Low-energy floppy modes in high-temperature ceramics

Journal Article · Mon Jul 31 04:00:00 EDT 1995 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.75.858· OSTI ID:112967

Vashishta, P; Kalia, R K ^[1]; Ebbsjoe, I ^[2]

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1. Concurrent Computing Laboratory for Materials Simulations, Department of Physics and Astronomy and Department of Computer Science, Louisiana State University, Baton Rouge, Louisiana 70803-4001 (United States)
2. Studsvik Neutron Research Laboratory, University of Uppsala, S-611 82 Nykoeping (Sweden)

Enhancement of the phonon density of states due to low-energy floppy modes in crystalline and glassy states of the high-temperature ceramic Si{sub 3}N{sub 4} is investigated using the molecular-dynamics method. Floppy modes appear continuously in the glass as the connectivity of the system is reduced. In the crystal, they appear suddenly at 20% volume expansion. The density of states due to the floppy modes varies linearly with energy, and the specific heat is significantly enhanced by the floppy modes.

• DOE Contract Number: FG05-92ER45477
• OSTI ID: 112967
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 5 Vol. 75; ISSN 0031-9007; ISSN PRLTAO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ENERGY-LEVEL DENSITY
GLASS
PHONONS
SILICON NITRIDES
SPECIFIC HEAT
THERMODYNAMIC PROPERTIES