Atmosphere controlled conductivity and Maxwell-Wagner relaxation in Bi0.5K0.5TiO3—BiFeO3 ceramics

Morozov, Maxim I.; Einarsrud, Mari‐Ann; Grande, Tor

doi:10.1063/1.4863798

Cited by 43 publications

(46 citation statements)

References 34 publications

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“…4a. No temperature dispersion of the maximum 21 The temperature of e 0 max is included in Table 1. The shift in the maximum permittivity observed during cooling points to a first order phase transition.…”

Section: Resultsmentioning

confidence: 99%

“…The electroded sample was first heated/ cooled to/from 400 1C to remove Maxwell-Wagner contributions to the permittivity. 21 The reported data are obtained from the 2nd heating cycle to 720 1C and 800 1C for 0.8BFO and 0.9BFO, respectively. High temperature X-ray diffraction (HTXRD) was performed using a y-y Bruker D8 ADVANCE diffractometer utilizing Cu K a radiation and a VANTEC-1 position sensitive detector.…”

Section: Methodsmentioning

confidence: 99%

“…2 illustrates that the sintering atmosphere during fabrication of the ceramics is important for the conductivity, which falls in line with previous reports showing that conductivity can be reduced significantly by annealing in an inert or reducing atmosphere. 21 Although the results presented herein are on BKT substituted BFO, we propose that the present observations give valuable insight into the thermal evolution of the electrical conductivity of bulk pure BFO. [22][23][24][25] The ferroelectric phase transition temperatures of 0.8BFO and 0.9BFO were determined by three different methods in reasonable agreement.…”

mentioning

confidence: 96%

“…[22][23][24][25][26] The conductivity of 0.7BFO-0.3BKT can be manipulated by thermal treatment in an oxidizing or an inert atmosphere. 20,21 The aliovalent substitution of Fe 3+ with e.g. Ti 4+ and Ni 2+ on the perovskite B site has profound effect on the conductivity of BFO [27][28][29] where tetravalent cations reduce the conductivity and divalent cations increase the conductivity.…”

Section: +mentioning

confidence: 99%

“…20 A Maxwell-Wagner type relaxation in BFO-BKT, coupled to the electrical conductivity and point defects, has also been reported. 21 One of the main challenges with to BFO is the high electrical conductivity giving rise to dielectric loss. 3 Pure and acceptor substituted BFO shows the characteristics of p-type conductivity in air, relating conductivity to the presence of Fe…”

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confidence: 99%

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Electrical conductivity and thermopower of (1 − x) BiFeO₃– xBi_0.5K_0.5TiO₃(x = 0.1, 0.2) ceramics near the ferroelectric to paraelectric phase transition

Wefring

Einarsrud

Grande

2015

Phys. Chem. Chem. Phys.

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Ferroelectric BiFeO 3 has attractive properties such as high strain and polarization, but a wide range of applications of bulk BiFeO 3 are hindered due to high leakage currents and a high coercive electric field.Here, we report on the thermal behaviour of the electrical conductivity and thermopower of BiFeO 3 substituted with 10 and 20 mol% Bi 0.5 K 0.5 TiO 3 . A change from p-type to n-type conductivity in these semi-conducting materials was demonstrated by the change in the sign of the Seebeck coefficient and the change in the slope of the isothermal conductivity versus partial pressure of O. A minimum in the isothermal conductivity was observed at B10 À2 bar O 2 partial pressure for both solid solutions. The strong dependence of the conductivity on the partial pressure of O 2 was rationalized by a point defect model describing qualitatively the conductivity involving oxidation/reduction of Fe 3+ , the dominating oxidation state of Fe in stoichiometric BiFeO 3 . The ferroelectric to paraelectric phase transition of 80 and 90 mol% BiFeO 3 was observed at 648 AE 15 and 723 AE 15 1C respectively by differential thermal analysis and confirmed by dielectric spectroscopy and high temperature powder X-ray diffraction.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 96%

Section: +mentioning

confidence: 99%

mentioning

confidence: 99%

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Electrical conductivity and thermopower of (1 − x) BiFeO₃– xBi_0.5K_0.5TiO₃(x = 0.1, 0.2) ceramics near the ferroelectric to paraelectric phase transition

Wefring

Einarsrud

Grande

2015

Phys. Chem. Chem. Phys.

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Exploring Charged Defects in Ferroelectrics by the Switching Spectroscopy Piezoresponse Force Microscopy

et al. 2021

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information storage, [1,2] memristors based on tunneling, [3,4] energy storage devices, [5] etc. Tailoring the defect structure permits fine tuning of the functional properties of ferroelectrics. [6][7][8][9][10] The surfaces and interfaces are directly influenced by the nearby defects, and bulk properties are rendered by the defects via multiple mechanisms. [11,12] Up to date, the number of techniques allowing studies of defects with a high spatial resolution is limited, and they are mainly based on local monitoring of the crystalline structure or chemical composition. [13][14][15][16] Most of these local compositional methods like transmission electron microscopy, X-ray tomography, electron holography, etc. do not have a high enough sensitivity or need challenging sample preparation. [13] The optical method of second harmonic generation can be used to monitor the defect concentration and off-stoichiometry, [16] however it is limited in resolving the type of charged defects and yields only micrometer-scale spatial resolution. Thus, the novel experimental approaches allowing accurate measurement of the defect concentration and/or corresponded functional properties at the nanoscale are highly desirable.In ferroelectrics, charged defects affect polarization reversal as they directly participate in the screening of the depolarization electric field [8,[17][18][19][20] since they can become mobile Monitoring the charged defect concentration at the nanoscale is of critical importance for both the fundamental science and applications of ferroelectrics. However, up-to-date, high-resolution study methods for the investigation of structural defects, such as transmission electron microscopy, X-ray tomography, etc., are expensive and demand complicated sample preparation. With an example of the lanthanum-doped bismuth ferrite ceramics, a novel method is proposed based on the switching spectroscopy piezoresponse force microscopy (SSPFM) that allows probing the electric potential from buried subsurface charged defects in the ferroelectric materials with a nanometer-scale spatial resolution. When compared with the compositionsensitive methods, such as neutron diffraction, X-ray photoelectron spectroscopy, and local time-of-flight secondary ion mass spectrometry, the SSPFM sensitivity to the variation of the electric potential from the charged defects is shown to be equivalent to less than 0.3 at% of the defect concentration. Additionally, the possibility to locally evaluate dynamics of the polarization screening caused by the charged defects is demonstrated, which is of significant interest for further understanding defect-mediated processes in ferroelectrics.

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Local structural coupling of A- and B-site disorder in perovskite bismuth-based piezoelectrics

et al. 2019

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The local and average structure of (1-x)Bi0.5K0.5TiO3-xBiFeO3 (BKT-xBFO, x = 0.25 and 0.5) solid solutions are studied by synchrotron X-ray total scattering from ambient to 773 K. Pair distribution functions (PDFs) demonstrate that disordered BKT-0.25BFO and BKT-0.5BFOshow the same structural coherence length of ~16 Å as pure Bi0.5K0.5TiO3, while their average structures are pseudocubic at all temperatures. Complementary density functional theory (DFT) calculations suggest distinctly different local structural distortions in BKT-0.25BFO and BKT-0.5BFO with random cations distribution on both A-and B-lattice. Based on the experimental and theoretical analysis, we propose that the optimal piezoelectric properties found at the structural phase boundary composition of x = 0.25 originate from tetragonal and rhombohedral polar nanoregions (PNRs) in an on average pseudocubic matrix. In contrast, for x = 0.5 there are only pseudorhombohedral polar distortions in a pseudocubic matrix phase.

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Atmosphere controlled conductivity and Maxwell-Wagner relaxation in Bi0.5K0.5TiO3—BiFeO3 ceramics

Cited by 43 publications

References 34 publications

Electrical conductivity and thermopower of (1 − x) BiFeO₃– xBi_0.5K_0.5TiO₃(x = 0.1, 0.2) ceramics near the ferroelectric to paraelectric phase transition

Electrical conductivity and thermopower of (1 − x) BiFeO₃– xBi_0.5K_0.5TiO₃(x = 0.1, 0.2) ceramics near the ferroelectric to paraelectric phase transition

Exploring Charged Defects in Ferroelectrics by the Switching Spectroscopy Piezoresponse Force Microscopy

Local structural coupling of A- and B-site disorder in perovskite bismuth-based piezoelectrics

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Atmosphere controlled conductivity and Maxwell-Wagner relaxation in Bi0.5K0.5TiO3—BiFeO3 ceramics

Cited by 43 publications

References 34 publications

Electrical conductivity and thermopower of (1 − x) BiFeO3– xBi0.5K0.5TiO3(x = 0.1, 0.2) ceramics near the ferroelectric to paraelectric phase transition

Electrical conductivity and thermopower of (1 − x) BiFeO3– xBi0.5K0.5TiO3(x = 0.1, 0.2) ceramics near the ferroelectric to paraelectric phase transition

Exploring Charged Defects in Ferroelectrics by the Switching Spectroscopy Piezoresponse Force Microscopy

Local structural coupling of A- and B-site disorder in perovskite bismuth-based piezoelectrics

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Electrical conductivity and thermopower of (1 − x) BiFeO₃– xBi_0.5K_0.5TiO₃(x = 0.1, 0.2) ceramics near the ferroelectric to paraelectric phase transition

Electrical conductivity and thermopower of (1 − x) BiFeO₃– xBi_0.5K_0.5TiO₃(x = 0.1, 0.2) ceramics near the ferroelectric to paraelectric phase transition