Intrinsic and impurity luminescence of rare earth ions doped KYF4 nanophosphors

► In KYF4 hexagonal nanopowder an intense self-trapped exciton luminescence is detected. ► This excitonic luminescence in KYF4 hexagonal nanopowders is not quenched at 300 K. ► Emission band of excitonic luminescence overlaps with Ce3+ and Tb3+ 4f-5d absorption. ► In hexagonal KYF4 nanopowders an efficient energy transfer to Ce3+ and Tb3+ was found.