Effect of thickness and composition on the structure and ordering in La-doped intergranular films between Si3N4 crystals

Yun Jiang, Steve Garofalini

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Molecular dynamics simulations were used to determine the effect of the composition and thickness on the atomistic structure of La-Si-O-N intergranular films (IGFs) between prism and misaligned high-index silicon nitride crystals. Results showed that ordered La adsorption onto the prism-terminated surface is not affected by the orientation of the opposing crystal, although the extent of the ordering away from the interface is affected by IGF thickness. La adsorption at ordered sites 1 and 2 on the prism surface occurred for almost all of the compositions in both 1.8 and 0.6 nm thick IGFs and at sites farther from the prism interface in the thicker IGF, similar to adsorption in triple points. La adsorption on the prism surface occurred at sites precisely the same as seen in high-angle annular dark field scanning transmission electron microscopy studies. Saturation of available sites is affected by the thickness of the IGF, which governs the number of La ions (and N ions) in the IGF, with lower site filling in the thinner IGF. There are clear energy differences for La in the interior of the IGF vs. the interface based on composition and IGF thickness, with the thicker IGF showing greater variation in driving forces for segregation or La incorporation into the IGF. Fracture is affected by both composition and thickness and occurs in the glassy IGF and not in the ordered interfacial regions, consistent with experimentally observed intergranular fracture for La-doped silicon nitride. Segregation of La to the interface affects N distribution within the interior of the IGF, which affects strength.

Original languageEnglish
Pages (from-to)5368-5377
Number of pages10
JournalActa Materialia
Volume59
Issue number13
DOIs
Publication statusPublished - Aug 2011

Fingerprint

Prisms
Crystals
Chemical analysis
Thick films
Adsorption
Silicon nitride
Film thickness
Ions
silicon nitride
Crystal orientation
Molecular dynamics
Transmission electron microscopy
Thin films
Scanning electron microscopy
Computer simulation

Keywords

  • Ceramics
  • Fracture
  • Interface structure
  • Molecular dynamics

ASJC Scopus subject areas

  • Ceramics and Composites
  • Metals and Alloys
  • Polymers and Plastics
  • Electronic, Optical and Magnetic Materials

Cite this

Effect of thickness and composition on the structure and ordering in La-doped intergranular films between Si3N4 crystals. / Jiang, Yun; Garofalini, Steve.

In: Acta Materialia, Vol. 59, No. 13, 08.2011, p. 5368-5377.

Research output: Contribution to journalArticle

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