Controlled Two-Step Formation of Faceted Perovskite Rare-Earth Scandate Nanoparticles

Abstract

A general approach to the formation of well-faceted nanoparticles is discussed and successfully applied to the production of several rare-earth scandates. Two steps were used, with higher temperatures first to nucleate the perovskite phase, followed by lower temperatures to smooth the particle surfaces. Exploiting these two different regimes led to smaller nanoparticles with more faceting. This general approach may be tailored to other material systems as a step towards producing shape-controlled nanoparticles for a desired application.

Modified Winterbottom Construction Including Boundaries

“…Experimental TEM image of 5-fold Au MTPs supported on faceted LnScO 3 nanoparticles , containing re-entrant surfaces with the shape overlaid in (a) for clarity. The inverted orientation is shown in (b).…”

“…For the experimental data, oxide substrates were synthesized using a hydro-sauna method for producing faceted, rare-earth scandate nanoparticles. , Au nanoparticles were prepared on these substrates using a deposition precipitation reaction, as described by Zanella et al Transmission electron microscopy (TEM) was performed using a JEOL ARM300F operated at 300 kV located at the NUANCE center at Northwestern University and on the Argonne Chromatic Aberration-corrected TEM (ACAT) operated at 200 kV at the Center for Nanoscale Materials in Argonne National Lab.…”

Identifying Support Effects in Au-Catalyzed CO Oxidation

“…Oxide supports of LaScO 3 , NdScO 3 , and SmScO 3 were synthesized using a hydro-sauna method that produces faceted nanoparticles. , Au was then deposited on the substrates using a deposition–precipitation method as outlined in studies by Zanella et al TEM characterization was carried out using the Argonne Chromatic Aberration-corrected transmission electron microscope (ACAT) operated at 200 kV for observing the surface reconstructions and nanoparticle structure, and a FEI Talos operated at 200 kV in both moderate-angle and high-angle annular dark-field modes was used to measure particle sizes. Additionally, some microscopy was performed using a JEOL ARM300F at 300 kV for nanoparticle morphology determination, and a Hitachi HD-2300 scanning transmission electron microscope at 200 kV was used to observe the morphology of the support using secondary electrons.…”

Chemisorption-Driven Roughening of Hydrothermally Grown KTa1–xNbxO3 Nanoparticles

“…Two different growth regimes were defined; the terracing regime occurs when terrace nucleation dominates and is characterized by the growth of rough surfaces, while the smoothing regime occurs when terrace growth rate dominates, resulting in flat nanoparticle surfaces. N R and G R are affected by many variables, including the overall driving force of the reaction, chemical potentials of each component in the system, and temperature, and therefore, it is important to understand these relationships so that these variables may be tuned for specific shapes, as demonstrated on LnScO 3 nanoparticles …”

“…N R and G R are affected by many variables, including the overall driving force of the reaction, chemical potentials of each component in the system, and temperature, and therefore, it is important to understand these relationships so that these variables may be tuned for specific shapes, as demonstrated on LnScO 3 nanoparticles. 10 On this note, we took a further step in understanding how the growth conditions control the surface roughness via an additional termhow chemisorption promotes the formation of three-dimensional nuclei that lead to rough surfaces. The systems of interest here were KTO and KNbO 3 (KNO), which have many similarities.…”