Calcium concentration dependence on the intergranular film thickness in silicon nitride

Journal Article · Fri Apr 01 04:00:00 EST 1994 · Journal of the American Ceramic Society; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1994.tb07246.x· OSTI ID:7045350

Tanaka, Isao; Kleebe, H J; Cinibulk, M K; Bruley, J; Ruhle, M ^[1]; Clarke, D R ^[2]

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1. Max Planck Inst. fuer Metallforschung, Stuttgart (Germany). Inst. fuer Werkstoffwissenschaft
2. Univ. of California, Santa Barbara, CA (United States). Materials Dept.

High-resolution electron microscopy and nano-beam analytical electron microscopy have been used to characterize both the intergranular silicate film thickness and its local composition in a series of high-purity Si[sub 3]N[sub 4] ceramic doped with 0--450 at. ppm Ca. Calcium was detected at both two-grain junctions and triple junctions, even in the 80-ppm-Ca-doped specimen. The thickness of the intergranular film at two -grain junctions was found to depend sensitively on Ca content. In undoped material, the thickness was 1.0 [+-] 0.1 nm. With increasing Ca content, the thickness decreased in the dilute region ([<=]80 ppm Ca), but then increased. The variation in film thickness can be qualitatively understood in terms of the balance of three long-range forces acting normal to the film, namely the van der Waals dispersion force, a structural steric'' force, and an electrical-double-layer force. By comparing the measured thicknesses to those predicted, estimates for the structural correlation length and the inverse Debye length can be made. These estimates have values of [approximately]0.22 nm and approximately 0.3-0.5 nm, respectively, for the calcia-free and 80 ppm calcia materials.

• OSTI ID: 7045350
• Journal Information: Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 77:4; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
&amp; Refractories-- Structure &amp; Phase Studies
CHEMICAL COMPOSITION
DATA
DIMENSIONS
DOPED MATERIALS
EXPERIMENTAL DATA
GRAIN BOUNDARIES
INFORMATION
MATERIALS
MICROSTRUCTURE
NITRIDES
NITROGEN COMPOUNDS
NUMERICAL DATA
PHASE STUDIES
PNICTIDES
SEGREGATION
SILICON COMPOUNDS
SILICON NITRIDES
THICKNESS