Simple mass-preparation and enhanced thermal performance of Ce: YAG transparent ceramics for high power white LEDs

Abstract

Ce: YAG transparent ceramics have great potential in the high power white light-emitting diodes based on chip packaging technology due to the superior optical property and thermal conductivity. However, it is still a challenging issue to explore a simple and efficient mass-preparation method and to solve the heat dissipation problem. In this study, the batched Ce: YAG ceramics with different Ce3+ concentrations were fabricated by Isobam gel casting plus vacuum sintering. Their optical properties were systematically investigated and the temperature change, thermal distribution and heat flux were effectively analyzed by ANSYS software. All ceramics were obtained in the optimized 76.0 wt% solid loading slurries composed of 0.3 wt% ammonium citrate tribasic and 0.5 wt% Isobam. The temperature difference between the simulation and the experiment of the Ф16 mm and Ф20 mm Ce: YAG ceramics was 0.57 °C and 3.48 °C at about 120 s in transient thermal state, which indicated that the simulation result was credible. Meanwhile, when the diameter of ceramic was increased by 4 mm, the average temperature was lowered by 20–30 °C with the decreasing rate of 5–7.5 °C/mm. Therefore, both simulation and experimental results proved that properly increasing the ceramic area was a simple and efficient method to solve the heat dissipation and high temperature problem, and Isobam gel casting had the potential advantages in the simple mass-fabrication of transparent ceramics.