Low-temperature solid-state reaction synthesis of SrY2O4 with high near-infrared reflectance and low thermal conductivity

Abstract

The near-infrared (NIR) reflective thermal insulation coating can effectively reflect heat and protect the base materials. With excellent high-temperature stability and low thermal conductivity, SrY₂O₄ attracted much attention due to its unique thermophysical characteristics. However, the NIR reflectance of SrY₂O₄ is scarcely reported. In this work, a novel low-temperature solid-state reaction synthesis of SrY₂O₄ is explored, which aims to solve the problems of high temperature (1400–1650 °C) and repeated calcination during the synthesis process via conventional solid-state reaction method, and the NIR reflectance of SrY₂O₄ is evaluated. SrY₂O₄ powders with few Y₂O₃ impurities are obtained at 1100–1300 °C via low-temperature solid-state reaction method. And Y₂O₃ impurities are successfully eliminated, resulting in a simple synthesis of single-phase SrY₂O₄ powder at 1200 °C by adjusting the ratio of raw materials to n (Sr²⁺):n (Y³⁺) = 1.10:2. The thermal decomposition process and composition of the precursor were analyzed by Fourier transform infrared spectrum (FTIR) and thermogravimetric/differential scanning calorimetry (TG-DSC), respectively. The cell parameters, micromorphology, NIR reflectance and thermal conductivity of SrY₂O₄ powders synthesized via low-temperature and conventional solid-state reaction method are comparative studied. The result shows that single-phase SrY₂O₄ powder obtained via low-temperature solid-state reaction method has smaller cell parameters, minor particle size and higher NIR reflectance. The NIR reflectance maintains above 90 % and thermal conductivity at 25 °C is 7.37 W m⁻¹ K⁻¹.