Stabilization of dielectric anomaly near the magnetic phase transition in Ca2+ doped BiFeO3 multifunctional ceramics

Tirupathi, Patri; Chandra, Amreesh

doi:10.1016/j.jallcom.2013.02.095

Cited by 45 publications

(14 citation statements)

References 30 publications

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“…Amongst the multiferroic ceramics being widely investigated, BiFeO 3 is a promising candidate for novel applications which allow mutual control of the electric polarization with a magnetic field and magnetization by an electric field [6,7]. BiFeO 3 is ferroelectric below T C ∼ 1103 K and antiferromagnetic below T N ∼ 653 K, having rhombohedrally distorted perovskite ABO 3 (A = Bi, B= Fe) structure [4].…”

Section: Introductionmentioning

confidence: 99%

Room temperature dielectric and magnetic properties of Gd and Ti co-doped BiFeO3 ceramics

Basith¹,

Kurni²,

Alam³

et al. 2014

Journal of Applied Physics

107

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Room temperature dielectric and magnetic properties of BiFeO3 samples, co-doped with magnetic Gd and non-magnetic Ti in place of Bi and Fe, respectively, were reported. The nominal compositions of Bi0.9Gd0.1Fe1−xTixO3 (x = 0.00-0.25) ceramics were synthesized by conventional solid state reaction technique. X-ray diffraction patterns revealed that the substitution of Fe by Ti induces a phase transition from rhombohedral to orthorhombic at x > 0.20. Morphological studies demonstrated that the average grain size was reduced from ∼ 1.5 µm to ∼ 200 nm with the increase in Ti content. Due to Ti substitution, the dielectric constant was stable over a wide range of high frequencies (30 kHz to 20 MHz) by suppressing the dispersion at low frequencies. The dielectric properties of the compounds are associated with their improved morphologies and reduced leakage current densities probably due to the lower concentration of oxygen vacancies in the compositions. Magnetic properties of Bi0.9Gd0.1Fe1−xTixO3 (x = 0.00-0.25) ceramics measured at room temperature were enhanced with Ti substitution up to 20 % compared to that of pure BiFeO3 and Ti undoped Bi0.9Gd0.1FeO3 samples. The enhanced magnetic properties might be attributed to the substitution induced suppression of spiral spin structure of BiFeO3. An asymmetric shifts both in the field and magnetization axes of magnetization versus magnetic field (M-H) curves was observed. This indicates the presence of exchange bias effect in these compounds notably at room temperature.

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Section: Introductionmentioning

confidence: 99%

Room temperature dielectric and magnetic properties of Gd and Ti co-doped BiFeO3 ceramics

Basith¹,

Kurni²,

Alam³

et al. 2014

Journal of Applied Physics

107

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“…Frequency-dependent loss in dielectric relaxation peaks indicates polaronic conduction relaxation mechanism. [17][18][19] Polaronic conduction can be explained by considering formation of mixed valence state (Fe 2þ /Fe 3þ ) and oxygen vacancies. The origin of Fe 3þ /Fe 2þ and oxygen vacancies are due to defect formation during high temperature sintering process, which cannot avoid normal conventional synthesis process.…”

Section: Resultsmentioning

confidence: 99%

Origin of giant dielectric permittivity and weak ferromagnetic behavior in (1−x)LaFeO₃−xBaTiO₃ (0.0 ≤ x ≤ 0.25) solid solutions

et al. 2016

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The solid solutions of (1 À x) LaFeO 3 -xBaTiO 3 (0.0 x 0.25) have been synthesized successfully by the conventional solid-state reaction method. Room temperature (RT) X-ray diffraction studies reveal the stabilization of orthorhombic phase with Pbnm space group. Complete solubility in the perovskite series was demonstrated up to x ¼ 0:25. The dielectric permittivity shows colossal dielectric constant (CDC) at RT. The doping of BaTiO 3 in LaFeO 3 exhibit pronounced CDC up to a composition x ¼ 0:15, further it starts to decrease. The frequency-dependent dielectric loss exhibits polaronic conduction, which can attribute to presence of multiple valence of iron. The relaxation frequency and polaronic conduction mechanism was shifted towards RT as function of x. Moreover, large magnetic moment with weak ferromagnetic behavior is observed in doped LaFeO 3 solid solution, which might be the destruction of spin cycloid structure due to insertion of Ti in Fe-O-Fe network of LaFeO 3 .

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“…18 Phase formation and structural characterization was carried out following the X-ray powder diffraction (XRD) technique using the Cu K a (k ¼ 1.5404 Å ) wavelength as incident wavelength in the X-ray diffractometer model: PHILIPS-PW3373 XPERT-PRO. For dielectric constant and impedance measurements in the frequency range of 100 Hz to 1 MHz, a N4L-PSM 1735 impedance analyzer was used.…”

Section: Methodsmentioning

confidence: 99%

Effect of oxygen annealing on the multiferroic properties of Ca2+ doped BiFeO3 nanoceramics

Tirupathi

Mandal

Chandra

2014

Journal of Applied Physics

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The high leakage current in divalent ion doped BiFeO 3 systems is limiting their large scale application. It is clearly shown that the methodology of oxygen annealing will prove to be an effective procedure for suppressing the detrimental consequences that originate from the oxygen vacancies. The samples annealed under oxygen also show different particle morphologies and packing density that can help in tuning the relevant physical properties, viz., magnetic, ferroelectric, and magnetoelectric. The difference in magnetic behaviour in samples annealed in air and oxygen can be explained in terms of the modification in the Fe-O-Fe bonds, domain wall pinning centres, and crystal anisotropy. Another important observation is the stabilization of a dielectric anomaly near the magnetic transition temperature. This observation can make this multiferroic system very interesting for application in sensors where the change in the magnetic parameters can be observed by monitoring the electrical parameters. Detailed analysis of the dielectric and impedance curves indicate towards the presence of non-Debye type processes in samples obtained by annealing in air or oxygen. From the calculated activation energy values, the vacancy related relaxation mechanism is predominant in air annealed samples, while the oxygen annealed samples show the presence of two type of relaxation processes, viz., electron hopping mechanism stabilizes at low temperature while, at higher temperatures, the process associated with the diffusion of doubly ionized oxygen ions predominates. The ac-conductivity data suggests that the correlated barrier tunnelling mechanism, where single electron or two electrons hopping through neighbouring lattice sites leads to ac-conduction. V C 2014 AIP Publishing LLC.

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Stabilization of dielectric anomaly near the magnetic phase transition in Ca2+ doped BiFeO3 multifunctional ceramics

Cited by 45 publications

References 30 publications

Room temperature dielectric and magnetic properties of Gd and Ti co-doped BiFeO3 ceramics

Room temperature dielectric and magnetic properties of Gd and Ti co-doped BiFeO3 ceramics

Origin of giant dielectric permittivity and weak ferromagnetic behavior in (1−x)LaFeO₃−xBaTiO₃ (0.0 ≤ x ≤ 0.25) solid solutions

Effect of oxygen annealing on the multiferroic properties of Ca2+ doped BiFeO3 nanoceramics

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Stabilization of dielectric anomaly near the magnetic phase transition in Ca2+ doped BiFeO3 multifunctional ceramics

Cited by 45 publications

References 30 publications

Room temperature dielectric and magnetic properties of Gd and Ti co-doped BiFeO3 ceramics

Room temperature dielectric and magnetic properties of Gd and Ti co-doped BiFeO3 ceramics

Origin of giant dielectric permittivity and weak ferromagnetic behavior in (1−x)LaFeO3−xBaTiO3 (0.0 ≤ x ≤ 0.25) solid solutions

Effect of oxygen annealing on the multiferroic properties of Ca2+ doped BiFeO3 nanoceramics

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Origin of giant dielectric permittivity and weak ferromagnetic behavior in (1−x)LaFeO₃−xBaTiO₃ (0.0 ≤ x ≤ 0.25) solid solutions