Experimental and Theoretical Investigation on Ta-Doped NiTe Nanorods for Nonlinear Optical Applications

NiTe-based nanomaterials have attracted considerable attention for a wide range of technological applications due to their favorable physicochemical properties and compositional flexibility. In this study, a series of four Ta-incorporated NiTe (NT) nanostructures was successfully prepared using a single-step hydrothermal synthesis approach to systematically examine the effect of Ta addition on their structural, optical, and optoelectronic characteristics. X-ray diffraction (XRD) results confirmed the formation of the hexagonal NiTe crystal structure, with a noticeable increase in crystallite size from 16.062 to 21.138 nm upon Ta incorporation. Raman spectral analysis confirmed the presence of characteristic lattice vibration modes, while X-ray photoelectron spectroscopy (XPS) offered comprehensive information regarding elemental composition and oxidation states. Morphological observations from field-emission scanning electron microscopy (FESEM) demonstrated a distinct evolution from nanoparticle assemblies to nanorod-like architectures upon Ta doping. Optical absorption studies (UV–vis-NIR spectroscopy) revealed a systematic redshift in the direct band gap, decreasing from 2.91 to 2.37 eV with increasing Ta content. Moreover, nonlinear optical (NLO) investigations established the presence of reverse saturable absorption (RSA) behavior, as indicated by positive nonlinear absorption coefficients. The optical and electronic properties have also been studied theoretically. Collectively, these findings underscore the strong suitability of Ta-doped NiTe nanostructures for advanced optoelectronic applications, particularly in high-efficiency nonlinear optical devices.