Thermally stimulated currents of Lanthanum metaniobate ceramics

A series of LaNb3O9 samples was prepared at 1325-1360 °C by the solid state reaction. The structures, temperature dependence of thermally stimulated currents and impedances were investigated. The samples show single phase of LaNb3O9 by XRD analysis. The SEM analysis exhibits that the grain size increases and the porosity factor decreases with increasing sintering temperature. The stimulated current decreases with increasing sintering temperature and a large current of ∼ 110 µA without applied voltage was observed in the LaNb3O9 sample sintered at 1325 °C. The polarization-electric field and temperature dependence of impedance results suggest that the temperature dependence of current does not originate from pyroelectric effect, but from the release of thermally stimulated current.