Preparation and characterization of high infrared emissivity Mn-doped NCO spinel composites

NiCr2O4 (NCO) spinel composites with different Mn/Ni atomic ratios (Mn/Ni = 0.05, 0.10, 0.15, and 0.20) were synthesized via solid state reaction method. Phase compositions and microstructure of samples were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The TG-DSC curves showed that the appropriate baking temperature for Mn-doped NCO spinel preparation was approximately 1 320 °C. X-ray diffraction patterns exhibited the formation of NCO spinel with Fd-3m space group. Valence state of the Mn ions was determined from 2p and 3s X-ray photoelectron spectra. Manganese ions were mostly in divalent and trivalent states, and the ratio of Mn2+/Mn3+ was 0.78-0.98. Fourier transform infrared spectroscopy (FTIR) was used to analyze the spectral emissivity of Mn doped NCO spinel. It was revealed that the infrared emissivity of Mn-doped NCO spinel in 1.8-5 μm could be significantly enhanced with increasing content of Mn2+, reaching as high as 0.9398. Mn-doped NCO spinel showed excellent radiation performance and good prospect in high emissivity applications in the temperature range of 800-1 200 °C.