Eur. Phys. J. Appl. Phys. 33, 69-76 (2006)
https://doi.org/10.1051/epjap:2005084

Heating rate effects in simulated liquid Al₂O₃

Dept. of Physics, College of Natural Sciences, HochiMinh City National University, 227 Nguyen Van Cu Str., Distr. 5, HochiMinh City, Vietnam

Corresponding author: vvhoang2002@yahoo.com

Received: 28 February 2005
Revised: 21 September 2005
Accepted: 29 September 2005
Published online: 30 November 2005

Abstract

The heating rate effects in simulated liquid Al₂O₃ have been investigated by Molecular Dynamics (MD) method. Simulations were done in the basic cube under periodic boundary conditions containing 3000 ions with Born-Mayer type pair potentials. The temperature of the system was increasing linearly in time from the zero temperature as , where is the heating rate. The heating rate dependence of density and enthalpy of the system was found. Calculations show that static properties of the system such as the coordination number distributions and bond-angle distributions slightly depend on . Structure of simulated amorphous Al₂O₃ model with the real density at the ambient pressure is in good agreement with Lamparter's experimental data. The heating rate dependence of dynamics of the system has been studied through the diffusion constant, mean-squared atomic displacement and comparison of partial radial distribution functions (PRDFs) for 10% most mobile and immobile particles with the corresponding mean ones. Finally, the evolution of diffusion constant of Al and O particles and structure of the system upon heating for the smallest heating rate was studied and presented. And we find that the temperature dependence of self-diffusion constant in the high temperature region shows a crossover to one which can be described well by a power law, . The critical temperature T_c is about 3500 K and the exponent is close to 0.941 for Al and to 0.925 for O particles. The glass phase transition temperature T_g for the Al₂O₃ system is at anywhere around 2000 K.