Hydrothermally Synthesized Bi‐Cr‐Te Nanocomposites With Enhanced Nonlinear Two‐Photon Absorption

Abstract This study highlights the importance of exploring BiCrTe nanocomposites to uncover their distinctive properties and potential applications. Three BiCrTe samples were synthesized using hydrothermal methods by varying the concentrations of Bi and Cr while maintaining a constant Te content. X‐ray diffraction (XRD) confirmed the presence of Bi₂Te₃ and Cr₂Te₃ phases, supported by transmission electron microscopy (TEM) observations. A reduction in Bi content led to smaller crystallite sizes. Raman spectroscopy revealed characteristic vibrational modes associated with Bi₂Te₃ and Cr. Field emission scanning electron microscopy (FESEM) confirmed the nanoparticle‐like morphology of the composites. X‐ray photoelectron spectroscopy (XPS) provided detailed surface composition and electronic structure data, verifying the presence of all constituent elements. UV‐Vis spectroscopy demonstrated a blueshift in absorbance with decreasing Bi content, with bandgap (Eg) values ranging from 3.31 to 3.61 eV. This increase in bandgap correlated with a reduction in refractive index (n). Nonlinear optical (NLO) studies revealed two‐photon absorption behavior, along with a positive nonlinear absorption coefficient (β), third‐order susceptibility (χ ⁽³⁾), and refractive index (n₂). These findings indicate that BiCrTe nanocomposites hold significant promise for advanced optoelectronic applications.