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Perovskite-type LaAlO 3 nanoparticles have been prepared by a facile, rapid, and environmentally friendly molten salts method using alkali metal nitrates as low-temperature fluxes. Starting from hydrated lanthanum and aluminum nitrates and alkali metal hydroxides, the proposed methodology consists briefly of two steps: a mechanically induced metathesis reaction followed by short firing at temperatures above nitrates melting points. The purpose of the first is twofold: on the one hand to generate in situ the alkali metal nitrate flux and on the other hand, to obtain a La and Al-containing precursor material suitable for the synthesis of bulk LaAlO 3 nanoparticles in molten nitrates. Different alkali metal nitrates and eutectic mixtures were used to analyze the influence of melt basicity in the reaction outcome. Single phase LaAlO 3 was obtained directly, without any purification step when using three molten media: LiNO 3 , NaNO 3 , and their mixture; using KNO 3 as flux either alone or as part of eutectic compositions, prevents complete conversion, and the title material is obtained mixed with additional crystalline phases such as lanthanum hydroxinitrates and carbonates. As-prepared LaAlO 3 powders are composed of loosely agglomerated nanoparticles with very fine crystallite size (32-45 nm). The present method reduces considerably previously reported synthesis time/temperatures for this material. D. Lupas-contributing editor Manuscript No. 30188.J ournal might well be useful to prepare other perovskite and garnettype complex oxides based on Ln 2 O 3 -Al 2 O 3 combinations (Ln: lanthanides and yttrium) for optical, electronic, and structural applications.

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.