Phase and microstructure evolution in precursor plasma-sprayed YIG coatings

Yttrium iron garnet (YIG) coatings were prepared using a liquid precursor plasma spray (PPS) method. Regular and reverse co-precipitated feedstock sols were directly sprayed through a radio frequency (RF) plasma torch. X-ray diffraction (XRD) analyses revealed the formation of amorphous coating in the as-sprayed condition. Post-annealing treatments resulted into nanostructured garnet coatings and the crystallinity of the coatings increased as a function of increasing annealing temperature. Coating annealed at 1000 °C/h exhibited a saturation magnetization of 65 emu/cc and a coercivity of 37 Oe. PPS approach feeds on molecularly mixed precursor liquids or sols, obviating the need for pre-mixed powders and thus opening up new avenues for developing nanostructured magnetic oxide coatings.