Programme

P.36 -- Poster, VCTP-44

Date: Tuesday, 30 July 2019

Time: 08:30 - 10:00

Molecular dynamics simulations of structural transformation and mechanical properties in densified MgSiO3

Le Van Vinh

Phenikaa University

Molecular dynamics simulations of densified MgSiO3 have been carried out to study the structural and mechanical properties under uniaxial tension. The network structure consists of SiOx and MgOy units which link to others by corner-, edge- and face- sharing bonds. The Si-rich and Mg-rich regions exist in densified MgSiO3. The stress-strain curves exhibit the elastic and plastic characteristics. The transformations of SiOx and MgOy units occur with increasing strain, at which the corner-, edge- and face- sharing bonds among SiOx and MgOy units change. The Si-rich and Mg-rich regions increase with increasing strain. Under pressure, the transition of units SiOx, MgOy occurs from low to high coordination number. The topology of each SiOx type is less affected than that of each MgOy type upon compression. With increasing pressure above 20 GPa, oxygen atoms become more ordered to form the distorted oxygen sublattice in fcc, hcp or icosahedral clusters, at which these clusters contain a few ten to hundred atoms. The Young’s modulus increases with increasing pressure due to the increasing fraction of high coordination number and the decrease of the volume of each SiOx and MgOy types.

Presenter: Le Van Vinh