Enhanced phonon density of states in impure anharmonic crystals

Journal Article · Tue Nov 10 04:00:00 EST 1992 · Modern Physics Letters B; (Singapore)

DOI:https://doi.org/10.1142/S0217984992001368· OSTI ID:6730808

Indu, B D ^[1]

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1. Garhwal Univ., Srinagar, Uttar Pradesh (India). Dept. of Physics

In this paper, the expression for the density of states of an isotopically disordered anhormonic crystal is investigated with the help of double-time thermodynamic Green's functions. The cubic and quartic anharmonicities are taken into account besides the force constant changes and mass differences caused by the substitutional isotopic impurities. It is found that the density of states can be separated into defect, anharmonic and interference terms. The density of states is considerably enhanced due to the defects and impurities present in a real crystal and shows strong temperature and impurity concentration dependences which cannot be obtained by the traditional harmonic theory.

• OSTI ID: 6730808
• Journal Information: Modern Physics Letters B; (Singapore), Journal Name: Modern Physics Letters B; (Singapore) Vol. 6:26; ISSN 0217-9849; ISSN MPLBET
• Country of Publication: United States
• Language: English

Related Subjects

661300* -- Other Aspects of Physical Science-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANHARMONIC CRYSTALS
CONCENTRATION RATIO
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
CRYSTALS
ENERGY-LEVEL DENSITY
EQUATIONS
FUNCTIONS
GREEN FUNCTION
HARMONIC POTENTIAL
ISOTROPY
MATERIAL SUBSTITUTION
NUCLEAR POTENTIAL
PHONONS
POTENTIALS
QUASI PARTICLES
RANDOMNESS
TEMPERATURE DEPENDENCE
THERMODYNAMICS