Articles
All articles | Recent articles
Influences of Cation Disorder in Commercial Spinel Powders Studied by 27Al MAS NMR on the Sintering of Transparent MgAl2O4 Ceramics
A. Krell1, E. Brendler2
1 Fraunhofer-Institut für Keramische Systeme und Technologien (IKTS, Fraunhofer Institute for Ceramic Systems and Technologies), 01277 Dresden, Germany
2 TU Bergakademie Freiberg (Freiberg University of Mining and Technology), Faculty of Chemistry and Physics, 09599 Freiberg, Germany
received August 16, 2012, received in revised form September 21, 2012, accepted October 14, 2012
Vol. 4, No. 2, Pages 51-58 DOI: 10.4416/JCST2012-00029
Abstract
At the Stockholm Conference of the European Ceramic Society 2011 it was shown that, together with the particle size of raw powders and the homogeneity of particle coordination in the green bodies, the real structure of the lattices is a third major influence on sintering, which may differ significantly even at fixed stoichiometry. Antisite defects govern the whole defect chemistry of MgAl2O4 and should, therefore, affect diffusion and sintering. This possibility is investigated here with solid state 27Al MAS nuclear magnetic resonance measurements of the occupancy of octahedral and tetrahedral sites. Based on previous results with model powders synthesized in order to identify lattice effects at constant particle size distribution, homogeneity and composition, the study has now been extended to commercial spinel powders supplied by Asian, European, and American manufacturers. The results confirm a correlation of increasing cation disorder with improved sintering densification.
Download Full Article (PDF)
Keywords
Spinel (MgAl2O4), transparency, sintering, antisite defects, 27Al NMR
References
1 Krell, A., Blank, P.: The influence of shaping method on the grain size dependence of strength in dense submicrometre alumina, J. Eur. Ceram. Soc., 16, 1199 – 1200, (1996).
2 Krell, A., Klimke, J., Hutzler, T.: Advanced spinel and sub-μm Al2O3 for transparent armour applications, J. Eur. Ceram. Soc., 29, 275 – 281, (2009).
3 Krell, A., Klimke, J.: Effect of the homogeneity of particle coordination on solid state sintering of transparent alumina, J. Am. Ceram. Soc., 89, 1985 – 1992, (2006).
4 Krell, A., Hutzler, T., Klimke, J.: Transmission physics and consequences for materials selection, manufacturing, and applications, J. Eur. Ceram. Soc., 29, 207 – 21, (2009).
5 Ball, J.A., Murphy, S.T., Grimes, R.W., Baconrisen, R.W., Smith, R., Uberuaga, B.P., Sickafus, K.E.: Defect processes in MgAl2O4 spinel, Solid State Sci., 6, 717 – 724, (2008).
6 Schmocker, U., Waldner, F.: The inversion parameter with respect to the space group of MgAI2O4 spinels, J. Phys. C: Solid State, 9, L235 – L237, (1976).
7 Fischer, P.: Neutron diffraction of MgAl2O4 and ZnAl2O4 spinel structures depending on their thermal history (in German), Z. Kristallog., 124, 275 – 302, (1967).
8 Krell, A., Hutzler, T., Klimke, J., Potthoff, A.: Fine-grained transparent spinel windows by the processing of different nanopowders, J. Am. Ceram. Soc., 93, 2626 – 2666, (2010).
9 Krell, A., Waetzig, K., Klimke, J.: Influence of the structure of MgO·nAl2O3 spinel lattices on transparent ceramics processing and properties, J. Eur. Ceram. Soc., 29, 2887 – 2898, (2012).
10 Bratton, R.J.: Initial sintering kinetics of MgAl2O4, J. Am. Ceram. Soc., 52, 417 – 419, (1969).
11 Apetz, R., Van Bruggen, M.P.B.: Transparent alumina: a light scattering model, J. Am. Ceram. Soc., 86, 480 – 486, (2003).
12 Yamamoto, H., Mitsuoko, T., Iio, S.: Translucent polycrystalline ceramic and method for making same, Europ. Patent Application EP - 1 053 983, (2000).
13 Brun, E., Hafner, S.: The electric quadrupole splitting of Al27 in spinel MgAl2O4 and corundum Al2O3: I. Paramagnetic nuclear resonance of Al27 and cation distribution in spinel (in German), Z. Kristallog., 117, 37 – 62, (1962).
14 Behrens, H.-J., Schnabel, B.: The second order influence of the nuclear quadrupole interaction on the central line in the NMR of quadrupolar nuclei using rapid sample spinning, Physica 114B, 185 – 190, (1982).
15 Maekawa, H., Kato, S., Kawamura, K., Yokokawa, T.: Cation mixing in natural MgAl2O4 spinel: A high-temperature 27Al NMR study, Am. Mineral., 82, 1125 – 1132, (1997).
16 Krell, A., Blank, P., Ma, H., Van Bruggen, M., Apetz, R.: Transparent sintered corundum with high hardness and strength, J. Am. Ceram. Soc., 86, 12 – 18, (2003).
17 Šepelák, V., Indris, S., Heitjans, P., Becker, K.D.: Direct determination of the cation disorder in nanoscale spinels by NMR, XPS, and Mössbauer spectroscopy, J. Alloy. Compd., 434/435, 776 – 778, (2007).
18 Rasmussen, M.K., Foster, A.S., Hinnemann, B., Canova, F.F., Helveg, S., Meinander, K., Martin, N.M., Knudsen, J., Vlad, A., Lundgren, E., Stierle, A., Besenbacher, F, Lauritsen, J.V.: Stable cation inversion at the MgAl2O4 (100) surface, Phys. Rev. Lett., 107, 036102/1 – 4, (2011).
Copyright
Göller Verlag GmbH
