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2019
Journal Article
Titel
Synthesis and thermal stability of ZrO2@SiO2 core-shell submicron particles
Abstract
ZrO2@SiO2 core-shell submicron particles are promising candidates for the development of advanced optical materials. Here, submicron zirconia particles were synthesized using a modified sol-gel method and pre-calcined at 400 °C. Silica shells were grown on these particles (average size: ∼270 nm) with well-defined thicknesses (26 to 61 nm) using a seeded-growth Stöber approach. To study the thermal stability of bare ZrO2 cores and ZrO2@SiO2 core-shell particles they were calcined at 450 to 1200 °C. After heat treatments, the particles were characterized by SEM, TEM, STEM, cross-sectional EDX mapping, and XRD. The non-encapsulated, bare ZrO2 particles predominantly transitioned to the tetragonal phase after pre-calcination at 400 °C. Increasing the temperature to 600 °C transformed them to monoclinic. Finally, grain coarsening destroyed the spheroidal particle shape after heating to 800 °C. In striking contrast, SiO2-encapsulation significantly inhibited grain growth and the t RT m transition progressed considerably only after heating to 1000 °C, whereupon the particle shape, with a smooth silica shell, remained stable. Particle disintegration was observed after heating to 1200 °C. Thus, ZrO2@SiO2 core-shell particles are suited for high-temperature applications up to ∼1000 °C. Different mechanisms are considered to explain the markedly enhanced stability of ZrO2@SiO2 core-shell particles.
Author(s)
Finsel, Maik
Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
Hemme, Maria
Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
Döring, Sebastian
Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
Rüter, Jil S.V.
Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
Dahl, Gregor T.
Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
Krekeler, Tobias
Electron Microscopy Unit, Hamburg University of Technology, Eißendorfer Straße 42, D-21073 Hamburg, Germany
Kornowski, Andreas
Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
Ritter, Martin
Electron Microscopy Unit, Hamburg University of Technology, Eißendorfer Straße 42, D-21073 Hamburg, Germany
Weller, Horst
Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, D-20146 Hamburg, Germany