TM‐dopedBaYYbF8films were epitaxially grown on both (100) and (111) GaAs substrates usingCaF2or LiF as intermediate layers. TheBaYYbF8phase was found to be a previously unreported cubic phase with a lattice constant of 0.5711 nm, which is different from a monoclinic phase reported for bulk crystals. The films produced UV and visible radiation with wavelengths at 360 nm (UV), 450–480 nm (blue), and 500–550 nm (green) when pumped by laser radiation at 647 nm. ©1995 American Institute of Physics.