Site Occupancies, Electron-Vibration Interaction and Energy Transfer of CaMgSi 2 O 6 : Eu 2+ , Mn 2+ Phosphors for Potential Temperature-Sensing and Anti-counterfeiting Applications.

Eu 2+ -, Mn 2+ - and Eu 2+ -Mn 2+ -doped CaMgSi 2 O 6 phosphors have been prepared by a high-temperature solid-state reaction. Systematic investigation of the concentration- and temperature-dependent luminescence of Mn 2+ showed that Mn 2+ ions occupy two distinct sites in CaMgSi 2 O 6 . Electron-vibration interaction (EVI) analyses of Mn 2+ 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. Eu 2+ -Mn 2+ energy transfer is also discussed, and its efficiency is estimated by lifetime and luminescence spectra. The different thermal quenching behaviours of Eu 2+ and Mn 2+ , the distinct emission colours of Eu 2+ (blue, band peak at ∼451 nm) and Mn 2+ (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.