Synthesis and characterization of Sm, Dy and Er-doped β-Ca3(PO4)2 phosphors.

1 mol% Re₂O₃–99 mol% Ca₃(PO₄)₂ (Re = Sm, Dy and Er) powder samples were prepared by solid-state sintering method. The structural, thermal, vibrational and optical properties were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC), Raman and photoluminescence techniques. XRD studies confirm the formation of β-Ca₃(PO₄)₂ with the rhombohedral crystal structure. FESEM images reveal the formation of flake-like agglomerated particles of size in the range of 100–700 nm. DSC analysis shows that β-TCP → α-TCP structural phase transition occurs at 1286 ºC, followed by α-TCP → α'-TCP transformation at 1469 ºC. Raman spectra of the samples show antisymmetric and symmetric stretching and bending vibration bands of P-O linkages. Photoluminescence studies found intense reddish-orange emission in Sm-doped samples, white light emission in Dy-doped samples and yellow emission in Er-doped samples. The luminescence intensity of Sm and Dy-doped β-TCP samples is found to be significantly higher than that of Er-doped samples. [ABSTRACT FROM AUTHOR]