摘要:

We have studied the effects of fast neutron (E>0.1 MeV) irradiation at reactor (∼ 360 K) and low (∼ 20 K) temperatures on the superconducting properties of polycrystalline orthorhombic YBa2Cu3O7−y. Measurements were made on the superconducting critical temperatureTc, critical currentJc, Meissner effect and magnetic field dependence ofJc. TheTcdrops by an irradiation at reactor temperature andJcincreases with increasing fluence. On the other hand with the irradiation at low temperature,Tcrises andJcincreases. Results of observation of Meissner effect and the magnetic field dependence ofJcare consistent with the behavior ofTcandJc.

ISSN:1042-0150    

DOI:10.1080/10420158908230304

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The yield and the polar angular distributions of secondary particles emitted from cone-covered surfaces were studied. A model taking into account both the influence of the local incidence angleIand the blocking of the emitted particles by the surface relief was elaborated. For an emission anglea, the transport effect of the particles generated inside the solid was simulated by the standard relationF(a) = (cosa)nand the emission dependence on the local incidence angle was assumed to behave asE(I) = (cosI)-m. Calculations showed that form= 1 the surface topography only slightly alters the polar angular distribution shape but the yield of the collected particles is always higher than that from a flat surface whenmis more than unity. Forn= 2, the shape of the distribution curve is significantly different from that of the corresponding flat surface whatever themvalues. Forn=0, whenE(I) very rapidly increases with the incidence angle both the angular distributions shape and the yield are strongly modified by the surface topography.

ISSN:1042-0150    

DOI:10.1080/10420158908230305

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The change of charge-carrier concentration and lifetime in high-resistivity float-zone n- and p-Si with equilibrium concentrations of electrons n0=(2 to 30)× 1012cm−3and holes p0=(5 to 30)× 1011cm−3when irradiating by60Co γ-rays (T= 330 K) is studied. There is a drastic increase of the initial charge- carrier removal rate and the coefficient for the radiation variation of their lifetime. The results obtained are explained on the assumption of the dependence of the annihilation probability of Frenkel pairs on the charge state of vacancy (V) and interstitial Si atom (I).The energetic position of the levels separating the states I0/I++and V−/V0which are at Ec−(0.43−0.45) eV and Ec−(0.47−0.54) eV, respectively, is estimated.

ISSN:1042-0150    

DOI:10.1080/10420158908230306

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Ne, Ar, Sb, and Xe ions have been implanted, at 30 keV or 80 keV and at various incidence angles, into Si substrates maintained at room temperature during implantation. Implantation-induced Si disorder was measured using RBS-channelling. The effects upon disorder of various incidence angles were studied over a fluence range of 1012-1016ions·cm−2.

ISSN:1042-0150    

DOI:10.1080/10420158908230307

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Low dose implanted lithium depth profiles in preamorphized silicon have been measured in the energy range of 5 keV to 2 MeV by means of three different nuclear reaction techniques and SIMS measurements, and they are compared to theory. Though the agreement is good for the mean projected range, we find systematic deviations for the range straggling.

ISSN:1042-0150    

DOI:10.1080/10420158908230308

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

An ion track model was applied to describe MeV ion induced adhesion improvement of Au thin films on amorphous SiO2. Good agreement with experimental data was found when assuming that ion track energy densities above and below a certain interval do not contribute to the adhesion enhancement; damage effects detrimental to adhesion may be associated with the high energy densities in the vicinity of the ion path.

ISSN:1042-0150    

DOI:10.1080/10420158908230309

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Cl and Ar ions have been implanted, at 30 keV and at various incidence angles, into Si substrates maintained at room temperature during implantation. Implantation induced Si disorder was measured using RBS channelling. The effects upon disorder of various incidence angles were studied over a fluence range of 1012-6·1015ions·cm−2

ISSN:1042-0150    

DOI:10.1080/10420158908230310

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Measurements of both secondary electron emission coefficientγand SiL23Auger yield ρAobtained from (111) Si target bombarded by high fluence of noble gas ions were performed. For Si irradiated at room temperature at doses more than 1017ions per cm2, monotonous increasing variation ofγand ρAversus incidence angleiwas observed. For Si irradiated at a temperature more than a critical value,γ(i) and ρA(i) curves exhibited, superimposed to monotonous variation, some minima when the ion beam penetrates the crystal along low index directions. In the range 20–650°C, the Auger yield temperature dependence showed a sharp variation around a critical value depending on the ion mass for a given incident energy. These results are linked to an amorphous-crystalline phase transition.

ISSN:1042-0150    

DOI:10.1080/10420158908230311

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

We present a new real time technique to study the change in surface composition of solids, particularly insulators, due to electron bombardment. Secondary Ion Mass Spectrometry is used to monitor the surface composition during erosion by an electron beam. The technique is illustrated for LiNbO3and NaCl targets. We observe a preferential loss of oxygen in the case of LiNbO3and an alkali-metal enriched surface layer for NaCl.

ISSN:1042-0150    

DOI:10.1080/10420158908230312

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

An experimental investigation of the secondary ion emission from organic films under heavy ion bombardment at high energies was carried out by using a time-of-flight mass spectrometer coupled to a Tandem heavy ion accelerator. Preliminary results obtained at 3 MeV/A are reported and discussed.

ISSN:1042-0150    

DOI:10.1080/10420158908230313

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor