KNb_(1-x)Ti_xO_(3-δ)固溶体的合成与表征  

Synthesis and Characterization of KNb_(1-x)Ti_xO_(3-δ) Solid Solutions

作　　者：向军[1] 李莉萍[2] 

机构地区：[1]华东船舶工业学院数理系,江苏镇江212003 [2]吉林大学物理系,吉林长春130023

出　　处：《高压物理学报》2003年第3期187-192,共6页Chinese Journal of High Pressure Physics

基　　金：江苏省高校自然科学研究计划项目资助 (0 1KJD1 40 0 0 1 )

摘　　要：利用高温高压法首次合成了KNb1 -xTixO3-δ(x =0～ 0 .4)系列固溶体 ,并使用X射线衍射、TG DTA、Raman谱和交流阻抗谱等对样品的结构、热稳定性和导电性进行了表征。XRD结果表明 ,随掺杂量的增加 ,晶胞体积减小 ;Ti掺杂引起了固溶体结构的转变 ,x <0 .1 5的样品为正交钙钛矿结构 ,而x≥ 0 .1 5的样品几乎为纯四方相结构。Raman谱和DTA结果显示 ,Ti掺杂使四方相区宽化 ,并且随掺杂量的增加 ,相变温度逐渐下降。阻抗谱测量表明 ,所有样品均以离子导电为主 ,其中KNb0 .85Ti0 .1 5O2 .92 5的氧离子导电率最高 ,在 80 0℃时达到 5 .6× 1 0 - 3S·cm- 1 ,在测量温度范围内 ,电导率可以拟合成两条直线 。KNb 1-xTi xO 3-δ (x=0～0.40) solid solutions were synthesized under high temperature and high pressure for the first time. The structural characteristics and ionic conductivity of KNb 1-x·Ti xO 3-δ solid solutions were investigated by XRD,TG-DTA,Raman and impedance spectroscopy techniques. XRD results showed that Ti-doping resulted in structural transformation, the samples of x<0.15 have orthorhombic perovskite structure, but the samples of x≥0.15 are single tetragonal phase.With the increase of doping amount,the cell volume decrease.The Raman spectra at different temperatures and DTA curve indicate that the structure of the solid solutions had been changed,Ti-doping broadens tetragonal phase zone,and curie temperature decrease with the increase of dopant content. The ionic conductivity of the samples measured by impedance spectroscopy shows that in all the samples the ions are main carriers.KNb 0.85Ti 0.15O 2.925 has the highest conductivity of 5.6×10 -3S·cm -1 at 800 ℃. A marked curvature at T=630 ℃ has been observed in the Arrhenius plot of the bulk conductivity.The activation energy below 630 ℃ is lower than that above 630 ℃,and the cause is discussed.

关 键 词：KNb1-xTixO3-δ 固溶体 合成 表征 高温高压法 氧离子导体 结构相变 固体电解质 钙钛矿氧化物 阻抗谱 

分 类 号：O646[理学—物理化学] TM24[理学—化学]