Modelling of grain boundary resistivities of n-conducting BaTiO3 ceramics

Preis, Wolfgang; Sitte, Werner

doi:10.1016/j.ssi.2006.06.003

Cited by 33 publications

(30 citation statements)

References 13 publications

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“…(i) The resistivity of grain boundaries in BaTiO 3 -based PTCRs increases rapidly by many orders of magnitude above the paraelectric-ferroelectric phase transition temperature (Curiepoint) [2,3,5]. This so-called positive temperature coefficient (PTC) effect is mainly caused by double Schottky barriers at the grain boundaries [6,7]. (ii) At high temperatures, the grain boundaries provide extremely fast diffusion paths for the transport of oxygen, resulting in selective re-oxidation of grain boundary regions during the cooling process after sintering [8][9][10].…”

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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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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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“…This double-Schottky-barrier model has been outlined in detail by numerous authors [1][2][3][4][5]7]. However, the effect of diffusion profiles of cation vacancies on the grain boundary resistivity has rarely been treated in literature so far [6,8,16].…”

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confidence: 99%

“…As the chemical diffusion coefficient of the bulk necessary for the description of these transport processes increases strongly with increasing temperature according to an Arrhenius-law with an activation energy around 2.2-2.75 eV [17,19], the diffusion is frozen-in below approximately 1000-1100°C [16]. Within the framework of the Schottky approximation the space charge density in the depletion zone is given by the concentrations of the immobile ionic defects (at temperatures below 900°C)…”

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confidence: 99%

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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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Modelling of surface exchange reactions and diffusion in composites and polycrystalline materials

Preis

2009

Monatsh Chem

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Modelling of grain boundary resistivities of n-conducting BaTiO3 ceramics

Cited by 33 publications

References 13 publications

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

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

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

Modelling of surface exchange reactions and diffusion in composites and polycrystalline materials

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