Electron paramagnetic resonance and optical absorption studies of manganese ions doped in polyvinyl(alcohol) complexed with polyethylene glycol polymer films

• Published in: Ionics 2012-07, Vol.18 (7), p.695-701
• Main Authors: Rajavardhana Rao, T., Omkaram, I., Sumalatha, B., Veera Brahmam, K., Linga Raju, Ch
• Format: Article
• Language: English
• Subjects: Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Electrochemistry; Energy Storage; Optical and Electronic Materials; Original Paper; Renewable and Green Energy
• ISSN: 0947-7047; 1862-0760
• DOI: 10.1007/s11581-012-0666-3

Electron paramagnetic resonance (EPR), optical absorption, and infrared spectral studies have been carried out on Mn 2+ ions doped in poly(vinyl alcohol) (PVA) complexed with polyethylene glycol (PEG) films prepared by solution cast technique. The EPR spectra of 0.25 mol% Mn 2+ ions doped polymer complex (PVA+PEG) at room temperature exhibit sextet hyperfine structure (hfs), centered at g ≈ 1.99. The spin–Hamiltonian parameter values indicate that the ground state of Mn 2+ ion is d 5 and the site symmetry around Mn 2+ ions in tetragonally distorted octahedral site. The spin concentration participating in the resonance is measured as a function of temperature and it is observed that it obeys Boltzmann’s law. The paramagnetic susceptibility ( χ ) is calculated from the EPR data at various temperatures (93–333 K) and it obeys the Curie–Weiss law. The optical absorption spectra exhibits two bands which are assigned to 6 A 1g (S)→ 4 A 1g (G) or 4 E g (G) and 6 A 1g (S)→ 4 T 2g (G) transitions. The infrared spectrum exhibits few bands due to the presence of O–H, C–H, and C=C groups.