Microwave Combustion Synthesis and Third Order Nonlinear Optical Traits and Optical Limiting Behavior of Sr2+ Ion Doped ZnAl2O4 Nanoparticles
Abstract
Zinc aluminate (ZnAl2O4) nanoparticles, doped with strontium (Sr), were synthesized using the microwave combustion process, incorporating varying strontium levels (x = 0, 0.1, 0.3, and 0.5). The cubic crystalline structure of the samples was confirmed through X-ray diffraction (XRD) analysis. The crystallite size of the Sr2+-substituted ZnAl2O4 ranged from 08.37 to 11.40 nm. Fourier transform infrared (FT-IR) spectra revealed distinctive stretching frequencies. As the concentration of Sr2+ doping increased, the energy gap values decreased from 5.45 to 3.87 eV. This reduction can be attributed to the formation of sub-bands and quantified using the Kubelka-Munk function. High-resolution scanning electron microscopy (HR-SEM) images unveiled nanocluster grain boundaries, offering valuable insights. Energy-dispersive X-ray spectroscopy (EDX) analysis confirmed the presence of Zn2+, Sr2+, Al3+, and O2- elements within the samples. In terms of magnetic characteristics, pure ZnAl2O4 exhibited diamagnetic behavior, whereas the Sr2+-doped ZnAl2O4 system displayed superparamagnetic properties. Nonlinear optical properties, including the nonlinear index of refraction (10-8 cm2/W), nonlinear absorption coefficient (10-4 cm/W), and third-order nonlinear susceptibility (10-6esu), were evaluated through Z-scan experiments. The results of the optical limiting analysis indicate the potential applications of these materials in devices like optical switches and optical power limiters.