Superior Oxygen Ion Conductivity of Lanthanum Gallate Doped with Strontium and Magnesium

Abstract

The solid solution range of the La(Sr)Ga(Mg)O, perovskite was investigated and the oxygen ion conductivities of corresponding compositions were measured. The solubility of strontium could be extended by the addition of magnesium ions to establish a balance in the oxygen vacancies associated with A and B sites. In this way, the Sr limit in the solid solution was increased to more than 20% of the La content. Doping with either Sr or Mg enhanced oxygen ion conductivity, but whereas Sr doping yielded decreased activation energy with increasing concentration, Mg produced a higher activation energy with increased Mg content. La08Sr,,Ga,9Mg,,028, was found to have the highest conductivity apart from CeO,-based electrolytes at temperatures below 700°C, while La0 ,Sr,2Ga,,,Mg,150,,,, has the highest conductivity except for Bi20, at temperatures above 700°C. IntroductionThe most extensively studied electrolytes for solid oxide fuel cells have been based on Bi20,, CeO2, and Zr02 with the fluorite or related structure.'-4 In the search for new oxygen ion conductors, perovskites (ABO,) offer an interesting alternative because the structure is very tolerant of

Doping and defect association in AZrO3(A = Ca, Ba) and LaMO3(M = Sc, Ga) perovskite-type ionic conductors

“…An electrochemical reactor with a ceramic proton-conducting membrane based on doped BaZrO 3 has also been used to study the electrochemical promotion of catalysis. 6 Also in this field of conducting solids, the oxygen transport properties of the LaGaO 3 -based perovskite have been widely investigated, [8][9][10][11][12][13][14][15][16][17][18] owing to the higher oxygen ion conductivity than the conventional Y/ZrO 2 electrolyte at lower temperatures. The incorporation of cation dopants to form the system La 1Ϫx -Sr x Ga 1Ϫy Mg y O 3Ϫδ (often termed LSGM) gives rise to the highly mobile oxygen vacancies that are responsible for the observed † Based on the presentation given at Dalton Discussion No.…”

Sol–gel synthesis and characterization of Co-doped LSGM perovskites

“…As a consequence, the resulting ionic conductivities of LSGM at 700 • C is about four times larger than that of conventional yttria-stabilized zirconia (YSZ) electrolyte [1][2][3] and it is apparent that a significant decrease in the SOFC operating temperature would be an important practical advance. 4 Following the initial discovery, [1][2][3][4][5] numerous experimental studies have been carried out on LSGM materials, which also include the effect of transition-metal doping. [6][7][8][9][10][11] It is generally believed that doping with a transition metal cation is undesirable for the ionic conductor due to the appearance of n-or p-type conduction.…”

Chemical Preparation of Pure and Strontium‐ and/or Magnesium‐Doped Lanthanum Gallate Powders

“…The phase-evolution behaviors of pure (i.e., LaGaO 3 LSG samples (after calcination at 1340°C for 6 h) also had an orthorhombic crystal structure, with experimental lattice parameters of a ϭ 5.491 Å, b ϭ 5.523 Å, and c ϭ 7.764 Å. Although single-phase LG could be formed from the starting X-rayamorphous resins at temperatures as low as 850°C, single-phase LSG could be produced only after calcination at 1340°C for 6 h (see Fig.…”