Phase transitions in ferrimagnetic and ferroelectric ceramics by ac measurements

Peláiz‐Barranco, A.; Gutiérrez-Amador, M. P.; Huanosta, A.; Valenzuela, R.

doi:10.1063/1.122360

Cited by 145 publications

(52 citation statements)

References 10 publications

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“…In the temperature range from 570 to 620 K, n vs. T shows an unusual variation that is well supported by Raman, dielectric, calorimetry, and complex impedance results. Similar anomaly for n and A was observed by Pelaiz-Barranco et al 82 around T N for ferrimagnetic Zn 0.44 Mn 0.56 Fe 2 O 4 . These results can indicate the coupling of ferroelectric and magnetic phase and can be associated with a critical behavior in electrical conductivity parameters (n and A).…”

Section: H Complex Conductivity Spectroscopysupporting

confidence: 70%

Dielectric anomalies due to grain boundary conduction in chemically substituted BiFeO3

Kumari

Ortega

Kumar

et al. 2015

Journal of Applied Physics

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We describe systematic studies on Nd and Mn co-doped BiFeO 3 , i.e., (Bi 0.95 Nd 0.05 ) (Fe 0.97 Mn 0.03 )O 3 (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 BiFeO 3 (BFO) after low percentage chemical substitution. Strong dielectric dispersion and a sharp anomaly around 620 K observed near the Neel temperature (T N $ 643 K 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. V C 2015 AIP Publishing LLC. [http://dx

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Section: H Complex Conductivity Spectroscopysupporting

confidence: 70%

Dielectric anomalies due to grain boundary conduction in chemically substituted BiFeO3

Kumari

Ortega

Kumar

et al. 2015

Journal of Applied Physics

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“…where, σ is the total electrical conductivity, 2 f ω π = and the coefficient A and exponent s are temperature and material dependent parameters [22]. The term A comprises the ac dependence and characterizes all dispersion phenomena.…”

Section: Resultsmentioning

confidence: 99%

Flux growth and low temperature dielectric relaxation in piezoelectric Pb[(Zn_1/3Nb_2/3)_0.91Ti_0.09]O₃ single crystals

Singh

Kumar

Sinha

et al. 2009

Cryst. Res. Technol.

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Single crystals of Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3 (PZNT 91/9) have been grown by flux method after modifications in temperature profile, flux ratio and addition of excess ZnO/B2O3 which resulted in enhanced perovskite yield (more than 95%). Only a few crystals showed the presence of pyrochlore phase/variation in composition. A comparative characterization of these crystals were carried out in respect of piezoelectric charge coefficient d33, dielectric constant, ac conductivity and hysteresis loop after cutting and poling the crystals along [001] direction. The total activation energy for conduction has been found to increase with Ti‐content in the sample. The effect of ZnO on growth behavior has been analyzed. A detailed analysis of PZNT (91:9) has been carried out at low temperature in respect of the various thermodynamic parameters related to the dielectric relaxation mechanism, like optical dielectric constant, static dielectric constant, free energy of activation for dipole relaxation, enthalpy of activation and relaxation time, have been calculated in the vicinity of transition temperature in the lower temperature region. The activation energy for relaxation at ‐10 and ‐49 °C have been found to be 0.09 and 0.02 eV respectively. The results were analyzed and a detailed dielectric analysis and low temperature relaxation behavior of PZNT crystals were interpreted. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…If the ac conductivity is assumed to originate from QMT, s is predicted to be temperature independent but is expected to show a decreasing trend with ω, while for CBH the value of s should show a decreasing trend with an increase in temperature. The exponent s has been found to behave in a variety of forms [18][19][20]. In general, the frequency dependence of conductivity does not follow the simple power relation as given above but follows a double power law [18][19][20][21] given as…”

Section: Nf)mentioning

confidence: 99%

Electrical Properties and AC Conductivity of (Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃ Ceramic

et al. 2012

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Lead-free perovskite (Bi 0.5 Na 0.5 ) 0.94 Ba 0.06 TiO 3 (BNBT06) was prepared by conventional ceramic fabrication technique at 1160 • C/3h in air atmosphere. The crystal structure, microstructure, dielectric, polarization, piezoelectric properties, and ac conductivity of the sample were studied. X-ray diffraction data confirmed the formation of a single phase tetragonal unit cell. Williamson-Hall plot was used to calculate the lattice strain and the apparent particle size. The experimental relative density of BNBT06 was found to be ∼96-97% of the theoretical one with an average grain size ∼4 μm. Room temperature dielectric constant and loss factor at 1 kHz were found to be equal to 781 and 0.085, respectively. Longitudinal piezoelectric charge coefficient of the poled sample under 2.5 kV/mm at 80 • C in silicone bath was found to be equal to 124 pC/N. Complex impedance and electric modulus spectroscopic analyses showed the dielectric relaxation in the material to be of non-Debye type. The Nyquist plots and conductivity studies showed the NTCR character of BNBT06. The correlated barrier hopping model (CBHM) as well as jump relaxation model (JRM) was found to successfully explain the mechanism of charge transport in BNBT06. The ac conductivity data were used to evaluate the minimum hopping length, apparent activation energy, and density of states at Fermi level.

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Phase transitions in ferrimagnetic and ferroelectric ceramics by ac measurements

Cited by 145 publications

References 10 publications

Dielectric anomalies due to grain boundary conduction in chemically substituted BiFeO3

Dielectric anomalies due to grain boundary conduction in chemically substituted BiFeO3

Flux growth and low temperature dielectric relaxation in piezoelectric Pb[(Zn_1/3Nb_2/3)_0.91Ti_0.09]O₃ single crystals

Electrical Properties and AC Conductivity of (Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃ Ceramic

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Phase transitions in ferrimagnetic and ferroelectric ceramics by ac measurements

Cited by 145 publications

References 10 publications

Dielectric anomalies due to grain boundary conduction in chemically substituted BiFeO3

Dielectric anomalies due to grain boundary conduction in chemically substituted BiFeO3

Flux growth and low temperature dielectric relaxation in piezoelectric Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3 single crystals

Electrical Properties and AC Conductivity of (Bi0.5Na0.5)0.94Ba0.06TiO3 Ceramic

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Product

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Flux growth and low temperature dielectric relaxation in piezoelectric Pb[(Zn_1/3Nb_2/3)_0.91Ti_0.09]O₃ single crystals

Electrical Properties and AC Conductivity of (Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃ Ceramic