Relaxor dielectric behavior in BaTiO3 substituted BiFeO3–PbTiO3 multiferroic system
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(0.9 − x)BiFeO3–xPbTiO3–0.1BaTiO3 for 0.20 ≤ x ≤ 0.24 ceramic sample was prepared by conventional solid state reaction method. X-ray diffraction analysis confirmed the existence of morphotropic phase boundary (MPB) between monoclinic (Cc) and tetragonal (P4mm) phases. Dielectric measurements revealed the diffusive and dispersive relaxor-like behavior for all the composition in the vicinity of MPB. A broad dielectric maximum was observed in temperature dependent real part of dielectric permittivity for all the compositions. The relaxor-like character was quantified by using Vogel–Fulcher relationship, which yielded activation energy of 0.190–0.225 eV, characteristic frequency of the order of 1012 Hz and freezing temperature ranging 189.0–200.5 °C. The low remnant polarization and high coercive field suggests that the polarization in nanodomains is weakly coupled, which limits the long range ordering of dipoles and alters the system from normal ferroelectric to relaxor ferroelectric. The high value of tetragonal strain (c/a ~ 1.16) results in a weak piezoelectric response for all the ceramic compositions.
KeywordsBaTiO3 Dielectric Permittivity BiFeO3 Morphotropic Phase Boundary Piezoelectric Coefficient
Sanjeev Kumar is thankful to PEC University of Technology, Chandigarh for providing financial assistance in the form of RIPA project. Naveen Kumar is thankful to PEC University of Technology for proving scholarship. He is also thankful to NRC-M (Materials Engineering, IISc, Bengaluru) for carrying out characterization work.
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