Hydroxyapatites (HA) have good biocompatibility and are used as bioceramics for artificial bones. The application areas can be extended further if transparent and dence HA ceramics can be prepared. The preparation of dense and transparent HA ceramics were attempted using a spark plasma sintering technique at relatively low temperatures (900-1000 deg C) under a pressure of 80 MPa for a short time of 10 minutes. The sintered body was almost fully dense (70%. The microstructure was examined by SEM, TEM, STEM and EDX. The HA ceramics exhibited a microstructure with grains, approximately 100nm size. A number of intragranular voids, 5-10nm in size, with flat boundaries were also observed. The voids were believed to have been generated by evaporation during spark plasma sintering and were stabilised during cooling. The grain boundaries were clean without a glassy phase.
