RESUMEN
Nanoparticles of MgSb2O6 were synthesized using a microwave-assisted wet chemistry method, followed by calcination at 700 °C. Their ability to detect different concentrations of propane gas (C3H8) at various operating voltages was evaluated. The material's crystalline phase was identified using X-ray powder diffraction (XRD). The morphology was analyzed by scanning electron microscopy (SEM), finding bar- and polyhedron-type geometries. Through transmission electron microscopy (TEM), we found particle sizes of 8.87-99.85 nm with an average of ~27.63 nm. Employing ultraviolet-visible (UV-Vis) spectroscopy, we found a band gap value of ~3.86 eV. Thick films made with MgSb2O6 powders were exposed to atmospheres containing 150, 300, 400, and 600 ppm of propane gas for dynamic testing. The time-dependent sensitivities were ~61.09, ~88.80, ~97.65, and ~112.81%. In addition, tests were carried out at different operating voltages (5-50 V), finding very short response and recovery times (~57.25 and ~18.45 s, respectively) at 50 V. The excellent dynamic response of the MgSb2O6 is attributed mainly to the synthesis method because it was possible to obtain nanometric-sized particles. Our results show that the trirutile-type oxide MgSb2O6 possesses the ability, efficiency, and thermal stability to be applied as a gas sensor for propane.
RESUMEN
We report here on the development of composite thick films exhibiting hybrid superconducting and ferromagnetic properties, produced through a low-cost, fast, and versatile process. These films were made of high Tc cuprate superconductor Bi2Sr2(Ca,Y)2Cu3O10 (with Y:Ca ratio of 5%) and ferromagnetic perovskite La2/3Ba1/3MnO3, synthesized by melting-quenching annealing process on a MgO substrate. Curie temperature for La2/3Ba1/3MnO3 was determined (~336 K ) by magnetic field assisted thermogravimetric analysis (TGA), while superconducting behavior of Bi2Sr2(Ca,Y)2Cu3O10/MgO films was observed through temperature-dependent resistance measurements. Superconducting features in our hybrid compound were corroborated by temperature-dependent resistivity and magnetic susceptibility.
RESUMEN
Thick films (≥ 1 μm) of YBa2Cu3O7-δ were deposited by the dip-coating method on MgO (100) substrates at room temperature. After that, superconducting films were obtained by using the melt-annealing method with different thermal treatments. These films showed both different crystalline orientations and critical current densities (Jc). Additionally the thick films displayed superconducting transitions (Tc) around 89.5 K and critical current densities ≥ 2x10(4) A/cm² at 77 K and 0t. The highest Tc and Jc values achieved were attributed mainly to the higher oxygen content and the growth of larger grain sizes as determined by XRD and SEM analysis respectively.
Películas gruesas (≥ 1 μtm) de YBa2Cu3 O7-δ se depositaron por el método dip-coating a temperatura ambiente en sustratos de MgO (100). Con el fin de obtener películas superconductoras se utilizó luego el método de fundido-recocido con diferentes tratamientos térmicos. Las películas obtenidas así, mostraron diferentes orientaciones cristalinas y diferentes densidades de corriente crítica (Jc). Las películas presentaron además, transiciones superconductoras (Tc) de aproximadamente 89,5 K y densidades de corriente crítica ≥ 2x10(4) A/cm² a 77 K y 0t. Los valores más altos de Tc y Jc logrados se atribuyeron principalmente al alto contenido de oxígeno y al crecimiento de granos grandes, como se determinó por los métodos de análisis XRD y SEM respectivamente.
Filmes espessos de YBa2Cu3O7-δ (≥ 1mícron) foram depositados por dip-coating de revestimento na temperatura ambiente em substratos de MgO (100). Então, a fim de obter supercondutores filmes, utilizou-se a derreter-annealing método com diferentes tratamentos térmicos. Os filmes obtidos apresentaram orientações de cristal um pouco diferentes, e densidade de corrente crítica (Jc). Os filmes mostraram transições supercondutoras (Tc) de 89,5 K e densidades de corrente crítica (Jc) ≥ 2x104 A/cm2 a 77 K e 0t. Valores de Tc e Jc obtidos foram atribuídas principalmente ao elevado conteúdo de oxígano e crescimento de grãos grande, determinada por DRX e MEV, respectivamente.