Abstract:
The Olivine (Mg, Fe) 2SiO₄ of USA has been studied with two dimensional X-ray diffracto meter (D8 discover with GADDS). The two distinct phases of orthorhombic structure, one with Mg₈ [Fe₂ SiO₄] and the other with Mg₂ SiO₄ is observed. We also observed phase transitions due to presence of iron and Silicon preferably the structural change of Mg₈[Fe₂ SiO₄] from orthorhombic to spinnel like (spinnel chord) structure. Magnesium ions in Mg₈[Fe₂ SiO₄] shuffle, arrange at the five vertices of a pentagon and the remaining three at the central but with displaced position from the plane of the pentagon, Thus resulting into a three dimensional spinnel chord like structure. We evidenced the same from diverse orientations of phase peaks and indeed from Kossel lines.
