X-ray, Raman and FTIRS studies of the microstructural evolution of zirconia particles caused by the thermal treatment |
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Authors: | Dmitry A Zyuzin Svetlana V Cherepanova Elena B Burgina Victor G Kostrovskii |
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Institution: | a Boreskov Institute of Catalysis SB RAS, pr. Akademika Lavrentieva 5, 630090 Novosibirsk, Russia b Institute of Solid State Chemistry SB RAS, 630090 Novosibirsk, Russia c Semenov Institite of Chemical Physics RAS, Moscow, Russia |
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Abstract: | Genesis of the structure of zirconia particles prepared by precipitation of amorphous hydrated zirconia by ammonia from the ZrO(NO3)2 solution followed by a mild hydrothermal treatment (HTT) of precipitate, washing and calcination under air up to 1000 °C has been studied by X-ray diffraction (XRD), Raman and FTIRS. As revealed by FTIRS of lattice modes, the local structure of amorphous zirconia subjected to HTT is close to that in m-ZrO2. This helps to obtain nearly single-phase monoclinic nanozirconia (particle size 5-15 nm) already after a mild calcination at 500 °C. Stability of this phase with nanoparticles sizes below the critical value determined by thermodynamic constraints is due to its excessive hydroxylation demonstrated by FTIRS. Dehydroxilation and sintering of these nanoparticles at higher (600-650 °C) temperatures of calcination leads to reappearance of the (111) “cubic” reflection in XRD patterns. Modeling of XRD patterns revealed that this phenomenon could be explained by polysynthetic (001) twinning earlier observed by HRTEM. |
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Keywords: | Monoclinic zirconia Hydrothermal treatment Polysynthetic twinning Whole XRD pattern modeling |
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