Preparation of high-purity YAG powders by Gel Solid-State Reaction

YAG crystal possesses chemical stability, mechanical intension, thermal conductivity and isotropy. These properties make it widely be used as functional and structural materials. YAG powder was successfully synthesized by gel solid-state reaction. AlOOH were reacted respectively with Y-2(C2O4)(3)center dot 10H(2)O (Route Y-I) and Y2O3 (Route Y-II). The XRD indicated that the main phases were from YAM to YAP, finally to YAG with the increase of temperature in both routes, and YAG began to generate at 1250 degrees C. The single-phase YAG generated after holding for 4h at 1450 degrees C in the Y-I, but a little bit of YAP and Al2O3 was still remained in the Y-II. It was that Y-2(C2O4)(3)center dot 10H(2)O might be decomposed into high-activity, loose-structure yttrium oxide, which promoted the diffusion of Al3+ ion. According to XRD analysis, YAG generated slowly during 1250 degrees C similar to 1300 degrees C and then fast during 1300 degrees C similar to 1450 degrees C. The SEM images showed that the primary particles of Y-I were 2-3 mu m, larger than that of Y-II. Particle distribution indicated that the average diameter is 18.68 mu m in the Y-I and 9.35 mu m in the Y-II.