Bestimmung der Hyperfeinstrukturaufspaltungen der Scandium-Grundzustände2D3/2 und2D5/2 und des Quadrupolmomentes des Sc45-Kernes
The hyperfine structure splittings of the electronic ground states2D3/2 and2D3/2 of the stable isotope Sc45 have been measured by the atomic beam magnetic resonance method. From these splittings the magnetic dipole and electric quadrupole interaction constants are found to bea3/2=(269,560±0,02) Mc/sb3/2=−(26,37±0,1) Mc/sa5/2=(109,034±0,01) Mc/sb5/2=−(37,31±0,1) Mc/s. The values of the electric quadrupole moment calculated fromb3/2 andb5/2 differ by about 5% indicating that the configuration 3d 4s2 of the ground states is perturbed by higher configurations.
A brief visit to the BeCl2/ZnCl2 system and the prediction of a new polymorph of ZnCl2
Abstract Reactions of zinc chloride with beryllium chloride in the molar ratios of 1:1 and 3:2 at T = 300°C in sealed ampoules lead to the formation of the two compounds Be1−xZnxCl2 (x = 0.563(2) and 0.489(3), respectively). Their composition and crystal structures were evidenced by single crystal X-ray structure analysis. Both compounds crystallize isotypic to β-BeCl2 in the tetragonal space group I41/acd, No. 142, tI96, with a = 10.7548(1), c = 19.4656(5) Å, V = 2251.50(7) Å3, Z = 32 at T = 100 K for the first and a = 10.7511(3), c = 19.2335(10) Å, V = 2223.1(2) Å3, Z = 32 at T = 100 K for the second compound. The positions of the Be atoms are mixed-occupied by Zn atoms. The compounds were additionally characterized by powder X-ray diffraction and infrared spectroscopy. Plots according to Vegard’s law allowed for extrapolation towards a neat ZnCl2 phase that would crystallize in the β-BeCl2 structure, which is the ZnI2 structure type. Quantum chemical calculations have confirmed that such a ZnCl2 modification would represent a true local minimum.
Effects of the mineral phase and valence of vanadium on vanadium extraction from stone coal
The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal. Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when the raw ore is leached by 4 mol/L H2SO4 at 90°C for 2 h. After the sample is roasted at 900°C for 2 h, the leaching rate of vanadium reaches the maximum, and more than 70% of vanadium can be leached. The crystal of vanadium-bearing mica minerals decomposes and the content of V(V) increases with the rise of roasting temperature from 600 to 900°C, therefore the leaching rate of vanadium increases significantly with the decomposition of the mica minerals. Some new phases, anorthite for example, form when the roasting temperature reaches 1000°C. A part of vanadium may be enwrapped in the sintered materials and newly formed phases, which may impede the oxidation of low valent vanadium and make the leaching rate of vanadium drop dramatically. The leaching rate of vanadium is not only determined by the valence state of vanadium but also controlled by the decomposition of vanadium-bearing minerals and the existence state of vanadium to a large extent.