White up conversion emission has been observed in sol-gel derived alpha-Y2Si2O7 nano powders activated with ytterbium and erbium ions when excited with the 950 nm emission of a laser diode. Measurements of the sample emission intensity dependence on the pumping power under atmospheric pressure condition were performed to provide possibly an explanation for the UC mechanism. The emission intensities of each Er3+ transition decreased when the pumping power was increased from 1.7 to 2.5 W with the observation of the bright wide band under atmospheric pressure condition. When the sample was subject to very low pressure at 0.03 mbar and the pumping power was set from 0.9 to 2.5W, the white emission brightness increased. The CIE coordinates (x, y) for YSYE were found to be (0.330, 0300 (1.7 W-0.3 mbar)) and (0.339, 0.304 (2.5 W-atmospheric pressure)) under the 950 nm laser diode excitation. (C) 2015 Elsevier B.V. All rights reserved.