Surface Concentration of Defects at Grain Boundaries in Sintered Alumina Determined by Positron Annihilation Lifetime Spectroscopy |
| J. Kansya, A. Si Ahmedb, J. Liebaultb,c and G. Moyab aInstitute of Physics and Chemistry of Metals, Silesian University, Bankowa 12, 40-007 Katowice, Poland bLaboratoire Materiaux et Microelectronique de Provence (U.M.R./CNRS n° 6137), Faculte des Sciences de St. Jerome Case 222, 13397 Marseille Cedex 20, France cEcole Nationale Superieure des Mines de Saint-Etienne Departement Ceramiques Speciales, 42023 Saint-Etienne Cedex 2, France |
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| Sintered alumina samples of grain diameters spanning from 1.2 to 4.5μm have been investigated by positron annihilation lifetime spectroscopy. One series of samples was produced from material containing about 150 ppm impurities (mainly SiO2). The second one was made from material having about 2700 ppm of various elements (SiO2, MgO, CaO). Two models of positron trapping at grain boundaries are compared: The first one relates to the diffusion-limited regime; and the other one -- to the transition-limited regime of trapping. As a result the relative change of surface concentration of defects at grain boundaries is determined. Additionally, the positron diffusion constant in bulk alumina at room temperature, D+=0.36±10 cm2/s, is estimated. |
| DOI: 10.12693/APhysPolA.100.737 PACS numbers: 78.70.Bj, 77.84.Bw, 61.72.Mm |