Phase evolution of nanocrystalline Mn-based oxides screened under different calcination temperatures using different precursors for proficient application in near infrared pigmentation.

[Display omitted] • Mn-based oxides were acquired by calcining the precursors of MnCl 2.4H 2 O, MnCO 3 , MnO 2 , and KMnO 4. • The phase formation was influenced by the temperatures (400–1000 °C) and precursors. • The obtained phases were analyzed for their thermal and spectroscopic properties. • The nanostone was seen in the form of Mn 3 O 4 , while the nanorod-like shape was observed in Mn 2 O 3. • The Mn 3 O 4 phase exhibited a high NIR reflectance of 68 % in the solar region and 91 % in the color region. We examined how different calcination temperatures and precursors affect the formation of Mn-based oxides. The formation of these oxides was influenced by both the temperature (400–––1000 °C) and the type of precursors used (MnCl 2 ·4H 2 O, MnCO 3 , MnO 2 , and KMnO 4). When MnCl 2 ·4H 2 O was calcined at 800 and 1000 °C/3h, we obtained pure tetragonal Mn 3 O 4 phase materials. Calcining MnCO 3 at 600 and 1000 °C resulted in cubic Mn 2 O 3 and tetragonal Mn 3 O 4 phase materials, respectively. Heating commercial MnO 2 powder at 600 and 800 °C transformed it into cubic Mn 2 O 3 phase materials. At 400 °C, the tetragonal MnO 2 phase remained, but at 1000 °C, mixed Mn 3 O 4 and Mn 2 O 3 phases formed. Calcining KMnO 4 at 1000 °C/3h led to the formation of δ-MnO 2 materials. The morphological features of Mn 2 O 3 and Mn 3 O 4 materials exhibited different sizes and shapes, including nanostone-like, nanorod-like, and nanoflakes morphologies. The thermal analysis revealed significant differences in weight loss and thermal events, including exo and endothermic peaks. The Raman spectra and UV–Vis DRS measurements data support the formation of Mn-based oxides. The highest NIR reflectance for the various synthesized materials of Mn 3 O 4 phase indicates a reflectance of 68 % in the solar region and 91 % in the color pigment region. [ABSTRACT FROM AUTHOR]