紫外拉曼光谱研究钇掺杂的氧化锆体系表面相变

本文用紫外拉曼 ,近可见拉曼光谱和XRD检测了不同焙烧温度下Y2 O3-ZrO2 的相变过程。紫外拉曼光谱对样品表面相变极其灵敏 ,而近可见拉曼光谱和XRD提供的主要是体相和表面的混合信息。在紫外拉曼谱图中 ,只观察到单斜相的谱峰 ,没有明显的四方晶相的信号 ,这表明样品的表面主要是单斜晶相。然而 ,XRD和近可见拉曼光谱的结果显示Y2 O3-ZrO2 体相是四方晶相。焙烧温度超过 40 0°时 ,紫外拉曼 ,近可见拉曼和XRD晶之间明显不同的结果表明Y2 O3-ZrO2 在表面区四方相很易转变为单斜相 ,体相中的四方相由于钇的添加而稳定存在。根据紫外拉曼和XRD结果 ,当升高温度时 ,在样品的表面形成一单斜相层 ,体相钇稳定的四方相 ,且由于Y2 O3的存在抑制了单斜相进一步向体相发展。

Phase Transformation in the Surface Region of Y - ZrO2 Detected by UV Raman Spectroscopy

The changes of Y 2O 3-ZrO 2 (rttrium doped ZrO 2) from its tetragonal to monoclinic phase are characterized by UV Raman spectroscopy, near-visible Raman spectroscopy and XRD UV Raman spectroscopy is particularly sensitive to the surface region of Y 2O 3-ZrO 2 because the sample absorbs UV light From UV Raman spectra, only information of monoclinic phase is detected This sufficiently corroborates that the surface region of the sample is mainly in monoclinic phase However, from the XRD patterns and near-visible Raman spectra, the bulk of the sample is in tetragonal phase This substantiates that the phase transformation from tetragonal to monoclinic starts from the surface region It turns out that the tetragonal phase of Y 2O 3-ZrO 2 at surface region is easily converted into the monoclinic phase when the calcination temperature is above 400℃ However, the tetragonal phase of the bulk of Y 2O 3-ZrO 2 is relatively stable compared with ZrO 2 Based on the UV Raman spectra and XRD patterns, it is suggested that a thin layer of monoclinic phase is formed in the surface region of a particle and the monoclinic shell doesn't extend into the bulk owing to the presence of yttrium oxide