Structural modifications, low temperature magnetic behavior and optoelectronic trends in A-site substituted spinel ferrites

MnxZn1-xFe2O4 nanoparticles having cubic spinel phase were synthesized through chemical sol-gel method. The results showed a linear increase in crystallite size, lattice constant, packing factor, and number of unit cells per sample with x, following Vegard's law. High specific surface area (20.34-34.35 m(2)/g) has been observed which shows suitability for energy storage applications. Magnetic properties were improved, likely due to the blocking state of tiny nanoparticles. Switching in direct (4.26-5.12 eV) and indirect (3.03-4.63 eV) bandgaps and Urbach energy was observed at x = 0.5. Refractive index showed tunable trend against incident wavelength making the system a potential candidate for hetero-lasers and non-linear optics. Nyquist plot revealed a non-Debye relax-ation phenomenon and the contribution of grain boundaries and grains. Variations in dispersion energy (2.61-30.49 eV), excitation energy (8.44-10.25 eV), optical spectrum moments (M-1: 0.3047 to 2.9757, M-3: 0.0041 to 0.0283 eV(-2)), and high frequency dielectric constants (1.30-3.98) have been observed.