Influence of polymerizing agent on structure and spectroscopic properties of nano‐crystalline La_0.8Sr_0.2MnO₃ powders

Abstract

Key words nano-crystalline powders, strontium-doped lanthanum manganite, polymerizing agent.Strontium-doped lanthanum manganite (La 1-x Sr x MnO 3 or LSM) is the material most widely used on solid oxide fuel cells cathode. In this work, nano-scale La 0.8 Sr 0.2 MnO 3 powders have been synthesized by polymeric precursor-based methods using different polymerizing agents with the aim of evaluating the influence of this change in the final powder. The powders calcined at 700 °C for 2 h have been characterized by X-ray diffraction (XRD), scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FTIR) in order to investigate the quality of both synthesis routes. It is shown that the crystal structure and morphology of the particles are significantly dependent on the preparation conditions. Single phase and La 0.8 Sr 0.2 MnO 3 nano-crystalline particles less than 30 nm were obtained using ethylene glycol as polymerizing agent. FTIR results have been indicated that only the powder obtained using gelatin presented small traces of hydroxyl groups on its surface.

Synthesis of Functional Ceramic Materials for Application in 2 kW Stationary SOFC Stacks

“…The modified polymeric precursors method used employs gelatin as polymerizing agent. Details of the powder preparation by this route may be found in a previous publication [3]. For the study herein, stoichiometric amounts of samarium and cerium nitrates (Sigma-Aldrich.…”

“…Solid oxide fuel cells (SOFCs) have been studied at the Federal University of Rio Grande do Norte, Brazil, during the last five years. A wide variety of ceramic materials has been synthesized, including the traditional strontium-doped lanthanum manganites (LSM) and stabilized zirconia, such as ZrO 2 -8Y 2 O 3 and ZrO 2 -8CeO 2 [1][2][3], as well as novel compositions [4].…”

“…To overcome additional difficulties such as low ionic conductivity and high activation energy to oxygen dissociation, often related to low operating temperatures, LSCF powders are normally mixed to electrolyte materials forming composite cathodes [5,6]. Recent research at UFRN has successfully resulted in novel synthesis processes based on the modified polymeric precursor method and microwave-assisted combustion for the production of low-/intermediary-temperature SOFCs [3,4].…”

“…Among the various synthesis methods commonly used to prepare materials for SOFC components, microwave based routes and modified polymeric precursors methods, especially the ones using gelatin as polymerizing agent, have been scarcely reported in the literature. These alternative synthesis routes have being mainly implemented in an attempt to minimize the energy consumption and total powder production time [3], necessary for large scale applications.…”

Luminescence Properties of Co-Doped Eu3+, Bi3+ Lu2O3/Polyvinylpyrrolidone Films

“…For example, due to polymeric properties, the hybrid films are "softer" and more flexible in their structure of all inorganic films that produce crack-free hybrid films. In this way many complexes, like citric acid (CA) ethylenediame tetra-acetic acid (EDTA), ethylene glycol (EG), triethylenetetramine (TETA) and polyvinylpyrrolidone (PVP), were studied in order to develop new materials [6,7]. Kozuka et al [8] discovered that the thickness of films can be increased by the addition of PVP; the PVP was thought to be hybridized through hydrogen bonding, retarding condensation and promoting structural relaxation in films [8,9].…”