Temperature dependence on the electron paramagnetic resonance spectra of natural jasper from Taroko Gorge (Taiwan)
IR@CGCRI: CSIR-Central Glass and Ceramic Research Institute, Kolkata
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| Title |
Temperature dependence on the electron paramagnetic resonance spectra of natural jasper from Taroko Gorge (Taiwan)
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| Creator |
Hemantha Kumar, G N
Parthasarathy, G Chakradhar, R P S Rao, J Lakshmana Ratnakaram, Y C |
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| Subject |
Microstructure and Characterization
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| Description |
Structural properties of natural jasper from Taroko Gorge (Taiwan) have been investigated by means of powder X-ray diffraction, electron paramagnetic resonance (EPR) and Fourier transform infrared spectroscopic techniques. The EPR spectrum at room temperature exhibits a sharp resonance signal at g = 2.007 and two more resonance signals centered at g a parts per thousand 4.3 and 14.0. The resonance signal at g = 2.007 has been attributed to the E' center and is related to a natural radiation-induced paramagnetic defect. Two more resonance signals centered at g a parts per thousand 4.3 and 14.0 are characteristic of Fe(3+) ions. The EPR spectra recorded at room temperature of jasper samples, heat-treated at temperatures ranging from 473 to 1,473 K exhibit marked temperature dependence. The resonance signal corresponding to E' center disappears at elevated temperatures. A broad, intense resonance signal centered at g a parts per thousand 2.0 appears at elevated temperatures. This resonance signal is a characteristic of Fe(3+) ions, which are present as hematite in the jasper sample. The intensity of the resonance signal becomes dominant at elevated temperatures at a parts per thousand yen873 K, masking g a parts per thousand 4.3 and g a parts per thousand 14.0 resonance signals. The EPR spectra of jasper heat-treated at 673 K have been recorded at temperatures between 123 and 296 K. The population of spin levels (N) has been calculated for the broad g a parts per thousand 2.0 resonance signal. It is found that N decreases with decreasing temperature. The linewidth (Delta H) of g a parts per thousand 2.0 resonance signal of the heat-treated jasper is found to increase with decreasing temperature. This has been attributed to spin-spin interaction of the Fe(3+) ions present in the form of hematite in the studied jasper sample.
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| Publisher |
Springer
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| Date |
2010-04
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| Type |
Article
PeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://cgcri.csircentral.net/802/1/chakradhar4'10.pdf
Hemantha Kumar, G N and Parthasarathy, G and Chakradhar, R P S and Rao, J Lakshmana and Ratnakaram, Y C (2010) Temperature dependence on the electron paramagnetic resonance spectra of natural jasper from Taroko Gorge (Taiwan). Physics and Chemistry of Minerals, 37 (4). pp. 201-208. ISSN 0342-1791 |
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| Relation |
http://cgcri.csircentral.net/802/
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