Lattice dynamics of colloidal crystals

Journal Article · Mon Nov 01 00:00:00 EST 1982 · Phys. Rev. A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.26.2869· OSTI ID:6434215

Hurd, A J; Clark, N A; Mockler, R C; O'Sullivan, W J

Photon correlation spectroscopy was performed on a dilute bcc colloidal crystal in a thin-film cell to measure its response to thermal fluctuations with wave vectors along lattice symmetry directions. The phonon dispersion curves show a definite harmonic-lattice behavior for longitudinal and transverse modes. We present a Langevin treatment of the lattice dynamics, based on harmonic potentials and a theory of hydrodynamic interactions which is exact to lowest order in sphere volume fraction and includes important unsteady flow effects. The model takes into consideration the discreteness of the lattice, which is important near the Brillouin-zone boundary, and has the correct behavior for long-wavelength fluctuations as well (underdamped transverse modes, overdamped longitudinal modes). The mass renormalization of propagating transverse lattice modes is discussed, along with the effects of the thin-film configuration on their propagation. The role of backflow in overdamping longitudinal modes is made clear. From the measured dispersion curves for longitudinal wave vectors, we obtained the following elastic constants: c/sub 11/ = 6.96 dyn/cm/sup 2/ and c/sub 12/ = c/sub 44/ = 2.43 dyn/cm/sup 2/.

• Research Organization: Department of Physics, University of Colorado, Boulder, Colorado 80309
• OSTI ID: 6434215
• Journal Information: Phys. Rev. A; (United States), Vol. 26:5
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COLLOIDS
CRYSTAL STRUCTURE
DISPERSION RELATIONS
ELASTICITY
FUSION HEAT
PHONONS
POLYSTYRENE
SPECTROSCOPY
THERMODYNAMIC PROPERTIES
DISPERSIONS
ENTHALPY
MATERIALS
MECHANICAL PROPERTIES
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PETROCHEMICALS
PETROLEUM PRODUCTS
PHYSICAL PROPERTIES
PLASTICS
POLYMERS
POLYOLEFINS
POLYVINYLS
QUASI PARTICLES
SYNTHETIC MATERIALS
TENSILE PROPERTIES
TRANSITION HEAT
360102* - Metals & Alloys- Structure & Phase Studies