Localization effect for doping and collaborative diffusion in Er³⁺:YAG melt

Coordination geometry variations of cations in yttrium aluminium garnet (YAG) melt system doped with various Er3+ concentrations were quantitatively simulated at the classical molecular dynamic level. Our calculated radial distribution functions were discussed upon different ionic pairs, mean square displacement, and diffusion coefficient of ions, on which we clarified two important aspects, namely structure and dynamic properties in YAG melts with intermediate-range order (IRO). Our results show that Er3+ doping affects microscopic dynamic melt structures only in a confined scale localizing in the first nearest neighbour of Er3+ and O2-. Furthermore, such a localization effect is not varied with Er3+ concentration and system temperature. In the present melt system, Y3+, Al3+, and Er3+ cations with intrinsic differences (such as mass and electronegativity scales) were found to follow the same diffusion process in this system, which is mainly caused by the wholly collective rearrangement of the network-forming structure. In this Er3+:YAG melt system, there is an equivalence within both structure and dynamics for Er3+ and Y3+, which cannot be affected by the system temperature and Er3+ concentration, ascribing to the origin of the segregation coefficient of Er3+ in YAG to be equal to 1.