Synthesis and photoluminescence of Si3N4 nanowires from La/SiO2 composites and Si powders

Large-scale Si3N4 nanowires were successfully synthesized by the reaction of La/SiO2 composites and Si powders in N2 atmosphere at 1200°C for 6h. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrometry, scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). The results show that the products mainly consist of hexagonal Si3N4 nanowires and a small amount of Si2N2O. The Si3N4 nanowires have a length of several hundreds of microns and a diameter of 100–200nm, and Si3N4 nanowires grow along [100] direction. The growth of Si3N4 nanowires follows vapor–solid (VS) mechanism, and the growth process of the nanowires is simply discussed. The photoluminescence (PL) spectrum of Si3N4 nanowires at room temperature shows four emission peaks at 406, 472, 495 and 605nm.