کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9756986 | 1495290 | 2005 | 7 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Fe3+ ions in alkali lead tetraborate glasses-an electron paramagnetic resonance and optical study
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موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آنالیزی یا شیمی تجزیه
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چکیده انگلیسی
Glass systems of composition 90R2B4O7 + 9PbO + 1Fe2O3 (R = Li, Na and K) and 90Li2B4O7 + (10 â x)PbO + xFe2O3 (x = 0.5, 1, 3, 4, 5, 7 and 9 mol%) have been investigated by means of electron paramagnetic resonance (EPR) and optical absorption techniques. The EPR spectra exhibit three resonance signals at g â 6.0, 4.2 and 2.0. The resonances at g â 6.0 and 4.2 are attributed to Fe3+ ions in rhombic and axial symmetry sites, respectively. The g â 2.0 resonance signal is due to two or more Fe3+ ions coupled together with dipolar interaction. The EPR spectra of 1 mol% of Fe2O3 doped in lithium lead tetraborate glass samples have been studied at different temperatures (123-433 K). The intensity of g â 4.2 resonance signal decreases and the intensity of g â 2.0 resonance signal increases with the increase of temperature. The line widths are found to be independent of temperature. The EPR spectra exhibit a marked concentration dependence on iron content. A decrease in intensity for the resonance signal at g â 4.2 with increase in iron content for more than 4 mol% has been observed in lithium lead tetraborate glass samples and this has been attributed to the formation of Fe3+ ion clusters in the glass samples. The paramagnetic susceptibility (Ï) is calculated from the EPR data at various temperatures and the Curie constant (C) has been evaluated from 1/Ï versus T graph. The optical absorption spectrum of Fe3+ ions in lithium lead tetraborate glasses exhibits three bands characteristic of Fe3+ ions in an octahedral symmetry. The crystal field parameter Dq and the Racah interelectronic repulsion parameters B and C have also been evaluated. The value of interelectronic repulsion parameter B (825 cmâ1) obtained in the present work suggests that the bonding is moderately covalent.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy - Volume 62, Issues 1â3, November 2005, Pages 51-57
Journal: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy - Volume 62, Issues 1â3, November 2005, Pages 51-57
نویسندگان
R.P. Sreekanth Chakradhar, G. Sivaramaiah, J. Lakshmana Rao, N.O. Gopal,