Anomalous phase transitions of lead-free piezoelectric xNa0.5Bi0.5TiO3(1x)BaTiO3 solid solutions with enhanced phase transition temperatures

K. Datta, P. A. Thomas, and K. Roleder
Phys. Rev. B 82, 224105 – Published 10 December 2010

Abstract

Temperature-dependent structural phase transitions and dielectric properties for a series of xNa0.5Bi0.5TiO3(1x)BaTiO3 (NBT-BT) samples where x ranges from 0.05 to 0.30 have been investigated. Non-ambient x-ray diffraction together with dielectric data as a function of temperature have demonstrated an enhancement in the ferroelectric to paraelectric phase transition temperature with the increase in NBT content, including inhibition of two well-known low-temperature polymorphic phase transitions of BaTiO3. Anomalous dielectric response has been observed for samples with x0.20 suggesting a crossover from a first-order to a second-order phase transition. The critical point lies between x=0.15 and x=0.20. Deviation from the classical Curie-Weiss law has been seen for samples having x0.10. A modified Curie-Weiss law was employed to model the dielectric response in the paraelectric phase and the maximum value of the critical exponent γ was found to be 1.45 for x=0.30. It is suggested that the dielectric properties are heavily influenced by the induced strain upon doping rather than chemical inhomogeneities and structural disorder, which are common occurrences in doped ferroelectrics.

    • Received 28 June 2010

    DOI:https://doi.org/10.1103/PhysRevB.82.224105

    ©2010 American Physical Society

    Authors & Affiliations

    K. Datta and P. A. Thomas*

    • Department of Physics, University of Warwick, Coventry-CV4 7AL, United Kingdom

    K. Roleder

    • Institute of Physics, Silesian University, Katowice, Poland

    • *p.a.thomas@warwick.ac.uk

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    Issue

    Vol. 82, Iss. 22 — 1 December 2010

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