| 초록 |
YAG (yttrium aluminum garnet, Y3Al5O12) powders were synthesized by a mechanochemical solid reaction of Y2O3 with AlOOH, γ-Al2O3, respectively. Phase development of the resultant YAG samples during grinding and calcinations were compared between the two types of aluminum source. The reaction of Y2O3 with AlOOH was activated by mechanical energy and the use of fine instead of heat energy, leading to the direct formation of YAG without second phases such as YAP (yttrium aluminum perovskite, YAlO3) and YAM (yttrium aluminum monoclinic, Y4Al2O9) with calcination at 800℃. However, the sample containingγ-Al2O3 and Y2O3 yields YAP along with YAM after calcination at 900℃ because γ-Al2O3 transformed into alpha-Al2O3 during grinding, which makes it difficult to diffuse Al3+ into Y2O3 lattice, and then by increasing temperatures to 1300℃, a well-crystallized phase of pure YAG was obtained. YAG powders showed good sinterability, although the samples were hardly agglomerated after grinding. After the same calcination of two samples at 1000℃, YAG samples containing the AlOOH and γ-Al2O3 were densified to ~96.7 and ~92.9% of the theoretical density, respectively, by sintering at 1600℃ for 4 h under atmospheric conditions. It is suggested that the use of a fine, type of starting materials and grinding time are believed to be important factors in the mechanochemical synthesis of YAG. |
