Monazite-type LaPO4 was synthesized using the wet precipitation and mechanochemical reaction methods. Mixtures of xLaPO(4)-(1 - x)ZrO2 (x = 0-1) were dry-pressed to disks or plates and cold isostatically pressed (CIP) at 100 MPa for 10 Min and then sintered at temperature between 1500 and 1600degreesC for 1, 3, and 5 h in air, respectively. Relative densities larger than 96.8% (x less than or equal to 0.4) and 92% (x = 0.5-1) were achieved. It was found that these composites with x greater than or equal to 0.25 and single-phase LaPO4 were machinable, that is, they could be cut and drilled using conventional tungsten carbide metal-working tools. The drilling rates were measured by applying a fixed load of 49 N to the drill at 6400 rpm. X-ray diffraction results showed that the LaPO4 did not react with ZrO2, at least at 1600degreesC in air. The linear thermal expansion coefficient, thermal conductivity, bending strength, and Young's modulus of the sintered composites were measured. (C) 2002 Elsevier Science Ltd. All rights reserved.