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Title: Enhancement in the transport critical current density J{sub c} in YBa{sub 2}Cu{sub 3}O{sub 7−δ} added with an insulating nano crystalline YBa{sub 2}HfO{sub 5.5} perovskite

When a magnetic field is applied to type II superconductors, such as YBa{sub 2}Cu{sub 3}0{sub 7−δ} (YBCO), the flux quanta penetrate the material as a regular array of vortices. However when transport currents are applied, they act to move these vortices, thus lowers the critical current density (J{sub c}) as well as destroying superconductivity. The development of microstructures made of YBCO materials has enabled engineers to increase the critical current density, within Type II materials by introducing flux pinning centres into the material. The microstructure and flux pinning properties of YBa{sub 2}Cu{sub 3}O{sub 7−δ} system with varying levels (0-5 wt. %) of a nano perovskite ceramic insulator; YBa{sub 2}HfO{sub 5.5} addition was studied in detail. Orthorhombic YBa{sub 2}Cu{sub 3}O{sub 7−δ} powder was prepared through conventional solid state route and a modified combustion method was used for synthesizing nanocrystalline YBa{sub 2}HfO{sub 5.5}. The structure and microstructure of the samples examined by X-ray diffraction and scanning electron microscopy showed that YBa{sub 2}HfO{sub 5.5} and YBCO remained unreacted even at higher processing temperature without deteriorating the superconducting properties. The scanning electron microscope image shows that YBa{sub 2}HfO{sub 5.5} forms an electrical-network between grains. These observations suggest that the YBa{sub 2}HfO{sub 5.5} addition tomore » the Y-123-compounds improve the electrical connection between superconducting grains and substantial improvements in the relative electrical transport properties of the composites. The variation of sintering temperature, density, critical transition temperature (T{sub c}) and magnetic field dependence of critical current density (J{sub c}) of YBa{sub 2}Cu{sub 3}O{sub 7−δ} having different proportions of YBa{sub 2}HfO{sub 5.5} in the matrix were also studied in detail. It is found that the addition of these elements considerably enhances the flux pinning strength of the system, and there is also an increase of critical temperature (T{sub c}) and critical current density (J{sub c}) up to an optimum value of 8.76 × 10{sup 4} A/cm{sup 2} for a concentration of 2 wt % addition of nano YBa{sub 2}HfO{sub 5.5}. The enhancement of the critical current density in the YBa{sub 2}Cu{sub 3}O{sub 7−δ} - YBa{sub 2}HfO{sub 5.5} samples is attributed to the sustained formation of the insulating and non-reacting YBa{sub 2}HfO{sub 5.5} phase acting as pinning center. The addition of YBa{sub 2}HfO{sub 5.5} in YBa{sub 2}Cu{sub 3}O{sub 7−δ} bulk superconductor also enhances the pinning force density from 3 ×10{sup 6} N/m{sup 3} to 69.6 × 10{sup 6}N/m{sup 3} at 77 K.« less
Authors:
; ;  [1] ;  [2]
  1. Electronic Materials Research Laboratory, Department of Physics, Mar Ivanios College, Thiruvananthapuram- 695 015, Kerala (India)
  2. Department of Physics, St. John's College, Anchal-691306, Kerala (India)
Publication Date:
OSTI Identifier:
22264017
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1576; Journal Issue: 1; Conference: OMTAT 2013: 2. international conference on optoelectronic materials and thin films for advanced technology, Kochi, Kerala (India), 3-5 Jan 2013; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE; BARIUM OXIDES; COPPER OXIDES; CRITICAL CURRENT; CRITICAL TEMPERATURE; CURRENT DENSITY; DENSITY; HIGH-TC SUPERCONDUCTORS; MAGNETIC FIELDS; MAGNETIC FLUX; MICROSTRUCTURE; NANOSTRUCTURES; ORTHORHOMBIC LATTICES; PEROVSKITE; SCANNING ELECTRON MICROSCOPY; SUPERCONDUCTIVITY; X-RAY DIFFRACTION; YTTRIUM OXIDES