Title: Complex Fluorine Chemical Potential Effects on the Shape and Compositional Heterogeneity of KTa_1–xNb_xO₃ Nanoparticles

Abstract

When kinetic conditions dominate and dictate the growth in a nanoparticle synthesis, properties of the synthesis environment can have considerable effects on the properties of the products. Such effects were studied here, where the solution environment was changed via the addition of KF to the hydrothermal syntheses of KTa_1–xNb_xO₃ and KTaO₃. One result demonstrated the straightforward cause-and-effect relationship between the solution and reaction kinetics: KF directly increased the solution stability of the Ta species and therefore decreased its reaction rate, resulting in a change in composition heterogeneity of Ta and Nb in the KTa_1–xNb_xO₃ particles. However, not all effects are so simple; changing the chemical potential of the solution with KF can also promote the formation of particles with anisotropic defect enhanced kinetic Wulff shapes instead of cuboidal shapes. The increased F chemical potential in the solution enabled the formation of planar defects in the bulk, which accelerated growth in-plane to form particles characterized by flat rectangular flake geometries. In this work, thermodynamic modeling with density functional theory calculations confirmed that sufficient KF concentrations can drive the formation of a defect phase K_n+1Ta_nO_3nF.

Authors:

Ly, Tiffany  ^[1];

• Search DOE PAGES for author "Ly, Tiffany"
• Search DOE PAGES for ORCID "0000-0002-8675-1467"

Wen, Jianguo  ^[2];

• Search DOE PAGES for author "Wen, Jianguo"
• Search DOE PAGES for ORCID "0000-0002-3755-0044"

Marks, Laurence D. ^[1]

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+ Show Author Affiliations

1. Northwestern Univ., Evanston, IL (United States)
2. Argonne National Lab. (ANL), Argonne, IL (United States)

Publication Date:

Fri Nov 13 00:00:00 EST 2020

Research Org.:

Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials

Sponsoring Org.:

National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division

OSTI Identifier:

1798072

Grant/Contract Number:  

AC02-06CH11357; DMR-1507101

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physical Chemistry. C

Additional Journal Information:

Journal Volume: 124; Journal Issue: 47; Journal ID: ISSN 1932-7447

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Oxides; Nanoparticles; Defects; Kinetics; Perovskites