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Title: High temperature Ir segregation in Ir-B ceramics: Effect of oxygen presence on stability of IrB2 and other Ir-B phases

The formation of IrB2, IrB1.35, IrB1.1 and IrB monoboride phases in the Ir–B ceramic nanopowder was confirmed during mechanochemical reaction between metallic Ir and elemental B powders. The Ir–B phases were analysed after 90 h of high energy ball milling and after annealing of the powder for 72 h at 1050°C in vacuo. The iridium monoboride (IrB) orthorhombic phase was synthesised experimentally for the first time and identified by powder X-ray diffraction. Additionally, the ReB2 type IrB2 hexagonal phase was also produced for the first time and identified by high resolution transmission electron microscope. Ir segregation along disordered domains of the boron lattice was found to occur during high temperature annealing. Furthermore, these nanodomains may have useful catalytic properties.
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [1]
  1. Univ. of Central Florida, Orlando, FL (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
OSTI Identifier:
1265282
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Advances in Applied Ceramics
Additional Journal Information:
Journal Volume: 114; Journal Issue: 8; Journal ID: ISSN 1743-6753
Publisher:
Taylor & Francis
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE iridium diboride; mechanochemistry; ceramics; Ir segregation; metal clustering; catalyst