Dielectric anomalies due to grain boundary conduction in chemically substituted BiFeO3

Shalini Kumari; N. Ortega; A. Kumar; S. P. Pavunny; J. W. Hubbard; C. Rinaldi; G. Srinivasan; J. F. Scott; Ram S. Katiyar

doi:10.1063/1.4915110

Dielectric anomalies due to grain boundary conduction in chemically substituted BiFeO₃

Shalini Kumari^*, N. Ortega, A. Kumar, S. P. Pavunny, J. W. Hubbard, C. Rinaldi, G. Srinivasan, J. F. Scott, Ram S. Katiyar

^*Corresponding author for this work

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Abstract

We describe systematic studies on Nd and Mn co-doped BiFeO₃, i.e., (Bi_0.95Nd_0.05) (Fe_0.97Mn_0.03)O₃ (BNFM) polycrystalline electroceramics. Raman spectra and X-ray diffraction patterns revealed the formation of rhombohedral crystal structure at room temperature, and ruled out structural changes in BiFeO₃ (BFO) after low percentage chemical substitution. Strong dielectric dispersion and a sharp anomaly around 620K observed near the Neel temperature (T_N similar to 643K of BFO) support strong magneto-dielectric coupling, verified by the exothermic peak in differential thermal data. Impedance spectroscopy disclosed the appearance of grain boundary contributions in the dielectric data in the region, and their disappearance just near the Neel temperature suggests magnetically active grain boundaries. The resistive grain boundary components of the BNFM are mainly responsible for magneto-dielectric coupling. Capacitive grain boundaries are not observed in the modulus spectra and the dielectric behavior deviates from the ideal Debye-type. The ac conduction studies illustrate short-range order with ionic translations assisted by both large and small polaron hopping. Magnetic studies indicate that the weak antiferromagnetic phase of BNFM ceramics is dominated by a strong paramagnetic response (unsaturated magnetization even at applied magnetic field of 7 T). The bulk BNFM sample shows a good in-plane magnetoelectric coupling (ME) coefficient.

Original language	English
Article number	114102
Number of pages	13
Journal	Journal of Applied Physics
Volume	117
Issue number	11
DOIs	https://doi.org/10.1063/1.4915110
Publication status	Published - 21 Mar 2015

Keywords

Impedance spectroscopy analysis
Doped BiFeO3
Electrical-Properties
Magnetic-properties
Raman-scattering
Thin-films
Ferroelectric properties
Multiferroic properties
Neutron-diffraction
Leakage current

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10.1063/1.4915110

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Cite this

@article{554bd35ecf7e4029ab254d53cd9eb8b0,

title = "Dielectric anomalies due to grain boundary conduction in chemically substituted BiFeO3",

abstract = "We describe systematic studies on Nd and Mn co-doped BiFeO3, i.e., (Bi0.95Nd0.05) (Fe0.97Mn0.03)O3 (BNFM) polycrystalline electroceramics. Raman spectra and X-ray diffraction patterns revealed the formation of rhombohedral crystal structure at room temperature, and ruled out structural changes in BiFeO3 (BFO) after low percentage chemical substitution. Strong dielectric dispersion and a sharp anomaly around 620K observed near the Neel temperature (TN similar to 643K of BFO) support strong magneto-dielectric coupling, verified by the exothermic peak in differential thermal data. Impedance spectroscopy disclosed the appearance of grain boundary contributions in the dielectric data in the region, and their disappearance just near the Neel temperature suggests magnetically active grain boundaries. The resistive grain boundary components of the BNFM are mainly responsible for magneto-dielectric coupling. Capacitive grain boundaries are not observed in the modulus spectra and the dielectric behavior deviates from the ideal Debye-type. The ac conduction studies illustrate short-range order with ionic translations assisted by both large and small polaron hopping. Magnetic studies indicate that the weak antiferromagnetic phase of BNFM ceramics is dominated by a strong paramagnetic response (unsaturated magnetization even at applied magnetic field of 7 T). The bulk BNFM sample shows a good in-plane magnetoelectric coupling (ME) coefficient.",

keywords = "Impedance spectroscopy analysis, Doped BiFeO3, Electrical-Properties, Magnetic-properties, Raman-scattering , Thin-films, Ferroelectric properties, Multiferroic properties, Neutron-diffraction, Leakage current",

author = "Shalini Kumari and N. Ortega and A. Kumar and Pavunny, {S. P.} and Hubbard, {J. W.} and C. Rinaldi and G. Srinivasan and Scott, {J. F.} and Katiyar, {Ram S.}",

note = "This work was supported by the DOE Grant DE-FG02-08ER46526 and NSF (Fellowship EPS 01002410). N. Ortega acknowledges financial support from the NSF-RII Grant R10701525 and Dr. Ashok Kumar was supported by DOD Grant W911NF-11-1-0204. The authors thank Josue Ortiz Morales (MCC) for his help in the XPS measurements.",

year = "2015",

month = mar,

day = "21",

doi = "10.1063/1.4915110",

language = "English",

volume = "117",

journal = "Journal of Applied Physics",

issn = "0021-8979",

publisher = "American Institute of Physics",

number = "11",

}

TY - JOUR

T1 - Dielectric anomalies due to grain boundary conduction in chemically substituted BiFeO3

AU - Kumari, Shalini

AU - Ortega, N.

AU - Kumar, A.

AU - Pavunny, S. P.

AU - Hubbard, J. W.

AU - Rinaldi, C.

AU - Srinivasan, G.

AU - Scott, J. F.

AU - Katiyar, Ram S.

N1 - This work was supported by the DOE Grant DE-FG02-08ER46526 and NSF (Fellowship EPS 01002410). N. Ortega acknowledges financial support from the NSF-RII Grant R10701525 and Dr. Ashok Kumar was supported by DOD Grant W911NF-11-1-0204. The authors thank Josue Ortiz Morales (MCC) for his help in the XPS measurements.

PY - 2015/3/21

Y1 - 2015/3/21

N2 - We describe systematic studies on Nd and Mn co-doped BiFeO3, i.e., (Bi0.95Nd0.05) (Fe0.97Mn0.03)O3 (BNFM) polycrystalline electroceramics. Raman spectra and X-ray diffraction patterns revealed the formation of rhombohedral crystal structure at room temperature, and ruled out structural changes in BiFeO3 (BFO) after low percentage chemical substitution. Strong dielectric dispersion and a sharp anomaly around 620K observed near the Neel temperature (TN similar to 643K of BFO) support strong magneto-dielectric coupling, verified by the exothermic peak in differential thermal data. Impedance spectroscopy disclosed the appearance of grain boundary contributions in the dielectric data in the region, and their disappearance just near the Neel temperature suggests magnetically active grain boundaries. The resistive grain boundary components of the BNFM are mainly responsible for magneto-dielectric coupling. Capacitive grain boundaries are not observed in the modulus spectra and the dielectric behavior deviates from the ideal Debye-type. The ac conduction studies illustrate short-range order with ionic translations assisted by both large and small polaron hopping. Magnetic studies indicate that the weak antiferromagnetic phase of BNFM ceramics is dominated by a strong paramagnetic response (unsaturated magnetization even at applied magnetic field of 7 T). The bulk BNFM sample shows a good in-plane magnetoelectric coupling (ME) coefficient.

AB - We describe systematic studies on Nd and Mn co-doped BiFeO3, i.e., (Bi0.95Nd0.05) (Fe0.97Mn0.03)O3 (BNFM) polycrystalline electroceramics. Raman spectra and X-ray diffraction patterns revealed the formation of rhombohedral crystal structure at room temperature, and ruled out structural changes in BiFeO3 (BFO) after low percentage chemical substitution. Strong dielectric dispersion and a sharp anomaly around 620K observed near the Neel temperature (TN similar to 643K of BFO) support strong magneto-dielectric coupling, verified by the exothermic peak in differential thermal data. Impedance spectroscopy disclosed the appearance of grain boundary contributions in the dielectric data in the region, and their disappearance just near the Neel temperature suggests magnetically active grain boundaries. The resistive grain boundary components of the BNFM are mainly responsible for magneto-dielectric coupling. Capacitive grain boundaries are not observed in the modulus spectra and the dielectric behavior deviates from the ideal Debye-type. The ac conduction studies illustrate short-range order with ionic translations assisted by both large and small polaron hopping. Magnetic studies indicate that the weak antiferromagnetic phase of BNFM ceramics is dominated by a strong paramagnetic response (unsaturated magnetization even at applied magnetic field of 7 T). The bulk BNFM sample shows a good in-plane magnetoelectric coupling (ME) coefficient.

KW - Impedance spectroscopy analysis

KW - Doped BiFeO3

KW - Electrical-Properties

KW - Magnetic-properties

KW - Raman-scattering

KW - Thin-films

KW - Ferroelectric properties

KW - Multiferroic properties

KW - Neutron-diffraction

KW - Leakage current

U2 - 10.1063/1.4915110

DO - 10.1063/1.4915110

M3 - Article

SN - 0021-8979

VL - 117

JO - Journal of Applied Physics

JF - Journal of Applied Physics

IS - 11

M1 - 114102

ER -