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Usually, the kinetic models used in the study of sintered ceramic are performed by means of indirect physical tests, such as, results obtained from data of linear shrinkage and mass loss. This fact is justified by the difficulty in the determinations of intrinsic parameters of ceramic materials along every sintering process. In this way, the technique of atomic force microscopy (AFM) was used in order to determine the importance and the evolution of the dihedral angle in the sintering of 0.5 mol% MnO 2 -doped tin dioxide obtained by the polymeric precursor method.

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“…The liquid phase formed during sintering process is found by means of determination of dihedral angle [16,17].…”

Section: Introductionmentioning

confidence: 99%

Surface equilibrium angle for anisotropic grain growth in SnO2 systems

et al. 2007

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“…According to references [16][17][18], the grain-boundary (GB) wetting can take place in oxide scale formed on the Cu surface during high temperature oxidation of the Bi 2 O 3 -coated Cu at 770 8C. Let us consider the GB wetting using the Bi 2 CuO 4 -Bi 2 O 3 system as an example.…”

Section: Grain-boundary-wetting Transition In the Scalementioning

confidence: 99%

“…Let us consider the GB wetting using the Bi 2 CuO 4 -Bi 2 O 3 system as an example. The GB wetting transition can be realized when a ceramic composite of Bi 2 CuO 4 and Bi 2 O 3 at the eutectic melting temperature between them is heated in air [17]. Figure 5a shows the starting microstructure of such a composite.…”

Section: Grain-boundary-wetting Transition In the Scalementioning

confidence: 99%

Mechanisms of Accelerated Oxidation of Copper in the Presence of Molten Oxides

Белоусов

2007

Oxid Met

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“…Previously, we demonstrated that ceramic composites Bi 2 CuO 4 + x Bi 2 O 3 are candidates for membrane materials [3]. At moderate temperatures, these composites have an extremely high (compared to conventional solid electrolytes) ionic conductivity, which is caused by the formation of a so-called liquidchannel grain boundary structure at 770°ë (the eutectic temperature [4]) [5]. However, under these conditions, the above composites lose their mechanical strength and become plastic.…”

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confidence: 99%

“…The nature of the first two inflection points (730 and 770°ë ) is rather clear: The first is caused by the α -Bi 2 O 3 δ -Bi 2 O 3 phase transition [6], i.e., by the formation of the phase exhibiting a higher oxygen ionic conductivity, and the second is due to the melting of the Bi 2 CuO 4 -Bi 2 O 3 eutectic with the concurrent formation of a liquid-channel structure [5]. However, the nature of the inflection at 813°ë is unclear.…”

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confidence: 99%

Specific Features of the Mixed Electronic-Ionic Conductivity of ZrO2/(Bi2CuO4 + xBi2O3) Composites

et al. 2005

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Materials with mixed electronic-ionic conductivity are basic components of oxide fuel cells and electrochemical membranes [1]. Therefore, one of the important challenges of modern materials science is the search for new materials with appropriate transport properties meeting the requirements for their practical use [2].A specific feature of our approach to the search for new compositions for such materials is the combination of phases of which one has electronic and the other ionic conductivity. Previously, we demonstrated that ceramic composites Bi 2 CuO 4 + x Bi 2 O 3 are candidates for membrane materials [3]. At moderate temperatures, these composites have an extremely high (compared to conventional solid electrolytes) ionic conductivity, which is caused by the formation of a so-called liquidchannel grain boundary structure at 770°ë (the eutectic temperature [4]) [5]. However, under these conditions, the above composites lose their mechanical strength and become plastic.Therefore, the aim of this work is to obtain a composite ceramic with mixed electronic-ionic conductivity that will be mechanically strong at temperatures of about 800°ë . To this end, we proposed to use a composite consisting of zirconia and a mixture of bismuth cuprate and oxide ( ZrO 2 + Bi 2 CuO 4 -Bi 2 O 3 ) as an electrochemical membrane. As distinct from the already studied system Bi 2 CuO 4 -Bi 2 O 3 , this composite should be mechanically strong (due to the zirconia matrix) and plastic (due to the appearance of a liquid phase above 770°ë ) and should be both a good electronic (due to bismuth cuprate) and ionic (due to bismuth oxide) conductor.Composites ZrO 2 /(Bi 2 CuO 4 + 20 wt % Bi 2 O 3 ) (80, 70, 60, or 50 vol % ZrO 2 ) were synthesized by the ceramic method. The initial reagents were zirconyl nitrate (ZrO(NO 3 ) 2 ) · 2H 2 O and reagent grade bismuth ( Bi 2 O 3 ) and copper (CuO) oxides. Zirconia ZrO 2 was obtained by decomposition of ZrO(NO 3 ) 2 at 900°ë for 5 h. A mixture of Bi 2 CuO 4 + 20 wt % Bi 2 O 3 (BCO/BO) was prepared by mechanical blending of corresponding amounts of Bi 2 CuO 4 and Bi 2 O 3 with subsequent annealing at 720°ë for 10 h in air. ZrO 2 + BCO/BO mixtures were homogenized in an agate mortar under an acetone layer. Then, the composites were compacted into a parallelepiped (4 × 10 × 2 mm) at a pressure of 3000 kg/cm 3 with the use of an aqueous 10% polyvinyl alcohol solution as a binder and were sintered at 730°ë for 20 h in air.The electrical conductivities of the resulting composites were measured in the temperature range 660-850°ë by the dc four-point method with a Solartron SI 1287 potentiostat and by the ac complex impedance method at frequencies ranging from 1 Hz to 1 MHz and a signal amplitude of 100 mV with a Solartron SI 1255B frequency analyzer. The temperature of the samples was monitored with an accuracy of ± 1 K using a Pt-Pt/Rh thermocouple located in immediate proximity to a sample. For a better contact between the analyte and electrodes, an electrochemical cell was preheated to 780°ë .The resul...

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Cited by 13 publications

References 57 publications

Surface equilibrium angle for anisotropic grain growth in SnO2 systems

Surface equilibrium angle for anisotropic grain growth in SnO2 systems

Mechanisms of Accelerated Oxidation of Copper in the Presence of Molten Oxides

Specific Features of the Mixed Electronic-Ionic Conductivity of ZrO2/(Bi2CuO4 + xBi2O3) Composites

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