摘要:

Detailed dependences of the energy distributions of fast ionized recoils ejected from both single- and polycrystalline copper targets bombarded by 30 keV Ar+ions on the geometry of the experiment have bccn investigated. The model of an isolated vibrating atomic row proves to bereasonable for describing many of the features obtained in ejected recoil energy distributions.

ISSN:0033-7579    

DOI:10.1080/00337578308207401

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Trivalent rare-earth trace impurities are the emitters of thermoluminescence (TL) in the fluorite mineral. In this paper the cerium associated part of the TL spectrum is explained as originating from three types of Ce3+centres: (1) compensated locally by substitutional O2−impurity in the adjacent lattice position, (2) associated with interstitial F−in the tetragonal or trigonal symmetry, (3) unassociated with other impurities. At smaller radiation doses (< 100 Gy) the emission is predominantly from O2−compensated Ce3+centres. The spectrum at high doses (≳100 Gy) originates from Ce3+centres without O2−compensators in the immediate vicinity. It is hypothesized that at low doses an electron is captured in the Ce3+-O2−impurity centre leading to the conversion of Ce3+to Ce2+. At high doses, a hole also is captured, with the result that this Ce3+-O2−centre then gets converted to Ce2+-O−. This changed configuration is stable up to 500°C. As a result of this, at high doses the glow peaks appearing below 300°C produce emission mainly from Ce3+centres without O2−compensators, whereas at lower doses the spectra are of O2−compensated centres.

ISSN:0033-7579    

DOI:10.1080/00337578308207402

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Nous présentons ici une étude par résistivité électrique de l'endommagement de l'iridium à basse température par des électrons et par les neutrons ďun réacteur.

ISSN:0033-7579    

DOI:10.1080/00337578308207403

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Anion voidage and anion void lattice formation in electron irradiated (100 keV–1 MeV) fluorite (CaF2) has been investigated byin situtransmission electron microscopy. At low fluences (≲1 dpa) the damage consists of randomly distributed anion voids and large bubble-like defects associated with fluorine gas. At higher fluences (≳ 1 dpa) the anion voids form a three-dimensional ordered superlattice with asimple cubicstructure, whose axes are commensurate with those of the matrix. The superlattice has a unit cell parameterA0in the range 15–30 nm and a ratioA0/R(superlattice parameter/anion void radius) in the range 3–6. The fully ordered superlattice “crystallizes” from randomly distributed anion voids by an ordering process in which locally ordered areas grow together after a fashion similar to that of epitaxy, leaving distorted superlattice regions between individual, fully ordered blocks.

ISSN:0033-7579    

DOI:10.1080/00337578308207404

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

An order of magnitude for the formation energy of the vacancy in diamond (9–15 eV) is estimated using the fact that a crystalline layer irradiated with energetic ions transforms into an amorphous layer when the free energy of the crystalline phase, plus the defects it contains, becomes larger than the free energy of the amorphous phase. This estimation necessitates the knowledge of the free energy of crystallization and of the critical dose of irradiation for which the phase transition occurs. The critical dose is obtained from experimental results giving the variation of the defect concentration versus dose (this is the dose at which the defect concentration saturates). The free energy of crystallization is calculated using the fact that it is related to the bond deformation energy.

ISSN:0033-7579    

DOI:10.1080/00337578308207405

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The parameters of spatial distribution of B+, P+, N+, O+, Ar+, As+and Sb+implanted impurities have been determined within a wide energy range of 30–1000 keV for soda-lime glasses with the composition 1Na2O-4SiO2. The calculated values ([Rcirc]p, Δ[Rcirc]p,Sk) agree well with the experimental results.

ISSN:0033-7579    

DOI:10.1080/00337578308207406

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Metamict damage cross-sections for pollucite, CaAl12O19and spinel, irradiated with 3 MeV Ar+ions, are found to be 0.8±0.4, ∼ 10−2and ∼ 5 × 10−4nm2respectively. The results for CaAl12O19are discussed and compared to neutron-irradiated BeO. Crystal structures with close packing of oxygen ions (CaAl12O19, spinel) have very small damage cross-sections.

ISSN:0033-7579    

DOI:10.1080/00337578308207407

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Energy-loss moments of the electronic energy loss are calculated as functions of impact parameter for protons of 1 to 7 MeV incident upon Be, Al, Cu, Ag, and Ta targets. The Lindhard dielectric-function formalism is used, in the local-density approximation. The target-atom electron densities are Lenz-Jensen, and the projectile is a point charge. The moments are fitted by a simple algebraic function, and the energy and Z2dependence of the parameters of this function are given.

ISSN:0033-7579    

DOI:10.1080/00337578308207408

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

At a weight gain of approximately 20 to 30 mg/dm2during the oxidation of zirconium-base alloys at reactor operating temperatures the oxidation rate accelerates. This is the so-called transition. A mechanistic model has been developed to describe the transition based on the growth and interconnection of small pores along the oxide-metal interface. Once the pores interconnect, coolant can reach the oxide-metal interface and oxidation accelerates. The model has been programmed and incorporated into the previously reported oxidation model. Good agreement has been obtained between the model predictions and experimental data.

ISSN:0033-7579    

DOI:10.1080/00337578308207409

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The radiation damage and disordering phenomena produced at room temperature during Fe+, Bi++and Xe+ion implantations in a Fe-40 at.% A1 ordered alloy were studied byin situtransmission electron microscopy. Progressive, but not total disordering was achieved in the thinnest areas of the specimens during high fluence implantations (> 1015ions/cm2). Simultaneously, the athermal formation of a new phase occurs in the case of Fe+and Bi++implantations. The diffusion-less mechanism suggests a martensitic like transformation.

ISSN:0033-7579    

DOI:10.1080/00337578308207410

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor