5 (Ln=La, Ce, Pr, Nd)

“…On heating the compound goes in gas phase partially or fully, the pressure in inner chamber increases, the quartz membrane bends and a thin quartz filament (displacement indicator, 3) attached to the membrane goes away from the null-position. The indicator is returned in the null-position by changing pressure in the outer chamber, and this pressure is registered with the help of the mercury barometer (4) and the cathetometer (5). The temperature of the compound studied is measured by the thermocouple (7) and the voltmeter (9).…”

“…Numerous literature data [7][8][9] on diffraction and chemical investigations give fragmentary and contradictory information: there are generally indicated solid solutions in the compositional range LnSe 1.9 -LnSe 1. 5 .…”

“…These compounds have characteristic layered structures that make them a very promising example of quasi-two-dimensional substances [1][2][3]. Because of the quasi-two-dimensional structure, these compounds should exhibit anisotropic physical properties as it was shown for similar structures CeS 2 and LaS 2 compounds [4,5]. Besides, considerable interest to polychalcogenides has arisen because charge density waves (CWD's) were observed in these compounds [6].…”