Optical properties and characterization of zinc nitride nanoneedles prepared from ball-milled Zn powders

Zinc nitride nanoneedles (ZNNs) with diameters at stem and tip parts as 200–300 nm and 30–70 nm respectively have been prepared by the nitridation of ball-milled zinc powders at 600 °C for 120 min under NH3 gas environment. The structural, compositional and morphological characterizations of the product were conducted by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy and transmission electron microscopy. From transmission spectrum data, an indirect band gap of 2.72 eV has been calculated for ZNNs whereas photoluminescence studies exhibited a strong UV excitonic mission band at 395 nm as well as two weak defect related blue emissions at 453 and 465 nm. A vapor–solid (VS) process based growth mechanism for the formation of ZNNs has also been discussed briefly.

Research Highlights
► Zn3N2 nanoneedles (ZNNs) are prepared by the nitridation of ball-milled Zn powders.
► A vapor-solid process based growth mechanism governs the formation of ZNNs.
► An indirect band gap of 2.72 eV is calculated for ZNNs using transmission spectrum.
► PL emission exhibits a strong UV band associated with two weak blue emission bands.