Fabrication of Transparent Hydroxyapatite Sintered Body with High Crystal Orientation by Pulse Electric Current Sintering

Transparent hydroxyapatite (HAp) sintered body with a high crystal orientation and a relative density of 99.7% was fabricated by the pulse electric current sintering method; the c ‐axis of HAp crystals with a hexagonal column morphology and ca. 200 μm × 25 μm in size was oriented perpendicular to the pressure direction. The sintered temperature increased to 1200°C at a heating rate of 50°C/min for 10 min and a pressure of 50 MPa was applied. The orientation indexes were calculated from X‐ray diffraction patterns of the planes perpendicular and parallel to the pressure direction. The optical transmittance was greater than 70% over the wavelength of 700 nm.