Patent ID: 7897268

Claim:
A composite structure made of yttrium oxide formed on a surface of a substrate by aerosol deposition comprising yttrium oxide polycrystals as a main component, wherein substantially no amorphous structure exists on a boundary face between crystals which form the structure, and both a cubic system and a monoclinic system exist in the crystal system of the yttrium oxide polycrystals, and wherein the composite structure is formed by generating an aerosol containing a mixed powder of yttrium oxide fine particles and assisting particles having a larger diameter than that of the yttrium oxide fine particles, and ejecting the aerosol from a nozzle so that the yttrium oxide fine particles and the assisting particles impact against the substrate surface at high speed, wherein the assisting particles cause the yttrium oxide particles to be deformed or fractured so as to form the composite structure made of yttrium oxide on the substrate surface, but the assisting particles bounce back after impacting the substrate surface so that assisting particles do not constitute the composite structure unless they are incorporated therein accidentally.