F. Fajardo

Synthesis, structural and morphological characterization of the perovskite LaYbO3

In this work we report synthesis of the LaYbO3 ceramics material by the solid state reaction technique and its structural and morphological characterization from X-ray diffraction and Scanning Electron Microscopy experiments. Rietveld refinement of the diffraction patterns reveals that this material crystallizes in an orthorhombic perovskite, Pnma space group (#62) with lattice parameters a=6.0233A, b=8.2080A and c=5.7203A. Systematic monitoring of the synthesis process is carried out through analysis of results of X-ray diffraction. The surface morphology of the samples was qualitatively analysed as a function of the sintering process.

Characterization of ceramics materials mixed with Co3O4

We have performed the preparation, structural, electrical and mechanical characterizations of ceramic materials composed of kaolinite Al2(Si2O5)(OH)4 and alumina (Al2O3) mixed with different concentrations of cobalt oxide (Co3O4). Ceramic samples were prepared from a base concentration of alumina 30% and kaolinite 70%, mixed with various concentrations of cobalt oxide in steps of 4% up to a value of 20%. The samples were sintered by the standard solid-state reaction method at a temperature of 1350 °C. In all samples with cobalt was found the presence of mullite. It was determined that alumina and cristobalite decreased when the cobalt concentration was increased due to the formation of the cobalt spinel. In order to determine the crystal structure of the samples, crystallographic analysis from X-ray diffraction experiments and also the semi-quantitative phase analysis were performed. Results were compared with theoretical parameters through the PowderCell 2.4 software. By increasing the concentration of cobalt oxide was found a significant increase in the resistance of materials to friction wear and a small decrease on the mean value of the dielectric constant. Through flexion measurements is observed the increases of the elasticity modulus by about 45% for the sample with 4% of cobalt oxide when compared with the samples without cobalt.