The Effect of Lithium Doping on the Sintering and Grain Growth of SPS-Processed, Non-Stoichiometric Magnesium Aluminate Spinel

Yuval Mordekovitz; Lee Shelly; Mahdi Halabi; Sergey Kalabukhov; Shmuel Hayun

doi:10.3390/ma9060481

The Effect of Lithium Doping on the Sintering and Grain Growth of SPS-Processed, Non-Stoichiometric Magnesium Aluminate Spinel

Materials (Basel). 2016 Jun 16;9(6):481. doi: 10.3390/ma9060481.

Authors

Yuval Mordekovitz¹, Lee Shelly², Mahdi Halabi³, Sergey Kalabukhov⁴, Shmuel Hayun⁵

Affiliations

¹ Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 8410501, Israel. yuvalmor@post.bgu.ac.il.
² Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 8410501, Israel. leeshel@post.bgu.ac.il.
³ Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 8410501, Israel. mahdi@post.bgu.ac.il.
⁴ Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 8410501, Israel. kalabukh@bgu.ac.il.
⁵ Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 8410501, Israel. hayuns@bgu.ac.il.

Abstract

The effects of lithium doping on the sintering and grain growth of non-stoichiometric nano-sized magnesium aluminate spinel were studied using a spark plasma sintering (SPS) apparatus. Li-doped nano-MgO·nAl₂O₃ spinel (n = 1.06 and 1.21) powders containing 0, 0.20, 0.50 or 1.00 at. % Li were synthesized by the solution combustion method and dense specimens were processed using a SPS apparatus at 1200 °C and under an applied pressure of 150 MPa. The SPS-processed samples showed mutual dependency on the lithium concentration and the alumina-to-magnesia ratio. For example, the density and hardness values of near-stoichiometry samples (n = 1.06) showed an incline up to 0.51 at. % Li, while in the alumina rich samples (n = 1.21), these values remained constant up to 0.53 at. % Li. Studying grain growth revealed that in the Li-MgO·nAl₂O₃ system, grain growth is limited by Zener pining. The activation energies of undoped, 0.2 and 0.53 at. % Li-MgO·1.21Al₂O₃ samples were 288 ± 40, 670 ± 45 and 543 ± 40 kJ·mol^-1, respectively.

Keywords: SPS; grain growth; lithium; magnesium aluminate spinel; precipitation.