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First-principles calculation of structural and energetic properties for A2Ti2O7 (A = Lu, Er, Y, Gd, Sm, Nd, La)

Published online by Cambridge University Press:  31 January 2011

Z.L. Zhang ,
H.Y. Xiao ,
X.T. Zu ,
Fei Gao  and
W.J. Weber
Z.L. Zhang
Affiliation:
Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu, 610054, People’s Republic of China
H.Y. Xiao*
Affiliation:
Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu, 610054, People’s Republic of China
X.T. Zu
Affiliation:
Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu, 610054, People’s Republic of China
Fei Gao
Affiliation:
Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu, 610054, People’s Republic of China
W.J. Weber*
Affiliation:
Pacific Northwest National Laboratory, Richland, Washington 99352
*
a) Address all correspondence to this author. e-mail: hyxiao@uestc.edu.cn
b) This author was an editor of this journal during the review and decision stage. For the JMR policy on review and publication of manuscripts authored by editors, please refer to http://www.mrs.org/jmr_policy
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Abstract

A first-principles method was used to investigate the structural and energetic properties for A2Ti2O7 (A = Lu, Er, Y, Gd, Sm, Nd, La), including the formation energies of the cation antisite-pair, the anion Frenkel pair that defines anion-disorder, and the coupled cation antisite-pair/anion-Frenkel. It is proposed that the 〈A–O48f〉 interaction may have more significant influence on the radiation resistance behavior of titanate pyrochlores, although the 〈Ti–O48f〉 interactions are relatively stronger than the 〈A–O48f〉 interactions. It was found that the defect formation energies are not simple functions of the A-site cation radii. The formation energy of the cation antisite-pair increases continuously as the A-site cation varies from Lu to Gd, and then decreases continuously with the variation of the A-site cation from Gd to La, in excellent agreement with the radiation-resistance trend of the titanate pyrochlores. The band gaps in these pyrochlores were also measured, and the band gap widths changed continuously with cation radius.

Keywords

DefectsElectronic structureLanthanide
Type
Articles
Information
Journal of Materials Research , Volume 24 , Issue 4 , April 2009 , pp. 1335 - 1341
Copyright
Copyright © Materials Research Society 2009

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