Microwave-assisted sintering synthesis of greenish-yellow emitting Sr2 SiO4 :Eu2+ phosphors.

Europium ion (Eu2+ ) doped Sr2 SiO4 phosphors with greenish-yellow emission were synthesized using microwave-assisted sintering. The phase structure and photoluminescence (PL) properties of the obtained phosphor samples were investigated. The PL excitation spectra of the Sr2 SiO4 :Eu2+ phosphors exhibited a broad band in the range of 260 nm to 485 nm with a maximum at 361 nm attributed to the 5f-4d allowed transition of the Eu2+ ions. Under an excitation at 361 nm, the Sr2 SiO4 :Eu2+ phosphor exhibited a greenish-yellow emission peak at 541 nm with an International-Commission-on-Illumination (CIE) chromaticity of (0.3064, 0.4772). The results suggest that the microwave-assisted sintering method is promising for the synthesis of phosphors owing to the decreased sintering time without the use of additional reductive agents.

Luminescence enhancement of (Sr1-x Mx )2 SiO4 :Eu2+ phosphors with M (Ca2+ /Zn2+ ) partial substitution for white light-emitting diodes.

Eu2+ -doped Sr2 SiO4 phosphor with Ca2+ /Zn2+ substitution, (Sr1-x Mx )2 SiO4 :Eu2+ (M = Ca, Zn), was prepared using a high-temperature solid-state reaction method. The structure and luminescence properties of Ca2+ /Zn2+ partially substituted Sr2 SiO4 :Eu2+ phosphors were investigated in detail. With Ca2+ or Zn2+ added to the silicate host, the crystal phase could be transformed between the α-form and the ß-form of the Sr2 SiO4 structure. Under UV excitation at 367 nm, all samples exhibit a broad band emission from 420 to 680 nm due to the 4f6 5d1  â†’ 4f7 transition of Eu2+ ions. The broad emission band consists of two peaks at 482 and 547 nm, which correspond to Eu2+ ions occupying the ten-fold oxygen-coordinated Sr.(I) site and the nine-fold oxygen-coordinated Sr.(II) site, respectively. The luminescence properties, including the intensity and lifetime of Sr2 SiO4 :Eu2+ phosphors, improved remarkably on Ca2+ /Zn2+ addition, and promote its application in white light-emitting diodes. Copyright © 2016 John Wiley & Sons, Ltd.