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Effect of pH on Crystallization of Nanocrystalline Zirconia in a Microwave-hydrothermal Process
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| 【文章作者】欧阳海波;李翠艳;LI Kezhi;LI Hejun;ZHANG Yulei; |
| 【文章摘要】 Nanocrystalline zirconia(ZrO) was synthesized using a microwave-hydrothermal process.The effect of pH on the crystallization of the ZrO_2 powders was investigated.The phase and microstructure of ZrO_2 powders were examined using X-ray diffraction(XRD),Raman spectroscopy,and transmission electron microscopy(TEM).Results show that pure m-ZrO_2 can be obtained at low pH(pH<2).Pure t-ZrO_2 is formed at pH = 7 and 14.The size of the ZrO_2 crystals is in the range of 8-26 nm and decreases with increasing pH.The formation of m-ZrO_2 results from the precipitation of ZrO_2 from solution.The t-ZrO_2 is formed through the in-situ structural rearrangement of amorphous Zr(OH)_xO_y.The stabilization of t-ZrO_2 is attributed to the small crystal size and the adsorption of hydroxy ions on the surfaces of the crystals. |
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