Nanopowders containing nanoparticles having a core particle with a thin film coating. The core particles and thin film coatings are, independently, formed from at least one of a rare earth metal-containing oxide, a rare earth metal-containing fluoride, a rare earth metal-containing oxyfluoride or combinations thereof. The thin film coating may be formed using a non-line of sight technique such as atomic layer deposition (ALD). Also disclosed herein are nanoceramic materials formed from the nanopowders and methods of making and using the nanopowders.