| Using hot stage electron microscopy, a technique for the
in situ study of the thermal decomposition of magnesium
hydroxide and the successive stages of the formation of
magnesia has been developed. It essentially consists of dipping
a nickel sample grid in a gelatinous precipitate of
magnesium hydroxide and examining the perforations on
the grid at different temperatures in the hot stage. In this
way, it has been possible to go up to 950°C and the observations
at various temperatures have been recorded in
micrographs and in selected area diffraction patterns. It
has been observed that the decomposition commences
around 350°C, and distinct crystalline particles develop at
about 550°C. Complete conversion into periclase has been
observed at 900°C. |
