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Phys. Rev. B 75, 014111 (2007) [5 pages]

Effects of vacancies on the properties of disordered ferroelectrics: A first-principles study

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L. Bellaiche1, Jorge Íñiguez2, Eric Cockayne3, and B. P. Burton3
1Physics Department, University of Arkansas, Fayetteville, Arkansas 72701, USA
2Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra (Barcelona), Spain
3Ceramics Division, Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8520, USA

Received 8 September 2006; revised 2 November 2006; published 22 January 2007

A first-principles-based model is developed to investigate the influence of lead vacancies on the properties of the disordered Pb(Sc1∕2Nb1∕2)O3 (PSN) ferroelectric. Lead vacancies generate large, inhomogeneous, electric fields that reduce barriers between energy minima for different polarization directions. This naturally explains why disordered ferroelectrics with significant lead vacancy concentrations have broadened dielectric peaks at lower temperatures, and why lead vacancies smear properties in the neighborhood of the ferroelectric transition in PSN. We also reconsider the conventional wisdom that lead vacancies reduce the magnitude of dielectric response.

© 2007 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevB.75.014111
DOI:
10.1103/PhysRevB.75.014111
PACS:
61.72.Bb, 61.43.−j, 61.72.Ji, 77.84.Dy