The results of electrical conductivity studies, structural measurements and thermogravimetric analysis of La 1?x Tb x NbO 4+δ (x = 0.00, 0.05, 0.1, 0.15, 0.2, 0.3) are presented and discussed. The phase transition temperatures, measured by high-temperature x-ray diffraction, were 480 °C, 500 °C, and 530 °C for La 0.9 Tb 0.1 NbO 4+δ , La 0.8 Tb 0.2 NbO 4+δ , and La 0.7 Tb 0.3 NbO 4+δ , respectively. The impedance spectroscopy results suggest mixed conductivity of oxygen ions and electron holes in dry conditions and protons in wet. The water uptake has been analyzed by the means of thermogravimetry revealing a small mass increase in the order of 0.002% upon hydration, which is similar to the one achieved for undoped lanthanum orthoniobate.
展开▼
