抄録
Sodium yttrium calcium-oxyhydroxyapatites powders with compositions of {[Ca9.98-0.9xY0.9xNa0.02](PO4)6[(OH)1.98-0.9xO0.9x_??_0.02], x=0-1.0 (here _??_ denotes vacancies at OH lattice sites} were synthesized by the wet process. Porous (Ca, Y, Na)-Ap (here Ap denotes apatite) ceramics having apparent porosities of around 33% were prepared at high temperature under steam flow. On the basis of the results of X-ray diffraction, all the obtained ceramics exhibited almost single-phase (Ca, Y, Na)-Ap with hexagonal structure. The impedance for all samples linearly changed from 106 to 104Ω at 50°C in the humidity range of 40-95%RH. Apatites produced by substituting Y3+ and Na+ for Ca2+ in apatite structure showed an excellent conductivity. This is attributed to both ordinary protonic conduction caused by the self-dissociation of physically adsorbed water and another conduction caused by OH vacancies introduced by substituting Y3+ and Na+ for Ca-sites.
