The positron lifetime spectroscopy and Doppler-broadening measurements indicate that there alwaysare some V-type defects in FZ Si during annealing from room temperature to 1150℃ . In NTD (neutrontransmutation doped) ...The positron lifetime spectroscopy and Doppler-broadening measurements indicate that there alwaysare some V-type defects in FZ Si during annealing from room temperature to 1150℃ . In NTD (neutrontransmutation doped) Si irradiated by 6×10￣(16) neutrons/ cm￣2 the main defect is V-type, the V_2 defectshave only an intensity of 7.3% and anncal out at the temperature lower than 200℃ . In NTD Si irradiatedby 1.2×10￣(18) neutrons/cm￣2 the intensities due to V- and V_2type defects are 59% and 35%. The formerdisappears at 55℃ . the latter increases above 200℃ , decreases greatly above 550℃ , and disappears at650℃ . In addition, V_4 appears at 125～200℃, V_4 and / or V_5 defects at 400～600℃ in high-dose irradiated NTD Si. It seems that radiation doses have a bigger influence on the formation and annealing behaviorof secondary V_2type defects. Above 700℃ a lot of dislocations and / or monovacancy-type defects are formed.展开更多
In this paper, the damage to methyl silicone rubber induced by irradiation with protons of 150 keV energy wasstudied. The surface morphology, tensile strength, Shore hardness, cross-linking density and glass transitio...In this paper, the damage to methyl silicone rubber induced by irradiation with protons of 150 keV energy wasstudied. The surface morphology, tensile strength, Shore hardness, cross-linking density and glass transition temperaturewere examined. Positron annihilation lifetime spectrum analysis (PALS) was perfomed to reveal the damage mechanisms ofthe rubber. The results showed that tensile strength and Shore hardness of the rubber increased first and then decreased withincreasing irradiation fluence. The PALS characteristics τ_3 and I_3, as well as the free volume V_f, decreased with increasingirradiation fluence up to 10^(15) cm^(-2), and then increased slowly. It indicates that proton irradiation causes a decrease of freevolume in the methyl silicone rubber when the fluence is less than 10^(15)cm^(-2), while the free volume increases when thefluence is greater than 10^(15)cm^(-2). The results on cross-linking density indicate that the cross-linking induced by protonirradiation is dominant at smaller proton fluences, increasing the tensile strength and Shore hardness of the rubber, while thedegradation of rubber dominates at greater fluence, leading to a decrease of tensile strength and Shore hardness.展开更多
SILICON is a quite important material in the application of energy resources technology. With the development of ion-implantation technique and the increasing interest in dopping, it is very important to know the rela...SILICON is a quite important material in the application of energy resources technology. With the development of ion-implantation technique and the increasing interest in dopping, it is very important to know the relationship between the vacacies induced by the particle irradiation damage and the annealing temperature. The positron annihilation is a very useful method for studying defects in the semiconductor, because the annihilation characteristics of trapped positron are influenced by the charge of the defects. It has been shown that the positrons can be trapped by defects created by irradi-展开更多
Void swelling,which induces the degradation of the original properties of nuclear materials under high-energy particleirradiation,is an important problem.The incubation period,a transient stage before the steady void ...Void swelling,which induces the degradation of the original properties of nuclear materials under high-energy particleirradiation,is an important problem.The incubation period,a transient stage before the steady void growth,determines the duration of service of nuclear materials.Several experimental studies have been performed on void observations by transmission electron microscopy(TEM),which,however,has a resolution limit for the size of defect clusters.Positron annihilation lifetime spectroscopy(PALS)enables the detection of small vacancy clusters,single vacancies,dislocations and precipitates.The use of these two methods provides complementary information toward detecting defect information in the incubation period.Here,defect structures during the incubation period in austenitic stainless steels,by means of PALS and TEM are reviewed.The role of alloying elements into determining the period is explained.Furthermore,the existing problems and research directions in this field are presented.展开更多
文摘The positron lifetime spectroscopy and Doppler-broadening measurements indicate that there alwaysare some V-type defects in FZ Si during annealing from room temperature to 1150℃ . In NTD (neutrontransmutation doped) Si irradiated by 6×10￣(16) neutrons/ cm￣2 the main defect is V-type, the V_2 defectshave only an intensity of 7.3% and anncal out at the temperature lower than 200℃ . In NTD Si irradiatedby 1.2×10￣(18) neutrons/cm￣2 the intensities due to V- and V_2type defects are 59% and 35%. The formerdisappears at 55℃ . the latter increases above 200℃ , decreases greatly above 550℃ , and disappears at650℃ . In addition, V_4 appears at 125～200℃, V_4 and / or V_5 defects at 400～600℃ in high-dose irradiated NTD Si. It seems that radiation doses have a bigger influence on the formation and annealing behaviorof secondary V_2type defects. Above 700℃ a lot of dislocations and / or monovacancy-type defects are formed.
文摘In this paper, the damage to methyl silicone rubber induced by irradiation with protons of 150 keV energy wasstudied. The surface morphology, tensile strength, Shore hardness, cross-linking density and glass transition temperaturewere examined. Positron annihilation lifetime spectrum analysis (PALS) was perfomed to reveal the damage mechanisms ofthe rubber. The results showed that tensile strength and Shore hardness of the rubber increased first and then decreased withincreasing irradiation fluence. The PALS characteristics τ_3 and I_3, as well as the free volume V_f, decreased with increasingirradiation fluence up to 10^(15) cm^(-2), and then increased slowly. It indicates that proton irradiation causes a decrease of freevolume in the methyl silicone rubber when the fluence is less than 10^(15)cm^(-2), while the free volume increases when thefluence is greater than 10^(15)cm^(-2). The results on cross-linking density indicate that the cross-linking induced by protonirradiation is dominant at smaller proton fluences, increasing the tensile strength and Shore hardness of the rubber, while thedegradation of rubber dominates at greater fluence, leading to a decrease of tensile strength and Shore hardness.
文摘SILICON is a quite important material in the application of energy resources technology. With the development of ion-implantation technique and the increasing interest in dopping, it is very important to know the relationship between the vacacies induced by the particle irradiation damage and the annealing temperature. The positron annihilation is a very useful method for studying defects in the semiconductor, because the annihilation characteristics of trapped positron are influenced by the charge of the defects. It has been shown that the positrons can be trapped by defects created by irradi-
文摘Void swelling,which induces the degradation of the original properties of nuclear materials under high-energy particleirradiation,is an important problem.The incubation period,a transient stage before the steady void growth,determines the duration of service of nuclear materials.Several experimental studies have been performed on void observations by transmission electron microscopy(TEM),which,however,has a resolution limit for the size of defect clusters.Positron annihilation lifetime spectroscopy(PALS)enables the detection of small vacancy clusters,single vacancies,dislocations and precipitates.The use of these two methods provides complementary information toward detecting defect information in the incubation period.Here,defect structures during the incubation period in austenitic stainless steels,by means of PALS and TEM are reviewed.The role of alloying elements into determining the period is explained.Furthermore,the existing problems and research directions in this field are presented.
