Synthesis, Characterization, and Thermophysical Evaluation of MgO Nanoparticles and Their Nanofluids Prepared via the Sol–Gel Method

This study focuses on the synthesis and characterization of magnesium oxide (MgO) nanoparticles prepared via the sol–gel method. The structural, functional, and optical properties of the synthesized MgO nanoparticles were analyzed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and ultraviolet–visible (UV–Vis) spectroscopy techniques. XRD analysis confirmed the formation of well-defined crystalline MgO nanoparticles with uniform crystallite size. FTIR spectra exhibited characteristic peaks corresponding to the asymmetric and symmetric stretching vibrations of Mg–O bonds, confirming the successful formation of MgO. The UV–Vis spectrum revealed a broad and prominent excitonic absorption band in the range of 260–300 nm, indicating the nanoscale nature of the particles. The optical band gap of the synthesized MgO nanoparticles was estimated to be 3.14 eV, consistent with the semiconductor behaviour of nanosized MgO. The prepared MgO nanofluids were evaluated for their thermophysical properties. The viscosity of the MgO–deionized water nanofluids was measured using an Ostwald viscometer, while the thermal conductivity was estimated based on the Maxwell model. The stability of the nanofluids was assessed through zeta potential analysis. The results demonstrate that MgO nanoparticles synthesized via the sol–gel route possess high crystallinity, excellent stability, and predominantly nano spherical morphology, making them suitable for heat transfer and fluid dynamic applications.