| Transparent polycrystalline neodymium-Yttrium Aluminum Garnet（YAG） ceramics withbetter chemical stability, excellent optical and high temperature mechanical property is be-coming a new high-power solid state laser host material. Masses of efforts have been paid todevelop the Nd:YAG materials.The best experimental parameter was determined by one orthogonal experiment and sev-eral single factor experiments. The factors investigated in the orthogonal experiment werereaction temperature, titration rate, stirring speed and aging time; and those considered in thesingle factor experiments included drying methods （oven drying, freeze drying, liq-uid-nitrogen allegro freeze drying）, heat treatment conditions of precursors, de-agglomerantetc. The results showed that the best conditions for Nd:YAG preparation were the followings:reaction temperature,25℃; titration rate,15mL/min; stirring speed,1000prm; aging time,24h;ammonium sulfate ratio,1:2; liquid-nitrogen allegro freeze drying, heating rate,10℃/min;calcined temperature,1100℃and soaking time,2h.Then the YAG formation mechanism in existence of ammonium sulfate was studied bythe means of DTA/TG, FT-IR, XRD and SEM etc. The results indicated that the phase trans-form-ation of precursor at elevated temperature experienced a complicated process whichincluded: the formation of sandwich type precursor,Al（OH）3--Y2（CO3）3·nH2Oâ†'Y2（SO4）3â†'Y2O2SO4â†'YAP（YAlO3）â†'YAG (Y3Al5O12).At last a new method, namely allegro freeze drying, was developed to synthesize YAGnanoparticles which hydrated aluminum nitrate, hydrated yttrium nitrate solution was firstlysprayed into liquid nitrogen （LN）. Then the freeze mass was dried in a Freeze dryer. After be-ing calcined at1100℃, well-crystallized, uniform grain, weak agglomeration YAG na-no-particle was produced. Compared with the solid-state reaction and co-precipitation me-thods, this process was environmental friendly, conditions mild, and process simple etc. |
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