Bariumtitanat als sperrschichthalbleiter

Heywang, Walter

doi:10.1016/0038-1101(61)90080-6

Cited by 490 publications

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“…The PTCR effect was first reported by Haayman et al [10] in perovskite-structured BaTiO 3 materials containing a small amount of donors. The PTCR effect is described qualitatively by the Heywang model [11] and later amended by Jonker [12]. This description is based on the formation of surface acceptor states [13] at the grain boundary, which create a potential barrier due to the upward bending of the conduction band in the depletion region.…”

Section: Introductionmentioning

confidence: 99%

Relaxation and Conduction Mechanisms of High Tc Lead-Free Ba (Zr,Ti)O3 Positive Temperature Coefficient of Resistivity Ceramic Using Impedance Spectroscopy

Rahman

Quader²,

Hossain³

2014

IJMEA

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Abstract:High T c lead-free Ba (Zr 0.52 Ti 0.48 )O 3 positive temperature coefficient of resistivity (PTCR) ceramic was produced by the standard solid state reaction technique. X-ray diffraction pattern confirms the formation of the tetragonal perovskite structure of the ferroelectric sample. The conduction and relaxation mechanisms of the piezoelectric ceramic have been studied on the basis of activation energy. The relaxation mechanism is investigated for this sample based on the peaks of the imaginary part of electrical impedance and modulus spectra. The Cole-Cole plots indicate that the grain effect is influenced by the increase of temperature up to 200 °C and disappeared beyond this temperature. The temperature versus electrical resistivity plots show that a phase transition occurs at the Curie temperature, T c =150 °C. The ceramic exhibits a PTCR jump of almost two orders of magnitude starting at 150 °C and ending at 275 °C with a high temperature coefficient of resistivity of ~25 % per °C. The electrical resistivity measurements also reveal that the sample shows semiconducting behavior beyond 275 °C with the value of negative temperature coefficient of resistivity of ~ 0.6% per °C.

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Section: Introductionmentioning

confidence: 99%

Relaxation and Conduction Mechanisms of High Tc Lead-Free Ba (Zr,Ti)O3 Positive Temperature Coefficient of Resistivity Ceramic Using Impedance Spectroscopy

Rahman

Quader²,

Hossain³

2014

IJMEA

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“…This fact can be of essential importance in practical applications. BT and BTZx are used as multilayer capacitor ceramics, piezoelectric transducers, PTRC thermistors, and chemical sensors [13][14][15]. Zirconium titanate (ZT) is used in varistor and tunable microwave filters and as the technical ceramic component [14,16,17].…”

Section: Introductionmentioning

confidence: 99%

Influence of Zr-substitution on phase transitions character in polycrystalline Ba(Ti1−x Zr x )O3

Kajtoch

2010

J Mater Sci

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The results of X-ray diffraction, scanning electron microscopy, and dielectric measurements performed for polycrystalline Ba(Ti 1-x Zr x )O 3 are presented. Data from these measurements show a change of the type of paraelectric-ferroelectric (PE-FE) phase transition (PT) from sharp PT (x \ 0.10), through diffuse phase transition (0.10 B x B 0.20), to relaxor type one (x = 0.30). The lack of structural PT at the temperature T m (the temperature of the maximum of real part of the electric permittivity e 0 ) for 0.10 B x B 0.30, suggest that this PE-FE transition is not connected with the change of crystal structure. A phase angle of about U & -90°, between electric current and applied voltage, suggests the occurrence of polar regions (clusters) below 400 K. The change of these clusters polarizability and their lability at the T m is postulated as possible origin of the observed maximum of e 0 .

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“…Their electric properties are determined by presence of basic phase potential barriers on the grain boundaries. In the 60-ties of last century, Heywang proposed a description of a PTC-R phenomenon mechanism on a basis of a model of a grain boundary energy structure responsible for a rapid increase in the effective resistance at specific temperatures, on an example of the BaTiO 3 ceramics [3].…”

Section: Introductionmentioning

confidence: 99%

The Positive Temperature Coefficient of Resistivity Effect in the Pb(Fe_1/2Nb_1/2)O₃Ceramics Admixed with Lithium

Bochenek

2009

Acta Phys. Pol. A

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In the paper technological conditions were looked for to obtain the Pb(Fe 1/2 Nb 1/2 )O 3 (PFN) ceramics and the PFN ceramics with the lithium admixture with the highest electric conduction and conditions appropriate for the PTC-R effect formation. Measurements of dc electrical resistivity, dielectric permittivity and dielectric loss were made as functions of temperature from room temperature to 190• C, at 1 kHz. The best set of values of dielectric loss and dielectric constant, from the ferroelectricity point of view, were obtained when the precursor with orthorhombic structure was employed. By creating appropriate technological conditions in the PFN ceramics the PTC-R effect can occur above the Curie temperature. Their electric properties are determined by presence of a basic phase of the potential barrier on the grain boundaries.

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Bariumtitanat als sperrschichthalbleiter

Cited by 490 publications

References 0 publications

Relaxation and Conduction Mechanisms of High Tc Lead-Free Ba (Zr,Ti)O3 Positive Temperature Coefficient of Resistivity Ceramic Using Impedance Spectroscopy

Relaxation and Conduction Mechanisms of High Tc Lead-Free Ba (Zr,Ti)O3 Positive Temperature Coefficient of Resistivity Ceramic Using Impedance Spectroscopy

Influence of Zr-substitution on phase transitions character in polycrystalline Ba(Ti1−x Zr x )O3

The Positive Temperature Coefficient of Resistivity Effect in the Pb(Fe_1/2Nb_1/2)O₃Ceramics Admixed with Lithium

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Bariumtitanat als sperrschichthalbleiter

Cited by 490 publications

References 0 publications

Relaxation and Conduction Mechanisms of High Tc Lead-Free Ba (Zr,Ti)O3 Positive Temperature Coefficient of Resistivity Ceramic Using Impedance Spectroscopy

Relaxation and Conduction Mechanisms of High Tc Lead-Free Ba (Zr,Ti)O3 Positive Temperature Coefficient of Resistivity Ceramic Using Impedance Spectroscopy

Influence of Zr-substitution on phase transitions character in polycrystalline Ba(Ti1−x Zr x )O3

The Positive Temperature Coefficient of Resistivity Effect in the Pb(Fe1/2Nb1/2)O3Ceramics Admixed with Lithium

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The Positive Temperature Coefficient of Resistivity Effect in the Pb(Fe_1/2Nb_1/2)O₃Ceramics Admixed with Lithium