Reshak, A. H. and Auluck, Sushil (2016) Influence of an oxygen vacancy on the electronic structure of the asymmetric mixed borate-carbonate Pb7O(OH)(3)(CO3)(3)(BO3). RSC Advances, 6 (23). pp. 18965-18972. ISSN 2046-2069

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Abstract

The influence of an oxygen vacancy on the electronic properties of a mixed borate-carbonate compound Pb7O(OH)(3)(CO3)(3)(BO3) is studied. We report calculations of the electronic band structure, the angular momentum resolved projected density of states and the valence electronic charge density distribution. The full-potential method within the generalized gradient approximation (PBE-GGA) and a recently modified Becke-Johnson potential (mBJ) shows an indirect band gap of 3.34 eV (PBE-GGA) and 3.56 eV (mBJ) for Pb7O(OH)(3)(CO3)(3)(BO3), while it is a direct gap of 1.10 eV (PBE-GGA) and 1.61 eV (mBJ) for the compound Pb-7(OH)(3)(CO3)(3)(BO3) which has one O vacancy. Thus, the O vacancy causes a significant reduction in the band gap and also changes it from indirect to direct. The band gap reduction in Pb-7(OH)(3)(CO3)(3)(BO3) is attributed to the appearance of new energy bands inside the energy gap of Pb7O(OH)(3)(CO3)(3)(BO3). The angular momentum resolved projected density of states for Pb7O(OH)(3)(CO3)(3)(BO3) and Pb-7(OH)(3)(CO3)(3)(BO3) show that there exists a strong hybridization between B and O of the BO3 group and between C and O of the CO3 group. The valence electronic charge density for both compounds is presented. It reveals the origin of chemical bonding characteristics and the influence of the O vacancy. After a careful comparison, it is found that the crystal structure of Pb7O(OH)(3)(CO3)(3)(BO3) without an O vacancy can be considered as a parent phase of defect Pb-7(OH)(3)(CO3)(3)(BO3).

Item Type:	Article
Additional Information:	Copyright for this article belongs to M/s Royal Society of Chemistry.
Subjects:	Chemistry
Divisions:	UNSPECIFIED
Depositing User:	Dr. Rajpal Walke
Date Deposited:	30 Jan 2018 08:12
Last Modified:	30 Jan 2018 08:12
URI:	http://npl.csircentral.net/id/eprint/2256

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