Elucidating the influence of molten salt chemistries on the synthesis and stability of perovskites oxides

Abstract

For the successful molten salt synthesis of La0.8Sr0.2MnO3, the salt cation is more influential than the anion. With a KNO3 solvent, pure phase LSM nanoparticles are synthesized at 600 °C in 1 hour.

Investigation into La(Fe/Mn)O3 Perovskites Formation over Time during Molten Salt Synthesis

“…This confirms that the XRD data of the washed samples (Figures ,,, and ) reliably reflects their compositions. The duration of MSS experiments most commonly ranges from several hours to under 1 h. ,,,− The “feeding-and-sampling” procedure reveals that MSS is remarkably fast, yielding a PTO phase within single minutes.…”

Volatilized Molten Salts: An Alternative Avenue for Synthesizing Single-Phase Perovskites

“…These findings are in contrast to the attempted MSS of LSM precursors in the liquid phase of these salts. 11 We postulate that KCl is able to volatilize more readily than LiCl in the LiCl−KCl eutectic and facilitate the successful formation of LSM. However, as the LiCl volatilization increases, Li + leaches Sr out of the perovskite.…”

“…Previous work in our group has highlighted how the molten salt ions directly influence the stoichiometry of LSM, with the cation of the molten salt having a greater influence than the anion on Sr incorporation and retention within the perovskite phase. 11 Upon melting, all of the liquid salt ions are always in contact with the precursors and products. For a eutectic mixture, the more acidic ions in the melt have significant control of the product fidelity.…”

“…This coincides with previous work in our group in which the salt cation has a significant impact on the product stoichiometry. 11 The above experiments were repeated but now with either KCl or LiCl instead of the LiCl−KCl eutectic. For the KCl vMSS, KCl did not volatilize enough in the span of 2 h to significantly impact LSM formation, as seen by the corresponding XRD pattern (Figure 3a) presenting numerous peaks for unreacted precursors.…”

“…In doing so, the molten salt can either act as an inert solvent or contribute as a reactant. − A notable ceramic material reportedly synthesized via the MSS is La 1– x Sr x MnO 3 (LSM), in which the resulting MSS nanoparticles could have enhanced performances in solid oxide fuel cells, , electrolyzers, , and gas sensors . Conventional synthesis methods of LSM require the heating of mixed precursors to temperatures above 1000 °C for many hours to achieve phase purity, yet the MSS can reduce the required temperatures by hundreds of degrees and shorten the dwell times. − Molten salts are comprised of cationic and anionic species, with the cations predominantly comprising alkali and alkaline-earth metals and the anions spanning nitrates, carbonates, sulfates, hydroxides, and chlorides. − The essential chemical basis for the MSS is known as the Lux-Flood acid–base theory: where the base is the O-ion donor and the acid is the O-ion acceptor. The acidity (readiness to accept O ions) of the molten salt solvent impacts the solubility of the precursor species within the melt.…”