Nucleation on Heating/Loading Path and Its Effects on the Evaluation of Nucleation Rate

Abstract

AbstractWe investigate the nucleation on heating/loading paths and its effects on the olivine phase transformation and the determinations of nucleation rate in in‐situ experiments by the numerical simulation based on the kinetic parameters from low temperature experiments in of Ni2SiO4 olivine phase transformation[1]. Results show that the high temperature experiments, of which samples are first loaded and then heated to the experimental conditions after annealing, are greatly affected by the nucleation during heating. The predicted nucleation rates based on these experiments are obviously overrated. Especially in the case that most of experiments have high target temperatures, the predicted nucleation rates will significantly deviate from their true values, which will have influences on the evaluations of olivine grain size and the rheological structures of subduction zones. Although there are many growth data of Mg2SiO4 olivine and a rough evaluation on the nucleation rate of (Mg0.89Fe0.11)2SiO4 olivine based on the feature of grain impingement, only Ref.[2] showed some nucleation rates of Mg2SiO4 olivine from in‐situ high temperature experiments, in which the sample is finally heated to the target experimental condition. The results in present study suggest that the experiments with low target temperature or those reached their experimental condition finally by loading are needed to derive the correct nucleation parameters of mantle olivine.