Synthesis of Nano-sized Ce3+/Eu3+ Codoped YAG Phosphor in a Continuous Supercritical Water System

Luminescent yttrium aluminum garnet (Y3Al5O12) nanoparticles codoped with Ce3+ and Eu3+ (YAG:Ce3+,Eu3+) were continuously synthesized by directly feeding potassium hydroxide solution and a metal salt solution to supercritical water (SCW). The effects of the Ce3+-to-Eu3+ concentration ratio on the photoluminescence of the synthesized nanoparticles were studied using a continuous SCW tubular reactor. At 20-s reaction time and a pH of 9.10 in the SCW reactor, the average size of the prepared phosphor nanoparticles was 60−150 nm and cubic or hexagonal particles coexisted with the spherical particles. The phosphor nanoparticles presented a broad emission band in the green-yellow spectral region due to Ce3+, as well as a sharp emission peak at around 610 nm in the red spectral region due to Eu3+. Without further thermal treatment, the YAG:Ce3+,Eu3+ phosphor synthesized in the continuous reactor under SCW conditions showed strong luminescence properties. Simultaneously, enhancement of the red spectral emission intensity in the YAG:Ce3+,Eu3+ phosphor could be controlled by increasing the Eu3+ concentration.