Raman scattering investigation of nanocrystalline δ-TiNx synthesized by solid-state reaction

Micro-Raman scattering has been used to study titanium nitride with rock salt structure (δ-TiNx) synthesized by mechanical milling of a mixture of metal Ti and hexagonal boron nitride (h-BN) powders. The influence of milling time on the Raman spectra of δ-TiNx was systematically studied. Three peaks at about 215, 315, and 557 cm−1, related to transverse acoustic (TA), longitudinal acoustic (LA), and transverse optical (TO) modes of cubic TiN, respectively, were observed in the Raman spectra of TiN nanocrystals. X-ray diffraction technique was used to study the crystal structures and the average particle sizes. Raman scattering (RS) was employed to investigate the evolution of δ-TiNx nanocrystalline. The change of lattice constant that caused by the N/Ti ratio is the main reason for the evolution in the Raman spectra of δ-TiNx nanocrystalline with increasing milling time. The internal stress and grain size play a minor role in Raman spectra of δ-TiNx nanocrystalline in present study.