Synthesis and Characterization of KNb1-xTixO3- Solid Solutions

KNb1-xTixO3- (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 KNb1-xTixO3- 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 x0.15 have orthorhombic perovskite structure, but the samples of x0.15 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. KNb0.85Ti0.15O2.925 has the highest conductivity of 5.610-3 Scm-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.