Issue 46, 2019, Issue in Progress

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 tm 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.

Graphical abstract: Synthesis and thermal stability of ZrO2@SiO2 core–shell submicron particles

Supplementary files

Article information

Article type
Paper
Submitted
04 Jul 2019
Accepted
19 Aug 2019
First published
28 Aug 2019
This article is Open Access
Creative Commons BY-NC license

RSC Adv., 2019,9, 26902-26914

Synthesis and thermal stability of ZrO2@SiO2 core–shell submicron particles

M. Finsel, M. Hemme, S. Döring, J. S. V. Rüter, G. T. Dahl, T. Krekeler, A. Kornowski, M. Ritter, H. Weller and T. Vossmeyer, RSC Adv., 2019, 9, 26902 DOI: 10.1039/C9RA05078G

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