La_(10-x)(SiO_4)_6O_(3-1.5x)的合成及其导电性能的研究

Synthesis and Conducting Properties of La_(10-x)(SiO_4)_6O_(3-1.5x)

利用溶胶-凝胶法在800℃合成了硅酸盐氧基磷灰石La10-x（SiO4）6O3-1.5x（x=0，0．17，0．33，0．50和0．67），经XRD表征所得产品为磷灰石相。以电化学阻抗谱研究了硅酸盐氧基磷灰石的导电性能，体系的电导率随着间隙氧和阳离子空位数量的增多而加大，La9.33（SiO4）6O2的电导率较La9．5（SiO4）6O2.25大，是由于前者有较多的阳离子空位所致，700℃时La10（SiO4）6O3的电导率为7．98×10^-3S·cm^-1，比La9.33（SiO4）6O2的电导率提高了5倍。氧分压从10^5-1Pa变化时电导率保持不变，证明硅酸盐氧基磷灰石在较宽的氧分压范围内为O^2-导电。

The synthesis of silicate oxyapatites La10-x （SiO4）6O3-1.5x（x =0, 0.17, 0.33, 0.50 and 0.67） via a sol-gel method at 800℃ was reported. The apatite phases were characterized by X-ray diffraction （XRD） and conducting properties were studied by electrochemical impedance spectroscopy （EIS）. It is found that the conductivities are influenced by the amount of cation vacancies and interstitial oxygen. The conductivity of La9.33 （ SiO4 ）6O2 with more cation vacancies is higher than that of La9.5（SiO4）6O2.25. The conductivity of La10（SiO4）6O3 with more interstitial oxygen is 7.98×10^-3 S·cm6-1, which is about 5 times higher than that of La9.33 （SiO4）6O2 at 700℃. The electrical conductivity is almost independent of the oxygen partial pressure from 10^5 to 1 Pa, which suggests that the oxyapatites exhibit almost pure O^2- ion conduction over a wide range of oxygen partial pressure.