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|title: ||Defect chemistry and relaxation processes: effect of an amphoteric substituent in lead-free BCZT ceramics|
|authors: ||Coondoo, Indrani|
Kholkin, Andrei L.
|issue date: ||2016|
|publisher: ||The Royal Society of Chemistry|
|abstract: ||The effect of praseodymium (Pr), an amphoteric substituent, on phase transition, dielectric relaxation and
electrical conductivity has been studied and analysed in 0.5Ba(Zr0 2Ti0 8)O3-0.5(Ba0 7Ca0 3)TiO3 (BCZT)
ceramics synthesized by a solid state reaction method. Structural investigations showed co-existence of
two phases tetragonal (P4mm) and rhombohedral (R3m) for compositions with x r 0.05 wt% Pr.
Temperature dependent dielectric studies revealed two phase transitions rhombohedral (R) - tetragonal
(T) and T - cubic (C) that gradually evolved into one T - C transition for x 4 0.05 wt% Pr in BCZT.
A dielectric relaxation behaviour was observed in the temperature range of 275 500 1C that was attributed
to the localized relaxation process (short-range hopping motion of oxygen vacancies) in the bulk of the
material. Grain and grain boundary conductivity evaluated from the impedance data revealed that Pr acts
as a donor dopant for x r 0.05 wt% while it is an acceptor for higher concentration, in accordance with
XRD observations. Defect chemistry analysis for better interpretation of the acquired data is presented.
Frequency and temperature dependent ac conductivity studies were also performed and the obtained
activation energy values were associated with possible conduction mechanisms.|
|publisher version/DOI: ||http://doi.org/10.1039/c6cp06244j|
|source: ||Physical Chemistry Chemical Physics|
|appears in collections||CICECO - Artigos|
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