Structural, magnetic, and magnetodielectric correlations in multiferroic Bi5Ti3FeO15

• Published in: Journal of materials science. Materials in electronics Vol. 32; no. 16; pp. 21379 - 21394
• Main Authors: Jena, Rasmita, Chandrakanta, K., Abdullah, Md. F., Pal, P., Kaushik, S. D., Singh, A. K.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-08-2021; Springer Nature B.V
• Subjects: Antiferromagnetism; Antisite defects; Characterization and Evaluation of Materials; Chemistry and Materials Science; Crystal defects; Crystal structure; Diffraction patterns; Distortion; Electric fields; Ferroelectricity; Fluorite; Iron; Magnetic fields; Magnetoimpedance; Materials Science; Multiferroic materials; Optical and Electronic Materials; Perovskites; Polarization; Raman spectra; Room temperature; Titanium
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-021-06641-8

We have investigated the structural, magnetic, magnetodielectric, and magnetoimpedance characteristics of Aurivillius-structured Bi
5
Ti
3
FeO
15
(BTFO) synthesized by a generic solid-state reaction route. Rietveld refinement of X-ray diffraction pattern at room temperature (RT) confirms orthorhombic crystal structure (space group
A2
1
am
). In BTFO, octahedral distortion of the perovskite unit occurs due to antisite defects Fe/Ti in the BO
6
site, which results in the formation of Fe–O clusters. Raman spectra also reveal Ti/FeO6 octahedral distortion due to the vibration of Bi ions in the perovskite layer. Magnetic field-dependent magnetization (
M
–
H
) and electric field-dependent polarization (
P
–
E
) measurement at RT indicate the existence of multiferroic behavior in BTFO. The
M
–
H
hysteresis at 5 K suggests that the non-interacting superparamagnetic state is dominant over the local short-range antiferromagnetic (AFM) ordering. The AFM interaction arises due to the random distribution of antisite defects Fe/Ti causing the distorted Fe–O octahedral unit. These canted spin interact via the Dzyaloshinskii–Moriya (DM) interaction. The superexchange interaction between the Fe–O–Fe ions is stronger than the next-nearest-neighboring Fe–O–O–O–Fe interaction. This happens due to the intermediate fluorite-like layer (Bi
2
O
2
)
2+
, which opposes the long-range exchange interaction. The negative magnetodielectric (MD) effect is more prominent at low frequency (~ 100 Hz) due to the extrinsic contribution. In contrast, in the high-frequency region (> 50 kHz), the intrinsic contribution dominates, which is further ascertained by magnetoimpedance (MI) measurement. The maximum magnitude of the MD effect is found to be ~ 0.32% at a magnetic field of 13 kOe at 150 K. Lastly, the ferroelectric characteristic of the sample is obtained from the
P
–
E
measurement with a polarization value of 4.35 µC/cm
2
with an applied electric field of 70 kV/cm.