The manipulation of natural mineral chalcopyrite CuFeS mechanochemistry: properties and thermoelectric potential.

In this study, the properties of the natural mineral chalcopyrite CuFeS after mechanical activation in a planetary mill were studied. The intensity of mechanical activation was controlled by changing the revolutions of the mill in the range 100-600 min. A series of characterization techniques, such as XRD, SEM, TEM, TA (DTA, TG, and DTG), particle size analysis, and UV-vis spectroscopy was applied and reactivity studies were also performed.

The Effects of Ultrasound Treatment of Graphite on the Reversibility of the (De)Intercalation of an Anion from Aqueous Electrolyte Solution.

Low cycling stability is one of the most crucial issues in rechargeable batteries. Herein, we study the effects of a simple ultrasound treatment of graphite for the reversible (de)intercalation of a ClO anion from a 2.4 M Al(ClO) aqueous solution.

Mechanochemistry for Energy Materials: Impact of High-Energy Milling on Chemical, Electric and Thermal Transport Properties of Chalcopyrite CuFeS Nanoparticles.

Chalcopyrite CuFeS , a semiconductor with applications in chemical sector and energy conversion engineering, was synthetized in a planetary mill from elemental precursors. The synthesis is environmentally friendly, waste-free and inexpensive. The synthesized nano-powders were characterized by XRD, SEM, EDX, BET and UV/Vis techniques, tests of chemical reactivity and, namely, thermoelectric performance of sintered ceramics followed.

Exchange interactions in ε-Fe2O3: GGA+U calculations.

We have studied the origin of magnetic interaction in ε-FeOby ab-initio electronic structure calculations. The exchange integrals of the Heisenberg hamiltonian have been calculated using the methods based on the density functional theory (DFT) employing generalized gradient approximation with orbital dependent potential extension for 3d electrons of Fe (GGA+U method). The calculations confirm the ground antiferromagnetic (AFM) state with two Fesublattices oriented up (Fe2 and Fe3) and two Fesublattices oriented down (Fe1 and Fe4).

Magnetic properties of rare-earth-doped LaSrMnO.

Rare-earth-doped ferromagnetic manganites LaRESrMnO (RE  =  Gd, Tb, Dy, and Ho) are synthesized in the form of sintered ceramics and nanocrystalline phases with the mean size of crystallites  ≈30 nm. The electronic states of the dopants are investigated by SQUID magnetometry and theoretically interpreted based on the calculations of the crystal field splitting of rare-earth energy levels. The samples show the orthorhombic perovskite structure of Ibmm symmetry, with a complete FM order of Mn spins in bulk and reduced order in nanoparticles.

Effects of Tb(3+) dopants in the La1-x Sr x MnO3 bulk and nanoparticle ferromagnets.

Three forms of La,Sr-manganites are synthesized and the role of Tb doping is investigated. First two systems are sol-gel nanoparticles and sintered ceramics of the composition La0.56Tb0.