Deposition of porous nano-WO3 coatings with tunable grain shapes by liquid plasma spraying for gas-sensing applications

Porous nanostructured WO 3 coatings were deposited by two routes, solution and suspension plasma spraying. The nanostructural characteristics of the coatings were tunable by adjusting the constituents of the starting liquid precursor and spray parameters. Planar or spherical WO 3 grains with controllable sizes in nano-scale have been fabricated. Complete formation of spherical WO 3 grains was attained during solution plasma spraying. Enhanced heating of the nano-WO 3 particles by augmenting plasma power gave rise to oriented WO 3 grain growth along (0   0   2) plane. The planar WO 3 grains with the dimension of ~50   nm, ~80   nm, and ~700   nm in thickness, width, and length respectively were fabricated by the suspension plasma spraying. The results provide clear insight into potential gas-sensing applications of the porous WO 3 coatings.