Grain growth in a YBa2Cu3O7−x superconductive ceramics

Imayev, M. F.; Kazakova, D.B; Gavro, A.N; Trukhan, A.P

doi:10.1016/s0921-4534(99)00573-0

Cited by 12 publications

(6 citation statements)

References 28 publications

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“…The constancy of H can be explained by comparison with Y123. It is known that the basal-planefaced grain boundaries in the Y123 ceramics grow due to initiation and movement of ledges [34,35]. Most likely the mechanism of plate thickening operating in Y123 is also observed in Bi2212.…”

Section: Discussionmentioning

confidence: 97%

“…Both L and F start to increase at the same temperature, indicating that within the temperature range 820-835°C the intercolony diffusion accelerates. As shown by Imayev et al [35] the necessary condition for the onset of grain growth in Y123 ceramics during annealing is the presence of a liquid film at the grain boundaries. In Bi2212 ceramics the temperature of the onset of colony growth also correlates with the temperature of the appearance of an eutecticum which is equal to 825°C [36].…”

Section: Effect Of Deformation Conditions On the Microstructure And Tmentioning

confidence: 93%

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Microstructure, texture and superconducting properties of Bi2212 ceramics, deformed by torsion under pressure

Imayev

Daminov

Reissner

et al. 2007

Physica C: Superconductivity and its Applications

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Section: Discussionmentioning

confidence: 97%

Section: Effect Of Deformation Conditions On the Microstructure And Tmentioning

confidence: 93%

Microstructure, texture and superconducting properties of Bi2212 ceramics, deformed by torsion under pressure

Imayev

Daminov

Reissner

et al. 2007

Physica C: Superconductivity and its Applications

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“…It is known that the grain growth in Y123 ceramics is an Ostwald ripening, and the Y123 grains grow due to the diffusion of atoms between grains through a liquid intergranular film [14]. The driving force of this process is the minimization of the free surface energy of the contacting grains.…”

Section: Discussionmentioning

confidence: 99%

Microstructure of superconducting ceramics YBa2Cu3O7–x sintered with addition of seed grains

Imayev¹,

Kabirova²,

Yakshibayeva³

2017

LoM

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The growth of seed grains of YBa 2 Cu 3 O 7-x (Y123) ceramics in fine-grained matrix was studied. For this, two batches of powders were prepared. The first batch consisted only of fine-grained powder with a particle size less than 1 μm and was used to prepare the so-called reference samples. The second batch was a fine-grained powder with addition of 5 wt. % seed grains with sizes 60 -80 μm. Powders were pressed and sintered in the temperature range 925 -1000°C for 5 h. The effect of sintering temperature on density, grain size, structure of the seed-growth zone were investigated. In samples of both types the highest density is observed after sintering at T = 925 °C, and at higher temperatures the density decreases due to a release of oxygen as a result of a partial decomposition of the Y123 phase on grain boundaries. Above T ≈ 960°C the density of the reference samples decreases more strongly than in the samples with seeds. Seeds initiate the growth of anomalously large grains. The strongest growth of large grains occurs at T ≈ 960°C. Above T ≈ 960°C the grain growth is significantly slowed down that is associated with an increase in porosity of the samples. Large grains affect the growth of grains of fine-grained matrix: in the samples with seeds the mean grain size of fine-grained matrix is higher than in the reference samples. A scheme explaining the effect of seed grains on grain growth of fine-grained matrix is proposed.

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“…4 эта точка обведена кружком). Известно, что в керамике Y123 при Т < 900°С роста зерен не происходит [8]. Как видим, значения дли- ны и плотности АКЗ этого образца близки к значениям L и n образцов, которые охлаждались без деформации (рис.…”

Section: результаты и их обсуждениеunclassified

Abnormal grain growth in YBa2Cu3O7−x high-Tc superconducting ceramics during high-temperature deformation

Kabirova¹,

Pavlova²,

Imayev³

2016

LoM

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Bimodal microstructure is formed in high-T c superconducting ceramics YBa 2 Cu 3 O 7−x deformed by torsion under pressure at T d = 1008°C. The appearance of second peak on the grain length distribution is associated with formation of abnormally coarse grains with length up to l = 300-500 μm. Cooling rate has almost no effect on the density of abnormal grains n and l, indicating that such grains are formed during deformation. The l value increases monotonically with increasing twist angle α, while n increases only up to α = 25°, and then drops. The value of α above which n decreases sharply corresponds to the formation of strong texture with a factor F ≥ 0.95. Formation of abnormal grains can be explained by strain-enhanced grain growth during deformation. Intergranular sliding produces damage zones, the healing of which takes place due to the local migration of grain boundaries. Apparently, abnormal grains appear in places of most intense intergranular sliding. As the texture increases the degree of freedom of movement of grains decreases, so the possibility of accommodation of sliding of neighboring grains decreases. This leads to increase in the number of damage zones and strain value in them that is accompanied by the growth of n and l. After it reaches a certain critical level of texture (F ≈ 0.95 at α ≥ 25°) the possibility of stress relaxation due to local migration of initial grains is exhausted, and dynamic recrystallization of abnormal grains begins. Therefore, when α ≥ 25° the n value is decreased sharply.

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Grain growth in a YBa2Cu3O7−x superconductive ceramics

Cited by 12 publications

References 28 publications

Microstructure, texture and superconducting properties of Bi2212 ceramics, deformed by torsion under pressure

Microstructure, texture and superconducting properties of Bi2212 ceramics, deformed by torsion under pressure

Microstructure of superconducting ceramics YBa2Cu3O7–x sintered with addition of seed grains

Abnormal grain growth in YBa2Cu3O7−x high-Tc superconducting ceramics during high-temperature deformation

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