Coal desulfurization

Organic sulfur is removed from coal by treatment with an organic solution of iron pentacarbonyl. Organic sulfur compounds can be removed by reaction of the iron pentacarbonyl with coal to generate CO and COS off-gases. The CO gas separated from COS can be passed over hot iron fillings to generate iron pentacarbonyl

Electronic and Magnetic Structures of Chain Structured Iron Selenide Compounds

Electronic and magnetic structures of iron selenide compounds Ce2O2FeSe2 (2212\ast) and BaFe2Se3(123\ast) are studied by the first-principles calculations. We find that while all these compounds are composed of one-dimensional (1D) Fe chain (or ladder) structures, their electronic structures are not close to be quasi-1D. The magnetic exchange couplings between two nearest-neighbor (NN) chains in 2212\ast and between two NN two-leg-ladders in 123\ast are both antiferromagnetic (AFM), which is consistent with the presence of significant third NN AFM coupling, a common feature shared in other iron-chalcogenides, FeTe (11\ast) and KyFe2-xSe2 (122\ast). In magnetic ground states, each Fe chain of 2212\ast is ferromagnetic and each two-leg ladder of 123\ast form a block-AFM structure. We suggest that all magnetic structures in iron-selenide compounds can be unified into an extended J1-J2-J3 model. Spin-wave excitations of the model are calculated and can be tested by future experiments on these two systems.Comment: 6 pages, 6 figures, 2 table

Effect of strain hardening on friction behavior of iron lubricated with benzyl structures

Sliding friction experiments were conducted with iron, copper, and aluminum in contact with iron in various states of strain. The surfaces were examined in dry sliding and with various benzyl compounds applied as lubricants. Friction experiments were conducted with a hemispherical rider contacting a flat disk at loads of from 50 to 600 grams with a sliding speed of 0.15 cm/min. Results indicate that straining increases friction for dry sliding and for surfaces lubricated with certain benzyl structures such as dibenzyl disulfide. With other benzyl compounds (e.g., benzyl formate), friction coefficients are lower for strained than for annealed iron

High - Temperature Superconductivity in Iron Based Layered Compounds

We present a review of basic experimental facts on the new class of high - temperature superconductors - iron based layered compounds like REOFeAs (RE=La,Ce,Nd,Pr,Sm...), AFe_2As_2 (A=Ba,Sr...), AFeAs (A=Li,...) and FeSe(Te). We discuss electronic structure, including the role of correlations, spectrum and role of collective excitations (phonons, spin waves), as well as the main models, describing possible types of magnetic ordering and Cooper pairing in these compounds.Comment: 43 pages, 30 figures, review talk on 90th anniversary of Physics Uspekh