Co-precipitation processed needle-like YAG dispersed in alumina powder

A co-precipitation method was used to prepare Al2O3-25 vol.% YAG powders fr om aqueous solutions of aluminum nitrate and yttrium nitrate followed by co -precipitation with an ammonia solution. The as-prepared powders were heat- treated up to 1400 degreesC. The microstructure and the phase evolution wer e observed by TEM and XRD. TEM shows the starting powders appear in whisker -like form. As the temperature is increased to 1250 degreesC, the hair-like form transformed to a needle-like form and has the YAC cubic structure. Po ssible growth mechanisms of needle-like YAG (YAG whisker) are discussed. (C ) 2001 Elsevier Science B.V. All rights reserved.