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

Abstract

LaCaBaCu 3 O 7 (La1113) is a superconductor below T C(onset) =80K and its structure is similar to the tetragonal YBCO. In this work the magnetic properties of a bulk La1113 sample are reported and compared to those of YBCO superconductor. We explore a possibly relation of this property to its particular crystalline structure, particularly to the oxygen deficiency. In contrast to a bulk YBCO, some magnetic characteristics of La1113 below T C are: the magnetic flux can penetrate easily the bulk in its vortex region (H C1 <H<H C2 ), fewer fields can be trapped than in YBCO, small currents are able to flow in the bulk and possible applications of La1113 are restricted under applied fields lower than 10KOe and in the range of 41K-76K. The critical current density is determined by currents flowing through grain boundaries. Peak effect is observed and it is probably caused by secondary phases or from clusters of oxygen vacancies acting as field induced pins. A first magnetic phase diagram for La1113 showing the irreversibility line is reported here. Finally, we found that the specific heat capacity of La1113 is 37.2mJ/K 2 mol.

Attaching Thiolated Superconductor Grains on Gold Surfaces for Nanoelectronics Applications

“…31) However in contrast to YBCO which at 77 K can support external magnetic fields up to 6 Â 10 4 Oe (or even more depending on its purity), 32) the La1113 can support less than 1 Â 10 4 Oe under the same conditions without losing its superconductivity. 33) This apparent ''disadvantage'' of La1113 could be useful for the fabrication of superconducting transistors controlled by relatively low applied magnetic fields as a transistor gate. Figure 5 shows a design of an external magnetic field gated superconducting transistor, in which, with the help of alkane (di)thiols, a superconductor nanograin bridges two gold (or other metal) electrodes, the source (S) and the drain (D).…”

The effect of additives on behavior of the high temperature LaxY1-xBa2Cu3O7-δ superconductor

“…whereas, at x=0.5 the composition is losing its superconductivity. It is known that a small changes in the crystalline structure of a high temperature cuprate superconductor (HTCS) produce large changes in its magnetic properties [31]. The structural changes are produced by chemical substitutions of cations or anions.…”

“…Thus, altering the position and occupancy of the atoms situated in the superconducting planes CuO 2 and also leads to increasing (or decreasing) the superconducting critical temperature (Tc). Indeed Luis et al [31] reported that by changing the oxygen content in the superconductor YBa 2 Cu 3 O 7 (YBCO-7) to ≤ 6.4, the occupancy of the oxygen situated in the Cu-O chains decreases and the crystalline structure changes from orthorhombic to tetragonal where the superconductivity is destroyed. transition at Tc = 95 K. A slightly higher Tc= 96 K for the x=0.4 sample behavior followed by a superconducting transition at x=0.6, Tc= 83 K [26,32].…”

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

“…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.…”