Physical Properties of GaN Nanotubes as Revealed by Computer Simulation

Book · Fri Jul 25 04:00:00 EDT 2008

OSTI ID:967008

Wang, Zhiguo; Gao, Fei; Zu, Xiaotao; Weber, William J

Single-crystalline wurtzite GaN nanotubes have been synthesized recently with proposed applications in nanoscale electronics, optoelectronics and the biochemical-sensing field. Molecular dynamics methods with a Stillinger-Weber potential are used to investigate the melting behavior, thermal conductivity and mechanical properties of these wurtzite-type single crystalline GaN nanotubes. Four major topical areas are summarized in this chapter. (1) The melting temperature of the GaN nanotubes increases with the thickness of the nanotubes to a saturation value, which is close to the melting temperature of bulk GaN. The simulations result reveal that the nanotubes begin to melt at the surface, and then the melting rapidly extends to the interior of the nanotubes as the temperature increases. (2) The thermal conductivity of nanotubes is smaller than that of the bulk GaN single crystal. The thermal conductivity is also found to decrease with temperature and increase with increasing wall thickness of the nanotubes. The change of phonon spectrum and surface inelastic scattering may account for the reduction of thermal conductivity in the nanotubes, while thermal softening and high frequency phonon interactions at high temperatures may provide an explanation for its decrease with increasing temperature. (3) At low temperatures, the simulation results show that the nanotubes exhibit brittle properties; whereas at high temperatures, they behave as ductile materials. The brittle to ductile transition temperature generally increases with increasing wall thickness of the nanotubes and increasing strain rate. (4) The simulation temperature, tube length and strain rate affect the buckling behavior of GaN nanotubes. The critical stress decreases with the increase of simulation temperature and tube length. The dependence of buckling on tube length is consistent with the analysis of equivalent continuum structures using Euler buckling theory.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 967008
• Report Number(s): PNNL-SA-55986; KC0201020
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BUCKLING
COMPUTERIZED SIMULATION
Computer simulations
Galliium nitride
INELASTIC SCATTERING
MECHANICAL PROPERTIES
MELTING
MOLECULAR DYNAMICS METHOD
MONOCRYSTALS
Mechanical Properties
NANOTUBES
Nanotubes
PHONONS
PHYSICAL PROPERTIES
SATURATION
STRAIN RATE
THERMAL CONDUCTIVITY
THICKNESS
TRANSITION TEMPERATURE
Thermal properties