Effect of Sr content on the crystal structure and electrical properties of the system La_2−xSr_xNiO_4+δ(0 ≤ x ≤ 1)

Abstract

Materials formulated as La(2-x)Sr(x)NiO(4+delta) (0 <or=x<or= 1) have been prepared and investigated by high-resolution neutron powder diffraction in order to correlate the structural variation induced by the incorporation of Sr into the crystal lattice with the electronic and thermal properties of each material. The evolution of the electrical conductivity and thermal expansion coefficients with temperature have been determined in order to study the potential use of these compounds as cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFC). These oxides show a good thermal expansion coefficient (TEC = 11-13 x 10(-6) K(-1)), and high electronic conductivity up to 273 S cm(-1). It is noticeable that a great enhancement of the electrical conductivity with the Sr content is concomitant with the shortening of the Ni-O1 bond length.

Effect of Sr substituted La2−xSrxNiO4+δ (x = 0, 0.2, 0.4, 0.6, and 0.8) on oxygen stoichiometry and oxygen transport properties

“…Therefore, these oxygen excess materials caught a lot of interest as cathodes for SOFC applications due to their potentially high oxygen transport property. [5][6]10,13 Most efforts on La 2−x Sr x NiO 4+δ (LSNO) have been devoted to understanding structural stability, electrical and thermal behavior of La 2−x Sr x NiO 4+δ compounds with only a few investigations of the transport of conducting species in the system. 2,[7][8][9][10] Moreover, materials in this group exhibit coefficient of thermal expansion (CTE) values in the range of 12.4-13.6×10 -6 K -1 , close to the common SOFC electrolyte materials such as the ceria-based electrolytes (13.2×10 -6 K -1 ).…”

Heteroepitaxy and crystallographic orientation transition in La1.875Sr0.125NiO4thin films on single crystal SrTiO3

“…Thermal strain should play a minimal role in the reorientation due to the nearly equal thermal expansion coefficients of the materials; LSNO being approximately 11.5 Â 10 À6 K À1 whereas STO being approximately 11 Â 10 À6 K À1 . 45,46 It should also be noted that from the XRD pattern in Fig. 1 and the pole figures in Figs.…”

Effects of strontium doping on the structure, oxygen nonstoichiometry and electrochemical performance of Pr2−Sr Ni0.6Cu0.4O4+ (0.1 ≤ x ≤ 0.5) cathode materials

“…The ASR value of PSNCO1703 at 650 C is 0.314 U cm 2 , while the ASR value can be obtained as low as 0.063 U cm 2 at 800 C. It can be seen that the relaxation frequencies are in the same order of magnitude of 1 Hz, and they show an increasing trend with the increase of testing temperature. This indicates that the ionic transfer at the cathode/ electrolyte interface is promoted due to the increase of testing temperature [27]. The impedance spectra recorded for all compositions at 800 C are presented in Fig.…”

“…It has been reported that the ionic conductivity of this kind of material is only approximately the same order of magnitude as the one of 8YSZ, while the values of electronic conductivity are in the magnitude of 10 1 e10 2 S cm À1 [11]. The electronic conductivity of these oxides almost reaches the requirement for the application as cathode materials and the enhancement of electronic conductivity can be achieved by doping strontium on the A site [22,27]. As for substitution on Ni site in Pr 2 NiO 4þd , our previous work has shown that Pr 2 Ni 0.6-Cu 0.4 O 4 is observed with the best cell performance in the Cu substituted Pr 2 NiO 4þd systems [28].…”