Heterogeneous solid-state reactions between MgO(00l) and iron oxide
The transport properties of the diffusing species in heterogeneous solid-state reactions are affected by concentration gradients, temperature gradients, stress fields and electric fields. In the present study, interfacial reactions between thin films of iron oxide and bulk monocrystalline MgO{001}, resulting in the formation of the spinel product MgFe2O4, were carried out separately as a function of time and temperature, applied external electric field and partial pressure of oxygen. Electron microscopy techniques have been utilized to investigate the reaction kinetics and interface morphology.The reaction couples were produced by means of pulsed-laser deposition (PLD). The setup for PLD has been described elsewhere. By depositing high-quality oxide films on bulk substrates, a well controlled geometry can be fabricated which is conducive to the study of fundamental processes in solid-state reactions. In producing the reaction couples, 600nm of iron oxide was deposited on monocrystalline MgO{001}. The reaction couples were then reacted under varying conditions and analyzed, using both scanning (SEM) and transmission electron microscopy (TEM).