Silica and Magnesia Dopant Distributions in Alumina by High-Resolution Scanning Secondary Ion Mass Spectrometry

• Published in: Journal of the American Ceramic Society Vol. 82; no. 4; pp. 1001 - 1008
• Main Authors: Gavrilov, Konstantin L., Bennison, Stephen J., Mikeska, Kurt R., Chabala, Jan M., Levi-Setti, Riccardo
• Format: Journal Article
• Language: English
• Published: Westerville, Ohio American Ceramics Society 01.04.1999; Blackwell
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; Exact sciences and technology; Miscellaneous; Technical ceramics; Additive; Sintering; Distribution; Silicon Oxides; Secondary ion mass spectrometry; Manufacturing; Experimental study; Alumina; Magnesium Oxides; Oxide ceramics
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1151-2916.1999.tb01866.x

Trace SiO2 and MgO additive distributions in sintered alumina have been studied using high‐resolution scanning secondary ion mass spectrometry (SIMS). When doped with each additive individually, evidence is seen for both strong silicon segregation to grain boundaries (Cgb/Cgrain similar/congruent 300) in SiO2‐doped alumina and strong magnesium segregation to grain boundaries (Cgb/Cgrain similar/congruent 400) in MgO‐doped alumina. When codoped with both SiO2and MgO, segregation of both ions to grain boundaries is reduced by a factor of 5 or more over single doping. The additive concentrations increase proportionally in the grains, and both dopants become more uniformly distributed throughout the bulk. It is concluded that codoping with these additives increases their mutual bulk solid solubility and decreases their interfacial segregation over single doping. The beneficial effect of MgO additions in controlling microstructure development in alumina and improving corrosion resistance to aqueous HF stems from its ability to redistribute silicon ions from grain boundaries into the bulk.