Non-toxic colored near infrared (NIR) reflective material is an ideal choice to reduce building energy consumption. Yttrium ferrite has good near infrared reflection performance and has broad application prospects in the field of solar reflective heat insulation materials. Yttrium ferrite powder was synthesized by low-temperature solid-state reaction and molten salt low-temperature solid-state reaction. The microstructure of yttrium ferrite materials, especially the distribution of charge states, and the relationship between its infrared reflectance and chromaticity was discussed. The research results show that:
(1) Yttrium ferrite nano-powder with hexagonal structure can be synthesized at 700℃ by low-temperature solid-state reaction. With the increase of calcination temperature, the powder structure changes from hexagonal to orthorhombic, and the near infrared reflectance increases from 18.20% to 88.65%.
(2) Orthorhombic yttrium ferrite powder can be synthesized by molten salt-assisted low-temperature solid-state reaction at 700℃. With the increase of calcination temperature, the particle morphology changes from disc-like to coral-like, and the near infrared solar reflectance of the powder increases to 51.70%.