A new yellowish-green-emitting phosphor: Eu2+-doped K4CaSi3O9

Highlights: ► Eu2+-activated K4CaSi3O9 shows a broad excitation extending from 250 to 450 nm. ► The phosphor presents bright yellowish-green color for the near UV excitation. ► There are two Eu2+ luminescence centers at 530 nm and 586 nm in K4CaSi3O9 lattices. ► K4CaSi3O9:Eu2+ has an excellent thermal stability with activation energy 0.161 eV. - Abstract: Eu2+-activated K4CaSi3O9 phosphors were synthesized by conventional solid-state reaction. The phase formation was confirmed by X-ray powder diffraction measurements. The photoluminescence excitation and emission spectra were investigated. The phosphor presents bright yellowish-green-emitting luminescence under the excitation of UV and near UV light. The luminescence absolute quantum efficiencies of the phosphors with different Eu2+-doping levels (1.0–5.0 mol%) were measured. The crystal structure and the site-occupancy of Eu2+ ions doped in K4CaSi3O9 crystal lattice were discussed. Two different Eu2+ centers were assigned according to the crystal structure and the luminescence characteristics. The dependence of luminescence intensity on temperatures (25–150 °C) was measured. The chromaticity coordinates and activation energy (ΔE) for thermal quenching were reported. The phosphor shows an excellent thermal stability on temperature quenching.