eng Oriental Scientific Publishing Company Material Science Research India 0973-3469 2024-04-30 21 1 11 17 22766 article M.B. Shelar * K. M. Patil 2 S. K. Nalugade 2 V.R. Chavan 2 R.M. Jadhav 2 M.S. Kore 2 Materials Research Laboratory, Department of Physics , D. Y. Patil College of Engineering and Technology (An Autonomous Institute), Kasaba Bawada, Kolhapur-416006, Maharashtra, India Department of Chemical Engineering, D. Y. Patil College of Engineering and Technology (An Autonomous Institute), Kasaba Bawada, Kolhapur-416006, Maharashtra, India The work is done on the Structural and optical properties of Manganese doped nickel nano ferrites prepared by auto route. The manganese is doped in nickel (Mn-Ni) mixed nano ferrites Mn_xNi_1-xFe₂O₄ (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) have been synthesized by a simple auto combustion route. The cubic spinel structure were confined by using X- ray Diffraction for Mn_xNi_1-xFe₂O₄ nano ferrite particles which shows favored positioning along with (311) direction. However, size of crystal increases from 20 nm to 26.38 nm increase in Mn content. The optical properties were examined by means of UV-visible absorption spectroscopy observed from 200 to 800 nm. Using the absorption spectra and Tauc’s relation, the band gap was calculated and varies between 3.57 and 3.80 eV.  The significant decline in the optical band gap was calculated with increasing manganese Composition from 3.80ev to 3.57 eV up to Mn=0.6, The further increase due to preparative crystallinity defects in composition from 3.67eV to 3.70 eV shows tunability of the optical band gap varying the concentration of Mn in nano ferrites. The present nanoparticles with variable narrow band gap may find applications in photocatalysis to increase the efficiency of photocatalytic reactions. https://www.materialsciencejournal.org/vol21no1/effect-of-mn-dopant-on-structural-and-optical-properties-of-nife2o4-nanoparticles-synthesized-by-autocombustion-method/ Auto combustion route Mn-Ni ferrite Structural properties Optical properties