Effect of Temperature on the Site Preference of Fe in Olivine

Biswas, Joydipa (2021) Effect of Temperature on the Site Preference of Fe in Olivine. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS Dissertation of Joydipa Biswas (16MS188)) 16MS188_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (2MB)

Abstract

The crystal structure of olivine is such that it contains two kinds of octahedral sites namely M1, which is smaller and less distorted, and M2, which is larger and more distorted. A problem of great geophysical importance is the site preference of Fe in olivine. Previous first principles-based calculations suggest that at T=0K, the Fe ion prefers to occupy the smaller M1 octahedra. However, as the temperature is increased there are conflicting reports on the site preference of Fe in olivine. In this study, we have used classical potential models to simulate the crystal structure of olivine (FeMgSiO4). Our calculations suggest that the sizes of the M1 and M2 octahedra rather become similar with rising in temperature, thereby indicating that there is no cross-over in site preference of Fe in olivine as suggested by some previous studies.

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