In the case of the OR mechanism, the growth of the particles occurs through dissolved ions propagating into regions of lower solute concentration (see Figure ). This diffusion controls the process of crystal growth, which ends when the solubility value reaches a thermodynamic equilibrium. As a result, this mechanism typically produces nanoparticles with regular shapes and a more homogeneous particle distribution . Usually, crystal growth under equilibrium conditions is related to the coarsening process also known as OR, which can be described as diffusion or reactionrate-limited growth to larger nanoparticles at the expense of smaller ones .