Luminescence properties, crystal structure and high thermal stable of (Gd0.85-xLux)2MgTiO6: Eu3+ red phosphors
A series of double perovskite (Gd 0.85- x Lu x ) 2 MgTiO 6 : 0.3Eu 3+ red phosphors were prepared via a typical high temperature solid-state reaction. XRD and HRTEM exhibits that the phosphors well crystallized as a double perovskite with the space group of P21/n symmetry. The luminescent properties of samples were investigated via excitation and emission spectra . The phosphors emit strong red light and weak orange red light under ultraviolet (UV) and near-UV excitation suggesting that Eu 3+ ions situated in the sites without inversion symmetry. The UV–vis spectra included a broad host absorption band assigned to O 2- -Eu 3+ and some peaks at 395 nm, 465 nm and 533 nm attributed to the typical f-f transition of Eu 3+ . The CIE chromaticity coordinates of all samples were near to the standard red light, indicating that the (Gd 0.85- x Lu x ) 2 MgTiO 6 : 0.3Eu 3+ was a potential candidate material for red emitting phosphors. The decay curves matched with the lines fitted by a one exponential decay formula and the decay time increased with increasing Lu 3+ -dopant concentration within x < 0.8. The temperature-dependent emission spectra from 298 K to 473 K were used to evaluate the thermal stability of Gd 0.9 Lu 0.8 Eu 0.3 MgTiO 6 phosphors and the activation energy of Gd 0.9 Lu 0.8 Eu 0.3 MgTiO 6 for 5 D 0 - 7 F 2 transition was calculated to be 0.158eV. The results revealed that the phosphors have the excellent thermal stability and were promising material for applications in LEDs.
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