Enhanced novel white emission in Ca_3(PO_4)_2:Dy~(3+) single-phase full-color phosphor by charge compensation

摘要

A novel single-composition white-emitting phosphor Ca_3(PO_4)_2:Dy~(3+) has been synthesized by a high-temperature solid-state reaction. The effect of charge compensators on luminescent properties of Ca_3(PO_4)_2:-Dy~(3+) is systematically investigated by the X-ray powder diffraction, UV-Vis diffuse reflectivity, photolumines-cence (PL) properties and lifetime. It is observed that the PL intensity of Dy~(3+) under 350 nm excitation increases in the order of Ca_(2.95)(PO_4)_2:0.05Dy~(3+), Ca_(2.90)K_(0.05)(PO_4)_2: 0.05Dy~(3+), Ca_(2.90)Na_(0.05)(PO_4)_2:0.05Dy~(3+), Ca_(2.90)Li_(0.05) (PO_4)_2:0.05Dy~(3+), and Ca_(2.95)(P_(0.95)Si_(0.05)O_4)_2:0.05Dy~(3+). The lifetimes of Dy~(3+) are 605.00, 604.67, 615.01, 645.64 and 621.26 u.s, respectively. A charge compensation model is proposed to explain the changes in the emission intensity and lifetime of Dy~(3+) in Ca_3(PO_4)_2 with different compensation methods. A white light-emitting diode (LED) was fabricated by using the white-emitting single-composition Ca_(2.95)(P_(0.95)Si_(0.05)O_4)_2:0.05Dy~(3+) pumped by a 365 nm UV-chip. Our results indicated that the CIE chro-maticity coordinates, color rendering index and correlated color temperature for white UV-LEDs were (0.302, 0.324), 83, and 6947 K, respectively. Therefore, our novel white Ca_(2.95)(P_(0.95)Si_(0.05)O_4)_2:0.05Dy~(3+) can serve as a key material for phosphor-converted white-light UV-LEDs.