关键词: E’心缺陷, 预辐照, 高温退火, 玻璃辐照损伤, 抗辐照性能

Abstract:

Silica glass and optical fibers are widely utilized in critical applications such as nuclear industry monitoring systems and remote sensing satellites due to their exceptional optical properties and robust radiation resistance. However， exposure to intense radiation can induce the formation of color center defects within the quartz glass matrix， which severely compromises its optical performance. Strategies to enhance the radiation resistance of glass materials are broadly categorized into pre-treatments and post-treatments. Pre-treatments improve material properties directly or indirectly via doping， gas loading and other techniques. Post-treatment approaches utilize photo-bleaching or thermal bleaching to facilitate the transformation or annihilation of radiation-induced color center defects， with thermal bleaching being extensively adopted due to its procedural simplicity and broad applicability. The pre-irradiation method employs a combination of initial irradiation and subsequent thermal annealing to eliminate the detrimental effects of precursor defects， thereby enhancing overall radiation resistance. Despite its potential， the optimal temperature ranges and annealing parameters require further clarification， and there is a noticeable lack of systematic comparative studies concerning defect evolution mechanisms under various annealing conditions. Based on pre-irradiation experiments， this study systematically investigates the formation dynamics of γ-irradiation-induced color center defects and the underlying mechanisms by which different high-temperature annealing behaviors influence radiation resistance.γ-irradiation experiments were conducted on a 1.25 MeV ??Co source platform at the China institute of atomic energy. The irradiation dose rate was maintained at 2 kGy/h， with total doses established at 1， 10， and 100 kGy. A systematic series of annealing treatments was subsequently conducted： room-temperature dark annealing for durations of 1， 3， and 6 months； high-temperature annealing in both air and hydrogen atmospheres at 400， 600， 800， and 1 000 ℃； and variable-duration isothermal annealing at 800 ℃ in an air atmosphere for 10， 20， 30， and 40 min. The annealed samples were then subjected to secondary irradiation at 2 kGy/h up to a total dose of 100 kGy. Changes in optical transmittance， alongside the types and concentrations of structural defects， were characterized using ultraviolet-visible （UV-Vis） spectrophotometry and electron paramagnetic resonance （EPR） spectroscopy.The experimental results demonstrate that γ-irradiation predominantly induces the generation of E’ center defects （g₁=2.004 4， g₂=2.003 5， g₃=2.003 1）， along with a minor presence of non-bridging oxygen hole centers （NBOHC）. When the total irradiation dose reached 100 kGy， the sample exhibited a maximum transmittance degradation of 23.5% （primarily located in the ultraviolet band）， while the E’ center concentration escalated to 2.228×10¹⁶ spins/g. Room-temperature annealing over a period of 6 months resulted in a marginal transmittance recovery of only 5.1%， primarily attributed to the gradual annihilation of NBOHC defects. In contrast， high-temperature annealing yielded significant restorative effects. The optimal treatment was identified as annealing at 800 ℃ in an air atmosphere， which improved the sample’s transmittance by 21.23% relative to its post-irradiation state. Crucially， following secondary irradiation， the transmittance of the samples annealed in air at 800 ℃ was 7.5% higher than their transmittance after the primary irradiation. Conversely， although annealing in a hydrogen atmosphere could successfully reduce defect concentrations in the short term， the newly formed Si-H bonds proved highly unstable and easily fractured during secondary irradiation， ultimately exacerbating the overall radiation damage.From the dual perspectives of optical performance and microstructural defect evolution， this paper systematically elucidates the mechanisms through which pre-irradiation methods under varying conditions impact the radiation resistance of quartz glass. These findings provide experimental foundation and theoretical reference for extending the operational service life of optical glass and fiber materials deployed in severe radiation environments.

Key words: E’ center, pre-irradiation, high temperature annealing, irradiation damage of glass, radiation resistance