摘要:

A new model is developed to describe the accumulation of amorphousness with increasing ion fluence in heavy ion implanted semiconductors. This is based upon simultaneous direct impact amorphisation and thermal relaxation to simpler disorder which can then be reamorphised. Although a defining equation for the amorphousfraction can be formulated and solved to a tri-exponential decay form neither the coefficients nor fluence exponents of this function can be determined exactly analytically but steady state conditions can be predicted analytically. Approximations show that the form of the amorphous fraction-fluence function and steady state amorphous fractions agree, qualitatively with respect to variations of ion flux and temperature, with experimental results.

ISSN:1042-0150    

DOI:10.1080/10420159708212953

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Fast heavy ions produce stable defects in most organic polymers. In this work poly(ethyleneterephthalate) was irradiated with Xe ions at an energy of about 11 MeV/u and an areal dose of about 2 × 1010cm−2. The tracks were characterized by soaking fluorescence tracers into the tracks using dimethylformamide as solvent. By analysing the band positions of solvatochromic dyes the local polarity can be obtained. A result of this characterization is that the dielectric number of the tracks is 10% decreased compared to the virgin polymer. By using the high polar solvent dimethylformamide as soaking agent it could be shown that there is no accomodation of this solvent in the tracks.

ISSN:1042-0150    

DOI:10.1080/10420159708212954

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

100 keV B+ions are implanted at high fluence into three polymers of technological importance and into a polymeric mixture, respectively. The boron depth distributions are measured by the neutron depth profiling technique. It is shown that the boron atoms redistribute after their implantation according to the nuclear (collisional) energy transfer distribution. This contrasts to low fluence implantation, where the boron atoms redistribute according to their electronic energy transfer distributions.

ISSN:1042-0150    

DOI:10.1080/10420159708212955

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Radiation effects of poly (phenyl methacrylate) (PPMA) have been investigated by electron spin resonance (ESR) and Fourier Transform Infrared (FTIR) spectroscopy. The ESR spectrum observed for gamma irradiated PPMA at liquid nitrogen temperature (LNT) is a sextet (six line spectrum), while the spectrum appears to be broadened at room temperature (RT). Free radicals associated with the RT and LNT spectra are identified by the magnetic parameters employed to simulate the spectra. Thus, the ESR spectrum at LNT is found to be a superposition of components arising from the macroradicals of the type∼CH2–Ċ(CH3)–CH2∼(I) and a difference singlet spectrum due to phenoxy radicals C6H5Ȯ (II). The spectrum at RT is also simulated with the same values of magnetic parameters, employed to simulate the LNT spectrum, except for the value of the β-hyperfine splitting. Thus, the RT spectrum is thought to consist of two types of radicals I and II. The gradual decrease in intensity of the 1750 cm−1FTIR absorption band with the increase of radiation dose indicates the cleavage of the phenoxy carbonyl (-COOC6H5) groups of PPMA.

ISSN:1042-0150    

DOI:10.1080/10420159708212956

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Rutherford Backscattering Spectrometry (RBS) has been employed to analyze the depth distribution of 300 keV Pb+, Hg+and Au+ions implanted into magnesium thin foils at room temperature to fluences in the range from 1 × 1015to 5 × 1016ions/cm2. Changes in the distribution profile of each of the implanted ions due to isochronal annealing sequences, in the range from 150°C to 430°C, have been investigated.

ISSN:1042-0150    

DOI:10.1080/10420159708212957

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The AlZn27Six(x= 0.5—12.7 wt. %) melt spun ribbons were annealed in the temperature range 300—550°C for different times from 1 to 10h. Another group of the same composition was exposed to gamma-ray radiation for different doses up to 1 MGy.

ISSN:1042-0150    

DOI:10.1080/10420159708212958

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Electron paramagnetic resonance (EPR) and Optical absorption spectra of vanadyl ions in calcium oxalate monohydrate single crystals have been studied. EPR spectrum at room temperature exhibits an isotropic octet spectrum. The detailed EPR analysis indicates that vanadyl ions exhibit liquid like behaviour. EPR spectrum has been studied at different temperatures. It is found that at 255 K, the EPR spectrum completely disappears. The optical absorption spectrum exhibits three absorption bands characteristic of vanadyl ions in tetragonal symmetry. From the optical data, the crystal field and tetragonal parameters have been evaluated.

ISSN:1042-0150    

DOI:10.1080/10420159708212959

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Luminescence emitted under γ-ray irradiation in Li2O single crystal has been measured at 77—298 K using a60Co source for the first time. Effects of annealing temperature (773 or 1073 K) and cooling rate (about 50 or 400 K/h) were studied.

ISSN:1042-0150    

DOI:10.1080/10420159708212960

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor