Electron Accumulation in the Grain Boundary of Yttria Doped Nanocrystalline Zirconia Ceramics: Experimental Evidences

ABSTRACTIt is expected that the grain boundary diffusion is the principal contributor to the transport properties of nanocrystalline zirconia, and that it controls the oxidation kinetics and hydrogen permeation. This process depends on the grain boundary character distribution (i.e. the fractions of different grain boundary types) and on the topological characteristics of the grain boundary network. Modeling of the random walk problem on a planar honeycomb network for different types of the grain boundary misorientation distributions (GBMD) in nanocrystalline zirconia film is presented in the current paper. The GBMD was calculated using the model texture. Changes of the oxidation rate for different types of the grain boundary character distribution and different ratios of the bulk and grain boundary diffusion coefficients are analyzed. In this study it was found that an increase of the frequency of low energy boundaries lowers the oxidation rate.

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Low-temperature isothermal sintering and microstructural characterization of nanocrystalline zirconia ceramics using small angle neutron scattering

Nanostructured Materials ◽

10.1016/s0965-9773(99)00218-4 ◽

1999 ◽

Vol 12 (5-8) ◽

pp. 689-692 ◽

Cited By ~ 8

Author(s):

U. Betz ◽

A. Sturm ◽

J.F. Loeffler ◽

W. Wagner ◽

A. Wiedenmann ◽

...

Keyword(s):

Low Temperature ◽

Neutron Scattering ◽

Small Angle ◽

Small Angle Neutron Scattering ◽

Microstructural Characterization ◽

Zirconia Ceramics ◽

Nanocrystalline Zirconia

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Analytical TEM of grain boundary phases in yttria-zirconia ceramics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100125762 ◽

1987 ◽

Vol 45 ◽

pp. 166-167

Author(s):

M.L. Mecartney ◽

P. Angelini

Keyword(s):

Grain Boundary ◽

Tetragonal Zirconia ◽

Ceramic Materials ◽

Liquid Phase Sintering ◽

Raw Material ◽

Aluminosilicate Glass ◽

Microstructural Development ◽

Ionic Conductors ◽

Zirconia Ceramics ◽

Amorphous Silicate

Yttria-zirconia ceramics have a broad range of applications, from use as structural materials (tetragonal zirconia) to ionic conductors (cubic zirconia). Similar to many ceramic materials, these zirconia ceramics often contain small amounts of amorphous silicate phases at grain boundaries and multiple grain junctions. These phases are a result of impurities, introduced during processing or from the original raw material, or are deliberate additions to aid in the densification via liquid phase sintering. Despite the universality of these grain boundary phases, as of yet little work has been undertaken to understand their effect on the microstructural development, chemistry, and physical properties of the materials. We report here our results on analyzing a series of yttria doped zirconia ceramics to which deliberate additions of various glass phases have been added.Samples were fabricated from zirconia powders which contained 3 mol% yttria and 8 mol% yttria. Aluminosilicate glass or borosilicate glass (5 wt%) was added to the powders before sintering. The samples were hot-isostatically pressed at 1650°C for 1-100 minutes.

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