Temperature-dependent Photoluminescence Properties of Eu²⁺-doped CaMgSi₂O₆ Phosphors

The solid-state reaction method was used to synthesize 0.025Eu²⁺-doped CaMgSi₂O₆ (Eu-CaMgSi₂O₆) powder in the reduction atmosphere of 5% H₂ + 95% N₂ at 1300°C with a duration of 4 h. The reduction atmosphere was removed when the temperature was down to 800°C. The XRD pattern showed that only the CaMgSi₂O₆ phase was observed in synthesized 0.025Eu²⁺-doped CaMgSi₂O₆ powder. Room-temperature photoluminescence excitation (PLE) and photoluminescence (PL) spectra of Eu-CaMgSi₂O₆ phosphors were recorded by using the Hitachi F-4500 fluorescence spectrophotometer at wavelength ranges of 200–430 and 350–600 nm, respectively. A new important finding is that the synthesized Eu-CaMgSi₂O₆ phosphor has three important PLE wavelengths. Therefore, Eu-CaMgSi₂O₆ phosphors are measured from 25°C (room temperature) to 200°C under three different PLE wavelengths to find the effect of temperature on the variations of maximum photoluminescence intensities (PLmax). All the PL spectra show that only one emission band with a central wavelength of 449 nm is found, which is independent of the PLE wavelengths and is caused by the transition of 4f⁷ → 4f⁶5d¹. Another important finding is that the different PLE wavelengths have an apparent effect on the PLmax value of the Eu-CaMgSi₂O₆ phosphor. Finally, the decay-time curves of Eu-CaMgSi₂O₆ phosphor under three PLE wavelengths are also investigated.