**4. Conclusions**

The use of microwave plasma treatments has been reviewed both for sintering nanoparticles (referred to as rapid discharge sintering (RDS), as a thermal processing route for crystalline phase changes, as well as for the oxidation of metal surfaces. For the fabrication of porous ceramics, the plasma treatments have the advantage of being rapid and flexible allowing for the tailoring and control of pore structures with processing conditions. Compared to the conventional methods such as air furnace treatment, the plasma treatments were demonstrated to yield improved results in terms of shorter treatment time, lower energy requirement and enhanced performance. The latter was demonstrated in the case of metal oxide layers (NiO and TiO<sup>2</sup> ), when evaluated for use in solar energy applications.
