Formation of small metallic precipitates of niobium in. alpha. -Al sub 2 O sub 3 implanted with Nb ions

Conference · Tue Jan 01 04:00:00 EST 1991

OSTI ID:5470521

Romana, L; Thevenard, P; Ramos, S; Canut, B; Gea, L ^[1]; Brunel, M ^[2]; Horton, L L ^[3]; McHargue, C J ^[4]

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1. Lyon-1 Univ., 69 - Villeurbanne (France). Dept. de Physique des Materiaux
2. Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France). Lab. de Cristallographie
3. Oak Ridge National Lab., TN (United States)
4. Tennessee Univ., Knoxville, TN (United States)

Niobium implantations have been performed in {alpha}-Al{sub 2}O{sub 3} single crystals to study the chemical interactions between the implanted species and the oxide and to study the microstructural evolution of the implanted layer. The investigation focused on both as-implanted specimens and specimens that underwent post-implantation anneals in a reducing atmosphere. Ion implantations were performed at 300 K with 150 keV particle energies and fluences ranging from 10{sup 16} to 2 {times} 19{sup 17} ions-cm{sup {minus} 2}. Rutherford backscattering spectroscopy (RBS) and X-ray photoemission spectroscopy (XPS) allowed the characterization of the implanted profiles and determination of the chemical state of the implanted ions. X-ray diffraction at glancing incidence and RBS analysis in a channeling geometry were performed to follow the microstructural evolution of the implanted layer. The oxidation state of niobium and the microstructure of the implanted layer were dependent on the atomic concentration of niobium in {alpha}-Al{sub 2}O{sub 3}. An amorphous phase was observed after a threshold fluence of 5 {times} 10{sup 16} ions-cm{sup {minus}2}. The amorphous phase contained small metallic precipitates of niobium with a mean diameter of 1 nm. The physical properties of such niobium clusters embedded in an amorphous oxide layer were studied in detail. Electrical conductivity measurements showed that a hopping process between the metallic precipitates was the likely mechanism operating for this system. 18 refs., 5 figs.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5470521
• Report Number(s): CONF-910707-1; ON: DE91015928
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
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Cermets
& Refractories-- Structure & Phase Studies
360206* -- Ceramics
Cermets
& Refractories-- Radiation Effects
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75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
AMORPHOUS STATE
CHALCOGENIDES
COHERENT SCATTERING
CRYSTAL STRUCTURE
CRYSTALS
DIFFRACTION
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
ION IMPLANTATION
METALS
MICROSTRUCTURE
NIOBIUM
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PHYSICAL RADIATION EFFECTS
PRECIPITATION
RADIATION EFFECTS
SCATTERING
SEPARATION PROCESSES
SPECTROSCOPY
TRANSITION ELEMENTS
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY