Atomistic Simulation Study of Interfaces in Nanophase Silicon

Abstract

ABSTRACTNanophase silicon was investigated using atomistic simulation. The simulations employed a modified Stillinger-Weber potential appropriate for crystalline and amorphous silicon. Computer “samples” of nanophase material were formed by compressing together three grains of several hundred atoms each, using Fletcher-Powell minimization and external pressures of 0.5 to 13.5 GPa. Relative densities obtained in the samples ranged from 65% to 98% as compared to the perfect crystal. The nanophase materials maintained crystalline order up to the interfaces and no highly disordered interfaces were observed. Calculated bulk moduli exhibited a linear dependence with respect to density, with no significant dependence on structure. The calculated thermal expansion coefficients were up to twice as large as that in the perfect crystal and were structure dependent.