Finsel, MaikMaikFinselHemme, MariaMariaHemmeDöring, SebastianSebastianDöringRüter, Jil S. V.Jil S. V.RüterDahl, Gregor ThomasGregor ThomasDahlKrekeler, TobiasTobiasKrekelerKornowski, AndreasAndreasKornowskiRitter, MartinMartinRitterWeller, HorstHorstWellerVossmeyer, TobiasTobiasVossmeyer2019-10-092019-10-092019-08-28RSC Advances 46 (9): 26902-26914 (2019)http://hdl.handle.net/11420/3519ZrO2@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 → 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.en2046-20692019462690226914RSC Publishinghttps://creativecommons.org/licenses/by-nc/3.0/TechnikJournal Articleurn:nbn:de:gbv:830-882.05134010.15480/882.242410.1039/c9ra05078g10.15480/882.2424Journal Article