Investigation of the crystal structure and electrochemical performance of Gd doped LaNb0.9Mo0.1O4.05

Abstract

Single phase La_1−xGd_xNb_0.9Mo_0.1O_4.05 (x = 0, 0.20, 0.40, 0.50, 0.60, 0.80 and 1.00) has been synthesized by a solid state reaction route. The crystal structures of all samples were investigated by high temperature X-ray diffraction. Both LaNb_0.9Mo_0.1O_4.05 and La_0.8Gd_0.2Nb_0.9Mo_0.1O_4.05 were found to possess modulated crystal structures at room temperature. The electrochemical performance of all samples was investigated by electrochemical impedance spectroscopy. LaNb_0.9Mo_0.1O_4.05 exhibited the highest total conductivity of 1.52 × 10⁻² S cm⁻¹ at 900 °C in air; however, in the intermediate temperature range, the conductivity of La_0.8Gd_0.2Nb_0.9Mo_0.1O_4.05 was higher than that of LaNb_0.9Mo_0.1O_4.05. The reason for these phenomena could be related to the influence of the negative effects of the modulated structure on the electrochemical performance and both the Gd and Mo dopants on the stability of the sample, which was investigated using the Bond Valence Sum approach.