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Journal of Materials Science

, Volume 46, Issue 23, pp 7377–7383 | Cite as

An experimental refinement of solid–solution relationship in Ca-α-Sialon ceramics by analytical electron microscopy

  • Bo Zhu
  • Hui Gu
  • Pei-ling Wang
Article

Abstract

Local dopant compositions within individual α-Sialon grains were measured by analytical electron microscopy (AEM) in hot-pressed Ca x Si12−3x Al3x O x N16−x (x = 0.3–1.4) ceramics. The reduction of local x values from the nominal dopant compositions is about 40% in general, and it reaches 60% for the end member (x = 1.4) which contains inclusions of AlN-based 21R phase. This results exhibit stronger departures from x than the previous report of 30% dopants missing in α-Sialon phase by electron probe micro-analysis (EPMA) [J Eur Ceram Soc 19:1637, 1999]. Amorphous films of ~1 nm thick were commonly found at grain boundaries (GBs), which could only take a small fraction of undetected dopants while the film composition exhibits a quite different behavior. The general presence of GB films can rationalize the discrepancy between AEM and EPMA results by their differences in probe size and detection geometry, while the much larger gap in the end member suggests the existence of Ca-rich glasses in the intergranular regions. By excluding this end member, a linear relation between dopant solution and lattice expansion is restored in α-Sialon structure, which leads to 20 and 80% increases of the expansion coefficients from those given in the previous and original reports, respectively. This study not only demonstrated the necessity of solubility study in ceramics by AEM refinement, but also opens a new front to correlate the solution behavior with the intergranular glass/amorphous structures, both were regarded so far as largely independent.

Keywords

Grain Boundary Analytical Electron Microscopy Solution Level Dopant Solution Thin Transmission Electron Microscopy Foil 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgements

This study is financially supported by the Natural Science Foundation Committee (Grant No. 50525205). The authors would like to thank Dr. Chen Zhang for materials processing, Ms. Ying-Xin Jia for powder XRD analysis, and Dr. Peng-Xiang Qian for assistance in the preparation of figures.

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Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  1. 1.State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of CeramicsChinese Academy of SciencesShanghaiChina
  2. 2.Jinma CorpDalianChina

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