Nucleation,growth and stability of CaAl2Si2O8 polymorphs |
| |
| Authors: | Toshiya Abe Katsuo sukamoto Ichiro Sunagawa |
| |
| Institution: | 1. Department of Mineralogical Sciences and Geology, Faculty of Science, Yamaguchi University, Yoshida, 753, Yamaguchi, Japan
2. Institute of Mineralogy, Petrology and Economic Geology, Faculty of Science, Tohoku University, Aramaki Aoba, 980, Sendai, Japan
|
| |
| Abstract: | By means of in situ observation, the nucleation and growth of triclinic, pseudo-orthorhombic and pseudo-hexagonal CaAl2Si2O8 were investigated and their relative stabilities established. Pseudo-hexagonal and pseudo-orthorhombic CaAl2Si2O8 nucleate prior to anorthite and grow in a supercooled anorthite melt before the latter appears. They either dissolve or transform to anorthite once the latter nucleates and starts to grow. Corundum and mullite also nucleate metastably prior to anorthite in this melt. The liquidus temperatures of the four metastably nucleated phases were determined precisely by in situ measurements of the transformation temperatures from a polyhedral to a rounded morphology. On the basis of the supercooling thus determined, the growth rate versus supercooling relations were measured and analysed for the respective phases. The growth rate of the stable phase is one order of magnitude higher than those of any metastable phases. However, the growth rates of the three CaAl2Si2O8 polymorphs normalized by the viscosities are nearly the same. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
