Effects of temperature and pressure on the crystal structure of forsterite

Rosnnr M. HlzeNl

Haruard Uniuersity, Department of Geological Sciences C amb ridge, M as sachuse tts 02 I 3 8


Abstract 

The crystal structure of synthetic forsterite has been studied as a function of temperature and pressure. Crystal structures have been refined from three-dimensional diffraction data collected at temperatures from -196'C to 1020'C and at pressures to 50 kbar. Volume compressibility and thermal expansion of individual magnesium octahedra are comparable to those of bulk foresterite. However, the silicon tetrahedron neither expands nor compresses within the range of conditions investigated. Thus, changes in Mg-O bond distances account for virtually all of forsterite's volume response to changes in temperature and pressure. Short Mg-O bonds vary significantly less with temperature and pressure than do long bonds, implying that shorter bonds are stronger. Octahedral distortions increase with temperature, but show no strong trends with increasing pressure.


To download the article click on the link below:

http://www.minsocam.org/ammin/AM61/AM61_1280.pdf