Luminescence Properties of Ca2Ga2SiO7:RE Phosphors for UV White-Light-Emitting Diodes

Luminescence Properties of Green Phosphor Ca2Ga2(Ge1-xSix)O7:y%Eu2+ and Application

Rare earth luminescent materials demonstrate significant advantages in lighting and energy saving, and detection etc. In this paper, a series of Ca₂Ga₂(Ge_1-xSi_x)O₇:y%Eu²⁺ phosphors were synthesized by high-temperature solid-state reaction and characterized by X-ray diffraction and luminescence spectroscopy methods. The powder X-ray diffraction patterns reveal that all the phosphors are isostructural with a space group of P4¯21m. The excitation spectra of Ca₂Ga₂(Ge_1-xSi_x)O₇:1%Eu²⁺ phosphors exhibit significant overlapping of the host and the Eu²⁺ absorption bands, which facilitates Eu²⁺ absorbing the energy to increase its luminescence efficiency when excited by visible photons. The emission spectra show that the Eu²⁺ doped phosphors have a broad emission band with a peak centered at 510 nm arising from the 4f⁶5d¹→4f⁷ transition. Variable temperature fluorescence reveals that the phosphor has a strong luminescence at low temperature but has a severe thermal quenching effect when temperature rises. The optimal Ca₂Ga₂(Ge_0.5Si_0.5)O₇:1.0%Eu²⁺ phosphor shows promise for application in the field of fingerprint identification based on the experimental results.

Synthesis and Photoluminescence Properties of Ca2Ga2SiO7:Eu(3+) Red Phosphors with an Intense (5)D0 → (7)F4 Transition

Novel melilite-type Ca2Ga2SiO7:Eu(3+) red-emitting phosphors with different Eu(3+) contents were synthesized via high-temperature solid-state reaction. The crystal structure, optical absorption, and photoluminescence properties were investigated, while density functional theory calculations were performed on the host lattice. The excitation spectra indicate that phosphors can be effectively excited by near-UV light for a potential application in white-light-emitting diodes. Because of the abnormally high intensity emission at about 700 nm arising from the (5)D0 → (7)F4 transition of Eu(3+), the phosphors Ca2Ga2SiO7:Eu(3+) show a deep-red emission with chromaticity coordinates (0.639, 0.358).

Multi-color luminescence properties and energy transfer behaviour in host-sensitized CaWO4:Tb3+,Eu3+phosphors

A series of host-sensitized and color-tunable CaWO₄:Tb³⁺,Eu³⁺phosphors have been successfully synthesizedviathe high-temperature solid-state reaction route and their photoluminescence properties and energy transfer mechanism have been carefully investigated.