Radiation‐induced conductivity in quartz crystals

AbstractA study is made of irradiation effects on α-quartz crystals using the techniques of electrical conductivity and dielectric loss measurements. The initial radiation-induced conductivity (RIC) induced by X-ray irradiation over the temperature range from 94 to 250 K is found to have a nearly constant activation energy of 0.29 ± 0.02 eV. Since a large RIC still results from irradiation at temperatures too low for alkalis to be liberated, it is proposed that the RIC is due to holes (as small polarons) rather than to alkalis. The dielectric loss measurements in Na-swept quartz are used to follow the changes in the relaxation peaks due to the Al-Na defect as a function of radiation dose and annealing. At the same time a low-temperature “irradiation peak” is studied. Restoration of the main Al-Na peak during annealing occurs in two stages: one near 500 K and the other above 600 K. From the observed behavior of the irradiation peak in various crystals, it is concluded that this peak is probably due to alkali centers. Finally, a defect model interpreting the two annealing stages is presented.

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Radiation-Induced Precipitation at Thin Foil Surfaces in Ni-Be Alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100055217 ◽

1982 ◽

Vol 40 ◽

pp. 598-599

Author(s):

T. Mukai ◽

T. E. Mitchell

Keyword(s):

Electron Microscopy ◽

High Voltage ◽

Electron Irradiation ◽

High Vacuum ◽

Thin Foil ◽

Homogeneous Precipitation ◽

High Voltage Electron Microscopy ◽

Voltage Electron ◽

High Voltage Electron ◽

Radiation Induced

Radiation-induced homogeneous precipitation in Ni-Be alloys was recently observed by high voltage electron microscopy. A coupling of interstitial flux with solute Be atoms is responsible for the precipitation. The present investigation further shows that precipitation is also induced at thin foil surfaces by electron irradiation under a high vacuum.

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Annealing Of Radiation Damage in Tungsten

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069053 ◽

1970 ◽

Vol 28 ◽

pp. 412-413

Author(s):

Robert C. Rau ◽

John Moteff

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Radiation Damage ◽

Thermal Annealing ◽

Neutron Fluence ◽

Dislocation Loops ◽

Defect Clusters ◽

Polycrystalline Tungsten ◽

Transmission Electron ◽

Radiation Induced

Transmission electron microscopy has been used to study the thermal annealing of radiation induced defect clusters in polycrystalline tungsten. Specimens were taken from cylindrical tensile bars which had been irradiated to a fast (E > 1 MeV) neutron fluence of 4.2 × 1019 n/cm2 at 70°C, annealed for one hour at various temperatures in argon, and tensile tested at 240°C in helium. Foils from both the unstressed button heads and the reduced areas near the fracture were examined.Figure 1 shows typical microstructures in button head foils. In the unannealed condition, Fig. 1(a), a dispersion of fine dot clusters was present. Annealing at 435°C, Fig. 1(b), produced an apparent slight decrease in cluster concentration, but annealing at 740°C, Fig. 1(C), resulted in a noticeable densification of the clusters. Finally, annealing at 900°C and 1040°C, Figs. 1(d) and (e), caused a definite decrease in cluster concentration and led to the formation of resolvable dislocation loops.

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