Phase transformation and luminescence properties of Y2.94Al5-xGaxO12: 0.06Ce3+phosphors

A series of Ga-substituted Ce3+-doped yttrium aluminum garnet (Y2.94Al5-xGaxO12: 0.06Ce3+) phosphors were synthesized at different atmospheres and temperatures. The structure, optical and thermal stability properties were analyzed using X-ray diffraction (XRD), photoluminescence (PL) and thermal measurements. A novel finding was revealed that gallium oxide (Ga2O3) was unstable in reducing atmosphere by XRD, and we explained the mechanism for the first time. In addition, it was found that Y3Al3Ga2O12 was formed due to Al3+ ions entering the lattice of Y3Ga5O12 gradually and the mechanism was clearly illustrated. The emission intensity of Y2.94Al5-xGaxO12: 0.06Ce3+ phosphors was determined by two aspects—the phase formation temperature and the band gap of host lattice. What's more, introducing 6 wt% H3BO3 as flux can improve thermal stability to maximum extent and the thermal ionization model was used to explain the thermal quenching mechanism. Finally, the critical parameters including color rendering index (CRI), correlated color temperature (CCT), light efficiency of light emitting diodes (LEDs) packaged with the resultant green phosphors and red phosphors were studied.