Massive Transformation in the Y2O3‐Bi2O3 System

Kuan Zong Fung, Anil V. Virkar, David L. Drobeck

研究成果: Article同行評審

15 引文 斯高帕斯(Scopus)

摘要

Cubic solid solutions in the Y2O3‐Bi2O3 system with ∼25% Y2O3 undergo a transformation to a rhombohedral phase when annealed at temperatures ≤ 700°C. This transformation is composition‐invariant and is thermally activated, and the product phase can propagate across matrix grain boundaries, indicating that there is no special crystallo‐graphic orientation relationship between the product and the parent phases. Based on these observations, it is proposed that cubic → rhombohedral phase transformation in the Y2O3‐Bi2O3 system is a massive transformation. Samples of composition 25% Y2O3‐75% Bi2O3 with and without aliovalent dopants were annealed at temperatures ≤ 700°C for up to 10000 h. ZrO2 as a dopant suppressed while CaO and SrO as dopants enhanced the kinetics of phase transformation. The rate of cubic/rhombohedra1 interface migration (growth rate or interface velocity) was also similarly affected by the additions of dopants; ZrO2 suppressed while CaO enhanced the growth rate. Diffusion studies further showed that ZrO2 suppressed while CaO enhanced cation interdiffusion coefficient. These observations are rationalized on the premise that cation interstitials are more mobile compared to cation vacancies in cubic bismuth oxide. The maximum growth rate measured was ∼10−10 m/s, which is orders of magnitude smaller than typical growth rates measured in metallic alloys. This difference is explained in terms of substantially lower diffusion coefficients in these oxide systems compared to metallic alloys.

原文English
頁(從 - 到)1638-1648
頁數11
期刊Journal of the American Ceramic Society
77
發行號6
DOIs
出版狀態Published - 1994 六月

All Science Journal Classification (ASJC) codes

  • 陶瓷和複合材料
  • 材料化學

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