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

机译：ZrO2纤维壳亚微米粒子的合成与热稳定性

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ZrO _(2) @SiO _(2) 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 St?ber approach. To study the thermal stability of bare ZrO _(2) cores and ZrO _(2) @SiO _(2) 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 ZrO _(2) 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, SiO _(2) -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, ZrO _(2) @SiO _(2) core–shell particles are suited for high-temperature applications up to ～1000 °C. Different mechanisms are considered to explain the markedly enhanced stability of ZrO _(2) @SiO _(2) core–shell particles.
机译：ZrO _（2）@sio _（2）核心壳亚微米粒子是开发先进光学材料的承诺候选人。这里，使用改性溶胶 - 凝胶法合成亚微米氧化锆颗粒，并在400℃下预煅烧。在这些颗粒（平均尺寸：〜270nm）上生长二氧化硅壳，使用种子生长STα方法具有明确定义的厚度（26至61nm）。为了研究裸Zro _（2）芯的热稳定性和ZrO _（2）@sio_（2）核 - 壳颗粒，它们在450至1200℃下煅烧。在热处理之后，通过SEM，TEM，茎，横截面EDX测绘和XRD的特征在于颗粒。非包封的裸ZrO _（2）颗粒主要在400℃的预煅烧后转化为四方相。将温度升至600℃，将它们转化为单斜。最后，在加热至800℃后，颗粒粗化破坏了球形颗粒形状。在引人注目的对比中，SiO_（2） - 占据显着抑制晶粒生长，并且在加热到1000℃后，T→M转变仅在加热到1000℃下进行，随后用光滑的二氧化硅壳保持稳定。在加热至1200℃后观察到颗粒崩解。因此，Zro _（2）@SiO _（2）核 - 壳颗粒适用于高达约1000°C的高温应用。考虑不同的机制来解释Zro _（2）@SiO_（2）核壳颗粒的显着增强的稳定性。

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