Impact of Ga3+ on the phase transition and luminescence properties of substituted Sr2SiO4:Eu2+ phosphor synthesized from a highly homogeneous oxide precursor based on a novel water-soluble silicon compound

摘要

A series of samples with the compositions Sr2(1-x.z/2)Eu2xLazSi1-zGazO4 were synthesized by an advanced solution method employing a water-soluble silicon (WSS) compound. It has been observed that the substitution of Si4+ by Ga3+ in charge compensated Sr2(1-x.z/2)Eu2xLazSi1-zGazO4 samples causes a phase transition from beta-phase to the alpha-phase of Sr(2)Sia(4) accompanied by a considerable red shift in the photoluminescence emission spectra. Internal quantum efficiencies are found to be 95% and 77% for Sr1.98Eu0.02SiO4 and Sr1.93Eu0.02La0.05Si0.95Ga0.05O4 respectively. The high quantum efficiency of the phosphors owe to the synthesis procedure as well as use of SrC12 as flux during the heat treatment in H-2/Ar atmosphere. To demonstrate its potential application, we fabricated a warm white light-emitting diode (WLED) using the Sr1.93Eu0.02La0.05Si0.95Ga0.05O4 phosphor, pumped with a 365 nm n-UV LED chip, which reflects the good color rendering index and color temperature.