The local structure characterization and resulting phase-transition mechanism of amorphous ZrO₂

Abstract

In the framework of Faber-Ziman's formalism, the radial atomic number density distributions ρ(r) for two amorphous ZrO₂-gel samples have been derived, and used to perform local structure simulations based on the monoclinic and tetragonal crystal skeletons in order to determine and investigate the local structure of amorphous ZrO₂. The results indicate that the topological structure of amorphous ZrO₂ bears more resemblance to monoclinic ZrO₂ structure than to the tetragonal one. Moreover, the random structure in the amorphous ZrO₂ is characterized mainly by the first-kind disorder in the short-range. According to this structural picture of amorphous ZrO₂, a phase-transition mechanism of amorphous ZrO₂ has been proposed, by which the crystallization of amorphous ZrO₂ is considered starting with the formation of monoclinic nuclei followed by their further growth or conversion to the tetragonal phase, depending on the particular kinetic conditions and chemical environments. This proposed mechanism can help in the understanding of some experimental results that are not yet well understood.