Enhanced solar absorbance and infrared emittance in Co-doped BaTiO3

Broadband absorber materials with high solar absorptivity and infrared emissivity are conducive to high-efficient and cost-effective heating technology in the civil and industrial field. The BaTi1-xCoxO3 ceramics are prepared by sol-gel method, showing mixed tetragonal/hexagonal phases. Co doping slightly reduces the phase transition temperature of BaTiO3. Meanwhile, BaTi1-xCoxO3 ceramics present a composite Mott/charge transform band nature and the Co-3d impurity level and oxygen vacancies level lead to a narrowed bandgap. The enhancement of the absorption induced by free carriers, impurity level and lattice vibration promote the UV-Vis-NIR absorption and mid-infrared radiation of BaTi1-xCoxO3 ceramics. In conclusion, the optimized BaTi0.95Co0.05O3 ceramic achieves a high solar absorptivity (0.88) in 0.25-2.5 mu m and a high infrared emissivity (0.83) in 8-14 mu m. The radiative performance presents good temperature stability, unaffected by phase structure and lattice thermal expansion, which provides prospective applications in solar energy conversion and infrared radiation heating.