Synthesis and characterization of a new high near-infrared reflectance yellow pigment: Bi2-xErxMoO6

A series of environmentally friendly near-infrared reflective pigments Bi2-xErxMoO6 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) were synthesized by high temperature solid-state method. The optical and structural characteristics of the synthesized pigment were characterized by ultraviolet-visible-near infrared diffuse reflection spectrum (UV-Vis-NIR spectrum), X-ray diffractometer (XRD), scanning electron microscopy (SEM). The color of the samples changed from milky white to yellow with increasing Er3+ doping concentration. Importantly, the Er3+- doped Bi2MoO6 pigments exhibit high NIR reflectance (ranging from 90.5% to 106.1%) in 700-2500 nm region and which is higher than the NIR reflectance of commercially available bismuth vanadate pigment (80%). Compared with BaSO4, Bi2-0.6Er0.6MoO6 exhibits 106.1% NIR reflectance and 99.6% NIR solar reflectance. The thermal insulation experiments show that the bottom temperature of the aluminum plate coated with Bi2MoO6: Er coating decreases by 3 degrees C compared with that of the TiO2 coating. Meanwhile, acid and alkali resistance tests show that these pigments may have a well chemically stable in the natural environment. We believe that the samples may have important applications in antisolar irradiation, energy saving and environmental protection.