Synthesis of α-Si3N4 crystallon by a solvothermal method at a low temperature of 180 °C

Alpha silicon nitride (α-Si3N4) crystallon has been synthesized by the solvothermal method with silica powder as the Si source, sodium azide (NaN3) as the N source, and thiosemicarbazide as the low-temperature additive at a low temperature of 180 ℃. The as-prepared sample has been characterized by x-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence spectrum (PL, type F-7000, Hitachi, Japan). The as-prepared α-Si3N4 micron-rod crystallon is single crystal with a smooth surface and a uniformed size, the maximum diameter being 2.0 µm. The main elements in the sample are Si and N with Si–N bonds and the ratio of Si and N are close to 3:4. The as-prepared α-Si3N4 micron-rod crystallon possesses good UV emission and its PL spectrum shows a strong ultraviolet emission at 380 nm.