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1.
PWO crystals doped with yttrium were grown with the Bridgman method in platinum crucible and by using an indigenously developed resistive heating furnace. After an exposure of γ-ray from a ^60Co source, with the dose rate of lS rad/h for 20h, the light output increases for about 15%, accompanied with vanishing of an optical absorption band at 420 nm. The excitation and emission spectra of PWO crystals were measured before and after irradiation with different dose rates. The optical absorption band at 420nm was also found in the PWO sample annealed in oxygen-rlch atmosphere. It is suggested that the absorption band at 42Onm is related to Pb^3 point defects existing in the PWO crystal. The unusual change of light output after irradiation probably results from the transformation of lead ions from Pb^3 to Pb^2 . 相似文献
2.
Copper Ion Beam Irradiation-Induced Effects on Structural,Morphological and Optical Properties of Tin Dioxide Nanowires 下载免费PDF全文
《中国物理快报》2016,(7)
The 0.8 MeV copper(Cu) ion beam irradiation-induced effects on structural,morphological and optical properties of tin dioxide nanowires(SnO_2 NWs) are investigated.The samples are irradiated at three different doses5 × 10~(12) ions/cm~2,1 × 10~(13) ions/cm~2 and 5 × 10~(13) ions/cm~2 at room temperature.The XRD analysis shows that the tetragonal phase of SnO_2 NWs remains stable after Cu ion irradiation,but with increasing irradiation dose level the crystal size increases due to ion beam induced coalescence of NWs.The FTIR spectra of pristine SnO_2NWs exhibit the chemical composition of SnO_2 while the Cu-O bond is also observed in the FTIR spectra after Cu ion beam irradiation.The presence of Cu impurity in SnO_2 is further confirmed by calculating the stopping range of Cu ions by using TRM/SRIM code.Optical properties of SnO_2 NWs are studied before and after Cu ion irradiation.Band gap analysis reveals that the band gap of irradiated samples is found to decrease compared with the pristine sample.Therefore,ion beam irradiation is a promising technology for nanoengineering and band gap tailoring. 相似文献
3.
Optical Waveguides and micro-mirrors have been successfully induced inside fused silica glass and k9 glass,respectively,by focusing a 800nm femtosecond(fs)pulsed laser with a repetition rate of 1kHz,The change of refractive index was determined to be 0.001-0.008 in the fused silica glass and 0.006 in the k9 glass.The refractive index change is dependent on both the dose of irradiation and the power density of the fs pulsed laser,Photoluminescence was observed in the irradiated region,and was attributed to the defects induced by fs laser irradiation.We discuss the relationship between the optical property and the luminescent propert property of the irradiated region. 相似文献
4.
ZHOU Xin FANG JianShu LIAO XiangPing ZHU QianQuan LIU ZhiMin TANG Bin 《中国科学:物理学 力学 天文学(英文版)》2013,(9):1664-1669
The effects of different defects on optical properties and plasmon resonances properties of Au nanoshell arrays were investigated by using the finite-difference time-domain(FDTD) theory.It is found that the optical properties of the nanoshell arrays are strongly influenced by different defects.We show that when the hollow Au nanoshell arrays are placed in air,there is a wide photonic band gap(PBG) in the infrared region,but the band gap becomes narrower as we introduced different defects.Based on the distributions of electric field component E z and the total energy distribution of the electric and the magnetic field,we show that there exhibit dipoles field distributions for the plasmon mode at the long-wavelength edge of the band gap,but composite higher order modes are excited at the short-wavelength edge of the band gap.The plasmon resonant modes also can be controlled by introducing defects. 相似文献
5.
Plasmon resonance coupling in strongly coupled gold nanotube arrays with structural defects 下载免费PDF全文
We theoretically investigate the transmission spectra and the field distributions with different defects in the gold nanotube arrays by using the finite-difference time-domain method.It is found that the optical properties of the nanotube arrays are strongly influenced by different defects.When there are no defects in the central nanotube,the values of peaks located at both sides of the photonic band gap have their maxima.Based on the distributions of electric field component E x and the total energy distribution of the electric and the magnetic field,we show that mainly a dipole field distribution is exhibited for the plasmon mode at the long-wavelength edge of the band gap but higher order modes of the composite are excited at the short-wavelength edge of the band gap.The plasmon resonant modes can also be controlled by introducing defects. 相似文献
6.
He Wen Li HuaWei Zhou HuiQiong Zhao HongKang Wang Hui Shi XingHua 《中国科学:物理学 力学 天文学(英文版)》2020,63(3):1-8
PbI2/MoS2,as a typical van der Waals(vdW)heterostructure,has attracted intensive attention owing to its remarkable electronic and optoelectronic properties.In this work,the effect of defects on the electronic structures of a PbI2/MoS2 heterointerface has been systematically investigated.The manner in which the defects modulate the band structure of PbI2/MoS2,including the band gap,band edge,band alignment,and defect energy-level density within the band gap is discussed herein.It is shown that sulfur defects tune the band gaps,iodine defects shift the positions of the band edge and Fermi level,and lead defects realize the conversions between the straddling-gap band alignment and valence-band-aligned gap,thus enhancing the light-absorption ability of the material. 相似文献
7.
Effect of vacancy defect clusters on the optical property of the aluminium filter used for the space solar telescope 下载免费PDF全文
We investigate the microstructures of the pure aluminium foil
and filter used on the space solar telescope, irradiated by photons
with different doses. The vacancy defect clusters induced by proton
irradiation in both samples are characterized by transmission
electron microscopy, and the density and the size distribution of
vacancy defect clusters are determined. Their transmittances are
measured before and after irradiating the samples by protons
with energy E=100~keV and dose φ =6× 1011/mm2.
Our experimental results show that the density and the size of
vacancy defect clusters increase with the increase of irradiation
doses in the irradiated pure aluminium foils. As irradiation dose
increases, vacancies incline to form larger defect clusters. In the
irradiated filter, a large number of banded void defects are
observed at the agglomerate boundary, which results in the
degradation of the optical and mechanical performances of the
filter after proton irradiation. 相似文献
8.
Hole-net structure silicon is fabricated by laser
irradiation and annealing, on which a photoluminescence (PL) band in a
the region of 650--750~nm is pinned and its intensity increases
obviously after oxidation. It is found that the PL intensity changes
with both laser irradiation time and annealing time. Calculations
show that some localized states appear in the band gap of the
smaller nanocrystal when Si=O bonds or Si--O--Si bonds are
passivated on the surface. It is discovered that the density and the
number of Si=O bonds or Si--O--Si bonds related to both the
irradiation time and the annealing time obviously affect the
generation of the localized gap states of hole-net silicon, by which
the production of stimulated emission through controlling oxidation
time can be explained. 相似文献
9.
Field-induced insulator-metal-insulator transitions in low-energy H2- ion-irradiated epitaxial La2/3Cal/3MnO3 thin films 下载免费PDF全文
Epitaxial La2/3Cal/3MnO3 thin films grown on LaA103 (001) substrates were irradiated with low-energy 120-keV H+ ions over doses ranging from 1012 ions/cm2 to 1017 ions/cm2. The irradiation suppresses the intrinsic insulator-metal (I-M) transition temperature and increases the resistance by reducing the crystallographic symmetry of the films. No irradiation-induced columnar defects were observed in any of the samples. The specific film irradiated at a critical dose around 8 x 1015 ions/cm2 is in a threshold state of the electric insulator where the I-M transition is absent. In an external field of 4 T or higher, the I-M transition is restored and thus an enormous magnetoresistance is observed, while a negative temperature coefficient resumes as the temperature is reduced further. Magnetic relaxation behavior is confirmed in this and other heavily irradiated samples. The results are interpreted in terms of the displacement of oxygen atoms provoked by ion irradiation and the resulting magnetic glassy state, which can be driven into a phase coexistence of metallic ferromagnetic droplets and the insulating glass matrix in a magnetic field. 相似文献
10.
Influence of defect states on band gaps two-dimensional phononic crystal in the of4340 steel in an epoxy 下载免费PDF全文
The band structures of a new two-dimensional triangle-shaped array geometry of 4340 steel cylinders of square cross section in an epoxy resin were studied by the plane-wave expansion and supercell calculation method. The band gaps of this type of phononic crystals with different defects were calculated such as defect-free, 60 crystal linear defect states, 120 crystal linear defect states, and 180 crystal linear defect states. It was found that the band gap will emerge in different linear defects of the phononic crystals and the bandwidth of linear defect states is larger than that of the free-defect crystal by about 2.14 times within the filling fraction F = 0.1-0.85. In addition, the influence of the filling fraction on the relative width of the minimum band gap is discussed. 相似文献
11.
This work reports experimental results of an effort undertaken to identify and characterize the radiation-induced defects created during gamma (γ)-irradiation of commercial glass on the basis of optical absorption measurements performed before and after irradiation. It is assumed that the induced absorption band formed after γ-irradiation of soda-lime-silica (SLS) glasses are created by some hole-type color centers related with non-bridging oxygen ions (NBO−) located in different surroundings.Results have been discussed taking into consideration the presence of iron as impurity in the glass structure. It is well known that the absorption bands of Fe3+ in the visible range is at 420-440 nm, in this study the band at 430 nm was followed. Also, the optical gap variations (ΔEopt) induced by γ-irradiation were investigated.Moreover, the study illustrated that the optical absorption sensitivity and the mechanism of fading either at room or elevated temperature has been discussed in relation to successive irradiation doses, dose rate and thickness. The results are discussed on the basis of the annihilation mechanisms of induced irradiation defects. 相似文献
12.
玻璃固化体作为放射性废物地质处置的第一道安全屏障,它的耐辐照性能研究至关重要.玻璃固化体主要网络结构硅氧四面体与石英玻璃的硅氧四面体是一致的,所以这里用石英玻璃代替玻璃固化体作为研究对象.本文采用Xe离子在相同条件下辐照石英玻璃和硼硅酸盐玻璃.利用纳米压痕技术和椭圆偏振仪表征了辐照前后样品的硬度、模量以及折射率的变化情况.结果表明:硼硅酸盐玻璃和石英玻璃的硬度均随着辐照剂量的增大而减小,硼硅酸盐玻璃的模量随着辐照剂量的增大而减小;石英玻璃的模量随着辐照剂量的增大而增大.模量的变化可能和密度的变化有关,这点与折射率的结果相符. 相似文献
13.
Amanpreet Kaur Sandhu Surinder Singh Om Prakash Pandey 《Indian Journal of Physics》2009,83(7):985-991
Silica based glasses are used as nuclear shielding materials. The effect of radiation on these glasses varies as per the constituents
used in these glasses. Glasses of different composition of SiO2-Na2OMgO-Al2O3 were made by melt casting techniques. These glasses were irradiated with neutrons of different fluences. Optical absorption
measurements of neutron-irradiated silica based glasses were performed at room temperature (RT) to detect and characterize
the induced radiation damage in these materials. The absorption band found for neutron-irradiated glasses are induced by hole
type color centers related to non-bridging oxygen ions (NBO) located in different surroundings of glass matrix. Decrease in
the transmittance indicates the formation of color-center defects. Values for band gap energy and the width of the energy
tail above the mobility gap have been measured before and after irradiation. The band gap energy has been found to decrease
with increasing fluence while the Urbach energy shows an increase. The effects of the composition of the glasses on these
parameters have been discussed in detail in this paper.
相似文献
14.
The effect of gamma irradiation in the dose range of 5-500 kGy on the optical absorption and luminescence spectra of Nd doped phosphate glass is reported. The spectral absorption of this glass before and after gamma irradiation was measured in the spectral range 300-900 nm at room temperature using spectrophotometer and synchrotron beamline. Drastic increase in absorption was noted below 600 nm after gamma irradiation, which was dependent on the dose of irradiation. Additional absorption (AA) spectra of irradiated sample shows generation of two absorption bands below 600 nm, which finally became one very broad band peak with increased intensity at irradiation dose of 500 kGy. AA spectra also show the presence of negative peaks at the location of absorption peaks of Nd3+. Photoluminescence of Nd doped phosphate glass shows two strong bands which decreases to a very low intensity with a red shift after gamma irradiation. These results indicate that irradiation produces different kinds of defects in the glass material along with conversion of valence state of Nd3+ to Nd2+. This change was found irreversible at room temperature. 相似文献
15.
M. Mohapatra R.M. KadamR.K. Mishra C.P. KaushikB.S. Tomar S.V. Godbole 《Physica B: Condensed Matter》2011,406(20):3980-3984
Gamma radiation induced changes were investigated in sodium-barium borosilicate glasses containing Eu. The glass composition was similar to that of nuclear waste glasses used for vitrifying Trombay research reactor nuclear waste at Bhabha Atomic Research Centre, India. Photoluminescence (PL) and electron paramagnetic resonance (EPR) techniques were used to study the speciation of the rare earth (RE) ion in the matrix before and after gamma irradiation. Judd-Ofelt (J-O) analyses of the emission spectra were done before and after irradiation. The spin counting technique was employed to quantify the number of defect centres formed in the glass at the highest gamma dose studied. PL data suggested the stabilisation of the trivalent RE ion in the borosilicate glass matrix both before and after irradiation. It was also observed that, the RE ion distributes itself in two different environments in the irradiated glass. From the EPR data it was observed that, boron oxygen hole centre based radicals are the predominant defect centres produced in the glass after irradiation along with small amount of E’ centres. From the spin counting studies the concentration of defect centres in the glass was calculated to be 350 ppm at 900 kGy. This indicated the fact that bulk of the glass remained unaffected after gamma irradiation up to 900 kGy. 相似文献
16.
Absorption spectra measurements of cerium-doped binary system from barium-borate glasses have been measured. The effects of dopant concentration of CeO2 and Al2O3 in the concentration range 0.54-2.9 and 4.8-9.2 mol%, respectively, and exposed to different irradiation doses have been measured in the range 1-7 eV and the result have been interpreted in terms of structural concepts. The radiation-induced broad band at 2.25-1.88 eV in the base glass is observed to be suppressed by the presence of cerium due to the transformation of Ce4+ to Ce3+. The released electrons are then used to annihilate positive holes responsible for this band. The resolution of the observed absorption spectra show two to seven induced bands depending on the glass composition. Absorption spectra of the irradiated binary glass system are found to be controlled by the cerium concentration. From the absorption edge studies, the values of optical band gap Eopt and Urbach energy ΔE have been evaluated. The oxidoreduction (redox) reaction Ce3+/Ce4+ is assumed to be related to the glass basicity and the possible complex-ion formation. The oxygen ion activity (O2−) is believed to be related to the basicity and to the possible oxygen ion formation in the glass melt, and the redox equilibrium is shifted toward the reduced state. 相似文献
17.
A. V. Kabyshev F. B. Konusov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2009,3(2):304-312
Optical absorption of leucoosapphire and polycrystalline corund (polycor) is studied after irradiation with cobalt ions and subsequent annealing in a vacuum. The structure of states localized in the forbidden band and induced by various imperfections has a higher stability to annealing as compared to the case of implantation of other types of ions into aluminum oxide. The fan-like behavior of the dose-dependent absorption spectra is a consequence of the defect-induced disordering of crystal lattices. It is determined that intrinsic radiation-induced defects, substitutional defects, complexes containing them, and Co nanoparticles have an influence on the parameters of the focal point of the absorption spectra. The parameters of the interband and exponential absorption demonstrate the formation of a new multidefect material with a band gap width ranging from 5.3 to 5.5 eV and an absorption edge at 2.0–5.2 eV caused by the localized states of defect clusters. 相似文献
18.
作为航天器电源系统的重要组成部分,太阳电池需要更高的转换效率和可靠性以及更长的使用寿命。通过在太阳电池表面覆盖抗辐照玻璃盖片,可以增强太阳电池对粒子辐射的防护,延长太阳电池的服役寿命,使航天器获得可靠的能源供应。硼硅酸盐玻璃就是一种理想的太阳电池玻璃盖片材料。采用蒙特卡罗方法,结合SRIM软件模拟研究质子辐照硼硅酸盐玻璃的损伤物理机理。基于粒子与物质相互作用的理论以及基本公式,通过分析不同入射能量的质子在硼硅酸盐玻璃中的阻止本领、电离能损、位移能损、空位的产生情况,对辐照损伤的物理机制进行研究。结果表明:能量为30~120 keV的质子辐照损伤主要发生在硼硅酸盐玻璃表面;质子沉积、空位分布等均为Bragg峰型分布;电离能损是能量损失的主要部分,随入射能量的增加而增大,导致电子的电离和激发;位移能损在玻璃内部随能量降低而增大,导致硼、氧和硅等空位缺陷的产生;电离效应和缺陷的产生是硼硅酸盐玻璃色心形成的重要原因。 相似文献
19.
Feroz A. Mir Sajad A. Rather Ishfaq A. Wani Javid A. Banday Shoukat H. Khan 《辐射效应与固体损伤》2013,168(11):906-912
Plant-isolated compounds, Osthol [7-methoxy-8-(3-methylbut-2-enyl) coumarin], were subjected to modification in the isopentenyl side chain to get an aldehyde of 2-methyl-4 (7-methoxy-2-oxo-2H-chromen-8-yl)-but-2-en-1-al. This modified compound was exposed to γ-radiation produced by 137Cs source at room temperature. Pre- and post-irradiation study was carried out by ultraviolet–visible spectroscopy. The compound shows a sharp absorption peak at 322?nm. This observed absorption band decreases with irradiation up to a certain dose and then increases with a further increase in the radiation dose. This compound exhibits almost a linear response up to 7?Gy. From the optical data analysis, this compound follows indirect allowed transition and the optical gap was found around 3.58?eV. The systematic decrease in the band gap was found with an increase in the radiation dose. Urbach energy is also found to decrease with radiation. This parameter gives a clear indication of the defects and free radical created in the system after irradiation. The present features shown by this compound may be exploited as sensitive dosimeter in 0–7?Gy γ-radiation environment. 相似文献