Effects of yttrium and sodium addition on preparation and humidity sensitivity of porous apatite ceramics

Sodium 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.


Published in:
Materials Science Research International, 5, 2, 116-121
Year:
1999
ISSN:
1341-1683
Keywords:
Note:
Himeji Inst Technol, Fac Engn, Dept Appl Chem, Himeji, Hyogo 6712201, Japan Swiss Fed Inst Technol, Ceram Lab, Mat Sci & Engn Dept, CH-1015 Lausanne, Switzerland
553HV
Times Cited:0
Cited References Count:14
Other identifiers:
Laboratories:




 Record created 2006-08-21, last modified 2018-03-17


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