engleski

XRD and laser Raman spectroscopy investigation of the stability of low temperature t-ZrO2

The influence of the precipitation pH and the presence of Na+ impurities on the stability of metastable t-ZrO2 were investigated. Zirconia samples with high content of t-ZrO2 phase were crystallized from zirconium hydroxide precipitated at pH 13, 7 and 2.5. The obtained samples were subjected to the influence of temperature, pressure and g-irradiation. The influence of these treatments on the metastable t-ZrO2 were investigated using XRD and laser Raman spectroscopy. The results of phase analysis showed that the change in the pH of zirconium hydroxide precipitation significantly changed the sensitivity of the metastable t-ZrO2 to temperature and pressure. The metastable t-ZrO2 was the most stable in the sample obtained from zirconium hydroxide precipitated at pH 2.5 and the most unstable in the sample obtained from zirconium hydroxide precipitated at pH 7. The presence of Na+ impurities decreased the stability of metastable t-ZrO2. All the samples were shown to be stable under high g-irradiation. The capability of laser Raman spectroscopy for the quantitative analysis was examined by comparing the values of the m-ZrO2 volume fraction (nm) obtained by this technique with corresponding values obtained by XRD. It was concluded that the relation proposed by Clarke and Adar, J. Am. Ceram. Soc. 65 (1982) 284., was correct but the reliability of the nm values estimated by the laser Raman spectroscopy was not high, especially in the region of 0.15 < nm < 0.70. The reason for the low reliability in this region was discussed.

nije evidentirano

nije evidentirano