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Radiation-induced changes of the structure and properties have been investigated for oxide and nitride materials, and the use of high-temperature insulators as temperature/dose monitors for in-reactor irradiation of materials test assemblies has been validated. It has been experimentally shown that the use of Al2O3 single crystals and BN ceramics provides means of monitoring the temperature of irradiation from 370 to 1900 K. The temperature is derived from measurements of the optical absorption or X-ray diffraction line shifts after post-radiation annealing of the monitors. We discuss the applicability of (a) the optical absorption and F-center luminescence spectroscopies of irradiated Al2O3 single crystals for gamma dose evaluation and (b) the isotopic analysis of irradiated BN ceramics for neutron dose evaluation.

A multilayer non-linear optical structure based on the metal nanoparticles has been fabricated by sequential vapor deposition of silica and implantation of 60 keV Cu- ions. The multilayer structure showed an enhanced non-linear optical response.

Metal-nanoparticle composites were fabricated by implantation of 60 keV Cu−, Ag−, and Au− ions into LiNbO3 single crystals. Monitoring of the chemical composition variations using ion-induced photon emission (IIPE) has shown that the ion implantation stimulates the accumulation of weakly bounded atoms at the irradiated surface. The contribution of weakly bounded atoms to IIPE was observed by stopping and subsequent renewal of ion implantation. The irradiated surface of nanocomposites experienced lasting rearrangement after ion implantation resulted in formation of surface structures. Results suggest that the heavy-ion implantation can be used for embedment of metal nanoparticles and initiation of self-organization on surfaces.

Anomalies of domain structure evolution in congruent lithium niobate with surface layers modified by implantation of Cu ions were investigated. Formation of residual domains and growth of areas occupied by domain patterns with high density of charged domain walls were studied during cyclic polarization reversal. Growth of unusual three-rayed star domains was observed during polarization reversal in low external field much less than the threshold field for conventional congruent lithium niobate. The complicated geometry of these domains in the bulk was revealed using scanning laser confocal microscopy combined with Raman spectroscopy.

The effects of annealing atmosphere (oxygen or vacuum) on Zn nanoparticles (NPs) embedded in SiO 2 fabricated by ion implantation are studied. The oxidation effect depends on the ratio of the diffusion length of O 2 molecules in the substrates to the projectile range of implanted ions. Up to 400 °C, annealing for 1 h in oxygen and vacuum induces almost the same increase of the optical absorption band of Zn NPs at ∼ 5 eV. In this temperature range, the diffusion length of O 2 molecules is less than ∼ 1 nm, i.e., much shorter than the projectile range. After annealing at 600 °C for 1 h, the vacuum atmosphere increases but the oxygen atmosphere decreases the absorption band of Zn NPs. At 600 °C, some fraction of Zn NPs transforms to ZnO NPs under the oxygen atmosphere since the diffusion length of O 2 molecules increases to ∼ 10 nm. Annealing in oxygen at 700 °C for 1 h gives rise to a complete transformation of Zn NPs to ZnO NPs, since the diffusion length increases to ∼ 30 nm, which is comparable to the projectile range. Similar results are also observed for Ni NPs and Cu NPs in the same temperature range, supporting the diffusion controlled oxidation of the NPs in SiO 2 .

Optical nonlinearity and dispersion were studied for Cu nanoparticle composite. Negative Cu− ions with 60 keV were applied for implanting into SrTiO3 at a flux of 10 μA/cm2 up to a total fluence of 1 × 1017 ions/cm2. The steady-state optical spectrum of Cu-implanted SrTiO3 showed a surface plasmon resonance resulting from the formation of nanoparticles. Transient transmission and reflection were measured by the pump–probe method with a femtosecond laser system. Optical nonlinearity originated from Cu:SrTiO3 nanoparticle composite and from SrTiO3 matrix overlap, in measured transient spectra. The nonlinear component of Cu:SrTiO3 composite was extracted from the transient spectra with the difference of time response. Nonlinear dielectric coefficient and dispersion around the surface plasmon resonance were derived from extracted transient spectra. The dispersion was compared with a local electric field factor.

Optical transmission and ion-induced photon emission of SiO 2 (silica glass), LiNbO 3 and Al 2 O 3 were measured during implantation of 60-keV Cu − or Au − ions. Conditions of stability of metal nanocomposites were determined and represented with the help of nonequilibrium phase diagrams. Formation of structures dynamically stable under ion bombardment diminished the efficiency of ion implantation for further accumulation of implants as in nanoparticles. Contributions from various radiation-induced processes (sputtering, radiation-induced diffusion, atomic collisions, electronic excitations, etc.) to formation of nanocomposites were evaluated.

Two different methods were applied to fabricate cuprous-oxide (Cu2O) nanoparticles (NPs) in silica glasses (SiO2), namely (i) low oxygen-pressure (LOP) oxidation of Cu NPs, which had previously been formed in SiO2by implantation of Cu ions and (ii) two-step annealing of Cu NPs in atmospheric-pressure oxygen gas (to convert Cu NPs to CuO) and in LOP-Ar gas (to convert CuO to Cu2O). The LOP oxidation at 800 °C converts a small portion of Cu NPs to the Cu2O phase, but most of the Cu NPs survive in the metallic state. By increasing the oxidation temperature to 900 °C, the Cu2O phase dissolves. On the other hand, the two-step annealing at different oxygen pressures converts all the Cu species to Cu2O NPs. Any diffraction peaks due to Cu NPs or CuO NPs, except Cu2O NPs, were not observed.

Optical properties of Au nanoparticle composites and a grid structure of Cu nanoparticle composite were studied. Negative ion implantation was applied to synthesize Au and Cu nanoparticles in amorphous SiO2 and Al2O3. Au nanoparticles were embedded within a depth of 30 nm by 60keV Au− implantation. The surface plasmon resonance (SPR) of Au:SiO2 and Au: Al2O3 composites shifted to red and to blue, respectively, compared to calculated ones by the Mie theory. Optical nonlinearity was measured with pump-probe femtosecond spectroscopy and the transient spectrum of Au: Al2O3 composite presented a large red shift from the SPR peak. Image mapping of far-field transmitted intensity of Cu-implanted SiO2 with a fine grid structure drawn by laser-lithography was observed by a scanning near-field optical microscopy (SNOM) system.

Surface recession due to sputtering under low-energy and high-fluence heavy-ion implantation makes shallower and broader depth profile of implanted ions than those calculated by conventional ion-range simulation-codes such as SRIM. Depth profiles of Zn atoms in silica glasses (SiO2) implanted with Zn+ ions of 60 keV up to 1.0×1017 ions/cm2 were evaluated using both experimental methods as Rutherford backscattering spectrometry (RBS), sputtering depth-profiling by X-ray photoelectron spectroscopy (XPS), and an advanced numerical simulation code TRIDYN, which includes the sputtering loss effects. The TRIDYN code predicts the shallowing of the projectile range from ∼46 to ∼27 nm with increasing the fluence up to 1×1017 ions/cm2, and very high-concentration (∼20 at%) of Zn atoms close to the surface. However, RBS and XPS results exclude such high concentration close to the surface. These results suggest remarkable redistribution of Zn atoms from the nearer surface to the deeper region during the implantation. In fact, Zn-atom concentration near the surface and that near the projectile range are, respectively, lower and higher than those by the SRIM code predictions.

Linear and nonlinear optical properties of Au and Cu nanoparticle composites, fabricated by ion implantation, were studied with evaluation of applicability to all-optical switching device. Negative ions of 60 keV were implanted into amorphous SiO 2 at fluxes of about 10 μA/cm 2 to a fluence of 1 × 10 17 ions/cm 2 . The surface plasmon resonance of the Au:SiO 2 composite was enhanced stronger than that of the Cu:SiO 2 composite because of a difference of the local field in nanoparticles. Nonlinear optical constants were evaluated by the Z -scan method with a tunable femtosecond laser system. The nonlinear absorption coefficients exhibited maximal values of −4.9 × 10 1 m/GW for Cu:SiO 2 and −1.3 × 10 2 m/GW for Au:SiO 2 around the surface plasmon resonance. For application of the composites to optical switching by optical bistability, it was estimated that the reflectivity of resonators is >0.94 for the Au:SiO 2 composite and that the switching energy was approximately 10 pJ/bit.

Kinetic processes of nanoparticle formation by ion implantation was studied for the insulators of a-SiO 2 , LiNbO 3 , MgO · 2.4(Al 2 O 3 ) and PMMA, either by changing ion flux or by using a co-irradiation technique of ions and photons. Under Cu-implantation of 60 keV Cu − , nanoparticles spontaneously formed without thermal annealing, indicating radiation-induced diffusion of implants. The high-flux implantation caused instable behaviors of nanoparticle morphology in a-SiO 2 , LiNbO 3 and PMMA, i.e. enhanced atomic rearrangement or loss of nanoparticles. The spinel MgO · 2.4(Al 2 O 3 ) also showed nanoparticle precipitation at 60 keV, but the precipitation tendency is less than the others. Combined irradiation of 3 MeV Cu ions and photons of 2.3 eV or 3.5 eV indicates that the electronic excitation during ion implantation significantly enhances nanoparticle precipitation, greatly depending on photon energy and fluence. The selectivity for photons can be applied to control nanoparticle precipitation.

Implantation of 60 keV Cu − ions into LiNbO 3 resulted in formation of complex nanocomposites consisting of metal Cu nanoparticles distributed among nanodomains of the host medium. The nanodomains of the host medium correspond to regions of a few hundred naometers in diameter with a constant refractive index. Distributions of the Cu nanoparticles and nanodomains in the implanted region do not correlate with each other. Variations of linear and non-linear optical absorption of the nanocomposites are mainly determined by the change of chemical composition and structure of implanted regions of LiNbO 3 .

Linear and nonlinear optical properties were studied for Cu nanoparticle composites with numerical calculation of the local electric field inside a nanoparticle. Negative Cu ions of 60 keV were implanted into amorphous SiO 2 and single crystals of SrTiO 3 and TiO 2 at a fixed dose rate of 10 μA/cm 2 to a total dose of 1×10 17 ions/cm 2 . The surface plasmon peak shifted to red and was enhanced with increasing refractive index values of the substrate. Complex nonlinear optical constants were evaluated by the z-scan method with a tunable femtosecond laser system over a range from 2.0 to 2.3 eV. The complex third-order optical susceptibility of the Cu:SiO 2 nanoparticle composite exhibited values of +1.6 to −3.1×10 −9 esu around the surface plasmon resonance and took a maximum at 2.1 eV. The real part indicated negative values over the range and the imaginary part changed from positive to negative toward the higher photon energy. Both parts steeply vary with the photon energy near the surface plasmon resonance. The dispersion roughly reflects the local field factor.

Negative ion implantation has been applied to polymers in order to modify the surface and to fabricate nanoparticles. Metal nanoparticles in the vicinity of a polymeric surface are promising for biomedical applications as well as nonlinear optical applications. Substrates of polymethyl methacrylate (PMMA) were implanted with Ag− and Cu− of 60 keV at 3 μA/cm2 up to 3×1017 ions/cm2. Optical absorption spectra of the implanted PMMA were measured in a photon range from 0.5 to 4.5 eV. A peak of surface plasmon resonance (SPR) emerges in the absorption spectra above about 1×1017 ions/cm2, both for the Ag− and Cu− cases. A coexisting absorption slope, due mostly to defects, increases but tends to saturate with ion fluence. The SPR peak of Ag-implanted PMMA is much broader than that of the Cu-implanted one. Corresponding to the SPR spectra, metal nanoparticles are observed by cross-sectional TEM. With increasing ion fluence, the Ag nanoparticles spread out towards the surface, in contrast to the localized Cu nanoparticles. The results demonstrate that metal nanoparticle fabrication in polymers is capable by using appropriate low-energy ions and provides a variety of spatial distributions dependent on ion species and fluence. In particular, Ag− ion implantation fabricates surface-exposed/gradient nanoparticles, which are suitable for biomedical applications such as anti-microbial effects.

Spectra of the optical transmission and ion-induced photon emission (IIPE) of silica glass were measured during implantation of 60 keV Cu − ions at ion fluxes from 1 to 75 μA/cm 2 up to a fluence of 2 × 10 17 ions/cm 2 , aimed at monitoring the formation of Cu nanoparticles. The precipitation threshold of Cu atoms is flux-dependent. At fluxes from 1 to 10 μA/cm 2 , the formation of nanoparticles is efficient up to fluences of 2 × 10 17 ions/cm 2 . The efficiency of IIPE of Cu + solutes in silica glass (band at 2.25 eV) is proportional to a total concentration of Cu solutes. In a single-phase region (solid solution of Cu atoms), the efficiency of IIPE of Cu + solutes is flux-independent. In a two-phase region (solid solution and Cu nanoparticles), the dynamic balance between the nanoparticles and Cu solutes determines the flux-dependent behavior of the efficiency of IIPE.

Silica glass was implanted with negative 60 keV Cu ions at an ion flux from 5 to 75 μA/cm2 up to a fluence of 1 × 1017 ions/cm2 at initial sample temperatures of 300, 573 and 773 K. Spectra of ion-induced photon emission (IIPE) were collected in situ in the range from 250 to 850 nm. Optical absorption spectra of implanted specimens were ex situ measured in the range from 190 to 2500 nm. IIPE spectra showed a broad band centered around 560 nm (2.2 eV) that was assigned to Cu+ solutes. The band appeared at the onset of irradiation, increased in intensity up to a fluence of about 5 × 1015 ions/cm2 and then gradually decreased indicating three stage of the ion beam synthesis of nanoclusters: accumulation of implants, nucleation and growth nanoclusters. The IIPE intensity normalized on the ion flux is independent on the ion flux below 20 μA/cm2 at higher fluences. The intensity of the band increased with increasing samples temperature, when optical absorption spectra reveal the increase of Cu nanoparticles size.

Optical nonlinearities have been studied for Cu nanoparticle composites in an insulator with a high dielectric constant. Negative Cu ion implantation with the energy of 60 keV is applied to synthesize Cu nanoparticles in SrTiO 3 . The surface plasmon peak on optical absorption shifts to red and is enhanced with the dielectric constant of matrix substrates. A numerical calculation of the local electric field inside a Cu nanoparticle suggests that optical nonlinearity of the Cu/SrTiO 3 composite is enhanced twice as much as that of the Cu/SiO 2 composite. Complex nonlinear optical constants were evaluated by the z-scan method with a tunable femtosecond laser system over a range of 2.0-2.3 eV. Both the real and the imaginary parts of the constant of the Cu/SrTiO 3 composite are negative in the range. The third-order optical susceptibility of the Cu/SrTiO 3 composite exhibits values of -1 to -2x10 -9 esu at 2.03 eV where there is a slope of the surface plasmon resonance.

Spectra of ion-induced photon emissions (IIPE) of silica glass were measured during implantation of 3 MeV Cu ions at a constant flux of 3–10 μA/cm2 up to a fluence of 9×1016 ions/cm2. Three bands compose the IIPE spectra: a tail of the oxygen-deficient center band, the band of Cu+ ions at 2.27 eV and the band of non-bridging oxygen hole center at 1.89 eV. Intrinsic defects of silica glass contribute to the IIPE at the onset of irradiation only. At fluences higher than 5×1014 ions/cm2, the fluence dependence of the Cu+-band of IIPE represents (a) the accumulation of Cu solutes preceding the nanoparticle formation and (b) no change of Cu solute concentration during nanoparticle growth. The intensity of the Cu+-band is proportional to the total concentration of Cu solutes. The balance of Cu solutes and Cu nanoparticles is sensitive to the ion flux. The concentration of Cu solutes necessary for nanoparticle formation cannot be attained at fluxes higher than 10 μA/cm2.

The light emission and transient optical loss (TOL) of KU-1 (Russia) and K-3 (Japan) fibers during pulsed reactor irradiation (pulse duration 80 μs, dose rate < 7 × 10 16 n/cm 2 s) have been measured in the visible region. The intensity of fast component of light emission obeys sub-linear dose rate dependence. The intensity of light emission and the TOL depend on the intensity of probing light. Lower intensity of the light emission is observed for higher intensity of probing light. The light emission quenching occurs for wavelengths shorter or longer than the wavelength of probing light. Probing with light enhances the TOL and shortens the decay time of TOL. A 'two-photon-flows' model has been introduced to analyze correlation between the effect of light emission quenching and the TOL enhanced by probing light. The effect of light emission quenching provides means to control the optical properties of fibers in radiation environments.

To extract electronic excitation effects from the synergistic damage processes, we have studied photon-irradiation effects on insulators under heavy ion irradiation. Copper ions (Cu2+) of 3 MeV energy at an ion flux of 2 μA/cm2 and 2.3 eV photons at 0.2 J/cm2pulse were used to amorphous SiO2 (KU-1) and spinel MgO·2.4(Al2O3), either sequentially or simultaneously to fluences up to 5 × 1017 ions/cm2. Atomic force microscopy and cross-sectional TEM were conducted to study the surface morphology and internal microstructure, respectively. The simultaneous photon irradiation at high photon densities significantly enhanced surface damage for the insulators, but alleviated bulk defects. The electronic excitation gave rise to significant reduction in dislocation loops in MgO·2.4(Al2O3), whereas single ion irradiation produced copious dislocation loops. The results demonstrate that intense electronic excitation, coexistent with heavy ions, excite transient sub-gap states and the absorbed energy results in enhancement of atomic migration, either damaging the surface or annealing the internal defects.

Optical absorption and nonlinear optical response were studied for metal nanoparticle composites. Negative ions, Cu−, Au−, Ag−, Ta− and W− with 60 keV were applied for implanting into amorphous(a)-SiO2 The absorption spectra of various metal ion implanted a-SiO2 showed a surface plasmon peak resulting from formation of nanoparticles. The surface plasmon resonance was widely located over the infrared and the visible range. Nonlinear optical property of Cu nanoparticles was measured with a pump–probe method using a femtosecond laser system. A wavelength of the pumping laser with a pulse width of 0.2 ps was tuned over a wide visible range of 533–606 nm around the surface plasmon resonance. Transient spectra, immediately after laser pumping at various wavelengths, excellently agreed with each other. The transient changes recovered within a few femtoseconds. The nonlinearity and transient response, excited by laser with a pulse width of 0.2 ps, were independent of excited wavelengths.

Negative ion implantation has been applied to fabricate metal nanocomposites of metals and polymers which are promising for nonlinear electronic, optical and biomedical applications. We have studied nanoparticle formation processes of Ag and their effects on surface properties of polymers, in comparison with those of Cu. Polycarbonate (PC) substrates were irradiated by negative Ag and Cu ions of 60 keV to various doses up to 3 × 1017 ions/cm2. Optical absorption spectra of the irradiated PC were measured in the range from 0.5 to 4.5 eV. Surface- and nanoparticle morphology of the PC were studied by AFM and cross-sectional TEM. Depth profiles of implant concentrations were evaluated by RBS. A surface-plasmon-resonance peak of Ag around 2 eV appears in the optical spectra of PC implanted to a dose of 1 × 1017 ions/cm2, whereas their defect absorption is not significant. The TEM and RBS measurements show that well-defined implantation is capable at this fairly low energy, though surface recession takes place because of ion sputtering. The structure of PC is stable enough for formation of Ag nanocomposites. Depth distribution of Ag nanoparticles significantly shifts towards the surface, differently from the case of Cu nanoparticles. Negative ion implantation provides nanoparticle formation for surface modification of polymers, with understanding the ion-induced precipitation processes in the polymers.

Linear and nonlinear optical properties were studied for Cu nanoparticle composites with high Cu concentrations. Negative Cu ions of 60 keV were implanted into amorphous SiO2 at a fixed flux of 10 μA/cm2 to fluences ranging from 3 × 1016 to 6 × 1017 ions/cm2. Implanted Cu contents were evaluated by Rutherford backscattering spectrometry with 2 MeV He+ ions. Optical absorption increased with the Cu concentration but the surface plasmon peak was maximized around a fraction of 0.10 and attenuated beyond that fraction. Nonlinear optical properties were evaluated by the z-scan method and pump-probe method with a femtosecond laser system. The nonlinear absorption constant increased with the volume fraction but deviated from linearity beyond a Cu volume fraction of 0.20. The laser-induced transient response was ∼1 ps and was independent of the Cu concentration.

Kinetic behaviors of nanoparticle formation in LiNbO 3 have been studied with negative Cu ion implantation and the effects on nonlinear optical properties have been discussed. Negative Cu ions of 60 keV are implanted into LiNbO 3 disks at fluxes up to 50 μA/cm 2 . Ion-induced photon spectroscopy was applied to monitor the ion-substrate interactions and the nanoparticle morphology was studied by cross-sectional TEM. Metal precipitation behaviors as well as the matrix stability significantly depended on ion flux. In a flux range of 3–10 μA/cm 2 , LiNbO 3 showed spontaneous formation of Cu nanocrystals of ∼10 nm, including nonspherical shape. Crystallinity of the LiNbO 3 lattice implanted was sustained up to 3 × 10 16 ions/cm 2 . The Cu nanoparticles in LiNbO 3 showed a sub-picosec nonlinear optical response. However, significant Li-atom release to the vacuum was detected by ion-induced photon spectroscopy, indicating formation of a Li-depleted zone. Particularly above a flux of 30 μA/cm 2 , significant coarsening of Cu particles and amorphization of the LiNbO 3 lattice occurred. The results indicate that metal nanoparticle formation in LiNbO 3 is sensitive to the ion flux and that the optimization is requisite to fabricate well-defined nanocomposites.

Metal nanoparticles fabricated by heavy-ion implantation of insulators are promising for non-linear optical applications. Spectra of optical transmission of silica glass in the visible region were measured during and after implantation of 3 MeV Cu2+ ions. Three absorption bands contribute to the spectra: transient absorption (TA) at 2.34 eV, a surface plasmon resonance (SPR) peak at 2.21 eV and a tail of residual absorption (RA), which increases when the photon energy is increased from 2.2 to 2.6 eV. The TA and a change of the SPR peak strongly contribute to the total transient absorption obtained as the difference in absorption during and after irradiation. The effect of RA shows up as a decrease of absorption after switching on the ion beam. The TA provides a means for selective electronic excitation by a laser during implantation of silica glass. The precipitation of Cu atoms and the growth of Cu nanoparticles are well distinguishable stages of nanoparticle formation. The SPR peak appears at a fluence of 3.3 × 1016 ions/cm2, corresponding to the onset of precipitation. At fluences higher than 3.4 × 1016 ions/cm2, when the growth of nanoparticles predominates, the fluence dependence of the SPR peak is linear.

The outward mass transport during implantation of 60 keV negative Cu, Ag and Au ions into LiNbO3 and Al2O3 was studied by using in situ time-resolved optical spectroscopy. Single crystals of LiNbO3 and Al2O3 were irradiated continuously or by pulses of ions. Spectra of ion-induced light emission at the wavelengths from 250 to 900 nm were in situ measured. The ratios of individual lines of the same atomic species (Li for LiNbO3 and Al for Al2O3) change with the dose. The change of energy distribution of sputtered atoms is explained by a competition between two mechanisms of sputtering: the sputtering induced by atomic collisions or electronic excitation. The result shows a strong relationship between irreversible structural change of implanted regions (formation of nanocomposite and damage) and energy distribution of sputtered atoms. r 2004 Elsevier Ltd. All rights reserved.

Although ion implantation has a unique merit in fabricating immiscible metal–insulator composites being promising for non-linear optical applications, high-flux implantation especially is subject to pronounced atomic transports, either inside or outside the solid. Negative Cu ions of 60 keV irradiated substrates of a-SiO 2 and MgO · 2.4(Al 2 O 3 ) at fluxes up to 100 μA/cm 2 . Atomic redistribution of Cu nanoparticles inside the substrate was observed by cross-sectional TEM. Atomic release of Cu implants out of the substrate was detected by ion-induced photon spectroscopy, with fast-response CCD cameras. Spontaneous metal precipitation in insulators is attained at high flux. The ion-induced photon spectra of a-SiO 2 consist of sharp line spectra and a broad luminescence. The presence of line spectra demonstrated the outward transport into vacuum and loss of Cu atoms via the surface to the vacuum. Cations in MgO · 2.4(Al 2 O 3 ) are also significantly released to the vacuum via the surface. The outward mass transport results from ion-induced sputtering/sublimation of implants, concurrently with radiation-induced diffusion towards the surface.

The magnetic sensors (coils and loops), made of mineral insulated (MI) cables, are intended for ITER. In MI-cables the radiation initiates electric charge separation, emergence of the radiation induced electromotive force (RIEMF) and leakage current between cable strand and sheath. This effect may impact the magnetic measurements and other tokamak diagnostics using MI-cables. In this study a set of MI-cables (with different sizes and strand materials) were irradiated on the pulse reactor BARS-6 with dose rates from 103 Gy/s up to 105 Gy/s in pulse maximum. The analysis of the obtained data and the transient electric processes under pulse action permits us to propose a model of radiation-induced separation of electric charge in MI-cables between the insulated central cable strand and the grounded metal sheath.

Radioluminescence (RL) of sapphire and polycrystalline alumina (p-Al2O3) under 8 MeV proton (flux 2 � 10 12 proton/cm 2 s), 150 MeV argon (4.3 � 10 8 ion/cm 2 s) and 253 MeV krypton (4.3 � 10 8 ion/cm 2 s) ion irradiation has been measured in the UV and visible ranges. The processes causing the changes of RL of sapphire with a dose differ from those of p-Al2O3. Radiation-induced annealing of oxygen vacancies in p-Al2O3 occurs with decreasing F þ -band. Inhomogeneous distribution of traps associated with grain boundaries causes electrical charging of microscopic regions in p-Al2O3 and an increase of F-band of RL. The accumulation of charge carriers at traps increases excitation probability of F þ -center and results in growth of F þ -band of sapphire. A ratio of initial to saturation intensity of the F þ -band increases with increasing the linear energy loss of incident particles.

Importance of non-linear optical responses of optical fibers for diagnostics of fusion plasma is discussed. The light emission and transient optical loss of KU-1 (Russia) and K-3 (Japan) fibers during pulsed reactor irradiation (pulse duration 80 µs, dose rate

The transient optical loss (TOL) of silica core optical fiber waveguides of KU-1 grade (Russia, OH content 1000 ppm) and K-3 grade (Japan, OH content 10 ppm) have been measured during pulsed reactor irradiation (BARS-6 pulsed fission reactor (IPPE), pulse 80 μs, dose per pulse

Optical and acoustic properties of the materials based on Al2O3, SiO2 and BN under 8 MeV proton irradiation (

The light emission intensity and transient optical absorption (TOA) have been measured in the wavelength range 400–750 nm in KU-1 silica core fibers under irradiation of the BARS-6 pulsed fission reactor (pulse duration 80 μs, fluence per pulse up to 5×10 12 n / cm 2 ( E >0.5 eV), dose rate up to 10 5 Gy/s). The fast light emission component attributed to Cherenkov radiation is followed by a weak emission tail with the characteristic time (150±50) μ s. The transient absorption reaches 2.5×10 −4 cm −1 (relaxation time 600–1200 μs). The sub-linear dependence of Cherenkov radiation on the dose rate and the occurrence of both the tail of light emission and transient absorption are ascribed to the appearance of optical inhomogeneities of the silica glass under intense pulsed reactor irradiation.

The opto-electronic performance of semiconductors during reactor operation is restricted by radiation-induced conductivity (RIC) and the synergistic effects of neutrons/ions and photons. The RICs of Si due to photons, protons and pulsed neutrons have been evaluated, aiming at radiation correlation. Protons of 17 MeV with an ionizing dose rate of 103 Gy/s and/or photons ( hν=1.3 eV ) were used to irradiate impurity-doped Si ( 2×10 16 B atoms/cm 3 ) at 300 and 200 K. Proton-induced RIC (p-RIC) and photoconductivity (PC) were intermittently detected in an accelerator device. Neutron-induced RIC (n-RIC) was measured for the same Si in a pulsed fast-fission reactor, BARS-6, with a 70-μs pulse of 2×10 12 n / cm 2 (E>0.01 MeV ) and a dose rate of up to 6×10 5 Gy / s . The neutron irradiation showed a saturation tendency in the flux dependence at 300 K due to the strong electronic excitation. Normalization of the electronic excitation, including the pulsed regime, gave a fair agreement among the different radiation environments. Detailed comparison among PC, p-RIC and n-RIC is discussed in terms of radiation correlation including the in-pile condition.

Using an acoustic technique of composite oscillator, the effect of preliminary deformation on the amplitude dependence (amplitude range from 10−6 to 3 × 10−4) of ultrasound damping and the Young's modulus (resonance frequencies) for V and V–(4–10)Ti–(4–10)Cr alloys has been studied. The alloys differed in composition, manufacture technology and also irradiation type (protons, neutrons), environments and fluence were varied. Neutron irradiation (fast reactor, BR-10) of the samples was carried out in argon (irradiation temperature TI=410°C) and liquid lithium (TI=480°C) environments. It has been found that, for anelastic deformations of the order of 10−8–10−6, irradiation may result in most cases in noticeable anelastic softening of alloys characterized by a Young's modulus decrease. The softening of the V–4Ti–4Cr alloy irradiated in Ar appeared to be the most significant. The experimental results of acoustic studies might be explained by changing the mobile dislocation point defect interaction, perhaps additionally influenced by existing internal stresses.

Spectra of the optical transmission of Al2O3 were measured during implantation of 60 keV Cu− ions at ion fluxes from 5 to 50 μA/cm2, to monitor formation of Cu nanoparticles. The precipitation threshold is flux-dependent. The formation of nanoparticles is (a) efficient up to a fluences of 2 × 1017 ions/cm2 and (b) most efficient for a flux of 50 μA/cm2. Intrinsic size effects have little influence on the linear and non-linear optical absorption of nanocomposites.

Spectra of radiation-induced luminescence (RIL) and photoluminescence (PL) of Al2O3 and BeAl2O4:Cr3− single crystals and BN ceramics have been obtained. In Al2O3 under 8 MeV proton irradiation, the recharging of defects causing RIL has been shown to occur in the track vicinity of 10−6 cm size. After neutron irradiation, an essentially non-equilibrium distribution of Cr3+ impurities over structurally distinguishable sites in the crystal lattice of BeAl2O4 was registered by PL spectroscopy. An effective temperature characterising this distribution under neutron irradiation exceeds the melting point of the material. The RIL and PL of BN were caused by colour centres on grain boundaries. Radiation-induced structural transformations in BN ceramics under neutron and 26.7 MeV Ne ion irradiation principally occur on the grain boundaries but not in the bulk of grains.

Features of experimental study and changes of electrical properties of dielectric materials under irradiation are reviewed. The results on radiation-induced conductivity (RIC) in single crystal Al2O3 exposed to fast reactor neutrons up to the dose of 4.7 × 1024 n/m2 and in single crystal Al2O3 and pyrolitic BN exposed to 7 MeV proton irradiation up to a dose of 2 × 1020 p/m2 are presented. In both cases, RIC did not exceed 10−12 S/cm, the initial value of the conductivity being equal to 10−14 S/cm. Results of calculations and measurements of likely leakage currents are presented. Formation of carbon and hydrocarbon layers on the surface results in the apparent phenomenon of radiation-induced electrical degradation of dielectrics. The defect clustering in dielectrics occurs in cascades and tracks during the thermal spikes. Under the doses of 3.3–3.5 × 1025 n/m2 dielectric breakdown strength of Al2O3 is two times as small, and the mechanical strength is 35.5% higher than initial values. The radiation-induced electrical degradation in metal-dielectric systems can be significant.

Results of optical, electrical and structural investigation of BN and A12O3 materials which allow one to determine the peculiarities of radiation induced degradation (RID) conceming electrical and optical properties of dielectric materials with respect to primary radiation induced processes have been reported. RID of the dielectrics results from the structural changes owing both to primary radiation damages in their crystal lattices during the dynamie stage of atomie displacement and changes of the chemical composition in thermal spikes. RID of the dielectrics under ion irradiation has been related with the electron-hole relaxation, thermal spikes and structural transformations in ion tracks. Microscopic non-equilibrium connected with atomie vibration excitations under irradiation has been shown to bring about non-equilibrium distribution of atoms over different structural sites in the crystal lattice of irradiated dielectrics.

We have investigated wavelength dispersion of photo-induced nonlinear dielectric function of Au nanoparticle materials. Transient transmission and reflection spectra were sequentially measured by the pump-probe method with a femtosecond laser system. The dispersion of real and imaginary parts of the nonlinear dielectric function of Au:SiO(2) nanoparticle material in the vicinity of the surface plasmon resonance was evaluated from these transient spectra with total differential. A local electromagnetic field factor and interband transition in Au nanoparticles directly dominate the dispersion.

The morphology and chemical composition of the surface of SiO2 that had been implanted with Zn ions of 60 keV and annealed in two different atmospheres, i.e., oxygen gas and a vacuum, were compared. In the as-implanted state, the surface mainly consisted of SiO2 with low roughness due to radiation-induced smoothing. A large number of domelike structures of ZnO appeared on the surface of the SiO2 after annealing in oxygen gas at 600 degrees C for 1 h, and the size increased with the annealing temperature up to 800 degrees C. After annealing at 900 degrees C, the surface roughness steeply decreased and the composition changed to Zn2SiO4. (c) 2006 American Institute of Physics.

Recently many groups have started studies of formation of zinc-oxide (ZnO) nanoparticle (NP) in transparent insulators, such as silica glass, sapphire, etc, using ion implantation techniques. In the early half of this article, we shortly review recent activities of ZnO NP formation using ion implantation combined with thermal oxidation. Some groups succeeded but the others did not. Even if they succeeded in the formation of ZnO nanostructures, one reported that they were in the shape of thin film and another reported the NP form. Based on our recent experimental results, we point out the importance of the oxidation temperature and the peculiar shapes and depth profiles of ZnO formed.

The light emission intensity at the wavelength of 400-750 nm in the KU-1 silica core (OH content 1000 ppm) fiber waveguide under irradiation at BARS-6 pulsed fission reactor (pulse duration 80 microsecond(s) , dose per pulse

Metal-nanoparticle composites consisting of copper and gold nanoparticles embedded in insulators (Cu:SiO2, Au:SiO2, and Cu:Al2O3) have been fabricated by metal-ion implantation. Nonlinear optical (NLO) absorption of the nanocomposites has been examined by the Z-scan method with a tunable femtosecond laser. We have measured (a) NLO absorption spectra near the surface-plasmon resonance and (b) laser-intensity dependence of NLO absorption, α(I). The results are compared to the data reported on NLO response for various laser pulse durations. By analyzing the laser-intensity dependence of Z-scan signals, the saturation intensity of light, IS, the coefficient of NLO absorption, β, and the radius of the beam waist, w0, are derived. This approach takes into account the saturation of optical absorption, whereas the conventional approach using the linear approximation α(I)≈α0+βI cannot do it. The analysis shows that transient optical absorption, |α(I)−α0|, decreases with shortening the laser pulse duration. The dec...

Accelerated mass transfer in VzOs monocrystals at selective action of IR—laser radiationDr Oleg A. Plaksin and Dr1 Vladimir A. StepanovThe Institute of Physics & Power Engineering,SU-249020,Obninsk, Kaluga region, USSRABSTRACTUnder continuous COt—laser radiation an acceleration of admixture diffusion processes was observed. It hasbeen shown that at laser radiation excitation of the oxygen system (01) in VzOs the anomalies of the diffusionprocesses kinetics depend on the character of phase transitions connected with oxygen vacancies11 INTRODUCTIONLaser radiation effect causes nonequilibrium conditions of diffusion processes, phase transitions and chemi—cal reactions in solids1 In case of non—resonance of laser radiation a change in the kinetics of the processesmentioned is connected with the temperature non—equilibrium1 The resonance effect of radiation may influence dif—ferent processes due to excitation of inner degrees of solids1 The paper shows experimentally possible initiationof diffusion prcesses as a result of selective excitation by IR—laser radiation of certain types of crystal lat—tice oscillations, Such initiation is possible if the oscillations excited govern the processes initiated1The experiments have been carried out with VZO5, the possibility of selective excitation of various oscilla—tions in a crystal lattice for which has been shown on the base of IR—spectra4. The quasilayered structure ofVOs consists of closely—paced V-O—planes (010) and of 01 atoms between them. The absorption lines (7OO—93O)ciand (97O-IO5O)cm4 (cf.Fig.1) are connected with the oscillations of atoms along closely—packed V—O—planes and

A method of measuring the temperature of metal nanoparticles under ion bombardment is proposed. Optical absorption in the range of the surface plasmon resonance of metal nanoparticles was measured during implantation of 3MeV Cu2+ ions into silica glass to derive a difference in optical absorption between beam on and off regimes. The radiation-induced differential (RD) spectra were similar to the spectra of thermomodulation (TM) and quite different from the spectra of nonlinear optical response measured by the pump-probe method. Increasing amplitude of RD and TM spectra was assigned to an increase of lattice temperature of Cu nanoparticles.