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EPR spectra of a new radiation-induced paramagnetic centre in kaolins

Published online by Cambridge University Press:  02 January 2018

Bernard A. Goodman ,
Niramon Worasith  and
Wen Deng
Bernard A. Goodman*
Affiliation:
College of Physical Science & Engineering, Guangxi University, Nanning, 530004 Guangxi, China State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, 530004 Guangxi, China
Niramon Worasith
Affiliation:
Department of Chemistry, Faculty of Science and Technology, Rajamangala University of Technology Krungthep, 2 Nang Lin Chi Road, Soi Suan Plu, Sathorn, Bangkok, Thailand
Wen Deng
Affiliation:
College of Physical Science & Engineering, Guangxi University, Nanning, 530004 Guangxi, China
*
*E-mail: [email protected]
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Abstract

The EPR spectrum of a previously unreported paramagnetic centre formed in kaolin minerals by exposure to γ radiation is described. This centre, which is referred to here as the ‘C-centre’, was seen initially during an investigation of the radiation dose response of the EPR signal in the natural Lampang kaolin from northern Thailand, and its EPR properties are now presented for a purified sample from this material. They suggest a paramagnetic centre with rhombic symmetry based on O− associated with a single 27Al atom. Computer simulations suggest spin Hamiltonian parameters of g1 = 1.976, g3 = 2.0417 and A(27Al) = 2.10 mT, with g2 ≈ 2.01. This C-centre was also seen as a minor radiationinduced component in both crude and purified Ranong kaolin samples, along with a stronger signal from the B-centre radical. It seems to be associated with the kaolinite component, but was lost on annealing to 300°C after which only the signal from the A-centre was visible.

Keywords

kaolinitefree radicalγ radiation27Al hyperfine structure
Type
Research Article
Information
Clay Minerals , Volume 51 , Issue 5 , December 2016 , pp. 707 - 714
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2016

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References

Allard, Th. & Calas, G. (2009) Radiation effects on clay mineral properties. Applied Clay Science 43, 143–149.Google Scholar
Allard, Th., Balan, E., Calas, G., Fourdrin, C., Morichon, E. & Sorieul, S. (2012) Radiation-induced defects in clay minerals: A review. Nuclear Instruments and Methods in Physics Research Section B, 277, 112–120.Google Scholar
Clozel, B., Allard, T. & Muller, I.-P. (1994) Nature and stability of radiation-induced defects in natural kaolinites: new results and a reappraisal of published works. Clays and Clay Minerals, 42, 657–666.CrossRefGoogle Scholar
Clozel, B., Gaite, J.-M. & Muller, J.-P. (1995) Al-O-Al paramagnetic defects in kaolinite. Physics and Chemistry of Minerals, 22, 351–356.CrossRefGoogle Scholar
Cuttler, A.H. (1980) The behaviour of a synthetic 57Fe-doped kaolin: Mössbauer and electron paramagnetic resonance studies. Clay Minerals, 15, 429–444.CrossRefGoogle Scholar
Hall, P.L. (1980) The application of electron spin resonance spectroscopy to studies of clay minerals: I. Isomorphous substitutions and external surface properties. Clay Minerals, 15, 321–335.Google Scholar
Kuentag, C. & Wasuwanich, P. (1978) Cljay. Economic Geology Bulletin No. 19. Economic Geology Division, Department of Mineral Resources, Thailand (in Thai).Google Scholar
Lombardi, K., Guimarães, J.L., Mangrich, A.S., Mattoso, N., Abbate, M., Schreiner, W.H. & Wypych, F. (2002) Structural and morphological characterization of the PP-0559 kaolinite from the Brazilian Amazon region. Journal of the Brazilian Chemical Society, 13, 270–275.CrossRefGoogle Scholar
Morichon, E., Allard, T., Beaufort, D. & Patrier, P. (2008) Evidence of native radiation-induced paramagnetic defects in natural illites from unconformity-type uranium deposits. Physics and Chemistry of Minerals, 35, 339–346.Google Scholar
Muller, J.-P. & Calas, G. (1993) In: Kaolin Genesis and Utilization (H.H. Murray, W. Bundy & C. Harvey editors). The Clay Minerals Society, Boulder, Colorado, USA.Google Scholar
Rink, W.J. & Odom, A.L. (1991) Natural alpha recoil particle radiation and ionizing radiation sensitivities in quartz detected with EPR: implications for geochron-ometry. International Journal of Radiation Applications and Instrumentation. Part D. Nuclear Tracks and Radiation Measurements, 18, 163–173.Google Scholar
Rink, W.J. & Shimoyama, Y. (1991) Improved detection of EPR signals used in quartz dating. Ancient TL, 9, 33–36.Google Scholar
Worasith, N. & Goodman, B.A. (2012) Influence of particle size on the paramagnetic components of kaolins from different origins. Clay Minerals, 47, 539–557.CrossRefGoogle Scholar
Worasith, N., Goodman, B.A., Jeyachoke, N. & Thiravetyan, P. (2011) Characterisation of modified kaolin from the Ranong deposit Thailand studied by XRD, XRF, SEM, FTIR and EPR. Clay Minerals, 46, 525–545.Google Scholar
Worasith, N., Ninlaphruk, S., Mungpayaban, H. & Goodman, B.A. (2013) Irradiation-induced free radicals in Thai kaolins. Proceedings of the Pure and Applied Chemistry International Conference 2013 (PACCON2013), pp. 294-297.Google Scholar
Yip, K.L. & Fowler, W.B. (1975) Electronic structures of El’ centres in SiO2. Physcial Review B, 11, 2327–2328.Google Scholar