Thin water films and particle morphology evolution in nanocrystalline MgO
Artikel i vetenskaplig tidskrift, 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

Författare

Daniel Thomele

Paris Lodron Universität Salzburg

Amir R. Gheisi

Friedrich-Alexander-Universität Erlangen Nurnberg (FAU)

Matthias Niedermaier

Paris Lodron Universität Salzburg

Michael S. Elsässer

Paris Lodron Universität Salzburg

J. Bernardi

Technische Universität Wien

Henrik Grönbeck

Kompetenscentrum katalys (KCK)

Chalmers, Fysik, Kemisk fysik

O. Diwald

Paris Lodron Universität Salzburg

Journal of the American Ceramic Society

0002-7820 (ISSN)

Vol. 101 11 4994-5003

Länk mellan katalytisk aktivitet och kvantmekaniska beräkningar

Vetenskapsrådet (VR), 2017-01-01 -- 2020-12-31.

Ämneskategorier

Fysikalisk kemi

Keramteknik

Materialkemi

DOI

10.1111/jace.15775

Mer information

Senast uppdaterat

2018-11-14