CaLaBa superconductor is a protorype of the YBa structure

In this work the calculation was made ab-initio of the structure of bands and DOS of the Topaz with Fluoride (F) and Hydroxide (OH) in the fundamental state, with model TB-LMTO-ASA. The conventional cell of these 2 crystals does not present the same dimensions, due to the ion replacement F by molecules OH. The energy states will be affected by this new structure with OH, doing to vary the behavior of the bands, the DOS and therefore varying the optical properties of the crystal.

(PO4)3- doped [Y0.75Ca0.25]SrBaCu3-x(PO4)xOy compounds with 0.00 ≤ x ≤ 0.30 were synthesized using the solid state reaction technique at normal pressure and temperture conditions. The X-ray diffraction patterns show that for x= 0.0 the samples crystallize into an orthorhombic phase, and for other x values the samples presented a tetragonal structure. The Rietveld method was used to refine the lattice constants. The analysis of structure with Rietveld refinement was done using a model that contains one Cu(2) in a four coordination and not in five coordination in the other 123 tetragonal structures. All samples are superconductors as reported previously [1].

[Y1-xCax]SrBaCu2.80(PO4)0.20Oy samples with 0.10 ≤ x ≤ 0.40 were syntherized using the solid state reaction technique. X-ray diffraction patterns show that all the compounds crystallized into a 123 tetragonal structure. The analysis of the structure with Rietveld refinement were made using a model that contains one Cu(2) in four coordination and not in five coordination as in the other 123 tetragonal structures. This fact allows that Tc increase with Ca concentration. All samples are superconductors as reported in a previous paper.

In this work, we study the crystallization and surface morphology of Cu thin films (exposed to environment) growth on SiO2/Si subsstrates. The samples thermally treated using a tubular furnace bet ween temperature range 250-1000ºC during an elapsed time of 3 hours, after was cooling to a rate of 1.4ºC/min. The crystalization process was measured by X-ray difraction (XRD), meanwhile the surface morphology was observed with scanning electron microscopy (SEM). The results was analyzed and permit us to know the temperature dependecy of the dynamics of surface atoms on the Cu/SiO2 system, are the range between 400-500ºC. During the annealing an oxidation process on sample surfaces occur and the presence of Cu silicides are detected.

The route by chemical solution deposition to grow textured layers of oxide superconductors has received the most scientific attention over the past two decades. Texture plays a predominant role in the technological applications of superconducting layers. We crystallized a precursor solution of Y, Ba and Cu acetates onto single crystal substrates of perovskite structure by the route of chemical solution deposition and we obtained textured superconducting layers of YBa2Cu3O7. We divided our results in two parts: a) We review the epitaxial growth of YBa2Cu3O7 superconducting layers through physical and chemical methods, and b) We study mainly the epitaxial growth of YBa2Cu3O7 superconducting layers by X ray diffraction.

Objetivo: Evaluar los parámetros fisicoquímicos del cuerpo de agua de la laguna y determinar la concentración de elementos químicos en los sedimentos de la laguna El Paraíso. Métodos: Se definieron cuatro puntos de muestreo equidistantes y en zig zag a lo largo la laguna, mediante el muestreo por juicio de experto, teniendo en cuenta el fondo, la extensión, la forma alargada y el leve movimiento horizontal del agua, con una densidad de 1/14 ha . Las muestras fueron tratadas químicamente para eliminar la materia orgánica. Las técnicas utilizadas fueron fluorescencia de rayos X por energía dispersiva y espectroscopia de absorción atómica. Resultados: Los parámetros fisicoquímicos registrados en el cuerpo de agua fueron: temperatura (19,08 °C), oxígeno disuelto (7,18 mg/L), pH (8,5), alcalinidad (184 mg/L), dureza (300 mg/L), transparencia (18,75 cm), pH del sedimento (8,16...