Synthesis and Conducting Properties of La_9(SiO_4)_(6-x)(VO_4)_xO_(1.5+0.5x)

The V-doped silicate oxyapatites La9(SiO4)6-x(VO4)xO1.5+0.5x(x=0, 0.5 and 1) were synthesized successfully via a sol-gel method at 800℃. The apatite phases were characterized by X-ray diffraction (XRD). Conducting properties were studied by electrochemical impedance spectroscopy (EIS). It is found that the conductivities are influenced by increasing vanadium content, the conductivity of La9(SiO4)5(VO4)O2 is 5.23×10-3·cm-1 at 700℃, it is about 5 times higher than La9(SiO4)6O1.5.The electrical conductivity of La9(SiO4)6O1.5 is almost independent of the oxygen partial pressure from 105 to 1Pa, but that of La9(SiO4)5(VO4)O2 is minor increased. This result may indicate n-type electron conduction generated in the vanadium doped system.