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Suan M.S.M.,Nanomaterials Engineering Research Group | Johan M.R.,Nanomaterials Engineering Research Group
Physica C: Superconductivity and its Applications | Year: 2013

The effects of Al2O3 nanoparticles on the structure and superconducting properties of YBa2Cu3O 7-δ matrix prepared by auto-combustion reaction were investigated. The auto-combustion reaction has successfully transformed the Al nitrate added YBCO precursor gels to very fine ashes which yielded to Al 2O3 and YBCO phases after the calcination process at 900 °C. The resultant reactions produced nanocrystalline YBa2Cu 3-O7-5 powders having well distributed Al 2O3 nanoparticles (∼10 nm). The TG/DTA analysis reveals that the Al nitrate added precursor gels decomposed by two-steps reaction at temperature of 180 and 220 °C due to the decomposition of Al nitrate followed by Y, Ba and Cu nitrates. The XRD pattern showed the ortho-rhombic structure of Al2O3 added YBa 2Cu3O7-δ powders having the particle size ranged in between 20 and 25 nm. SEM analysis showed that Al2O 3 nanoparticles were distributed along the grain boundaries of YBa2Cu3O7-δ matrix for the higher mol of Al nitrate. The higher concentration of Al2O3 reacts with the YBa2Cu3O7 matrix to form Al3+ rich spots and diffuse within the YBa2Cu3O 7-δ superconducting matrix which was confirmed by EDX analysis. The samples produced in this work were electrically superconducting at temperature above 85 K as measured by using standard four-probe technique. Formation of alumina precipitates and incorporation of Al3+ into YBa2Cu3O7-δ structure was found to significantly reduce the Tc of pure YBa2Cu 3O7-δ. © 2013 Elsevier B.V. All rights reserved. Source

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