Enhancing the efficiency of CaTiO₃ceramics by La³⁺-Al³⁺co-doping for high solar reflectivity and infrared emissivity

With the global demand for carbon neutrality rising, designing materials with high near-infrared solar reflectivity (R_NIR) and infrared emissivity (IR_e) within the atmospheric window (ATW) becomes increasingly crucial. These properties are vital for advancing zero-energy radiative cooling, which plays a key role in energy-efficient building cooling solutions. To address this, we synthesize a sequence of environmentally friendly La³⁺-Al³⁺co-doped ceramics Ca_1-xLa_xTi_1-yAl_yO₃ (x = 0, 0.5, y = 0, 0.4, 0.45, 0.5), using solid-state reaction at a high temperature of 1300 °C. The synthesized ceramics indicate that the doped La³⁺and Al³⁺ions induce lattice distortion due to the difference in their valencies and ionic radii, which effectively modulates the material's emission and reflection behavior. Furthermore, the doped ceramics exhibited a pale-yellow cool color with a high average R_NIR of 97.59 % and an ATW IR_e reached of 0.96. Additionally, a temperature reduction of 6.0 °C was observed, which was attributed to the increased band gap in the doped samples, as confirmed by both experimental measurements and first-principles calculations. These findings demonstrate the potential of co-doped ceramics as energy-efficient materials for passive radiative cooling, offering a sustainable solution for reducing building cooling energy consumption.