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Title: Defect structure of ultrafine MgB{sub 2} nanoparticles

Defect structure of MgB{sub 2} bulk and ultrafine particles, synthesized by solid state reaction route, have been investigated mainly by the aid of X-band electron paramagnetic resonance spectrometer. Two different amorphous Boron (B) precursors were used for the synthesis of MgB{sub 2}, namely, boron 95 (purity 95%–97%, <1.5 μm) and nanoboron (purity >98.5%, <250 nm), which revealed bulk and nanosized MgB{sub 2}, respectively. Scanning and transmission electron microscopy analysis demonstrate uniform and ultrafine morphology for nanosized MgB{sub 2} in comparison with bulk MgB{sub 2}. Powder X-ray diffraction data show that the concentration of the by-product MgO is significantly reduced when nanoboron is employed as precursor. It is observed that a significant average particle size reduction for MgB{sub 2} can be achieved only by using B particles of micron or nano size. The origin and the role of defect centers were also investigated and the results proved that at nanoscale MgB{sub 2} material contains Mg vacancies. Such vacancies influence the connectivity and the conductivity properties which are crucial for the superconductivity applications.
Authors:
;  [1] ; ;  [2] ;  [3] ;  [4]
  1. Department of Chemistry, Koc University, Rumelifeneri Yolu, Sariyer, Istanbul (Turkey)
  2. Institut für Physikalische Chemie, Universität Freiburg, Albertstr. 21 79104 Freiburg (Germany)
  3. Freiburger Materialforschungzentrum (FMF) für Physikalische Chemie, Universität Freiburg, Stefan-Meier Str. 21 79104 Freiburg (Germany)
  4. Pavezyum Chemicals, Orhanlı Mah. Ulu Sokak, No. 3, 34956 Tuzla, Istanbul (Turkey)
Publication Date:
OSTI Identifier:
22392025
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 20; 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; BORON; BY-PRODUCTS; CRYSTAL DEFECTS; ELECTRON SPIN RESONANCE; MAGNESIUM BORIDES; MAGNESIUM OXIDES; NANOPARTICLES; NANOSTRUCTURES; SUPERCONDUCTIVITY; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION