Studies of structures and phase transitions in pyrrhotite

摘要

This report contains a general introduction, the experimental section, general conclusions, and two appendices: using projection operators to construct the basis functions and the magnetic transition of bulk pyrrhotite samples in the low-temperature range. Four chapters have been removed for separate processing. They are: From pyrrhotite to troilite: An application of the Landau theory of phase transitions; Phase transition in near stoichiometric iron sulfide; A ordering, incommensuration and phase transitions in pyrrhotite. Part 1: A TEM study of Fe(sub 7)S(sub 8); and Part 2: A high-temperature X-ray powder diffraction and thermomagnetic study.