Structural and transport properties of (Mg,Fe)SiO3 at high temperature and high pressure

(Mg,Fe)SiO3 is primarily located in the mantle and has a substantial impact on geophysical and geochemical processes. Here, we employ molecular dynamics simulations to investigate the structural and transport properties of (Mg,Fe)SiO3 with varying iron contents at temperatures up to 5000 K and pressures up to 135 GPa. We thoroughly examine the effects of pressure, temperature, and iron content on the bond lengths, coordination numbers, viscosities, and electrical conductivities of (Mg,Fe)SiO3. Our calculations indicate that the increase of pressure leads to the shortening of the O-O and Mg-O bond lengths, while the Si-O bond lengths exhibit the initial increase with pressure up to 40 GPa, after which they are almost unchanged. The coordination numbers of Si transition from four-fold to six-fold and eventually reach eight-fold coordination at 135 GPa. The enhanced pressure causes the decrease of the diffusion coefficients and the increase of the viscosities of (Mg,Fe)SiO3. The increased temperatures slightly decrease the coordination numbers and viscosities, as well as obviously increase the diffusion coefficients and electrical conductivities of (Mg,Fe)SiO3. Additionally, iron doping facilitates the diffusion of Si and O, reduces the viscosities, and enhances the electrical conductivities of (Mg,Fe)SiO3. These findings advance fundamental understanding of the structural and transport properties of (Mg,Fe)SiO3 under high temperature and high pressure, which provide novel insights for unraveling the complexities of geological processes within the Earth's mantle.