Electron paramagnetic resonance of natural and gamma-irradiated alunite and kaolin mineral powders

Koksal F., Koseoglu R., Saka I., Basaran E., Sener F.

RADIATION EFFECTS AND DEFECTS IN SOLIDS, vol.159, no.6, pp.393-398, 2004 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 159 Issue: 6
  • Publication Date: 2004
  • Doi Number: 10.1080/10420150412331304169
  • Journal Name: RADIATION EFFECTS AND DEFECTS IN SOLIDS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED)
  • Page Numbers: pp.393-398
  • Keywords: electron paramagnetic resonance, free radicals, kaolin, alunite, HOLE ALUMINUM CENTERS, SPIN-RESONANCE, MAGNETIC-PROPERTIES, CRYSTALLINE SIO2, ALPHA-QUARTZ, RADICALS, CALCITE, LITHIUM, ACIDS
  • Ondokuz Mayıs University Affiliated: No

Abstract

Natural alunite and kaolin minerals obtained from West Anatolia were investigated by electron paramagnetic resonance (EPR) in natural and gamma-irradiated states at room temperature and at 113 K. The paramagnetic centres at ambient temperature in natural alunite were attributed to the (C) over dot H 2OH, (C) over dot O-3(-), (S) over dot O-2(-), (C) over dot O-2(-) and [AlO4 ](0) radicals. In natural kaolin, the paramagnetic centres were attributed to the (C) over dot O-3(-), (S) over dot O-2(-) (C) over dot O-2(-) and [AlO4](0) radicals. The gamma-irradiation does not produce any detectable effects on these radicals. At 113 K, the lines for (C) over dot H2OH could not be observed well, probably due to the anisotropic behaviour of the hyperfine interaction of the methylene protons, but the lines for [AlO4](0) centres were found to be perfectly observable at above 20 mW microwave power in both alunite and kaolin powders before and after gamma-irradiation. The EPR parameters of the observed paramagnetic centres were reported.