Concentration induced site symmetry transformation of Eu3+ luminescence center in β-Ca2P2O7

• Phosphors β-Ca2-xP2O7:xEu3+ can be efficiently excited at 393 nm.
• Emission intensity of β-Ca1.92P2O7:0.08Eu3+ is the strongest.
• Lattice distortion of β-Ca2P2O7:Eu3+ shows two distinct patterns based on different doping concentration.
• Site symmetry transformation occurs in β-Ca2P2O7:Eu3+ as the concentration of Eu3+ varies.
• β-Ca2-xP2O7:xEu3+ can sustain excellent properties at 423 K.

A series of high brightness orange-red phosphors β-Ca2-xP2O7:xEu3+ (x = 0.02, 0.04, 0.06, 0.08, 0.10, 0.12) were synthesized via solid state reaction in air atmosphere. The phase, morphology, photoluminescence properties and fluorescent thermal stability of the obtained phosphors were investigated. The chromaticity coordinates of the samples were calculated and located in the orange-red region. The intense emissions at 585, 591 nm (5D0 → 7F1), 610 nm (5D0 → 7F2) were observed under NUV excitation. Furthermore, the ratio of the emission of 5D0 → 7F2 transition to that of 5D0 → 7F1 transition changed dramatically with varied Eu3+ concentration, indicating the existence of the site symmetry transformation of Eu3+ luminescence center in the matrix. The phosphors performed excellent properties at 423 K with temperature quenching at 473–573 K, and may be potential orange-red phosphor in lighting field.

For the obtained phosphors β-Ca2-xP2O7:xEu3+ (x = 0.02, 0.04, 0.06, 0.08, 0.10, 0.12), the ratio of the emission of 5D0 → 7F2 transition to that of 5D0 → 7F1 transition changed dramatically from 2.04 (1%)–0.74 (6%), with varied Eu3+ concentration, indicating the existence of the site symmetry transformation of Eu3+ luminescence center in the matrix, compared with that of Sr2P2O7 and Ba2P2O7.Figure optionsDownload as PowerPoint slide