Diffusion potentials in BaTiO3 and the theory of ptc materials

Kulwicki, Bernard M.; Purdes, A. J.

doi:10.1080/00150197008241491

Cited by 76 publications

(20 citation statements)

References 18 publications

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“…Especially, donor-doped barium titanate is widely applied in PTCRs, where the resistance increases by several orders of magnitude above the ferroelectric-paraelectric phase transition temperature (Curie-point). This PTC behavior is well-known in literature and is clearly attributed to space charge effects at the grain boundaries [1][2][3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 81%

Modeling of transport properties of interfacially controlled electroceramics: Application to n-conducting barium titanate

Preis

Sitte

2009

J Electroceram

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Grain boundary regions in n-conducting barium titanate (BaTiO 3 ) are re-oxidized during the cooling process after sintering the ceramics in air. The kinetics of this reoxidation process is determined by rapid transport of oxygen along the grain boundaries and slow (rate-determining) diffusion of cation vacancies from the grain boundaries into the grains until the diffusion process is frozen-in. Based on numerical calculations of frozen-in diffusion profiles of cation vacancies at grain boundary regions for various cooling rates, a modified Schottkybarrier model is introduced in order to calculate the grain boundary resistivity as a function of temperature from the Curie-point up to 900°C. A change of the activation energy at approximately 500°C is predicted owing to an enrichment of holes in the space charge layers at elevated temperatures. The modeling results are compared with experimental data for BaTiO 3 -based positive temperature coefficient resistors (PTCRs).

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Section: Introductionmentioning

confidence: 81%

Modeling of transport properties of interfacially controlled electroceramics: Application to n-conducting barium titanate

Preis

Sitte

2009

J Electroceram

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“…It is well-known that the electrical properties of n-conducting BaTiO 3 are mainly governed by grain boundaries [1][2][3][4]. Therefore, donor-doped BaTiO 3 can be regarded as a model system for interfacially controlled electroceramics which is characterized by various interesting peculiarities with respect to its transport properties.…”

Section: Introductionmentioning

confidence: 99%

Characterization of electrical properties of n-conducting barium titanate as a function of dc-bias and ac-voltage amplitude by application of impedance spectroscopy

Preis

Hofer

Sitte

2015

J Solid State Electrochem

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The electrical properties of bulk and grain boundaries of donor-doped barium titanate ceramics have been characterized as a function of temperature (50-350°C) and voltage load (up to 140 V) by application of impedance spectroscopy. Both the grain boundary resistivities and the steepness of the R-T characteristics are diminished significantly with increasing voltage load. While the grain boundary resistances are strongly affected by the applied electric field, the grain boundary capacitance is almost independent of the dc-bias. The non-linearity of the resistivity of n-conducting BaTiO 3 has been investigated in detail by impedance spectroscopy as a function of dc-bias and a small ac-voltage signal as well as impedance measurements with high ac-voltage amplitudes (zero bias). The non-linear current response to high ac-voltage amplitudes at low frequencies (0.01 Hz) has been determined experimentally and analyzed by means of fast Fourier transform (FFT) as well as Lissajous analyses. Moreover, a finite element model (FEM) has been developed for the simulation of the ac-current response. The FEM calculations are in close agreement with the experimentally determined data for the variation of the grain boundary resistance with ac-voltage amplitude.

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“…10 This model takes into account the ferroelectric nature of the material and postulates that the spontaneous polarization below T C , or more appropriately the polar discontinuity arising from domain structures, effectively lowers the potential barrier in the vicinity of grain boundaries, thus lowering the resistivities below T C . It should be noted that the grain boundary is always more resistive than the interior of the grains, even in the ferroelectric (low resistance) phase.…”

confidence: 99%

“…4,5 It was identified quite early that the effect is dominant in polycrystalline samples, 6 with rich microstructures and an equally interesting domain structure embedded within grains, and several models have been proposed to explain the observed experimental behavior. [7][8][9][10] The most accepted among these models is the Heywang-Jonker model, which states that the presence of a potential barrier at the grain boundaries is responsible for enhanced resistivity of the boundary in comparison to the grain interior. According to the original Heywang model 7 (reviewed by Chen and Yang 4 ), there is a bi-dimensional layer of electron traps, i.e.…”

mentioning

confidence: 99%

Mapping grain boundary heterogeneity at the nanoscale in a positive temperature coefficient of resistivity ceramic

et al. 2017

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Diffusion potentials in BaTiO3 and the theory of ptc materials

Cited by 76 publications

References 18 publications

Modeling of transport properties of interfacially controlled electroceramics: Application to n-conducting barium titanate

Modeling of transport properties of interfacially controlled electroceramics: Application to n-conducting barium titanate

Characterization of electrical properties of n-conducting barium titanate as a function of dc-bias and ac-voltage amplitude by application of impedance spectroscopy

Mapping grain boundary heterogeneity at the nanoscale in a positive temperature coefficient of resistivity ceramic

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