Preparation of environmentally friendly high-emissivity Ca2+-Fe3+ co-doped LaAlO3 ceramic

Ca2+-Cr3+ co-doped LaAlO3 is an excellent ceramic material with high emissivity; however, it is harmful to the environment because of the presence of Cr3+ ions. In this study, Ca2+-Fe3+ co-doped LaAlO3 ceramic materials were successfully prepared via a high-temperature solid-state reaction. The emissivity of Ca2+-Fe3+ co-doped LaAlO3 was 0.91, which is approximately equal to that of Ca2+-Cr3+ co-doped LaAlO3. To compensate for the lack of data on the thermophysical properties of doped LaAlO3 high-emissivity ceramics, the thermal expansion coefficients and thermal conductivities of LaAlO3 doped with Ca2+-Fe3+ or Ca2+-Cr3+ were investigated. The thermal conductivities of La0.9Ca0.1Al0.9Fe0.1O3 and La0.9Ca0.1Al0.9Cr0.1O3 at 1200 degrees C were 3.802 and 3.707 W center dot m(-1)center dot K-1, respectively. The thermal expansion coefficients of La0.9Ca0.1Al0.9Fe0.1O3 and La0.9Ca0.1Al0.9Cr0.1O3 at 1200 degrees C were 11.49x10(-6) and 11.41x10(-6) K-1, respectively. These results indicate that Ca2+-Fe3+ co-doped LaAlO3 exhibits great potential as a new generation of environmentally friendly near-infrared radiating materials in the field of energy efficiency.