Unexpected Broadband Visible Emission from Sol-Gel Derived Yttrium Silicate Nanopowders under 803.5 nm Laser Diode Excitation*

We report the generation of efficient, wideband white light (WL) with a spec-trum ranging from 400 to 800 nm obtained from sol-gel derived $\gamma $-Y$_{2}$Si$_{2}$O$_{7}$ nano powders with average particle size $\sim$ 40nm when excited with the 803.5 nm emission of a laser diode. The WL intensity was found to increase with decreasing environment pressure and increasing laser pumping power. The decay time was 0.41 ms. The intensity reached its max value18 sec. After switching on the laser. The International Commission on Illumination (CIE) coordinates were found to be $x =$ 0.3408 and $y =$ 0.3100 under 803.5~nm excitation. These values lie in the yellowish region and correspond to color temperature values of 5030~K with a color rendering index of 85. The illuminance value was found to be 1456~lux.