C. E. Deluque Toro

CRYSTALLOGRAPHIC, FERROELECTRIC AND ELECTRONIC PROPERTIES OF THE Sr2ZrTiO6 DOUBLE PEROVSKITE

In this paper, we report structural analysis, ferroelectric behavior and electronic structure of Sr2ZrTiO6 double perovskite. Samples were produced by the solid state reaction recipe. Crystallographic analysis was performed by Rietveld refinement of experimental X-ray diffraction patterns. Results show that this material crystallizes in a tetragonal perovskite structure which corresponds to the space group I4/m. The curve of polarization as a function of applied voltage evidences a ferroelectric character with saturation polarization on the application of voltages up to 1800 V. Calculations of density of states and band structure for this manganite-like material were carried out by means of the density functional theory implemented into the Wien2k code. Results of total and partial density of states reveal the insulator character of this material with an energy gap of 2.66 eV.

Electronic Structure of the Double Perovskite Ba2Er(Nb,Sb)O6

In this work, we present a detailed study of the structural and the electronic structure of the double perovskite Ba2Er(Nb,Sb)O6. All calculations were performed with the Full-Potential Linear Augmented Plane Wave method (FP-LAPW) based on the Density Functional Theory (DFT). From the minimization of energy as a function of volume using the Murnaghans state equation has been obtained the equilibrium lattice parameter and the bulk modulus of these compounds. The study of the electronic structure was based in the analysis of the electronic density of states (DOS), and the density of charge, showing that these compounds have a total magnetic moment of 3.0 μB per formula unit due to Er atoms.

Propiedades estructurales, electrónicas y magnéticas de la perovskita BiRO3

Presentamos un estudio detallado de las propiedades estructurales, los estados, electronicos y magneticos de las perovskitas del tipo BiRO3, con R=Fe, Co, Ni, en su estructura cubica, con grupo de simetria Pm-3m. En la obtencion de los resultados se utilizo el metodo de Spin Polarizado de Ondas Planas Aumentadas y Linealizadas (SP-FP-LAPW) dentro del marco de la teoria DFT. El estudio estructural consistio en calcular las energias de cohesion en funcion del volumen y mediante su ajuste a la ecuacion de estado de Murnaghan se determinaron el modulo de volumen, el volumen de equilibrio y de este el valor de constante de red. En el estudio de las caracteristicas electronicas se han determinado curvas de energia en contra del numero de onda (k) y la densidad de estado (DOS) para cada polarizacion de spin.