摘要:

The sputtering of hexagonal and rhombohedral forms of boron nitride is studied by computer simulation and experimentally. The sputtering yield of the rhombohedral crystal is found to be up to twice as large as that of the hexagonal one in the energy range of Ar+ion bombardment from 0.3 to 4 keV. For both types of BN, boron is sputtered more easily than nitrogen. Computer calculated spatial and energy distributions of the particles sputtered from the (0001) face of a BN single crystal are studied. Spatial distributions exhibit preferential sputtering of B and N atoms in particular directions. These atoms form three distinct spots for each of the two components; the patterns for B and N are turned through an angle of 60° with respect to each other. Features of the backward and forward sputtering from a target containing a different number of the (0001) layers, as well as the mechanisms of particles ejection are discussed.

ISSN:1042-0150    

DOI:10.1080/10420159508220012

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The depth distributions of infrared absorption of PETP (polyethyleneterepthalate, ‘mylar') were measured for a number of different ion irradiation conditions. It turned out that at low fluences the depth profiles resemble the ones of the transferredelectronicenergy distribution. With increasing fluence the depth profiles of IR absorption approach the ones of the transferrednuclearenergy distribution, thus reflecting the increasing polymer destruction. The earlier assumed correlation of the depth profile shapes with the ratio of electronic to nuclear energy transfer can thus be ruled out.

ISSN:1042-0150    

DOI:10.1080/10420159508220013

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A new theoretical model and software tool is proposed for simulation of two-dimensional local ion implantation in a target of arbitrary geometry. The program uses an algorithm of numerical solution of the boundary value problem for Boltzmann transport equation in two dimensions and permits to calculate the angular and energy distribution function of the particles moving in a multilayered multicomponent target. The program is essentially time saving and can be implemented on an IBM PC AT standard configuration computer.

ISSN:1042-0150    

DOI:10.1080/10420159508220014

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The dislocation loops in rutile produced after irradiation by 0.4-1 MeV electrons at various temperatures have been analyzed. Loops formed during electron irradiation at 400°-500°C were pure edge interstitial of the type <100>{100} and were unfaulted. After leaving rutile specimens irradiated at high temperature for a number of days, there was evidence for the formation of crystallographic shear planes (CSP) on (121} withR= 1/2<011>. The displacement energies (Ed) of Ti in TiO2for various crystallographic directions have been obtained using the high voltage microscopes. The following results have been found: Ed<100> ∼52 eV, Ed<111> ∼50 eV and Ed<001> ∼47 eV showing that Edis only slightly dependent upon the direction of knock-on of atoms in the crystal. An apparent temperature dependence of the threshold displacement voltage was found, where the displacement energy (Ed) decrease with increasing temperature.

ISSN:1042-0150    

DOI:10.1080/10420159508220015

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The influence of γ-, electrons and reactor neutrons irradiation on the optical and electrophysical properties of Gd3Ga5O12single crystals is investigated. Experimental data and theoretical estimations of radiation defect concentration are compared.

ISSN:1042-0150    

DOI:10.1080/10420159508220016

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

An investigation has been made on the influence of reactor neutron irradiation on tensile properties of mild steel at ambient temperature. Flat tensile specimens with gauge section 15.5 mm × 2.9 mm × 2.5 mm were exposed to neutron irradiation (E > 0.1 MeV) to three different fluences of 0.6 × 1018, 1.2 × 1018and 4.8 × 10.18n/cm2. The irradiated specimens were tested in tension at room temperature. It was observed that while there was marked increase in the yield strength, there was relatively less increase in the ultimate tensile strength and the work hardening of the material was considerably reduced to due to neutron irradiation. Further, the ductility was also reduced progressively with the increasing fluence of neutron.

ISSN:1042-0150    

DOI:10.1080/10420159508220017

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Nonlocal stresses of a screw dislocation near a free surface in a semi-infinite hexagonal medium are investigated by a surface dislocation model. The nonlocal image force on the screw dislocation due to the existing free surface is also obtained. All classical singularities for the stress and image force are eliminated. The maxima of the stress and image force are evaluated. A zero point of the stress is found, which predicts that different states of the shear stress exist simultaneously near the dislocation. The appearance of a zero value at the free surface and a maximum of the dislocation image force can be used to explain the existence of the dislocation free zone.

ISSN:1042-0150    

DOI:10.1080/10420159508220018

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor