Incandescent Lamp-Like White-Light Emission from Doped and Undoped Oxide Nanopowders

We report the production of a broad band emission (ranging from 400 to 900 nm) following the monochromatic infrared light (803.5 nm) continuous wave excitation of either nominally un-doped or Nd-doped up to 20% yttrium oxide (Y2O3) nanopowders, Y3Al5O12(YAG) and Cr3+doped Gd3Ga5O12(GGG) nanocrystallites. Our experimental results indicate that such emission feature is (i) a nano-scale phenomenon, (ii) demands a threshold pumping power, (iii) cannot be ascribed to an overlap of sharp emission bands in the un-doped case and, (iv) even if assisted by the dopant presence, is a host matrix-related process. In the case of the Y2O3-based samples, we demonstrate the possibility to obtain “warm” white light with high efficiency and color rendering index approaching the theoretical limit with an alternative approach. Our experimental results make our white light emission very interesting at both fundamental and applicative levels and may open the way to an alternative route with respect to incandescent lamps