Facile synthesis of α‐Si3N4 nanoneedles and their photoluminescence properties.

Needle‐like α‐Si3N4 with unique structures has potential application in both field emission devices and tips for atomic force microscopes. Single‐crystalline, α‐Si3N4 nanoneedles have been prepared by using an improved chemical vapor deposition (CVD) method at 1200°C for 3 hours. The phases, chemical composition, and microstructure of the as‐prepared products were determined by X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) equipped with EDS. The as‐synthesized products show a needle‐like morphology with hundreds of micrometers in length and nanometer‐featured tips. The nanoneedles show a α‐Si3N4@SiOx core‐shell heterostructure as characterized by TEM, with single‐crystalline α‐Si3N4 core and an insulating amorphous silicon oxide shell. The growth of α‐Si3N4 nanoneedles corresponds to vapor‐liquid‐solid cap‐growth and base‐growth mechanism. Photoluminescence (PL) properties of the products were also characterized. An obvious emission peak at 400 nm under 254 nm UV excitation was observed. The nanoneedle morphology and photoluminescence properties of the products have potentials to be used in future optoelectronic nanodevices. [ABSTRACT FROM AUTHOR]