Hydrothermal synthesis and characteristics of anions-doped calcium molybdate red powder phosphors

Applying hydrothermal and subsequent heat-treatment process, CaMoO4:Eu3+ was doped with four anions (SiO32−, PO43−, SO42− and ClO3−) to prepare fine red powder phosphors. The introduction of small amount of anions into the host had little influence on the structure, which was confirmed by X-ray diffraction patterns. The anion-doped phosphor samples (except SiO32−) exhibited nearly spherical morphology, and the particle sizes were in the range of 0.3–0.4 μm for SO42−-doped samples, and 0.8–1.2 μm for PO43− and ClO3−-doped samples. Excited with 395 nm near-UV light, all samples showed typical Eu3+ red emission at 615 nm, and PO43−, SO42− and ClO3−-doped samples enhanced the red luminescence as compared with the individual CaMoO4:Eu3+ sample. In particular, relative emission intensity for optimum ClO3−-doped phosphors reached more than 6-fold that of the commercial red phosphor, which is highly desirable for the powder phosphors used in the solid-state lighting industry.