Reduced Activation Energy for Grain Growth in Nanocrystalline Yttria-Stabilized Zirconia

Shukla, Satyajit; Seal, Sudipta; Vij, Rashmi; Bandyopadhyay, Sri

doi:10.1021/nl0259380

Cited by 145 publications

(95 citation statements)

References 28 publications

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“…We have found no particular reduction in the activation energy as seen in ceramic nanocrystalline materials. 33 We have also found that in fcc nanocrystalline materials, twins appear in a mechanism that is similar to that postulated for larger grain materials, with an activation energy similar to that of grain-boundary diffusion. The activation energy that we found for grain-boundary migration of 34.7 kJ/ mol compares well with that found in previous studies in other fcc materials and with different interaction potentials which are in the the range of 24-31 kJ/ mol.…”

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confidence: 69%

Annealing twins in nanocrystalline fcc metals: A molecular dynamics simulation

2007

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We report fully three-dimensional atomistic molecular dynamics studies of grain growth kinetics in nanocrystalline Cu of 5 nm average grain size. We observe the formation of annealing twins as part of the grain growth process. The grain size and energy evolution was monitored as a function of time for various temperatures, yielding an activation energy for the process. The atomistic mechanism of annealing twin formation from the moving boundaries is described. DOI: 10.1103/PhysRevB.75.184111 PACS number͑s͒: 61.72.Mm, 61.82.Rx Annealing twins in face-centered-cubic metals have been observed as early as 1897, 1-3 and are a prominent feature observed in routine metallography of these materials. The formation of these twins is usually associated with the process of grain growth that occurs during annealing at relatively high temperatures. Twin boundaries are usually flat and extend across an entire grain. The resulting density of twins after an annealing treatment is controlled by grainboundary energy, prior deformation, and resulting grain size. [4][5][6][7][8][9][10][11] The formation of annealing twins is a very common experimental observation; the fraction of annealing twins typically increases with annealing time and therefore with the amount of grain growth. Up to two to three twins per grain are typically observed, and it has been suggested that the nucleation and growth of twinning are mechanistically linked to anomalous grain growth. [12][13][14] In addition, it has been shown that imposed shear stresses during annealing of deformed fcc metals with low stacking fault energies tend to result in recrystallized microstructures containing higher fractions of twin boundaries than those annealed without an imposed shear stress. 13 This appears to be true also for materials deformed by severe plastic deformation where high residual shear stresses are present.The mechanisms by which annealing twins are formed are not completely understood. Current theories propose that accidents at growing grains and particularly faults on ͕111͖-type planes are responsible for the formation of annealing twins. [15][16][17][18] The models of twin formation generally require grain-boundary migration. In the model of Mahajan et al., 15 the nucleation of Shockley partial dislocations at growth accidents on ͕111͖ steps is associated with grain-boundary migration.In nanocrystalline materials, there is strong evidence that deformation occurs through emission of Shockley partial dislocations from grain boundaries which are absorbed in the opposing grain boundaries. These mechanisms based on partial dislocations lead to twinning when partial dislocations are emitted in adjacent ͕111͖-type planes. The deformation response of these materials has been studied using molecular dynamics simulation techniques, [19][20][21] and similar theoretical work can help in the detailed understanding of the process of twin formation during annealing treatments.In the present work, we report on relatively long molecular dynamics simulations of grain growt...

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Annealing twins in nanocrystalline fcc metals: A molecular dynamics simulation

2007

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“…ZrO 2 shows versatile polymorphism with three different crystal structures: cubic (c-ZrO 2 ), tetragonal (t-ZrO 2 ) and monoclinic (m-ZrO 2 ) [17,18]. The point symmetry of the Zr site is C 2h and D 4h for the monoclinic and tetragonal form, respectively, indicating that the local monoclinic structure is less symmetric than tetragonal as well.…”

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Influence of titanium and lutetium on the persistent luminescence of ZrO_2

Carvalho¹,

Rodrigues²,

Hölsä³

et al. 2012

Opt. Mater. Express

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Non-doped as well as titanium and lutetium doped zirconia (ZrO 2 ) materials were synthesized via the sol-gel method and structurally characterized with X-ray powder diffraction. The addition of Ti in the zirconia lattice does not change the crystalline structure whilst the Lu doping introduces a small fraction of the tetragonal phase. The UV excitation results in a bright white-blue luminescence at ca. 500 nm for all the materials which emission could be assigned to the Ti 3+ e g  t 2g transition. The persistent luminescence originates from the same Ti 3+ center. The thermoluminescence data shows a well-defined though rather similar defect structures for all the zirconia materials. The kinetics of persistent luminescence was probed with the isothermal decay curve analyses which indicated significant retrapping. The short duration of persistent luminescence was attributed to the quasi-continuum distribution of the traps and to the possibility of shallow traps even below the room temperature. 1076-1078 (2000). 13. R. C. Garvie, R. H. Hannink, and R. T. Pascoe, "Ceramics steel," Nature 258(5537), 703-704 (1975)

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“…In addition, Zhou and Huebner [6] showed a significant enhancement of oxygen-vacancy concentration in nanocrystalline ceria as compared to conventional ceria powder. Shukla et al [7] proposed that this enhancement in oxygen-vacancy concentration may be one of the reasons for the reduced activation energy for the grain growth of nanocrystalline yttria-stabilized zirconia.…”

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The Effect of Oxygen Vacancies in the Early Stages of BaTiO₃ Nanopowder Sintering

Levi

Tsur

2005

Advanced Materials

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Reduced Activation Energy for Grain Growth in Nanocrystalline Yttria-Stabilized Zirconia

Cited by 145 publications

References 28 publications

Annealing twins in nanocrystalline fcc metals: A molecular dynamics simulation

Annealing twins in nanocrystalline fcc metals: A molecular dynamics simulation

Influence of titanium and lutetium on the persistent luminescence of ZrO_2

The Effect of Oxygen Vacancies in the Early Stages of BaTiO₃ Nanopowder Sintering

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Reduced Activation Energy for Grain Growth in Nanocrystalline Yttria-Stabilized Zirconia

Cited by 145 publications

References 28 publications

Annealing twins in nanocrystalline fcc metals: A molecular dynamics simulation

Annealing twins in nanocrystalline fcc metals: A molecular dynamics simulation

Influence of titanium and lutetium on the persistent luminescence of ZrO_2

The Effect of Oxygen Vacancies in the Early Stages of BaTiO3 Nanopowder Sintering

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The Effect of Oxygen Vacancies in the Early Stages of BaTiO₃ Nanopowder Sintering