A novel stearate melting method for synthesizing highly reactive YAG nanopowders

• Stearate melting method can synthesize well dispersed fine YAG nanopowders.
• The method ensures precise Y:Al ratio and cations mixing at atomic level.
• Pure and dispersed YAG powders can be obtained at low temperature of 750 °C.
• The YAG powders can be sintered into transparent ceramics at 1700 °C.

Ultrafine YAG powders were synthesized by a novel stearate melting method, in which yttrium stearate and aluminum tristearate, having similar physical and chemical properties, were co-melted and then calcined to produce fine YAG nanopowders. This method has the advantages of precise control of Y:Al ratio, homogeneous mixing of cations at atomic level, fine particle size, and good particle dispersion. The formation mechanism of the precursor and the YAG nanopowder was studied by means of XRD, FT-IR, TG–DTA, BET and FE-SEM. Pure YAG nanopowder can be obtained by calcining the co-melted precursor at a relatively low temperature (750 °C), much lower than those of the traditional solid-state reaction method and various wet chemical synthesis methods. The resultant YAG powders are well dispersed and have excellent sinterability. For the YAG powder calcined at 1000 °C, the green compact has the maximum shrinkage rate at about 1450–1550 °C and a total shrinkage of ∼16.70% during constant heating rate sintering. The compact can be sintered to 99.4% of the theoretical density at 1600 °C. The prepared YAG powder can be sintered into transparent ceramics at 1700 °C for 5 h by vacuum sintering.

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