engleski

The influence of thermal treatment on the phase development of ZrO2-NiO precursors

Structural and microstructural changes during thermal treatment of the amorphous precursors of the ZrO2-NiO system were examined by differential thermal analysis, X-ray powder diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and energy dispersive X-ray spectrometry. The amorphous precursors of the ZrO2-NiO system on the ZrO2-rich side of the concentration range were prepared by co-precipitation from aqueous solutions of the corresponding salts. The crystallization temperature of the amorphous precursors increased with an increase in the NiO content, from 405 °C (0 mol% NiO) to 600 °C (30 mol% NiO). The results of phase analysis indicated that maximum solubility of Ni2+ ions in the ZrO2 lattice (not, vert, similar5 mol%) occurred in the metastable products obtained after crystallization of the amorphous precursors. The results of Raman spectroscopy indicate that the incorporation of Ni2+ ions causes partial stabilization of the tetragonal polymorph of ZrO2, but could not stabilize the cubic ZrO2. A precise determination of unit-cell parameters using the whole-powder-pattern refinements shows that the unit-cell parameters of the tetragonal (t-)ZrO2-type solid solution decrease with an increase in Ni2+ ions up to not, vert, similar5 mol%. Further increase in the nickel content has no influence on the lattice parameters, but leads to an increased stability of metastable t-ZrO2-type products. The obtained results indicate the presence of very strong surface interactions between nickel oxide and zirconia.

ZrO2-NiO; XRD; Raman spectroscopy; FE-SEM; FT-IR spectroscopy; DTA

Molecular Spectroscopy and Molecular Structure 2006 - A Collection of Papers Presented at the XXVIIIth European Congress on Molecular Spectroscopy, Istanbul, Turkey - September 3&#8211 ; 8, 2006