Na2CaSiO4:Eu3+-deep red-emitting phosphors with intense 5D0→7F4 transition

Eu3+-doped Na2CaSiO4 phosphors Na2−xCa1−xEuxSiO4 were synthesized by a high temperature solid reaction, and their UV–vis luminescent properties and decay curves were investigated. The excitation spectra indicate that the Na1.89Ca0.89Eu0.11SiO4 phosphor can be effectively excited by near-ultraviolet (393 nm) light. Due to the abnormally high intensity at about 703 nm from 5D0→7F4 transition of Eu3+ ions, the phosphors Na2−xCa1−xEuxSiO4 show deep red-emitting with chromaticity coordinates (0.639, 0.359). The charge transfer bands and the varying of the intensity ratios between 5D0→7F2 and 5D0→7F4 transitions indicate that Eu3+ ions may occupy two different sites in Na2CaSiO4 host. -- Highlights: ► The samples Na2−xCa1−xEuxSiO4 show an abnormally high intensity at about 703 nm from 5D0→7F4 transition of Eu3+ irons. ► Sample Na1.89Ca0.89Eu0.11SiO4 show deep red-emitting and high color purity with chromaticity coordinates (0.639, 0.359). ► Sample Na1.89Ca0.89Eu0.11SiO4 can serve as a potential red LEDs phosphor and light-converting material candidate used in silicon solar cells