Site Occupancies, Electron-Vibration Interaction and Energy Transfer of CaMgSi2 O6 : Eu2+ , Mn2+ Phosphors for Potential Temperature-Sensing and Anti-counterfeiting Applications.

Eu2+ -, Mn2+ - and Eu2+ -Mn2+ -doped CaMgSi2 O6 phosphors have been prepared by a high-temperature solid-state reaction. Systematic investigation of the concentration- and temperature-dependent luminescence of Mn2+ showed that Mn2+ ions occupy two distinct sites in CaMgSi2 O6 . Electron-vibration interaction (EVI) analyses of Mn2+ ions revealed Huang-Rhys factors of 4.73 and 2.82 as well as effective phonon energies of 313 and 383 cm-1 for the two sites. Eu2+ -Mn2+ energy transfer is also discussed, and its efficiency is estimated by lifetime and luminescence spectra. The different thermal quenching behaviours of Eu2+ and Mn2+ , the distinct emission colours of Eu2+ (blue, band peak at ∼451 nm) and Mn2+ (yellow-red range, band peaks at ∼583 and 693 nm) endow the co-doped samples with potential applications in luminescence thermometry and temperature-/excitation wavelength-responsive dual anti-counterfeiting.