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LiMgPO4:Re3+ 材料的制备及其在辐射剂量测量方面的应用
孔熙瑞
学位类型硕士
导师陈朝阳
2018-05-24
学位授予单位中国科学院大学
学位授予地点北京
学位专业材料物理与化学
关键词Limgpo4 稀土元素:光激励发光 辐射检测
摘要

光激励发光(OSL)剂量监测技术是一种具有很好发展潜力的辐射剂量检测技术,该技术是基于荧光材料所具有的荧光发光强度与辐照剂量成正比的特性来确定辐照剂量的。由于该方法具有灵敏度高、可测量范围宽、可在线测量等众多优点,所以在空间剂量监测、核设施剂量监测、放射医疗等领域具有很好的应用前景。稀土元素掺杂的复式正磷酸盐是国际上最新出现的一种光激励发光材料,具有灵敏度高、性能稳定、制备方法相对简单等特点。本文针对光激励发光辐射测量技术的发展需求,研究了LiMgPO4:Tb3+ 陶瓷材料,LiMgPO4:Eu3+ 陶瓷材料和 LiMgPO4:Tb3+ 透明材料的制备方法及其发光和 γ 射线辐射剂量学特性,对其实用性能进行了对比,以开发出作为潜在的光激励发光材料应用在医学和个人辐射剂量计,为搭建后续的以光纤为基的实时在线辐射剂量平台提供了许多必要材料剂量学方面信息。 本研究工作中通过改进烧结过程成功地合成了具有光滑表面的 LiMgPO4:Tb\Eu, B 陶瓷材料。在第二次成瓷烧结过程中,MgO 坯体被用作样品的垫片和覆盖物,从而使得圆片样品具有两个光滑的平面。此外我们获得了一些重要的 OSL 剂量学参数,这些参数为开发合适的在线剂量检测方法提供了必要的参考。LiMgPO4:Tb,B 剂量片的 OSL 信号的衰减速度比商业 Al2O3:C 要快得多,该信号强度只需要 1 秒就能降低到初始值的 10%。此外辐照剂量率 (至少在 0.1 Gy / s以下) 对OSL信号几乎没有影响。当采用蓝光退火时间超过35秒以后,之前检测的较高剂量 (10 Gy)所带来的残留将不会对下一次较低剂量的检测 (约 0.1 Gy) 带来明显的影响。结果表明,在低剂量检测条件下,漂白时间可以大大缩短,有效缩短工作周期。当总电离剂量达到 30kGy 时,材料将达到其使用寿命。除此之外,LiMgPO4:Tb3+ 透明材料具有良好的透光性能,据我们所知这是第一次制备出透明的磷酸镁锂单晶材料。由于该材料不会阻止发射光和荧光灯的传播,所以获得的 OSL 信号可以较为完全地穿透材料。因此,这种材料的辐射剂量灵敏度是不透明的多晶陶瓷材料的 18.4 倍。正磷酸盐透明材料的出现将有助于 OSL 辐射测量和剂量探测器的发展。

其他摘要

Optical stimulated luminescence (OSL) dose monitoring technique is a kind of radiation dose detection technique with great potential, which is based on the characteristic that fluorescence luminescence intensity is proportional to irradiation dose to determine irradiation dose. Due to its faster and multiple readouts and higher sensitivity, the OSL technique has been successfully applied for personnel dosimetry, environmental dosimetry, medical dosimetry and space dosimetry. The rare earth elements doped orthophosphate materials are the new kind of OSL material used for dose meter, which has the characteristics of high sensitivity, stable performance and relatively simple preparation method. In this paper, the preparation methods of LiMgPO4:Tb3+ ceramic material, LiMgPO4:Eu3+ ceramics and LiMgPO4:Tb3+ transparent materials and their luminescent and gamma radiation dosimetry characteristics have been investigated. The practical properties were compared in order to develop a potential luminescent material used as a medical and personal radiation dosemeter. It provides many necessary materials and dosimetry information for building a real-time online radiation dosemetry based on fiber. In this study, LiMgPO4:Tb\Eu, B ceramic disc with smooth surfaces was synthesized successfully via improved sintering process. Moreover, in this method, MgO bodies are used as cushion and cover for the sample, which enables the disc sample has two flat and smooth surfaces. And these essential OSL parameters we acquired provide a valuable reference to developing a suitable on-line dose detection method. The OSL signal of LiMgPO4:Tb, B disc attenuates much faster than that of commercial Al2O3:C. It costs only 1 s to reduce the intensity to 10%. The factor of dose rate (under 0.1 Gy/s at least) does almost no influence on OSL signal with a range of 1 Gy to 10 Gy. The residue created by the previous detection of a higher dose (10 Gy) will do not any influence on next lower-dose detection (0.1 Gy) when the bleaching time is longer than 35 s. As a result, under the condition of low dose detection, the bleaching time could get to be drastically shortened, which can reduce the work cycle effectively. The material would reach its service life when the total-ionizing dose runs up to 30 kGy. To the best of our knowledge, the mono-crystal sample of LiMgPO4: Tb3+ with a great transparency property has been synthesized via melt crystallization method successfully at the first time. Besides, because this material would do not any prevention of the transmission of emitting light and fluorescent light, the OSL signal can penetrate through the transparent material with a tiny loss. As a result, the dose-response rate of this material is remarkably higher (about 18.4 times larger) than that of opaque polycrystal. These better results of transparent material will contribute to the development of OSL radiation measurements and dose detector.

文献类型学位论文
条目标识符http://ir.xjipc.cas.cn/handle/365002/5429
专题材料物理与化学研究室
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孔熙瑞. LiMgPO4:Re3+ 材料的制备及其在辐射剂量测量方面的应用[D]. 北京. 中国科学院大学,2018.
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