Mechanochemical synthesis of zirconia nanoparticles: Formation mechanism and phase transformation

作者：Isfahani Taghi Dallali; Javadpour Jafar; Khavandi Alireza; Dinnebier Robert; Rezaie Harnid Reza; Goodarzi Massoud

来源：International Journal of Refractory Metals and Hard Materials, 2012, 31: 21-27.

DOI：10.1016/j.ijrmhm.2011.08.011

• Mechanochemical synthesis
• Nanopowder
• Zirconia
• Formation mechanism
• Phase transformation
• Rietveld refinement

Studies on the synthesis and formation mechanism of zirconia nanopowder prepared by mechanochemical technique have been carried out by means of X-ray powder diffraction (XRPD), differential thermal and thermogravimetric analysis (DSC-TG), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM). A dry powder mixture of anhydrous ZrCl4 and CaO was milled in stoichiometric ratio to produce ZrO2. The milling resulted in the formation of crystalline CaO and partially amorphous ZrCl4 while there was no sign of chemical reactions during milling. Heating the as-milled powder resulted in the formation of amorphous zirconium hydroxide (ZrOH)(4)) and calcium chloride (CaCl2(2H(2)O)). According to our results, ZrCl4 hydrolyses during the heating stage while CaO adsorbs the produced HCl forming CaClOH and CaCl2 subsequently. Heat treatment of Zr(OH)(4) resulted in the production of zirconia (ZrO2). Based on Rietveld refinement it has been shown that an average critical crystallite size around 46 nm exists above which tetragonal zirconia (t-ZrO2) transforms to monoclinic zirconia (m-ZrO2).

• 出版日期2012-3