Luminescent and thermal properties of a new green emitting Ca6Sr4(Si2O7)3Cl2:Eu2+ phosphor for near-UV light-emitting diodes

Abstract A novel green emitting phosphor, Eu 2+ -activated Ca 6 Sr 4 (Si 2 O 7 ) 3 Cl 2 , was synthesized using the solid-state reaction and its temperature-dependent luminescence characteristic was reported for the first time. Crystallographic site-occupations of Eu 2+ ions in this host were assigned and two distinguishable Sr 2+ sites were confirmed. As the temperature increases, the emission lines of Ca 6 Sr 3.99 (Si 2 O 7 ) 3 Cl 2 :0.01Eu 2+ show an anomalous blue-shift along with the broadening bandwidth and decreasing emission intensity, which is ascribed in terms of the phonon-assisted back tunneling from the excited state of low-energy emission band to the high-energy emission band in the configuration coordinate diagram. Further, the luminescence quenching temperature, the activation energy for thermal quenching (Δ E ), and the chromaticity coordinates were also investigated. In view of its preferable excitation spectrum profile, intense green emission peaking at 511 nm, and high thermal luminescence stability, the as-prepared phosphor is expected to find applications as a new green emitting phosphor for near-UV light emitting diodes.