The Role of Mn(2+)-Doping on Structural, Morphological, Optical, Magnetic and Catalytic Properties of Spinel ZnFe2O4 Nanoparticles.

Spinel Mn(x)Zn(1-x)Fe2O4 (0.0 ≤ x ≤ 1.0) nanoparticles (NPs) were successfully synthesized by a facile one-pot microwave combustion method using urea as the fuel. The formation of single phase cubic spinel structure was confirmed by powder X-ray diffraction (XRD), Rietveld analysis and Fourier transform infrared (FT-IR) spectroscopy and the calculated average crystallite size is in the range of 37.57 nm to 25.43 nm. The high resolution scanning electron microscopy (HR-SEM) and high resolution transmission electron microscopy (HR-TEM) results indicated that the as-prepared spinel Mn(x)Zn(1-x)Fe2O4 NPs showed high crystallinity and uniform size distribution with particles-like morphologies. The energy dispersive X-ray (EDX) analysis was confirmed the elemental composition and purity of the samples. The estimated band gap energy from UV-Visible diffuse reflectance spectroscopy (UV-Vis. DRS) is about 1.88 eV to 2.35 eV. The broad visible emission band is observed in the entire photoluminescence (PL) spectroscopy for all compositions. The variation of magnetization (M(s)) value of the samples was studied by vibrating sample magnetometer (VSM) and the lower compositions (x = 0.0, 0.2 and 0.4) show a superparamagnetism and the higher composition (x = 0.6, 0.8 and 1.0) show a ferromagnetic behavior with hysteresis and that the M(s) values increased with increasing Mn2+ content to reach a maximum value of 60.99 emu/g for MnFe2O4. All composition of spinel Mn(x)Zn(1-x)Fe2O4 NPs were successfully tested as catalyst for the oxidation of benzyl alcohol into benzaldehyde, which has resulted 83.29 and 96.51% conversion efficiency of ZnFe2O4 and Mn0.6Zn0.4Fe2O4 respectively.