Enhancing photoluminescence with Li-doped CaTiO₃:Eu³⁺ red phosphors prepared by solid state synthesis

Red phosphors of Li-doped CaTiO₃:Eu³⁺ that enhance photoluminescence have been synthesized by a solid-state method, and their structure and morphology were confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The luminescence property was measured using photoluminescence excitation (PLE) and photoluminescence (PL) spectra, respectively. The effect of sintered temperature and Eu³⁺ and Li ⁺ concentration in as-prepared series phosphors was studied. Results indicate that the optimal luminescence properties of CaTiO₃:Eu ³⁺ (CTE) phosphors are typically obtained at 1300 °C with 12 mol% of Eu³⁺ concentration, and the emission intensity can be greatly enhanced by the incorporation of Li⁺ into the CTE phosphors, attributing that Li not only compensates positive charge defect by replacement of Ca²⁺ with Eu³⁺, but also plays a role of flux, which could enhance the crystallinity of the phosphors. The intensity of the optimal Li-doped CaTiO₃:Eu³⁺ phosphor (CLTE) is 2.3 times of that of CTE. PL spectrum showed that CLTE phosphor was efficiently excited by near-ultraviolet light at wavelength around 398 nm and emitted intensive red light with a peak around 616 nm corresponding to the ⁵D ₀→⁷F₂ transition of Eu³⁺. Furthermore, this phosphor has very good thermal stability and high color purity, implying the potential to be a promising red phosphor in white light emitting diodes.