Synthesis of YBa₂Cu₃O_7-δ Using Oxalate Precursors and Sol-Gel Method

Abstract

In this work we present the results about the preparation of the superconductor YBa2Cu3O7-δ (Y123) by sol-gel method using oxalate precursors. Samples were prepared by dissolving stoichiometric mixtures of Y(OOCCH3).4H2O, Ba(OOCCH3)2 and Cu(OOCCH3)2.H2O acetates in aqueous solution of oxalic acid, HCOO-COOH. The particulate sols obtained (2g.) were divided in two parts (1g. each one), from which the first one (sample A) was grinded, pellet, calcined (860°C) and sinterised at 860°C in oxidizing atmosphere, the second part (sample B) was grinded, pellet, calcined at 880°C and finally sinterized at 880°C in the same conditions, the XRD revels the superconductor Y123 is formed in the first sample, but coexisting with remarkable presence of the secondary phases: CuO, BaCu3O4, BaCO3 and BaCuO2, while in sample B the XRD reveals the obtention of high purity monophase Y123, the ac susceptibility measurement using a Quantum Design (SQUID) magnetometer indicates TC(onset)=92K for this sample, moreover the Rietveld refinement was done taking the orthorhombic Pmmm Y123 spatial group as a model, this suggest the cell´s parameters a=3.839Å, b=3.899 Å and c=11.702Å as reported in the literature. Therefore for the preparation of Y123-superconductor using oxalate precursors, the optimus sintering temperature is 880°C.

Magnetic Properties of the Superconductor LaCaBaCu3O7~!2010-02-11~!2010-04-01~!2010-06-29~!

“…Secondary phases are commonly found after the preparation of HTCSs. The phases obtained for YBCO by the preparation technique used here are Y 2 BaCuO 5 , CuO and BaCuO 2 [26], whereas for La1113 are CaO, Ca 2 CuO 3 , CuO and BaCuO 2 [11]. The presence of secondary phases is a possible explanation for the origin of the fishtail or peak effect [28,29] as we will discuss below.…”

“…The first step comprises the preparation of the solvent obtained by dissolution of stoichiometric amounts of Ca(OOCCH 3 [26]. The final samples consisted of polycrystalline bulk of La1113 and YBCO.…”

A Fluorine-Free Oxalate Route for the Chemical Solution Deposition of YBa2Cu3O7 Films

“…Figure 1 provides a schematic representation of the manufacturing process of the YBCO film followed in this work. Initially a precursor solution is obtained by sol-gel similar to previous reports [44][45][46][47][48]. Stoichiometric amounts of yttrium, barium and copper acetates (Y(OOCCH 3 ) 3 .4H 2 O, Ba(OOCCH 3 ) 2 and Cu(OOCCH 3 ) 2 .2H 2 O respectively) were mixed and completely dissolved in a solution of ethanol (C 2 H 5 OH) and oxalic acid (H 2 C 2 O 4 ) (1:1 ratio).…”

Visión retrospectiva de los 14 primeros años de investigación en materiales óxidos cerámicos superconductores en la UNMSM

“…En nuestro grupo, las primeras síntesis de las cerámicas de alta Tc fueron preparadas a través de la reacción de estado sólido. Posteriormente se realizaron mediante un proceso químico denominado sol-gel, estos métodos y sus posteriores tratamientos térmicos se encuentran claramente descritos en las referencias [10][11][12][13][14][15][16].…”

“…Los resultados obtenidos en este periodo de investigación son publicados en la Revista de Investigación de Física de la UNMSM [44], en la Revista Peruana de Química e Ing. Química de la UNMSM [45][46][47], en la revista de la Sociedad Química del Perú [9,14,[48][49][50], en el Advances in Science and Technology [16], en el Journal of Physics and Chemistry of Solids [51,52], en el Open Journal of Superconductivity [53], en el Japanese Journal of Applied Physics [39] y en el Hyperfine Interactions [54] La investigación de materiales superconductores es una disciplina que requiere de proyectos financiados para poder solventar no sólo la compra de los materiales precursores sino las medidas de caracterización en costosos equipos y para el acceso a la información de trabajos de otros investigadores. Por citar un par de ejemplos, una medida de la susceptibilidad magnética de una muestra de 100 mg en el rango de temperatura de 5 a 100 K usando un magnetómetro con sensor SQUID cuesta aproximadamente 300 Nuevos Soles, 75 euros; el acceso a la literatura científica, significa un costo elevado, medio millón de dólares americanos por año en suscripciones a revistas de investigación.…”