Effect of segregation on particle size stability and SPS sintering of Li2O-Doped magnesium aluminate spinel

Magnesium aluminate spinel (MAS) was prepared using the simultaneous precipitation method by varying the concentration of Li2O from 0 to 5 mol%. No residual chlorine from the LiCl precursor was detected in the final powders while Li achieved the target concentration in all samples and contributed to...

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Bibliographic Details
Published in:Journal of the European Ceramic Society 2019-08, Vol.39 (10), p.3213-3220
Main Authors: Caliman, L.B., Muche, D., Silva, A., Ospina R., C.A., Machado, I.F., Castro, R.H.R., Gouvêa, D.
Format: Article
Language:English
Subjects:
Interfaces
Magnesium aluminate spinel
Segregation
Sintering
Spark plasma sintering
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Summary:Magnesium aluminate spinel (MAS) was prepared using the simultaneous precipitation method by varying the concentration of Li2O from 0 to 5 mol%. No residual chlorine from the LiCl precursor was detected in the final powders while Li achieved the target concentration in all samples and contributed to stabilizing nanoparticles smaller than 10 nm. Li segregation to both interfaces (surfaces and grain boundaries) occurred and tended to be more pronounced at the grain boundaries stabilizing this type of interface during processing rather than surfaces. Spark plasma sintering (SPS) was used to consolidate the nanopowders into fully dense nanostructured pellets. The increase in Li content facilitated the sintering process and pore elimination occurred at 850–900 °C, a much lower temperature range as compared to conventional sintering (1650 °C). Samples containing 5 mol% Li sintered at 850 °C exhibited a medium grain size of ˜25 nm, microhardness of ˜24 GPa and ˜50% in-line optical transmission at the 800 nm.
ISSN:0955-2219
1873-619X
DOI:10.1016/j.jeurceramsoc.2019.04.017