POWDER FOR FILM FORMATION AND MATERIAL FOR FILM FORMATION

The present invention relates a coating powder comprising a rare earth oxyfluoride (Ln-O—F) and having : an average particle size (D50) of 0.1 to 10 μm, a pore volume of pores having a diameter of 10 μm or smaller of 0.1 to 0.5 cm3/g as measured by mercury intrusion porosimetry, and a ratio of the maximum peak intensity (S0) assigned to a rare earth oxide (LnxOy) in the 2θ angle range of from 20° to 40° to the maximum peak intensity (S1) assigned to the rare earth oxyfluoride (Ln-O—F) in the same range, S0/S1, of 1.0 or smaller in powder X-ray diffractometry using Cu-Kα rays or Cu-Kα1 rays.