Semiconducting barium titanate doped with oxygen-free compounds

Kovalenko, L. L.; V’yunov, O. I.; Белоус, А. Г.

doi:10.1016/s0955-2219(98)00354-9

Cited by 5 publications

(4 citation statements)

References 3 publications

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“…The observed low k values in the composition may support the hypothesis that chemical reactions occur during firing and degrade partially intrinsic characteristics of pure BaTiO 3 . Although it was not proved by the current work, the potential intermediate phases, such as Ba 10 A l2 O 13 as reported [8], might be responsible for the lowered values. The optimum composition of 76BaTiO 3 -20AlN-4glass exhibited k of 79.4 and tan δ of 0.014 at 1 MHz as a result of the low temperature firing of 850 • C. Microstructure evolution, which depends on the various compositions and firing condition, and effects of different firing atmospheres on dielectric properties including leakage current and temperature coefficient of capacitance are under investigation.…”

Section: Discussioncontrasting

confidence: 70%

“…There are limited reports concerning the mixture of ceramic powders with nitride compounds, where certain chemical reactions during firing while providing unexpected performance. As an example, Kovalento et al [8] reported that the addition of non-oxide additives such as TiB 2 , TiC, TiN and AlN to BaTiO 3 resulted in the unexpected phase development. They found a phase of barium aluminate Ba 10 A l2 O 13 that was identified at 970 • C in the (Ba,Y)TiO 3 -AlN system.…”

Section: Discussionmentioning

confidence: 99%

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Dielectric properties of the BaTiO3-AlN-additive system

et al. 2006

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The mixed system of BaTiO 3 and AlN has been investigated in terms of dielectric properties and microstructure. Two different types of additives, bismuth oxide and bismuth borosilicate glass, were used to lower sintering temperature. First, the addition of a fixed content (3 wt.%) of Bi 2 O 3 provided densification at 1200 • C where monotonous decreases of dielectric constant were found with increasing the content of AlN. On the other hand, the bismuth borosilicate glass was effectively used to decrease firing temperature to 850 • C, which is suitable for thick film capacitor applications. A practical demonstration of thick film capacitors using a Ag electrode on a 96% alumina substrate indicated that the optimum composition of 76BaTiO 3 -20AlN-4glass may be adequate for generating k of 79.4 and tan δ of 0.014 at 1 MHz as a result of the low temperature firing of 850 • C in air atmosphere.

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Section: Discussioncontrasting

confidence: 70%

Section: Discussionmentioning

confidence: 99%

Dielectric properties of the BaTiO3-AlN-additive system

et al. 2006

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“…The PTCR effect is very pronounced for yttrium and strontium modified barium titanate ceramics [11][12][13][14][15][16], for samples doped with niobium [10,17,18], holmium [19], strontium, lanthanum [14], niobium pentoxide, yttrium hexaboride [15,16], some oxygen-free compounds [20], and for other types of barium titanate ceramics [21] obtained with various synthesis procedures [15,16,21,22]. According to reference [10] this phenomenon can be explained by the formation of barrier layers at the grain boundaries at higher temperatures, and was more recently demonstrated by direct observations of temperature dependence of these potential barriers [18].…”

Section: Anomalous Resistivity Of Some Semiconducting Ceramicsmentioning

confidence: 99%

Bistability, autowaves and dissipative structures in semiconductor fibers with anomalous resistivity properties

Karpov

2012

Philosophical Magazine

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This work provides a discussion of bistability conditions, switching autowaves properties and emergence of dissipative structures in semiconducting fibers with anomalous positive dependence of electrical resistivity on temperature of a sigmoid type, (1 + e −T ) −1 . An open system thermodynamics approach is utilized for the analysis of this dissipative solid-state system. The approach aims to represent the structure of solution space of its governing equation in the form of physical phase diagrams, known as nonequilibrium phase diagrams, and two specific binary diagrams have been obtained here. One of the diagrams, where electrical power density and ambient temperature represent external parameters, shows a wide region with dissipative structures as nonuniform steady state temperature profiles on the fiber. A possibility of efficient external control over dissipative structure geometry is also demonstrated.

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“…Materials with positive temperature coefficient of resistance (PTCR) [1][2][3][4] based on ferroelectrics-semiconductors are of particular interest. These materials are characterized by the presence of semiconductor cores and dielectric boundaries of ceramic grains.…”

Section: Introductionmentioning

confidence: 99%

Semi-oxalate synthesis of (1−x)BaTiO3−xM0.5Bi0.5TiO3 (M = Li, Na, K) PTCR materials

et al. 2016

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(1x)BaTiO 3 -xM 0.5 Bi 0.5 TiO 3 (M = Li, Na, K) solid solutions were prepared using BaTiO 3 pre-synthesized by oxalate method. The stability limits of (1x)BaTiO 3 -xLi 0.5 Bi 0.5 TiO 3 solid solutions have been established. It was shown that increase in M 0.5 Bi 0.5 TiO 3 concentration results in reduction of ceramic grain size in the (1x)BaTiO 3 xM 0.5 Bi 0.5 TiO 3 (M = Li, Na, K) system. It was found that the positive temperature coefficient of resistance (PTCR) effect in lead-free materials is due to the presence of a semiconductor core, which is formed by sintering under reducing atmosphere, and dielectric grain boundaries, formed on additional oxidation in air. The use of barium titanate, pre-synthesized by oxalate method, in the synthesis of solid solutions reduced the sintering temperature of ceramics compared with solid state reaction technique. By comparing the electrical properties of the synthesized lead-containing and lead-free materials, it has been shown that lead-free materials exhibit better electrical properties for practical use compared with lead-containing materials.

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Semiconducting barium titanate doped with oxygen-free compounds

Cited by 5 publications

References 3 publications

Dielectric properties of the BaTiO3-AlN-additive system

Dielectric properties of the BaTiO3-AlN-additive system

Bistability, autowaves and dissipative structures in semiconductor fibers with anomalous resistivity properties

Semi-oxalate synthesis of (1−x)BaTiO3−xM0.5Bi0.5TiO3 (M = Li, Na, K) PTCR materials

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