Structure and electrical properties of Ca0.28Ba0.72Nb2O6 ceramics with addition of rare earth oxides (CeO2, La2O3)

Ca0.28Ba0.72Nb2O6 (CBN28) ceramics with addition of CeO2 and La2O3, were prepared by the conventional ceramic fabrication technique. XRD results showed that the single tungsten bronze structure of CBN28 was not changed by adding CeO2 or La2O3. SEM results indicated that both CeO2 and La2O3 dopants were effective in inhibiting the grain growth and suppressing the anisotropic growth behavior in tungsten bronze structure. It was also found that both two kinds of dopants had remarkable effects on the dielectric and ferroelectric properties of CBN28 ceramics. Compared with CBN28 ceramics, the dielectric constant around room temperature εr, dielectric loss tan δ, the degree of diffuseness γ and coercive field Ec were all ameliorated when doping proper amount of CeO2 or La2O3. The comprehensive electric performance was obtained in CBN28-0.3 wt% CeO2 and CBN28-0.4 wt% La2O3 ceramics. Besides, the underlying mechanism for variations of the electrical properties due to different dopants was explained in this work.