Highly efficient cyan-emitting garnet Ca3Hf2SiAl2O12: xCe3+ phosphor for solid state white lighting

In this paper, we have synthesized a new garnet structure compound Ca3Hf2SiAl2O12 and a series of Ce3+-doped Ca3Hf2SiAl2O12: xCe3+ phosphors. The crystal structure and luminescence properties of the Ca3Hf2SiAl2O12: xCe3+ are investigated in detail. Transmission electron microscopy analysis and XRD Rietveld refinement shows that Ca3Hf2SiAl2O12 is body-centered cubic and belongs to Iad (230) space-group with a = 12.3666 A. Ca3Hf2SiAl2O12: xCe3+ has broad excitation bands at 330 and 400 nm attributed to the characteristic Ce3+ 5d–4f transition and can produce cyan emission under 400 nm UV light excitation. The emission intensity of CHSA: 1%Ce3+ phosphor can reach 68.9% of YAG: Ce3+ (commercial) and 72.1% of Ca8Mg(SiO4)4Cl2: Eu2+ (commercial). The average decay lifetime of Ca3Hf2SiAl2O12: 1%Ce3+ is 48.91 ns, which is consistent with the nanosecond peculiarity of Ce3+. In the process of increasing the temperature from 25 °C to 250 °C, the integrated emission intensity of Ca3Hf2SiAl2O12: 0.5%Ce3+ only decreases to 57.8% (250 °C) and shows nice thermal stability compared with commercial YAG: Ce3+(P46-Y3). Furthermore, Ca3Hf2SiAl2O12: 0.5%Ce3+ exhibits outstanding quantum efficiency (74.7%). It reveals that Ca3Hf2SiAl2O12: xCe3+ possesses remarkable optical properties and can be utilized in UV-LEDs.