Structure, luminescence of Eu²⁺ and Eu³⁺ in CaMgSi₂O₆ and their co-existence for the excitation-wavelength/temperature driven colour evolution

Abstract

Luminescent materials with controllable colour evolution features are demanded for the development of multi-level anti-counterfeiting technologies. Here, we report the structural and luminescent properties of CaMgSi2O6:Ln (Ln = Eu2+, Eu3+,...

Site Occupancies, Electron–Vibration Interaction and Energy Transfer of CaMgSi2O6: Eu2+, Mn2+ Phosphors for Potential Temperature‐Sensing and Anti‐counterfeiting Applications

“…The XRD data of the phosphors Ca 1− y Mn y MgSi 2 O 6 ( y =0.01, 0.02, 0.03, 0.05, 0.08, 0.10), Ca 0.999− y Eu 0.001 Mn y MgSi 2 O 6 ( y =0.01, 0.03, 0.05, 0.08, 0.10) and Ca 0.99− x Eu x Mn 0.01 MgSi 2 O 6 ( x =0.001, 0.003, 0.005, 0.008, 0.010) are collected at RT. The XRD patterns of Eu 2+ ‐doped samples have been reported in our previous work, [16] and those of Mn 2+ ‐ and Eu 2+ /Mn 2+ ‐doped typical samples are presented in Figure 1a. The results show that they are consistent with the standard card PDF #78‐1390 of the host compound CaMgSi 2 O 6 .…”

“…The phase purity of the samples was checked by Rigaku D‐MAX 2200 VPC X‐ray diffractometer with CuKα radiation ( λ =1.5418 Å) at 40 kV and 26 mA with a scanning speed of 10° ⋅ min −1 and a scanning 2 θ range of 15–80°. The collection of the high‐quality powder X‐ray diffraction (XRD) data and the corresponding structural refinement of CaMgSi 2 O 6 are conducted in our previous report [16] …”

“…The collection of the high-quality powder X-ray diffraction (XRD) data and the corresponding structural refinement of CaMgSi 2 O 6 are conducted in our previous report. [16] The UV-vis excitation/emission spectra and luminescence decay were recorded on an Edinburgh FLS1000 spectrometer. A 450 W xenon lamp worked as the excitation source of steady-state spectra, a 150 W nF900 lamp with a pulse width of 1.0-1.6 ns and pulse repetition rate of 40 kHz was used to collect the decay curves of Eu 2 + ; the decay curves and time-resolved emission spectra of Mn 2 + were recorded on a 60 W μF900 flash lamp with a pulse width of 1.5-3.0 μs and pulse repetition rate of 10 Hz.…”

“…Both the good simulation qualities of emission band confirm the validities of the obtained S and � hω, thus indicating that Mn 2 + ions experience a weak coupling in this host, which is similar to our previous work in the case of Eu 2 + ions. [16] Luminescence of Eu 2 + and Mn 2 + co-doped CaMgSi 2 O 6…”

“…As previously discussed, Eu 2 + ions are thought to occupy the [CaO 8 ] sites. [16] Due to the similar ionic radii of Mn 2 + (0.83 Å) and Mg 2 + (0.72 Å) in sixfold coordination as well as Mn 2 + (0.96 Å) and Ca 2 + (1.12 Å) in eightfold coordination, it is reasonable to assume that Mn 2 + ions might enter both [CaO 8 ] and [MgO 6 ] sites. [18] The discussions on the luminescence of Mn 2 + in CaMgSi 2 O 6 will corroborate this viewpoint.…”