Raman Scattering Study of the Crystallization and Phase Transformations of ZrO₂

Abstract

X-ray diffraction, electron diffraction, and Raman scattering measurements are presented far dehydrated amorphous ZrO,.Although the material lacks sufficient crystallinity to diffract X rays, electron diffraction patterns indicate a microcrystallinity with a grain size of 15 to 30 A. Raman spectra characteristic of the metastable tetragonal polymorph were obtained from these materials. Heating the amorphous materials induces recrystallization into first a metastable tetragonal phase and then the stable monoclinic phase.

Total Oxidation of Naphthalene with Zirconia-Supported Cobalt, Copper and Nickel Catalysts

“…Raman spectroscopy was used to determine the structure of the added species and of the zirconia support [43], both in amorphous and crystalline form, as well as the structure adopted by the metal-O species, either supported or interacting. In fact, this spectroscopic technique is highly sensitive to oxygen displacement, owing to its high polarizability and to intermediate range order without long-range periodicity [44].…”

“…Raman spectroscopy was used to determine the structure of the added species and of the zirconia support [43], both in amorphous and crystalline form, as well as the structure adopted by the metal-O species, either supported or interacting. In fact, this spectroscopic technique is highly sensitive to oxygen displacement, owing to its high polarizability and to intermediate range order For Co 3 O 4 spinel structure (Co 2+ located at the tetrahedral site (Td) and Co 3+ at the octahedral one (Oh)), Raman peaks are predicted to appear at 194 cm -1 (F2g), 485 cm -1 (Eg), 523 cm -1 (F2g), 620 cm -1 (F2g, Td site), and at 693 cm -1 (A1g; Oh site) [45].…”

Unusual calcination temperature dependent tetragonal–monoclinic transitions in rare earth-doped zirconia nanocrystals

“…33 As is well known, Raman spectroscopy is an effective method for analysing the crystal structure of fine particles, and many studies have focused on the Raman scattering of crystalline zirconia. [34][35][36][37] Generally speaking, Raman scattering comes from both the surface and the bulk of a solid sample. FT Raman spectroscopy is often used to analyse fine structures mainly in the bulk region of the samples by eliminating the fluorescence disturbances; 38 whereas UV Raman spectroscopy is more sensitive to the surface region of zirconia because of the strong absorbance in the UV region.…”

Design, Synthesis, and Mechanistic Evaluation of Iron-Based Catalysis for Synthesis Gas Conversion to Fuels and Chemicals

“…Also the intensities of silanol groups decreased with increasing Zr density on ZrO 2 /SiO 2 surfaces (Table 1). Figure 4.2 shows that the Raman spectra of ZrO 2 /SiO 2 samples contains a sharp band at 477 cm -1 , attributed to three-dimensional amorphous zirconia [37][38][39][40]. These results show that these impregnation methods can terminate some of the hydroxyl groups on the SiO 2 surface and that they give a high dispersion of ZrO 2 for samples up to 20 wt.% ZrO 2 loading, for which ZrO 2 crystallites are not detected in their Raman spectra.…”