Production of dispersed nanometer sized YAG powders from alkoxide, nitrate and chloride precursors and spark plasma sintering to transparency

Yttrium aluminum garnet (YAG) was synthesized from different starting materials, i.e., alkoxide, nitrate and chloride precursors. The conversion steps from the precursors to crystalline YAG were studied by Raman spectroscopy. Dispersed YAG powders were formed at a relatively low temperature, around 800 °C by the chlorides route, whereas alkoxide precursors needed firing over 900 °C and nitrates even over 1100 °C. Lyophilized YAG gel was sintered to transparency by the spark plasma sintering method at 1500 °C with in-line transmittances close to 60% at 680 nm and over 80% in the infrared range.