Lanthanum phosphate powders were synthesized by direct solid-liquid reaction of lanthanum oxide and phosphoric acid at the La:P ratio of 1: 1. Phase-pure and fine grain size LaPO4 powders could be obtained by calcining the as-received powders at the temperature higher than 600 degreesC. It was demonstrated that the phase type, grain size and morphology of the LaPO4 powders were calcined at various temperatures. We have studied the microstructure of sintered LaPO4 ceramic and Al2O3/LaPO4 composite using the synthesized powders by SEM and TEM analysis. An interesting layered crystal structure and lots of dislocations inside LaPO4 grains and at the interface of Al2O3/LaPO4 composite were observed. Low hardness and multiple dislocations and dislocation networks indicated the layered LaPO4 ceramic could possess excellent machinability. As an example for engineering application, machinable Al2O3/LaPO4 composite with weak bonding was fabricated and characterized. (C) 2002 Elsevier Science B.V. All rights reserved.