Structural evolution induced by substitution of designated molybdate sites (MoO4?2) with different anionic groups (BO3?3, PO4?3 and SO4?2) in CaMoO4:Sm3+ phosphors-A study on color tunable luminescent properties

Article abstract of DOI:10.1016/j.jallcom.2017.08.117

A series of novel red emitting CaMoO₄:Sm³⁺ (1.0 mol %) phosphors substituted with different anionic groups (BO₃^?3, PO₄^?3 and SO₄^?2) were prepared using a high temperature solid state reaction method. The effects of anionic substitution on the crystalline structure and photoluminescence (PL) properties of the CaMoO₄:Sm³⁺, CaMoO₄-BO₃:Sm³⁺, CaMoO₄-PO₄:Sm³⁺and CaMoO₄-SO₄:Sm³⁺ phosphors were investigated. The structure, particle morphology, chemical composition, vibration modes, and PL properties of the phosphors were investigated by X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectrometry (FT-IR) and PL spectroscopy, respectively. The XRD patterns indicated that the crystalline structures of all the samples were consistent with the standard scheelite structure of CaMoO₄. The structural parameters of the pure phase of CaMoO₄:Sm³⁺ phosphor were obtained from the Rietveld analysis. Red PL attributed to the ⁴G_5/2 → ⁶H_9/2 transition of Sm³⁺ was observed at 646 nm when the CaMoO₄:Sm³⁺ samples were excited by 404 nm using a monochromatized Xenon lamp. Furthermore, orange-red color tunable emission has been achieved by substitution of different anionic groups (BO₃^?3, PO₄^?3 and SO₄^?2) into the CaMoO₄:Sm³⁺ phosphors. Among all the studied phosphors, the CaMoO₄-SO₄:Sm³⁺ phosphor showed the strongest PL emission compared to all other phosphors suggesting that it is a promising potential candidate for red emission in the near UV excited white LED applications.