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Title: Synthesis and characterization of hollow mesoporous BaFe{sub 12}O{sub 19} spheres

A facile method is reported to synthesize hollow mesoporous BaFe{sub 12}O{sub 19} spheres using a template-free chemical etching process. Hollow BaFe{sub 12}O{sub 19} spheres were synthesized by conventional spray pyrolysis. The mesoporous structure is achieved by alkaline ethylene glycol etching at 185 °C, with the porosity controlled by the heating time. The hollow porous structure is confirmed by SEM, TEM, and FIB-FESEM characterization. The crystal structure and magnetic properties are not significantly affected after the chemical etching process. The formation mechanism of the porous structure is explained by grain boundary etching. - Graphical abstract: Hollow spherical BaFe{sub 12}O{sub 19} particles are polycrystalline with both grains and grain boundaries. Grain boundaries have less ordered structure and lower stability. When the particles are exposed to high temperature alkaline ethylene glycol, the grain boundaries are etched, leaving small grooves between grains. These grooves allow ethylene glycol to diffuse inside to further etch the grains. As the grain size decreases, gaps appear on the particle surfaces, and a porous structure is finally formed. - Highlights: • Two-step synthesis method for hollow mesoporous BaFe{sub 12}O{sub 19} spheres is proposed. • Porosity of the product can be regulated by controlling the second step of chemical etching.more » • The crystal structure and magnetic properties are examined to be little affected during the chemical etching. • The mesoporous structure formation mechanism is explained by grain boundary etching.« less
Authors:
 [1] ;  [2] ; ;  [1] ;  [2] ;  [1] ;  [2]
  1. Center for Materials for Information Technology, The University of Alabama, Tuscaloosa, AL 35487 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
22443544
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 222; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BARIUM COMPOUNDS; CRYSTAL STRUCTURE; ETCHING; FERRITES; GLYCOLS; GRAIN BOUNDARIES; GRAIN SIZE; HEATING; MAGNETIC PROPERTIES; NANOSTRUCTURES; PARTICLES; POLYCRYSTALS; POROSITY; POROUS MATERIALS; PYROLYSIS; SCANNING ELECTRON MICROSCOPY; STABILITY; SURFACES; SYNTHESIS; TRANSMISSION ELECTRON MICROSCOPY