摘要:

Dr. F. Reynaud studied metallurgy at the School of Mines in Saint-Etienne (1962–1965). He joined the Laboratoire d'Optique Electronique du C.N.R.S. in Toulouse (France) first as a graduate engineer (1965), then as a scientist (1973). He received the Jules Garnier prize (1974) awarded by the French Society of Metallurgy and spent a sabbatical year (1975) in the Max-Planck-Institut für Metallforschung (Institut für Werkstoffwissenschaften) in Stuttgart (F.R.G.).

ISSN:0033-7579    

DOI:10.1080/00337578608207492

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Changes of electrical resistivitypand critical temperature Tcwere measured in the A-15 compound V3Si irradiated at low temperature (T⋍ 21 K) by electrons of energyE. An energy range (0.20 MeV < E < 0.35 MeV) is observed where the resistivity increases, whereas the critical temperature remains constant. This result can be interpreted within the framework of the linear chain model of Labbé-Friedel as the sign that the atoms Si start to be displaced atE=0.20 MeV leading to an increase in resistivity, the critical temperature being only affected when the atoms V are displaced atE=0.35 MeV. Comparison of experimental values of damage rates determined either bypor byTcwith calculated theoretical cross sections of V and Si in V3Si add some support to this interpretation. Displacement threshold energies were deduced from this analysis to be equal to (25±1) eV for Si and to (25±1) eV for V. Specific Frenkel pair resistivities were estimated asPFPSi=(4.2±0.5 μΩ.cm/at.% andPFPV=(27±3) μΏ.cm/at. % and decrease of critical temperature percent of vanadium vacancies was estimated as (2.5±0.2) K/% of displaced V atoms.

ISSN:0033-7579    

DOI:10.1080/00337578608207493

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Thermal decomposition ofγ-treated (0.1–0.5 MGy) ammonium permanganate was studied by IR spectroscopy over the temperature range 25–200°C. Decomposition is shown by a decrease in the MnO4- and NH4+peak intensities. NO3formation was observed only in the preirradiated samples and has been attributed to the oxidation of NH3to HNO3via HNO radicals. The samples attained additional stability towards gamma radiation when exposed in the pelletized state.

ISSN:0033-7579    

DOI:10.1080/00337578608207494

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

In this paper we study the activation energy for TLD-CaSO4:Dy which was fabricated by the Institute of Nuclear Energy Research. Two different methods have been used to determine the activation energy. The methods used were (1) the glow curve shape analysis method which contain four different equations, and (2) the variable heating rate method. The average activation energy values determined by glow curve shape analysis method are about 0.87 eV. The variable heating rate method shows the activation energy having a value of 1.19 eV. The symmetry factor, μ, is 0.52 and the kinetic order is 1.88. The results are compared with those obtained by other authors.

ISSN:0033-7579    

DOI:10.1080/00337578608207495

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

With a view to understanding the defects due to self-irradiation in241Am (α-active withT½=433 years) doped BaCO3and their role in thermally induced free radical reactions/electron-hole recombination, trap level spectroscopic studies were conducted on BaCO3:241Am and BaCO3: Eu (lanthanide analogue of Am) using Thermally Stimulated Luminescence (TSL) and Electron Spin Resonance (ESR) techniques. In the case of241Am-doped BaCO3phosphor, three glow peaks at 357, 420 and 500 K (for rate of heating β=2.5 K sec−1) were observed and their spectral character has shown that Am2+acts as the luminescent centre. The TSL glow pattern and the ESR spectrum arising due to internal α-irradiation was unaltered with further (external) γ-irradiation of the phosphor. The ESR studies on these samples have shown that the carboxy CO2- radicals are produced due to α-irradiation and their thermal instabilities are responsible for triggering the processes responsible for the observed TSL peaks. In the γ-irradiated BaCO3: Eu phosphor, paramagnetic radical ions O2- and CO3- were observed and the electron-hole recombination processes associated with their thermal destruction are identified as the mechanisms responsible for the thermally stimulated relaxation resulting in TSL at 383 and 430 K. It is observed that the pick-up of significant amounts of sodium impurity played an important role in the TSL processes. Sodium impurity helped the stabilisation of the (Na+-O2−)-complex in BaCO3:Eu which was absent in BaCO3:241Am. This is consistent with the total absence of O2−radical in241Am-doped samples probably due to internal heating caused by α-decay.

ISSN:0033-7579    

DOI:10.1080/00337578608207496

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A computational method is described for studying the use of thermoluminescent dosemeters in the assessment of both the absorbed dose and the time elapsed since an exposure. The method allows an estimate of a range of suitable values for electron lifetimes in low temperature traps for a single abnormal exposure superposed on a continuous background.

ISSN:0033-7579    

DOI:10.1080/00337578608207497

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Minimum displacement threshold energies for copper atoms in ordered and disordered Cu3Au and CuAu were determined at 20 K by electrical resistivity measurements during high energy electron bombardment: ECudmin, (20 K)=18 eV in all cases. Previously obtained defect production curves are reanalysed. The recovery of damage introduced by irradiation at 20 K with 0.66 and 2.36 MeV electrons was studied in the ordered compounds: the same stages are observed whatever incident electron energy; this suggests a single type of interstitial (Cu) migrating freely at 70 K; the Au interstitial is thought to take the place of a Cu atom and produce a Cu interstitial associated to an antistructure defect. For the disordered alloys, the recovery after irradiation with 2.4 MeV electrons is continuous from 20 to 250 K. For the four studied alloys, migration of vacancies occurs around 300–400 K and is responsible for long-range ordering of copper and gold atoms.

ISSN:0033-7579    

DOI:10.1080/00337578608207498

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

This paper describes the first experimental determination of the migration temperature of freely diffusing self-interstitials in magnesium. This observation was made possible by analysis of the elastic modulus and damping variations induced by the pinning of the dislocations by self-interstitials. A marked pinning stage is found between 9 K and 14 K, which is definite evidence for the long-range diffusion of the self-interstitial at these temperatures. Prior data are discussed and reinterpreted in the light of this finding.

ISSN:0033-7579    

DOI:10.1080/00337578608207499

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The Doppler broadening annihilation lineshape measurements have been performed in GaP and GaAs in the temperature ranges 132–675 K and 144–550 K respectively, in thermal equilibrium. The data show a pronounced vacancy trapping effect. From the knowledge of the threshold temperature,Tt, the vacancy formation energy has been predicted as 0.52 eV for GaP and 0.57 eV for GaAs.

ISSN:0033-7579    

DOI:10.1080/00337578608207500

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

For the production of lead microcones with defined positions on lead substrates the method of contamination lithography was found to be applicable. After deposition of three-dimensional contaminants in a SEM the sample surfaces were exposed to perpendicular Ar+-ion bombardment. Lead microcones with an apex angle of 20° and a tip radius of 150 nm have been produced. Some applications, especially integration in thin film devices as point contacts, should be possible.

ISSN:0033-7579    

DOI:10.1080/00337578608207501

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor