Profitable approach for the synthesis of Mn3O4 phase materials and its interesting pigmentation applications

A simple precipitation synthesis of Mn3O4 phase with average crystalline size of 27.8 nm in the form of asprecipitated product crystallized in tetragonal symmetry, space group, I41/amd (141) with the lattice parameters of a = 0.5761(3) nm and c = 0.9451(6) nm. The rod-shaped (diameter of - 400 nm) morphology with a spherical particle size of - 50 nm is observed for the as-precipitated product. A weight loss of - 4% is noted for the as-precipitated product powder up to 1000 degrees C with neither exothermic nor endothermic peaks in the thermal profiles. The UV-Vis absorbance spectrum reveals an absorption edge at 550 nm, which is due to optical band gap absorption with a calculated band gap (Eg) of 1.95 eV from the Tauc plot. The NIR (750 - 2500 nm) spectrum shows the NIR reflectance of 27-66 % and 50-69 % in the solar and color pigment regions, respectively. As a result, the present obtained Mn3O4 powder can be used in the color pigmentation industry. The Raman reveals a dominant peak at - 652 cm-1 and two minor peaks at 315 and 369 cm-1 are due to A1g, Eg, and T2g Raman active modes of tetragonal Mn3O4 phase materials.