Optical band gap and electrical conductivity studies on near stoichiometric LiNbO3 crystals prepared by VTE process

Bhatt, Rajeev ; Ganesamoorthy, S. ; Bhaumik, Indranil ; Karnal, A. K. ; Gupta, P. K. (2012) Optical band gap and electrical conductivity studies on near stoichiometric LiNbO3 crystals prepared by VTE process Journal of Physics and Chemistry of Solids, 73 (2). pp. 257-261. ISSN 0022-3697

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Official URL: http://www.sciencedirect.com/science/article/pii/S...

Related URL: http://dx.doi.org/10.1016/j.jpcs.2011.10.033

Abstract

Vapour transport equilibrium (VTE) technique was used to prepare near stoichiometric LiNbO3 (NSLN) crystals. Simultaneous occurrence of reduction has been observed during the Li-enrichment that results in the weak absorption bands centred at 1.7, 2.6 and 3.7 eV in the absorption spectrum. Annealing in oxygen atmosphere resulted in decrease in the intensity of these bands. The indirect and direct band-gap energies for NSLN crystals evaluated from absorption studies are reported. The energy of the phonon involved in the indirect transition is ~85 meV (685 cm-1). Near room temperature ac-conductivity measurements reveal lower conductivity for oxygen annealed NSLN crystal in comparison to as prepared NSLN and CLN specimens. The activation energies for ac-conductivity along the z-direction for NSLN and CLN crystals in the temperature range 500-1100 K are 1.03 eV and 0.96 eV, respectively.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:A. Optical Materials; B. Crystal Growth; D. Defects; D. Electrical Properties; D. Optical Properties
ID Code:83445
Deposited On:22 Feb 2012 12:53
Last Modified:22 Feb 2012 12:53

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