The positive temperature coefficient of resistivity in barium titanate

Huybrechts, Ben; Ishizaki, Kōzō; Takata, Masasuke

doi:10.1007/bf00362121

Cited by 296 publications

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“…It is seen from the figure that a considerable amount of Al ions is segregated ͓Al/ ͑Al+ Ti͒Ϸ0.04͔ at the grain boundary core, whereas Al ions are rarely detected ͓Al/ ͑Al+ Ti͒Ϸ0.00͔ in the region ϳ10 nm away from the boundary core. It is thus evident that, in H 2 , the solubility of Al acceptor in Nb-containing SrTiO 3 is negligible and Al ions segregate at grain boundaries, similar to the case of pure SrTiO 3 or BaTiO 3 . 17,19 On the other hand, Nb donors up to 2.4 at.…”

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confidence: 86%

“…͓DOI: 10.1063/1.2236212͔ Nonlinear electrical properties of electroceramics have been widely utilized for such devices as varistors, thermistors, boundary layer capacitors ͑BLCs͒, sensors, and switching devices. [1][2][3][4] The origin of the nonlinear properties is well known to be related to the electrically active grain boundaries in polycrystals.2,3,5-7 A number of investigations using high resolution transmission electron microscopy ͑HR-TEM͒ and nanometer scale analysis have shown that the nonlinear properties vary considerably with the chemical composition and structure of the grain boundariesspecifically the height of the potential barrier, the density of defects, and the impurities at the grain boundaries. [8][9][10][11][12][13] One of the key processing parameters that control these grain boundary properties is the doping of impurity elements.…”

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confidence: 99%

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confidence: 99%

“…2,3,[5][6][7] A number of investigations using high resolution transmission electron microscopy ͑HR-TEM͒ and nanometer scale analysis have shown that the nonlinear properties vary considerably with the chemical composition and structure of the grain boundariesspecifically the height of the potential barrier, the density of defects, and the impurities at the grain boundaries. [8][9][10][11][12][13] One of the key processing parameters that control these grain boundary properties is the doping of impurity elements.…”

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Acceptor segregation and nonlinear current-voltage characteristics in H2-sintered SrTiO3

Wang¹,

Kang²

2006

Applied Physics Letters

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The current-voltage characteristics with acceptor segregation at grain boundaries have been investigated in H 2 -sintered SrTiO 3 . Al-added SrTiO 3 was sintered in H 2 and then annealed in air for selective oxidation of grain boundaries. The samples showed nonlinear current-voltage characteristics, and both the breakdown voltage and nonlinearity coefficient increased with Al concentration. An energy dispersive spectroscopy analysis revealed that Al ions were segregated at the grain boundary, suggesting the formation of Schottky barriers at the boundary. The present results thus point toward the possibility of modifying the grain boundary composition in SrTiO 3 as well as fabricating effective switching devices by H 2 sintering. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2236212͔ Nonlinear electrical properties of electroceramics have been widely utilized for such devices as varistors, thermistors, boundary layer capacitors ͑BLCs͒, sensors, and switching devices. [1][2][3][4] The origin of the nonlinear properties is well known to be related to the electrically active grain boundaries in polycrystals.2,3,5-7 A number of investigations using high resolution transmission electron microscopy ͑HR-TEM͒ and nanometer scale analysis have shown that the nonlinear properties vary considerably with the chemical composition and structure of the grain boundariesspecifically the height of the potential barrier, the density of defects, and the impurities at the grain boundaries. [8][9][10][11][12][13] One of the key processing parameters that control these grain boundary properties is the doping of impurity elements. It is therefore critical to control the impurity doping for preparation of nonlinear devices with optimal properties.Many investigations have been made on the segregation of dopants and related electrical properties in ABO 3 -type perovskite titanates.9-17 When utilized as a multifunctional component of varistors and BLCs, SrTiO 3 is sintered in a reducing atmosphere and heat treated in air.1 Nevertheless, little research has been reported on the specific technical process in polycrystalline SrTiO 3 . To optimize the utilization of this material, it is necessary to understand the correlation between the dopant segregation and electrical properties. The present investigation systematically studies the control of nonlinear electrical properties with acceptor addition in H 2 -sintered SrTiO 3 using energy dispersive spectroscopy with a nanometer size probe.SrTiO 3 samples were prepared by the conventional powder processing technique from commercial SrTiO 3 ͑Ferro Corp., Penn Yan, USA͒, Nb 2 O 5 ͑Hermann C. Starck, Berlin, Germany͒ and Al 2 O 3 ͑Sumitomo Chem., Tokyo, Japan͒ powders. Niobium ͑0.4 mol % ͒, a donor dopant, and aluminum ͑0, 0.2, 0.5, 1, and 1.5 mol %͒, an acceptor dopant, were added to SrTiO 3 powder, and the powder mixtures were ball milled in ethyl alcohol for 24 h with a polyethylene bottle and zirconia balls. The addition of Nb is simply to make the grains conductive after sintering in H ...

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confidence: 86%

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confidence: 99%

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confidence: 99%

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Acceptor segregation and nonlinear current-voltage characteristics in H2-sintered SrTiO3

Wang¹,

Kang²

2006

Applied Physics Letters

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“…[14][15][16][17][18] Undoped BaTiO 3 is an insulator and as such cannot be used as a PTC thermistor. To that end, BaTiO 3 is n-type doped by replacing Ba with a trivalent donor such as La or by replacement of Ti by pentavalent Nb.…”

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Thin film thermistor with positive temperature coefficient of resistance based on phase separated blends of ferroelectric and semiconducting polymers

Lenz

Dehsari

Asadi

et al. 2016

Applied Physics Letters

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Titanium Compounds, Inorganic

Egerton¹

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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Properties and applications of technologically important inorganic compounds of titanium are surveyed. The most important compound is titanium dioxide which, because of its high refractive index, is manufactured as a white pigment at a scale of ca \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}${4\times 10^{6}{\hskip0.167em}{\hskip0.167em}{\rm{t}}/{\rm{yr}}}$\end{document} . Raw materials and pigment production processes are reviewed. Mixed oxides, eg, barium titanate, are important raw materials for electroceramics. Titanium hydrides provide a convenient method of hydrogen storage. Titanium boride, titanium carbide, and titanium nitride are used as components of hard materials, eg, for cutting tools. They are electrically conducting. The chlorides are the most important halides. Titanium trichloride is the basis of widely used polymerization catalysts. Titanium tetrachloride is an intermediate in the production of both titanium metal and (via the chloride process) titanium dioxide pigment. Titanium dioxide pigment is also made (in the sulfate process) by precipitation from solutions of titanium in sulfuric acid. Titanium sulfides may be used as cathodes in high efficiency batteries. The properties of some titanium compounds with silicon and phosphorus are reviewed. Analytical methods and health & safety aspects are summarized.

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The positive temperature coefficient of resistivity in barium titanate

Cited by 296 publications

References 81 publications

Acceptor segregation and nonlinear current-voltage characteristics in H2-sintered SrTiO3

Acceptor segregation and nonlinear current-voltage characteristics in H2-sintered SrTiO3

Thin film thermistor with positive temperature coefficient of resistance based on phase separated blends of ferroelectric and semiconducting polymers

Titanium Compounds, Inorganic

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