Luminescent properties of Eu ³⁺ doped layered perovskite structure M ₂TiO ₄(M=Ca, Sr, Ba) red-emitting phosphors

Series of Eu ³⁺ doped layered perovskite structure M ₂TiO ₄:Eu ³⁺ (M=Ca, Sr, Ba) red phosphors were prepared by the high-temperature solid state reaction method. Their phase compositions and photoluminescence properties were investigated by XRD, UV-Vis DRS and fluorescence spectra. The results indicated that pure Sr ₂TiO ₄ and Ba ₂TiO ₄ powers could be prepared under 1100°C for 2 hours, but Ca ₂TiO ₄ powers could not be synthesized even raising the calcination temperature and lengthening the calcination time. Ba ₂TiO ₄:Eu ³⁺ phosphor emitted 594 nm ( ⁵D ₀→ ⁷F ₁) and 615 nm ( ⁵D ₀→ ⁷F ₂) orange-red light under the excitation of 395 nm. Sr ₂TiO ₄:Eu ³⁺ phosphor gave a unusual and strong orange-red emission of 578 nm ( ⁵D ₀→ ⁷F ₀) and 626 nm ( ⁵D ₀→ ⁷F ₂) under the excitation of near ultraviolet or blue light, resulting in the better color purity and higher luminescent intensity. In addition, this phosphor had the highest luminous efficiency when excited by the charge migration excitation at 363 nm and it had the great potential to be a red phosphor for N-UV LED and blue light chip.