Sites occupancy of Eu2+/Mn2+ codoped Ca2(Mg0.5Al0.5)(Si1.5Al0.5)O7 blue-green phosphors

Ca2(Mg0.5Al0.5)(Si1.5Al0.5)O7:Eu2+/Mn2+ blue-green-emitting phosphors were prepared through Eu ions doping, high-temperature melting, quenching in ice and heat-treatment with the main component of high-aluminum blast furnace slag is employed as the main raw material. The matrix structure and photoluminescence performance were analyzed by XRD, PLE and PL spectra and luminescence thermal stability. Through chemical unit substitution of [Mg2+-Si4+] for [Al3+(Ⅰ)-Al3+(Ⅱ)] in Ca2Al(AlSi)O7, the structure unit 1 (Mg2+→Al3+(Ⅰ)) and structure unit 2 ((Si4+→Al3+(Ⅱ)) are formed in Ca2(Mg0.5Al0.5)(Si1.5Al0.5)O7 host matrix. Upon excitation of 324 nm, the PL spectrum is a combination of blue-light and green-light emission bands with peaks at 425 nm and 509 nm, attributed to the 5d-4f transition of Eu2+(I) and Eu2+(Ⅱ). The energy transfer (Eu2+(Ⅱ) → Eu2+(I)) is promoted when doped concentration of Mn2+ is 0.1 mol% with the critical distance is 7.83 Å. With the increasing heat-treatment temperature, the photoluminescence intensities of the samples increase. When the heat-treatment temperature is 975 °C, ΔE [Eu2+(I)] and ΔE [Eu2+(Ⅱ)] of the samples are 0.300 eV and 0.317 eV, respectively, indicating that the thermal stability of the unit 2 corresponding to blue-emitting is stronger than that of the unit 1 corresponding to green-emitting. •The main components of high-aluminum blast furnace slag employed as the main raw material.•Sites occupancy of Eu2+/Mn2+ codoped in matrix.•Two different structure units are formed by chemical unit substitution.