Infrared radiation property and enhancement mechanism of MgCr2O4 doped with NiO prepared at different temperature

It is crucial to develop high near- and mid-infrared emissivity radiation materials for energy-saving application in industrial furnaces at 1000 °C–1600 °C. In this study, NiO-doped MgCr 2 O 4 (MN), was prepared at different temperature using the solid-phase sintering method. The effect of temperature on infrared radiation property was investigated and the mechanism was discussed. The results show that the emissivity of MN in the near-to mid-infrared band is improved with the preparation temperature increasing from 1000 °C to 1600 °C. When the temperature is 1600 °C, the average infrared emissivity of MN is 0.88 in the wavelength range of 1.0–2.5 μm and 0.83 in the wavelength range of 2.5–14 μm. Compared with the samples treated at 1000 °C, the emissivity of MN is improved by 15 % in 1.0–2.5 μm waveband and 9 % in 2.5–14 μm waveband. The increase in temperature leads to an increase in the crystallinity of spinel. Moreover, at temperature above 1400 °C, the volatilization of Cr 2 O 3 results in an increase in the concentration of oxygen vacancies in spinel. At the same time, the Cr 5+ as well as Ni 3+ content increases and the forbidden bandwidth decreases, which were responsible for the increase of near- and mid-infrared radiation of MN.