A2La8(SiO4)6O2(A=Ca,Sr,Ba)的合成及其导电性能

Synthesis and Conducting Properties on A_2La_8(SiO_4)_6O_2 (A=Ca,Sr,Ba)

以溶胶-凝胶法和固相反应方法分别合成了硅酸盐氧基磷灰石A2La8(SiO4)6O2(A=Ca,Sr,Ba),经XRD表征,证明所得产品为磷灰石相。和固相反应方法相比,溶胶-凝胶法合成磷灰石反应温度低,高温焙烧时间短。电化学阻抗谱研究表明:随着A(A=Ca,Sr,Ba)半径的增大,电导率也逐步加大,活化能却逐步减小。700℃时溶胶-凝胶法合成的Ba2La8(SiO4)6O2的电导率(4.42×10-6 S·cm-1)要比固相反应法合成的电导率大一个数量级。离子迁移数和氧分压对电导率的研究表明,主要的电荷载体是O2-离子。

The synthesis of the silicate oxyapatites A2La8（SiO4）6O2 （A=Ca,Sr,Ba） via a sol-gel method and solid-state reactions were studied contrastively. The reaction time and temperature were decreased greatly by sol-gel method than solid-state reactions .The apatite phases were characterized by X-ray diffraction （XRD）, electrical conducting properties were studied by electrochemical impedance spectroscopy （EIS）. It was found that the ionic conduction in A2La8（SiO4）6O2 （A=Ca,Sr,Ba） increases with increasing radius of A2＋ cations, whilst the activation energy decreases. The conductivity of Ba2La8（SiO4）6O2 by sol-gel method is 4.42×10-6S·cm-1,it is higher about one orders of magnitude than by solid-state reactions at 700℃. Transport number of oxygen ion and the dependence of electrical conductivity on oxygen partial pressure indicate that the charge carriers of the silicate oxyapatite are oxygen ions.