ABSTRACT
It is an inevitable consequence of the laws of nature that if a material can change
from its current state to a more stable state, then it will do so. This may involve an
individual material changing its physical or chemical form, or it may be the result
of an interaction between two or more materials. Diamond, for example, is the
metastable form of carbon and over time it will convert to graphite. The only con-
sideration to be taken into account in determining if such change is of importance
is the length of time over which it will occur. In the case of the transition of
diamond to graphite the process occurs over millions of years and it may
hence be ignored. For other materials, the rate of change may be more of an
issue and chemical or compositional alterations may be needed to ensure stability
over an acceptable period.
