Volume 119, Number 3, August 2017
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||17 October 2017|
Direct evidence of the existence of Mn3+ ions in MnTiO3
1 School of Basic Sciences, Indian Institute of Technology Mandi - Kamand, Himachal Pradesh-175005, India
2 School of Engineering, Indian Institute of Technology Mandi - Kamand, Himachal Pradesh-175005, India
Received: 4 June 2017
Accepted: 18 September 2017
We investigate the room temperature electronic properties of MnTiO3 synthesised by different preparation conditions. For this purpose, we prepared MnTiO3 under two different cooling rates, one is naturally cooled while the other is quenched in liq.nitrogen. The samples were studied using optical absorbance, photoemission spectroscopy and band structure calculations. We observe significant changes in the structural parameters as a result of quenching. Interestingly, in the parent compound, our combined core level, valence band and optical absorbance studies give evidence of the Mn existence in both 2+ and 3+ states. The fraction of Mn3+ ions has been found to increase on quenching MnTiO3 suggests an increase in oxygen non-stoichiometry. The increase in the fraction of the Mn3+ ions has been manifested a) as slight enhancement in the intensity of the optical absorbance in the visible region. There occurs persistent photo-resistance when the incident light is terminated after shining; b) in the behaviour of the features (close to Fermi level) in the valence band spectra. Hence, the combined analysis of the core level, valence band and optical absorbance spectra suggests that the charge carriers are hole like which further leads to the increase in the electrical conductivity of the quenched sample. The present results provide a recipe to tune the optical absorption in the visible range for its applications in optical sensors, solar cell, etc.
PACS: 79.60.-i – Photoemission and photoelectron spectra / 78.56.-a – Photoconduction and photovoltaic effects / 75.47.Lx – Magnetic oxides
© EPLA, 2017
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