Study of discharge after electron irradiation in sapphires and polycrystalline alumina

Journal Article · Mon Nov 15 00:00:00 EST 2010 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3504856· OSTI ID:21476610

Zarbout, K ^[1]; Moya, G; Ahmed, A Si ^[1]; Damamme, G ^[2]; Kallel, A ^[3]

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1. IM2NP, UMR CNRS 6242, Aix-Marseille Universite, 13397 Marseille Cedex 20 (France)
2. CEA Ile-de-France, BP. 12, 91680 Bruyeres-le-Chatel (France)
3. Laboratoire des Materiaux Ceramiques, Composites et Polymeres, Faculte des Sciences de Sfax, Universite de Sfax, BP 1171, 3000 Sfax (Tunisia)

The fraction R of charges undergoing discharge during the time separating two electron pulses is derived from the induced current method developed in a scanning electron microscope. Irradiation is performed via a 10 keV defocused electron beam and low current density. The evolution of R with temperature (in the range 300-663 K) obeys to an Arrhenius type relation. Activation energies connected with the processes involved are deduced. In sapphire, no discernible discharge is observed due to the dominance of deep traps. In silver doped sapphire, R increases sharply from 10% to 70% as the temperature rises from 360 to 420 K, with a corresponding activation energy of 0.51 eV. In contrast, in polycrystalline alumina processed by solid state sintering (grain diameters of 1.7, 2.7, and 4.5 {mu}m) the degree of discharge increases continuously with temperature and grain size. The enhancement with grain size indicates that the sintering conditions influence strongly the efficiency of a gettering effect. The activation energy below 573 K is about 0.12 eV independently of grain size. Above 573 K, a second activation energy of 0.26 eV appears for the smallest grain size sample. The results suggest that discharge may stem from a density of trapping states, associated to grain boundaries in sintered samples, rather than from a single trapping level linked to the doping element as Ag in sapphire.

• OSTI ID: 21476610
• Journal Information: Journal of Applied Physics, Vol. 108, Issue 9; Other Information: DOI: 10.1063/1.3504856; (c) 2010 American Institute of Physics; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM OXIDES
CURRENT DENSITY
DOPED MATERIALS
ELECTRIC DISCHARGES
ELECTRON BEAMS
EV RANGE
GRAIN BOUNDARIES
GRAIN SIZE
HEAT TREATMENTS
IRRADIATION
KEV RANGE
POLYCRYSTALS
SAPPHIRE
SCANNING ELECTRON MICROSCOPY
SILVER
SINTERING
SOLIDS
TEMPERATURE DEPENDENCE
TRAPS
ALUMINIUM COMPOUNDS
BEAMS
CHALCOGENIDES
CORUNDUM
CRYSTALS
ELECTRON MICROSCOPY
ELEMENTS
ENERGY RANGE
FABRICATION
LEPTON BEAMS
MATERIALS
METALS
MICROSCOPY
MICROSTRUCTURE
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PARTICLE BEAMS
SIZE
TRANSITION ELEMENTS