A powder comprising rare earth element fluoride particles having an aspect ratio of up to 2, an average particle size of 10-100 μm, a bulk density of 0.8-1.5 g/cm3, and a carbon content of 0.1-0.5 wt % is amenable to atmospheric plasma spraying. An article obtained by spraying the rare earth fluoride spray powder to a substrate undergoes few partial color changes and performs well even when used in a halogen gas plasma.