UV Raman spectroscopic study on the surface phase of ZrO2 modified with Nd2O3 |
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Authors: | Jing Zhang Song YanMengqiong Yuan Xiang WangCan Li |
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Affiliation: | a School of Chemistry and Materials Science, Liaoning Shihua University, Fushun, Liaoning 113001, Chinab State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, China |
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Abstract: | The Nd2O3 modified ZrO2 was synthesized using two methods of co-precipitation (Nd-ZrO2) and wet impregnation (Nd/ZrO2). The surface and bulk crystalline phases of Nd2O3 modified ZrO2 were investigated by using UV Raman spectroscopy, visible Raman spectroscopy, and X-ray diffraction (XRD). It is observed that the tetragonal phase in the surface region of Nd-ZrO2 was not effectively stabilized by Nd2O3, as Nd2O3 is mainly present in the bulk of Nd-ZrO2. However, in Nd/ZrO2, it is found that with the impregnation of 0.5 mol% Nd2O3 on ZrO2, the surface tetragonal phase of Nd/ZrO2 can be stabilized even after calcination at 700 °C. The UV Raman results indicate that a disordered structure, or intermediate structure, which is involved in the transition from the tetragonal to the cubic phase, is formed at the surface region of Nd/ZrO2. The formation of the aforementioned intermediate structure inhibits the phase transition from tetragonal to monoclinic in the surface region of Nd/ZrO2. Furthermore, it is observed that the mixed tetragonal and monoclinic phases in the surface region of ZrO2 which has been impregnated with Nd2O3 can also be stabilized after calcination at 700 °C. This work provides a simple method for controlling the surface phase of ZrO2 at high temperatures. |
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Keywords: | ZrO2 Surfaces UV Raman spectroscopy XRD Nd2O3 Characterization methods |
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