Molten salts synthesis and electrical properties of Sr- and/or Mg-doped perovskite-type LaAlO3 powders

Abstract

Lanthanum-based LaBO 3 oxides adopting the very stable perovskite structure are currently considered attractive materials for a growing number of applications in the field of solid-state ionics. In particular, LaAlO 3 -based perovskites are promising electrolyte materials for solid oxide fuel cells because they show almost pure oxygen ion conductivity at low oxygen partial pressures and high temperatures as well as excellent thermal and chemical stability under the standard operating conditions. This article describes a low-temperature synthesis of pure and acceptordoped perovskite-type LaAlO 3 nanopowders via a facile and environmental-friendly molten salts method. Using hydrated metal nitrates and sodium hydroxide as raw materials, the proposed methodology consists of two steps: a mechanically induced metathesis reaction and short firing above NaNO 3 's melting point. The purpose of the first is twofold: i.e., to generate in situ the NaNO 3 flux and to obtain a suitable precursor for the synthesis of the target materials in molten nitrates. Accordingly, pure and Mg-and/or Sr-doped LaAlO 3 powders were obtained directly without using any purification step at temperatures B500°C. When preparing the Mg-containing samples, NaNO 2 was also added to the reaction mixture to increase melt reactivity. The formation of the target series in the molten salt is thought to proceed through a ''dissolution-precipitation'' mechanism with LaAlO 3 particles precipitating during cooling from a solution oversaturated with reactants. Electrical properties of the as-prepared materials were measured as a function of temperature and frequency by means of impedance spectroscopy and found comparable to those shown by similar materials prepared using more complicated routes.

Ionic and electronic transport in calcium-substituted LaAlO3 perovskites prepared via mechanochemical route

“…There are a number of works describing different approaches to the synthesis of LaAlO3 including conventional solid state reaction route [6˗9,12,20,21], solvothermal [22], combustion [23][24][25][26], reverse micelle [27], in situ polymerization [28], molten salt [29,30], precipitation [31], electrochemical [32] and mechanochemical [33] methods.…”

Effect of Cobalt-Doped Electrolyte on the Electrochemical Performance of LSCFO/CGO Interfaces

“…The Ce 0.8 Gd 0.2 O 2- powders with and without the addition of 1at.% Co sintering aid were prepared by a molten-salt route described elsewhere (7,8). The starting materials used were high purity (Aldrich, >99+ %) analytical grade cerium nitrate, gadolinium nitrate, cobalt nitrate hexahydrate and sodium hydroxide.…”

Preparation methods of thermoluminescent materials for dosimetric applications: An overview

“…Lasky and Moran (1978) used this method to produce LiF TL phosphors. Other TL materials produced by this method have been different metallic oxides (Jayaramaiah et al, 2011), some perovskites (Mendoza-Mendoza, et al, 2012).…”