Structural and electrical properties of Gd-doped BiFeO3:BaTiO3 (3:2) multiferroic ceramic materials

• Published in: Journal of materials science. Materials in electronics Vol. 30; no. 3; pp. 2154 - 2165
• Main Authors: Kar, B. S., Goswami, M. N., Jana, P. C., Das, P. S.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-02-2019; Springer Nature B.V
• Subjects: Barium titanates; Bismuth ferrite; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Crystal structure; Doping; Electric fields; Electrical properties; Electrical resistivity; Ferromagnetism; Gadolinium; Grain size; Grain size distribution; High temperature; Materials Science; Multiferroic materials; Nyquist plots; Optical and Electronic Materials; Polarization; Superconducting quantum interference devices; X-ray diffraction
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-018-0487-x

Gadolinium doped BiFeO
3
:BaTiO
3
(3:2) polycrystalline multiferroic ceramics have been prepared by high-temperature solid state reaction technique. X-ray diffraction (XRD) analysis at room temperature of the prepared materials confirmed the formation of the compounds with rhombohedral crystal structure. The average particle size of as prepared samples have been found in the range of 35 nm to 55 nm for different doping concentrations. The average grain size of as prepared samples are less than 100 nm which is confirmed from SEM study. The SEM of annealed compounds showed the uniform distribution of grains and the formation of dense ceramic with average grain size in the order of 4 µm. Dielectric studies of the materials reveals that the dielectric constant (
ε
r
) and tangent loss (tan δ) decreases with doping concentrations at room temperature. The variation of
ε
r
and tan δ with temperature was explained on the basis of Maxwell–Wagner mechanism. The values of grain resistance (
R
b
) and grain capacitance (
C
b
) were obtained from Nyquist plots for the different doping concentrations at 300 °C. The activation energy (
E
a
) was calculated from the curve of frequency dependent ac conductivity (
σ
a
c
) within the range 0.19 eV to 0.45 eV. The remnant polarization of the samples (0.53 µC/cm
2
) was measured from polarization versus electric field (P–E) hysteresis curves. The ferromagnetic behaviour of the Gd-doped BiFeO
3
:BaTiO
3
(3:2) sample has been studied by SQUID for the lowest doping concentration. The value of remnant magnetization was found 0.0235 emu/g at room temperature.