Effect of the replacement of Al–O by Si–N on the properties of Sr6Si25.6Al6.4N41.6O4.4:Eu2+ phosphors for white light-emitting diodes
Abstract
Oxynitride phosphors Sr6Si25.6−xAl6.4+xN41.6−xO4.4+x:Eu2+ are synthesized by gas pressure sintering of powder mixture of SrCO3, AlN, Si3N4 and Eu2O3 at 1800 °C and 0.5 MPa of N2 for 10 h, and their photoluminescence properties are investigated. Sr6Si25.6−xAl6.4+xN41.6−xO4.4+x:Eu2+ can be efficiently excited over a broad spectral range between 300 and 500 nm, and exhibit an intense green emission centered at about 515 nm with a full width at half maximum of 65 nm due to the 4f65d1–4f7 transition of Eu2+ ions. The influence of the replacement of Si–N by Al–O on luminescence properties and crystal structure is reported in a series of Sr6Si25.6−xAl6.4+xN41.6−xO4.4+x:Eu2+ phosphors. Different Sr sites are found in the crystal structure. The thermal quenching properties of the green phosphors are better than that of typical orthosilicate Ba2SiO4:Eu2+ phosphor. Their interesting photoluminescence properties indicate that the Sr6Si25.6Al6.4N41.6O4.4 phosphor is a promising green emitting candidate for white LEDs applications.