Pellets were formed by dry pressing about 0.25 g of oxide powder to 20.7 MPa in a 9.5-mm-diameter double-action die. The pellets were further compacted isostatically to 207 MPa with a 10-min hold. The pellets were then heated to 1000°C to assure complete conversion to Y203 and to remove adsorbed gases. After cooling, green densities were determined from geometric measurements. Mercury porosimetrys was used on a pellet of the MP and RP powders to obtain a pore entry size distribution.