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Photoelectrochemical behavior of titanate perovskite solid solutions

Kutty, TRN and Devi, L'Gomathi (1986) Photoelectrochemical behavior of titanate perovskite solid solutions. In: Indian Journal of Technology, 24 (7). pp. 391-398.

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Abstract

Various $MTiO_3$ perovskite solid solns., where M = Ca, Sr, Ba or Pb, were used as ceramic photoanodes in aq. alkali solns., with a view to understanding the photoelectrochem. behavior of the cubic and the tetragonal phases existing in these systems. Chem. etching of the electrode surface in dil. $HNO_3$ + HF enhances the limiting UV photocurrent of both the phases by one order of magnitude. Etching removes the damaged surface layer contg. the electron recombination centers. The photoresponse in the visible light was noticed for the electrodes of the tetragonal phases without mech. polishing and is unaffected by chem. etching. The cubic phases have photoresponse only on mech. polishing and is removed by etching. The visible photoresponse is due to the mid-band gap states arising from the lattice defects such as $Ti_{3+}-V0$ and M-vacancies. In the tetragonal phases, the acceptor states arising from the M-vacancies overlap with the valence band so that the photogenerated holes travels uphill and can align themselves with the O/OH- levels. In the cubic phases these energy states are lifted out of the valence band to form discrete levels within the band gap so that the hole diffusion is restricted.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Indian National Science Academy.
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 02 Jun 2008
Last Modified: 27 Aug 2008 13:24
URI: http://eprints.iisc.ernet.in/id/eprint/14086

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