Mössbauer 57Fe and 129I Spectra,as Well as the Local Environment of Atoms,in Chalcogenide CuI–AgI–As2Se3 and CuI–PbI2–SbI3–As2Se3 Films Deposited from Glass Solutions in N-Butylamine

Glass Physics and Chemistry - The results of a Mössbauer study of amorphous CuI–AgI–As2Se3 and CuI–PbI2–SbI3–As2Se3 films are presented, applied from glass...     

Effects of boron oxide composition,structure, and morphology on B4C formation via the SHS process in the B2O3–Mg – C ternary system

This study investigates the formation of B₄C in the B₂O₃–Mg–C ternary system via a magnesiothermic reduction process using two kinds of boron oxide (B₂O₃) ‒ the commercial B₂O₃ and that synthesized from boric acid via the coupled chemical-thermal process. In addition to the raw materials, the products were subjected to XRD, FTIR, SEM, and FESEM analyses to determine the effects of microstructural and morphological properties of boron oxide as an important raw material, on B₄C formation in the combustion synthesis process. For this purpose, powder mixtures of B₂O₃:Mg:C were prepared at a stoichiometric molar ratio of 2:6:1 and compacted into pellets using a uniaxial hydraulic press, which were subsequently subjected to the combustion synthesis process based on the self-propagating high-temperature synthesis (SHS). Finally, the samples thus obtained were leached in an aqueous hydrochloric acid solution. Analysis of the commercial B₂O₃ revealed the presence of large amounts of such by-products as magnesium borate (Mg₃B₂O₆) and magnesium oxide (MgO) along with relatively small amounts of boron carbide after the leaching process, while those obtained for the chemically-thermally synthesized B₂O₃ showed a relatively large amount of B₄C (from micron-sized particles to nanoparticles) together with a remaining carbon phase and very small amounts of magnesium borate as by-products. It can be, therefore, concluded that the changes in chemical composition and introduction of a hydrous HBO₂ phase in the boron oxide in the B₂O₃–Mg–C mixture as well as its varied microstructure, morphology, and particle size have significant effects on the efficiency of B₄C production through the SHS process.