Luminescence Properties Related to Defects in Y2O3:Ho3+ Nanocrystal

Abstract

In this paper, Y2O3:Ho3+ nanocrystals have been prepared by a solution combustion synthesis method. The luminescence properties of defects and Ho3+ ions in yttria nanocrystal have been studied under 325 nm laser excitation. The emissions which were corresponding to 5F4-5I8, 5S2-5I8 and 5G4-5I6 trasitions of Ho3+ were measured. It was observed that the characteristic emissions of Ho3+ were gradually submerged in the broad cingulum emissions with the decrease of the nanoparticle size. The research results indicated that the broad cingulum emissions originated from the defects of nanocrystals. With the decrease of size, surface atoms which have a lot of defects increase relatively. Those surface defects can easily absorb the energy of excitation photons producing the broad spectra emissions. The electron paramagnetic resonance experiments have been performed to definitely reveal the defects information. The electron paramagnetic resonance signal has a slight shift towards the direction of weak magnetic field with the decrease of nanocrystal size, which means that the corresponding g factor becomes bigger in smaller size sample.