Non-catalytic vapor synthesis of millimeter-scale α-Si3N4 nanowires from oxidized silicon powders

•Si3N4 nanowires were first synthesized only through heating oxidized Si powders.•The diameter of nanowires increased with change of oxygen content in Si powders.•The nanowires grown from high oxygen-containing Si powders had high luminescence.•Formation of α-Si3N4 nanowires followed an oxide-assisted growth mechanism.

Millimeter-scale single-crystalline α-Si3N4 nanowires were synthesized via heating oxidized silicon powders, without adding carbon and metal catalysts, at 1390 °C in N2 atmosphere based on an oxide-assisted growth process. The crystal structure, morphology and photoluminescence property of synthesized nanowires were investigated. With changing oxygen content of silicon powders from 3.28 wt% to 24.97 wt% by pre-oxidation, the average diameter of as-grown Si3N4 nanowires increased from 210 nm to 365 nm, however, the crystallized α-phase and [101] growth direction have not altered. The α-Si3N4 nanowires grown from the pre-oxided silicon powders have higher room temperature photoluminescence property than ones from the as-received silicon powders.