Evaluación de la estructura y microestructura de óxidos de Ni_xMg_1-xO, obtenidos por co-precipitación

Ni_xMg_1-xO oxides were prepared by thermal treatment at temperatures of 400°C, 600°C and 800°C from a hydrotalcite-like precursor obtained by co-precipitation at constant pH. The oxides obtained were characterized by X-ray diffraction methods. From the obtained results we concluded that the oxides calcined at temperatures of 400°C and 600°C are unstable that means that there exists the effect of memory and with a time they return to the precursor. Presence of Ni in Mg oxide provides stability of the compounds thermally treated at 800°C. In order to analyze the structure and microstructure, the reflections 111, 200 and 220 were used. The positions of the maxima of the diffraction peaks are shifted with respect to the simulated ones for MgO and NiO. This result reveals that in solid solutions studied compressive strains or vacation are present. The parameters of the microstructure (coherent domain size and microdeformations) were evaluated. The coherent domain size was found to be in the range of 8 - 10 nm and the presence of residual strains of microdeformation can be associated with the existence of extended defects.