Wet to Dry Controls Lanthanide Scandate Synthesis

Abstract

The choice of temperature and gas conditions used in a water pressure-controlled reactor is guided by density functional theory (DFT) to synthesize nearly phase-pure lanthanide scandate nanoparticles (LnScO3, Ln = La, Nd, Sm, Gd). In this synthetic method, low water-vapor partial pressures, well below water’s gas liquidus, inhibit particle growth, while an excess of water vapor results in undesired rare-earth hydroxide and oxyhydroxide secondary phases. The optimal humidity for high-purity LnScO3 particle synthesis is shown to vary with the lanthanide; DFT is used to calculate the thermodynamics of secondary phase formation for each lanthanide tested such that the role of water vapor may be quantified and used to maintain phase purity (greater than 96 mol %) across the series. The combination of thermodynamic calculation and experimental confirmation with this pressure-controlled reactor provides an opportunity to explore analogous syntheses of other inorganic perovskite nanoparticles.

Observing the Surface Termination of LaScO3 Perovskite Using Solid-State Nuclear Magnetic Resonance

“…LaScO 3 nanoparticles were prepared via two-line hydrosauna synthesis based on a procedure described in literature. 31 First an equimolar solution of lanthanum and scandium ions was prepared by dissolving 2 mmol each of La 2 O 3 and Sc 2 O 3 (99.99%, Sigma-Aldrich) in 10 mL of 15.8 M nitric acid stirred at 90 °C. After the liquid evaporated, the resulting nitrate precursor was dissolved in 20 mL of deionized water and then added dropwise to 25 mL of 10 M NaOH in an ice bath to precipitate a mixed-cation hydroxide hydrogel, the precursor for LaScO 3 growth.…”