The traditional superconductor YBa2Cu307.¡; (Yl23) has an orthorhombic crystalline structure with spatial group Pmmm and its critica! temperature is 90 K. The literature reports the use of reagent BaC03 for the preparation by the solid state reaction which requires one calcination and two thermal treatments in oxygen flow at 950 oc. In this work we report the comparison in the preparation of Y123 using the Ba02 reagent as another possibility for preparation; in this case we have used only two thermal treatments in oxygen flow at 950 °C; therefore reducing the costs in preparation. The powder XRD pattem of samples prepared with Ba02 confirm a well crystallized phase an the diffraction lines of the main phase can be indexed with an orthorhombic unit cell. The ac susceptibility measurement in the range 5-100 K using a Quantum Design (SQUID) magnetometer for two samples confirms the superc...

In the present work were making the qualitative and quantitative identification of the main mineralogical phases present in a specimen of clay, to show a method to adjust their crystalline structures and at the same time determine the concentrations of the mineralogical phases present in the specimen of clay. The data were obtained with an Universal Difractómeter and the Hanawalt method was applied for the identification of the phases, for it we use the softwares DRXWIN 2.2 and CreaFit 2.2. The Rietveld refinement were making using the FullProf program, it allowed refine the net parameters, atomic positions and it determine concentrations of the mineralogical phases present in the specimen, at the same time it allows represent graphically refine crystalline structure of each mineralogical phase and the Fourier Map.

It is known the YBa2Cu30H (Yl23) prepared by the solid reaction method coexists with a green phase Y2BaCu05 (Y211). In this work we study the behavior of the Y211 (pure) overheated at 11 00°C and 1300°C respectively. The starting sample was prepared by the conventional solid reaction method using appropriate amounts of Y203, BaC03 and CuO; the initial sample was green in color. From the X ray diffractogram (XRD) and using the Rietveld refinement we found that the crystalline structure is orthorhombic and belong to the Pnma spatial group. This is the sorne structure as the one found by Michael and Raveau 1 • The starting sample was overheated at 11 00°C under oxygen pressure of 0.1 atm. According with the XRD, there are no significant variations on its structure. Nevertheless after an overheating of 1300°C in the same oxygen pressure, a new phase Y203 with a cubic symmetry together ...

The LaCaBaCu2.80(X)0.20(O)7-δ compound with X=(P04)^(3-) and (BO3)^(3-) has been prepared by a solid state reaction method and we compare the resulting structures. phase formation and CriticaL Temperatures (Tc's) with the well known LaCaBaCu3(O)7-δ (La1113) superconductor. For both cases, the X-ray diffractogram revealed the BaCuO2 and CuO as extra phases; this is confirmed by SEM, EDX and HAEM. The Rietveld analysis suggested orthorhombic crystalline structures belonging to the Pmmm spatial group with a=3.849Å, b=3.880Å and c=11.630Å to the LaCaBaCu2.80(P04)0.20(O)7-δ, and a=3.884Å b=3.890Å and C=11.640Å to the LaCaBaCu2.80(BO3)0.20(O)7-δ. Tc's were calculated from the derivativa of magnetic susceptibility plots by using a SQUID detection system, these indicated the Tc's are 86K and 55K to the LaCaBaCu2.80(P04)0.20(O)7-δ and the LaCaBaCu2.80(BO3)0.20(O)7-δ respectively.

The LaCaBaCu2.80(X)0.20(O)7-δ compound with X=(P04)^(3-) and (BO3)^(3-) has been prepared by a solid state reaction method and we compare the resulting structures. phase formation and CriticaL Temperatures (Tc's) with the well known LaCaBaCu3(O)7-δ (La1113) superconductor. For both cases, the X-ray diffractogram revealed the BaCuO2 and CuO as extra phases; this is confirmed by SEM, EDX and HAEM. The Rietveld analysis suggested orthorhombic crystalline structures belonging to the Pmmm spatial group with a=3.849Å, b=3.880Å and c=11.630Å to the LaCaBaCu2.80(P04)0.20(O)7-δ, and a=3.884Å b=3.890Å and C=11.640Å to the LaCaBaCu2.80(BO3)0.20(O)7-δ. Tc's were calculated from the derivativa of magnetic susceptibility plots by using a SQUID detection system, these indicated the Tc's are 86K and 55K to the LaCaBaCu2.80(P04)0.20(O)7-δ and the LaCaBaCu2.80(BO3)0.20(O)7-δ respectively.

The ceramic industry is the most important activity of Chulucanas, capital of the Province of Morropón, and La Encantada District. Both districts belong to the department of Piura, where there is a great demand of clay as raw material for the ceramic paste elaboration. Traditionally have existed evidences of important clay deposits but they have not yet completely characterized. That is way, considering the importance of this raw material for the ceramic industry of the region and the difficulties to get cheap commercial ceramic material of quality; we show the results of the characterization by physics and chemistry techniques of clays extracted from the zone.

The present study has as main objecuve the search of new materials, among them the porous materials whose diversity of pore diameter confers lO the same specific properties, those that in turn determine a series of applications like adsorbents. catalysts, and shield materials, among others. The investigatíon consists of the synthes1s of macroporous materials by the method Sol-Gel, using reactive of low cost as sodium silicate (silicon source) and includes/understanos the following stages: 1) control of hydrolysis of the inorganic precursors: 2) formatíon oí the rnacrostructure material (hydrothermal synthesis) and 3) elimination of the organic matter by calcinations. The structural characterization and the degree of crystalinidad were made by means of Diffraction of Rays-X (DRX) and Electronic Diffraction of Area Selecta.(DEAS), whereas the morphologic analysis was made through an Ele...

The present study has as main objecuve the search of new materials, among them the porous materials whose diversity of pore diameter confers lO the same specific properties, those that in turn determine a series of applications like adsorbents. catalysts, and shield materials, among others. The investigatíon consists of the synthes1s of macroporous materials by the method Sol-Gel, using reactive of low cost as sodium silicate (silicon source) and includes/understanos the following stages: 1) control of hydrolysis of the inorganic precursors: 2) formatíon oí the rnacrostructure material (hydrothermal synthesis) and 3) elimination of the organic matter by calcinations. The structural characterization and the degree of crystalinidad were made by means of Diffraction of Rays-X (DRX) and Electronic Diffraction of Area Selecta.(DEAS), whereas the morphologic analysis was made through an Ele...