First-principles Calculation of the Formation Energy in MgO-CaO Solid Solutions

The electronic structure and total energy were calculated for ordered and disordered MgO-CaO solid solutions within the multiple scattering theory in real space and the local density approximation. Based on the dependence of the total energy on the unit cell volume the equilibrium lattice parameter and formation energy were determined for different solution compositions. The formation energy of the solid solutions is found to be positive that is in agreement with the experimental phase diagram, which shows a miscibility gap.Comment: 11 pages, 3 figure

Effect of chemistry and structure on voltage of Li intercalation oxides

With the aid of today's powerful computers, quantum mechanical methods are becoming accurate enough to determine the properties of materials before going into laborious and expensive synthesis processes. These `computer experiments' do not require any input other than the atomic numbers of the constituent species. In addition, they allow full control over the `experimental' parameters. In this way the effect of any parameter on the materials properties can be investigated, which is usually not possible in traditional experiments. We used the ab initio pseudopotential method to study the effects of chemistry and structure on the voltage obtained from intercalating Li ions into transition metal oxides. The effect of transition metal and anion chemistry was systematically studied by changing M in LiMO2, (M = Ti, V, Mn, Co, Ni, Cu and Zn) and X in LiCoX2 (X = Se, S and O), keeping the structure fixed at α-NaFeO2 layered structure. In addition, the effect of structure was studied by performing computer experiments on LiCoO2 and LiMnO2 in α-NaFeO2, LiScO2 and Al2MgO4 (spinel) structures. The computed voltages are in good agreement with experimental values. We found that, the electronic band structure and the extent of charge transfer between Li and O ions is correlated to the output voltage. We will explain how the output voltage is affected by the chemistry of the transition metal

Ferromagnetism in Rh-doped SnO 2 from first-principles calculation

The electronic structures and magnetic properties for Rh-doped SnO 2 crystals have been investigated by density functional theory. The results demonstrate a magnetic moment, which mainly arises from d orbital of Rhodium, of 1.0 μ B per Rhodium with a little contribution from the Oxygen atoms surrounding it. The Rh-doped SnO 2 system exhibits half-metallic ferromagnetism with high Curie temperature. Several doped configurations calculations show that there are some robust ferromagnetic couplings between these local magnetic moments. The p–d hybridization mechanism is responsible for the predicted ferromagnetism. These results suggest a recipe obtaining promising dilute magnetic semiconductor by doping nonmagnetic elements in SnO 2 matrix. Copyright EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg 2011