X-ray diffraction experiments, luminescence measurements and first-principles GGA + U calculations on YTaO4

Lim, Thong Leng and Low, Lay Chen and Nazarov, Mihail and Yoon, Tiem Leong and Ahmad Fauzi, M. N. (2013) X-ray diffraction experiments, luminescence measurements and first-principles GGA + U calculations on YTaO4. Computational Materials Science, 77. pp. 13-18. ISSN 0927-0256

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Abstract

The structural and electronic properties of yttrium tantalate (YTaO4) crystal are studied using experimental and first-principles total energy calculations. The band gap of the host lattice from absorption and luminescence experiment is measured to be 5.1 eV. This is close to 5.14 eV reproduced by means of GGA + U approach. In our calculation, we tune both the Hubbard energy U and the exchange parameter J to reproduce the energy gap measured experimentally. It is found that the Hubbard energy U plays a major role in reproducing the experimentally measured energy gap but the exchange parameter J does not. We also calculate the density of states (DOS) using the optimized U to interpret the experimentally measured luminescence spectra. Both the experimental and DOS calculation show that the valence band of tantalate (Ta) system is mainly composed of oxygen (O) 2p states. The lower conduction band is mainly composed of Ta 5d states, while the upper conduction band involves contribution mainly from yttrium (Y) 4d states, with the middle conduction band mainly a mixture of Ta and Y states.

Item Type: Article
Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK7800-8360 Electronics
Divisions: Faculty of Engineering and Technology (FET)
Depositing User: Ms Nurul Iqtiani Ahmad
Date Deposited: 18 Feb 2014 04:15
Last Modified: 18 Feb 2014 04:15
URI: http://shdl.mmu.edu.my/id/eprint/5270

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