Abstract:

Undoped, Dy³⁺ doped and Dy³⁺, K⁺ codoped calcium molybdate phosphors have been synthesized by solid-state reaction method. X-ray diffraction studies reveal the tetragonal structure of the prepared phosphors having crystallite size 15–50 nm. Scanning electron microscopy (SEM) studies reveal the morphology and crystallite size of the prepared phosphors. Photoluminescence studies indicate that there are blue and yellow emissions at 489 and 576 nm, respectively corresponding to Dy³⁺ ion. The introduction of K⁺ ion significantly influences the blue and yellow emissions which causes the near white light emission from this codoped phosphor. The intense absorption peak of the codoped phosphor at 210 nm is attributed to the band gap and a shoulder at 240 nm appears due to charge transfer from oxygen ions to neighbouring molybdenum ions. The band gap of the codoped phosphor is calculated as 5.5 eV from the absorption studies. The dielectric properties such as permittivity and dielectric loss are studied as a function of frequency.

Key words: X-ray diffraction, Photoluminescence, Absorption, Dielectric