Reduced grain boundary energies in rare-earth doped MgAl2O4 spinel and consequent grain growth inhibition. Issue 13 (October 2017)

• Record Type: Journal Article
• Authors: Hasan, Md M.; Dholabhai, Pratik P.; Dey, Sanchita; Uberuaga, Blas P.; Castro, Ricardo H.R.
• Is Part Of: Journal of the European Ceramic Society. Volume 37:Issue 13(2017)
• Page Start: 4043
• Page End: 4050
• Publication Date: 2017-10
• Subjects: Nanocrystals -- Thermodynamics -- Grain boundary energy -- Oxide; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2017.04.073
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: Grain growth inhibition in MgAl2 O4 spinel nanostructure was achieved by grain boundary (GB) segregation of rare-earth dopants. Microcalorimetric measurements showed that dense spinel compacts doped with 3 mol% of R2 O3 (R = Y, Gd, and La) had decreased GB energies as compared to the undoped spinel, representing reduction in the driving force for grain growth. Segregation energies of the three dopants to the Σ3 (111) GB were calculated by atomistic simulation. The dopants with higher ionic radius tend to segregate more strongly to GBs. The GB energies were calculated from atomistic simulation and, consistent with experiments, a systematic reduction in GB energy with dopant ionic size was found. High temperature grain growth experiments revealed a significant reduction of grain growth in the doped nanostructures as compared to the undoped one, which was attributed to increased metastability or possibly also a GB dragging originated from the dopant segregation.