ABSTRACT
Single-phase La0.8Sr0.2MnO3 (LSM) has been synthesized using a volatilized molten salt synthesis (vMSS) method for the first time with a LiCl-KCl eutectic with diameters of up to 300 nm, with the majority ranging from 50 to 100 nm. While deleterious to LSM formation when the MSS takes place in the liquid phase, a LiCl-KCl eutectic successfully facilitates LSM formation when volatilized. Specifically, KCl evaporates more readily than LiCl and promotes the formation of LSM via the vapor phase. As time progresses, LiCl volatilization increases and contributes negatively to Sr stoichiometry in the perovskite phase in accordance with Lux-Flood chemistry and to product phase purity. The vMSS is therefore a way to obviate the more immediate restrictions of Lux-Flood chemistry in the liquid phase. These results demonstrate the surprising versatility and flexibility of the MSS method to synthesize numerous potential energy-relevant materials with greater ease than previously thought.
ABSTRACT
In this work, we investigate the synthesis of (La0.8Sr0.2)MnO3 (LSM) in various molten salts to gain insight on the influence of molten salt ions for synthesizing materials critical for energy applications. LSM nanoparticles with a size range of â¼10-200 nm and with target stoichiometries were formed from oxide precursors via feeding into KNO3. Furthermore, feeding precursors into the melt compared to mixing and heating from room temperature results in complete formation of LSM that was otherwise unattainable using conventional molten salt synthesis methods. In LiCl-KCl eutectic, the high Lux acidity of Li+ and Cl- establishes a thermodynamic barrier that impedes Sr from reacting with other precursors in solution and increases Sr stability in the melt compared to the perovskite phase. As a result, LSM will not form in a LiCl-KCl eutectic under ambient conditions. Thus, this study further explicates the molten salt synthesis for perovskites and can serve as a guide for future syntheses.
