Relaxor Behavior in Ordered Lead Magnesium Niobate (PbMg1/3Nb2/3O3) Thin Films

Smitha Shetty, Anoop Damodaran, Ke Wang, Yakun Yuan, Venkat Gopalan, Lane Martin, Susan Trolier-McKinstry

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Abstract

The local compositional heterogeneity associated with the short-range ordering of Mg and Nb in PbMg1/3Nb2/3O3 (PMN) is correlated with its characteristic relaxor ferroelectric behavior. Fully ordered PMN is not prepared as a bulk material. This work examines the relaxor behavior in PMN thin films grown at temperatures below 1073 K by artificially reducing the degree of disorder via synthesis of heterostructures with alternate layers of Pb(Mg2/3Nb1/3)O3 and PbNbO3, as suggested by the random-site model. 100 nm thick, phase-pure films are grown epitaxially on (111) SrTiO3 substrates using alternate target timed pulsed-laser deposition of Pb(Mg2/3Nb1/3)O3 and PbNbO3 targets with 20% excess Pb. Selected area electron diffraction confirms the emergence of (1/2, 1/2, 1/2) superlattice spots with randomly distributed ordered domains as large as ≈150 nm. These heterostructures exhibit a dielectric constant of 800, loss tangents of ≈0.03 and 2× remanent polarization of ≈11 µC cm−2 at room temperature. Polarization–electric field hysteresis loops, Rayleigh data, and optical second-harmonic generation measurements are consistent with the development of ferroelectric domains below 140 K. Temperature-dependent permittivity measurements demonstrate reduced frequency dispersion compared to short range ordered PMN films. This work suggests a continuum between normal and relaxor ferroelectric behavior in the engineered PMN thin films.

Original languageEnglish (US)
Article number1804258
JournalAdvanced Functional Materials
Volume29
Issue number5
DOIs
StatePublished - Feb 1 2019

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All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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