Phys. Rev. B 73, 144109 (2006) [5 pages]Symmetry breaking at the nanoscale and diffuse transitions in ferroelectrics: A comparative study of PbSc1∕2Nb1∕2O3 and PbZr0.6Ti0.4O3Received 19 January 2006; published 13 April 2006 We use a first-principles-based approach on periodic nanometric supercells to compare the properties of Pb(Sc1∕2Nb1∕2)O3 (PSN), a ferroelectric with relaxor-like characteristics, and Pb(Zr0.6Ti0.4)O3 (PZT), a normal ferroelectric. Unlike in PZT, we find a breaking of the macroscopic symmetry at the nanoscale and easier polarization fluctuations in PSN, both caused by large internal electric fields. Such features lead to a broad dielectric response and a polarization tail in PSN. A discussion about the possible consequences of such findings for real (i.e., macroscopic) materials is also provided. © 2006 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevB.73.144109
DOI:
10.1103/PhysRevB.73.144109
PACS:
61.43.Bn, 77.22.Ch, 77.80.−e, 77.84.Dy
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