Kobune, M.Iida, H.Sorai, Y.Mineshige, A.Fujii, S.Setter, N.2006-08-212006-08-212006-08-21199910.2472/jsms.48.6Appendix_116https://infoscience.epfl.ch/handle/20.500.14299/233382WOS:000175670400008483Sodium yttrium calcium-oxyhydroxyapatites powders with compositions of {[Ca9.98-0.9xY0.9Na0.02](PO4)(6)[(OH)(1.98-0.9x)O(0.9)square(0.02)],x=0.1.0(here square 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 104 Omega at 50degreesC 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.humidity sensorhumidity sensitivitycalcium oxyhydroxyapatitewet processimpedanceyttriumsodiumporous ceramicstext::journal::journal article::research article