represents the surface of the as synthesized tape of the oxides mixture by the aqueous tape casting method. It can be seen that there are two types of particles with different morphology characteristics in the photographs. The larger particles are Y2O3powders with the particle size distribution from 1 μm to 3 μm. The finer particles are Al2O3powders with the particle size distribution from 200 nm to 600 nm. The morphology of Y2O3 powders is irregular or flake shape. But Al2O3 powders are near spherical. These spheres are the aggregates of the fine Al2O3 powders whose particle sizes are about 100 nm. The photographs indicate that the starting powders distribute homogeneously in the tapes.
Fig. 2(a) shows the tape, single slices of the tape, stacked slices with 30 layers and pressed slices with 30 layers, respectively. The thickness of the tapes were controlled at 100 μm. The diameter of the slice is designed at 20 mm. Fig. 2(b) shows the green body and the sintered YAG transparent ceramics. The green body underwent the binder removal and cold isostatic pressing procedures. As a result, the diameter shrunk from 20 mm to about 18 mm. During the sintering process, shrinkage occurred again and the diameter decreased from 18 mm to about 15 mm. Composite structure YAG ceramics with the thickness of 1.0 mm have high optical quality. The words behind the ceramics can be seen clearly.