“…An initiation phase wherein the new phase appears, to create nucleation sites, in an essentially random fashion, followed by a growth phase from the nucleation sites and finally a saturation phase as the amount of untransformed material diminishes. Given that the transformation in BAM:Eu includes the emergence of a new phases, it was thought likely that the transformation would follow such as process, at least in parts, and indeed the theory is widely and successfully used to describe transformations such as crystallisation, chemical reactions, phase changes and oxidation [23][24][25][26]. Herein, the transformation has additional features, associated with diffusion for example, so that the actual transformation is more complex than the basic theory suggests.…”