The luminescent behaviors and J-O theory analysis of red phosphor Ca1-xGeO3:xEu3+

The luminescent material Eu ³⁺-doped CaGeO ₃ has been synthesized using a high-temperature solid-state reaction technique. The crystal structure was analyzed using X-ray diffraction (XRD). The results showed that the samples belonged to the triclinic crystal system with the space group P 1 ̅ . The luminescent properties including photoluminescence excitation (PLE), Photoluminescence emission (PL) spectra, and lifetime, thermal stability, and diffuse reflectance spectroscopy (DRS) have been investigated. Under near-ultraviolet excitation at 390 nm, the phosphor emits red light with the highest intensity around 611 nm, which is dominated by the ⁵D ₀→ ⁷F ₂ electric dipole transitions. It indicates that Eu ³⁺ is in the inversion center of the crystal. The concentration quenching occurs at about 6 % doping from the concentration-dependent luminescence behavior. The energy transfer mechanism was analyzed to be mainly the energy transfer between neighboring ions. The thermal stability was 82.16 % at 423 K. The chromaticity coordinates are in the red area and the color purity approaches 99 %. Furthermore, the J-O theoretical results are used to confirm the experimental result. It suggests that Ca _1-xGeO ₃:xEu ³⁺ is an effective red luminescent material for illumination and backlight display applications.