Synthesis and photoluminescence of heavily La-doped α-Si3N4 nanowires via nitriding cyromilled nanocrystalline La-doped silicon powder

Abstract

In this paper, the synthesis of heavily La-doped α-Si3N4 nanowires is firstly reported via nitriding the cryomilled La-doped nanocrystalline Si powder. The crystal structure, electronic structure and band structure of La-doped α-Si3N4 are calculated by using the CASTEP program code based on the first principles plane-wave pseudo-potential method. The microstructure and photoluminescence of heavily La-doped α-Si3N4 nanowires are investigated. The results suggest that La has been already incorporated into Si lattice after the cryomilling process and then successfully entered the lattice of α-Si3N4 with the nitridation process. The as-synthesized heavily La-doped α-Si3N4 nanowires show high purity and good crystallinity with 30–40nm in diameter and several tens of micrometers in length. The optical property shows that there is an intense violet–blue visible emission from 350nm to 450nm with one peak at 388nm due to the recombination between the valence band and the N4+ level at room temperature, which is in agreement with the calculated band structure of La-doped α-Si3N4.