کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1790385 | 1524428 | 2014 | 7 صفحه PDF | دانلود رایگان |
• We introduce a sol–gel synthesis method for tetragonal ZrO2–SiO2 nanocomposites.
• We use two different polyalcohols, beside zirconyl chloride and tetraethoxysilane.
• Pure tetragonal zirconia forms in silica matrix, for 30% ZrO2 content up to 1200 °C.
• The use of PVA prevents the formation of ZrSiO4 phase at 1200 °C, for 50% ZrO2.
• The proposed method leads to a homogenous dispersion of zirconia in silica matrix.
In this study, we have synthesized zirconia–silica nanocomposites with different ZrO2 content (50% and 30%) using a modified sol–gel method, based on TEOS–Zr(IV)–NO3−–polyalcohols–H2O sols that successfully gelified to homogenous gels. The gels obtained at room temperature have been dried and then thermally treated at up to 150 °C when a redox reaction took place between the organic polyalcohol and zirconia nitrate, evidenced by DTA analysis, leading to the formation of zirconia nanoparticles precursors in the pores of silica matrix. The obtained precursors have been characterized by thermal analysis and FTIR spectroscopy, and further annealed at higher temperature in the range 500–1200 °C. XRD analysis of the resulted composites have evidenced the presence of nanocrystalline tetragonal zirconia as single crystalline phase up to 1200 °C in the case of 30% ZrO2 samples, and up to 1000 °C for the 50% ZrO2 samples. In the later samples, after being annealed at 1200 °C, several crystalline phases have been present. For all nanocomposites we have obtained a homogenous dispersion of zirconia within the silica matrix, evidenced by Zr and Si elemental maps, performed by SEM-EDX analysis.
Journal: Journal of Crystal Growth - Volume 401, 1 September 2014, Pages 462–468