Thin water films and particle morphology evolution in nanocrystalline MgO
Journal article, 2018

A key question in the field of ceramics and catalysis is how and to what extent residual water in the reactive environment of a metal oxide particle powder affects particle coarsening and morphology. With X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM), we investigated annealing-induced morphology changes on powders of MgO nanocubes in different gaseous H2O environments. The use of such a model system for particle powders enabled us to describe how adsorbed water that originates from short exposure to air determines the evolution of MgO grain size, morphology, and microstructure. While cubic nanoparticles with a predominant abundance of (100) surface planes retain their shape after annealing to T = 1173 K under continuous pumping with a base pressure of water p(H2O) = 10−5 mbar, higher water partial pressures promote mass transport on the surfaces and across interfaces of such particle systems. This leads to substantial growth and intergrowth of particles and simultaneously favors the formation of step edges and shallow protrusions on terraces. The mass transfer is promoted by thin films of water providing a two-dimensional solvent for Mg2+ ion hydration. In addition, we obtained direct evidence for hydroxylation-induced stabilization of (110) faces and step edges of the grain surfaces.

interfaces

coarsening

magnesium oxide

grain growth

Author

Daniel Thomele

Paris Lodron University of Salzburg

Amir R. Gheisi

University of Erlangen-Nuremberg (FAU)

Matthias Niedermaier

Paris Lodron University of Salzburg

Michael S. Elsässer

Paris Lodron University of Salzburg

J. Bernardi

Vienna University of Technology

Henrik Grönbeck

Competence Centre for Catalysis (KCK)

Chalmers, Physics, Chemical Physics

O. Diwald

Paris Lodron University of Salzburg

Journal of the American Ceramic Society

0002-7820 (ISSN)

Vol. 101 11 4994-5003

Catalytic activity from first principles

Swedish Research Council (VR), 2017-01-01 -- 2020-12-31.

Subject Categories

Physical Chemistry

Ceramics

Materials Chemistry

DOI

10.1111/jace.15775

More information

Latest update

11/14/2018