掺碳氧化铝晶体和陶瓷的制备及其热释光和光释光性能研究

发布时间：2018-03-31 12:51

本文选题：α-Al_2O_3:C晶体　切入点：α-Al_2O3:C陶瓷　出处：《昆明理工大学》2015年硕士论文

【摘要】：α-Al2O3:C晶体具有优异的热释光和光释光性能,在辐射剂量学领域,特别是光释光剂量学量领域有着十分重要的应用。目前,α-Al2O3:C释光探测器研究方面主要存在两个问题：第一,市场上的晶体生长方法单一(提拉法),晶体探测器价格昂贵,影响推广使用；其次,学术上,碳原子在α-Al2O3晶格中的位置和价态还存在分歧,碳元素在剂量学性能中的真实作用还存在争议。目前国内还鲜有开展有关α-Al2O3:C晶体的生长和剂量学方面的研究工作。本论文从α-Al2O3:C晶体探测器材料的实际需要出发和以目前国内外研究中存在的问题为出发点,主要开展以下两种材料的释光探测器研究工作：(1)晶体探测器的制备：采用导模法(EFG法)快速生长450×120×10mm α-Al2O3:C晶体,通过定向切割、研磨和抛光获得a方向5x5×lmm的α-Al2O3:C晶体探测器。晶体生长以6N高纯碳粉和5N高纯氧化铝粉为原料,成功生长了碳掺杂量为5000ppm的α-Al2O3:C晶体。研究了不同种类辐射源(β、241Am、137Cs、60Co)对晶体的热释光和光释光性能的影响。在中国计量科学院采用我们自己制备的α-Al2O3:C晶体探测器测得1μGy热释光的剂量响应信号,为世界目前己知的最高精度；低能量射线辐照时α-Al2O3:C晶体表现更高的热释光灵敏度为目前普遍使用的LiF(Mg, Cu, P)的3.5倍；高浓度碳掺杂(检测碳含量大于5000ppm)α-Al2O3:C晶体的主热释光峰温为255℃(即518K)附近,TL峰温随辐射剂量的增加向低温方向移动,为二级动力峰,低浓度碳掺杂(检测碳含量大约3000ppm)α-Al2O3:C晶体时主热释光峰温为190℃(463K)附近,TL峰温不随辐射剂量变化而变化,为一级动力学峰；碳掺杂浓度高的晶体晶格发生畸变,使晶体的陷阱能级也有所变化。在低辐射剂量下,不同辐照射线α-Al2O3:C晶体的TL和OSL响应曲线都呈良好线性,低能量射线241Am(58KeV)辐照时晶体的热释光灵敏度是高能量射线137Cs(660KeV)和60Co(1025KeV)3倍左右,137Cs(660KeV)和60Co(1025KeV)热释光和光释光灵敏度则很相近。(2)陶瓷探测器的制备：利用真空烧结法制备了α-Al2O3:C陶瓷,切割后获得5x5xlmm的α-Al2O3:C陶瓷探测器。实验结果表明：1850℃C烧结的α-Al2O3:C陶瓷具有最优的TL和OSL性能,其剂量学性能约为导模法生长的α-Al2O3:C晶体的60%。α-Al2O3:C陶瓷主热释光峰温为200℃C(473K)附近,TL峰温不随辐射剂量变化而变化,为一级动力学峰；OSL衰减曲线呈指数衰减,前期衰减很快,10s内衰减50%以上,但其衰减速率不如晶体10s内衰减90%以上,而后期衰速率逐渐变慢；光释光强度随辐照剂量增加而增强；在低辐射剂量(100-1000μGy)下,不同辐照射线α-Al2O3:C陶瓷的TL和OSL响应曲线都呈良好线性,低能量射线241Am(58KeV)辐照时陶瓷的热释光灵敏度是高能量射线137Cs(660KeV)和60Co(1025KeV)2-2.5倍左右,137Cs(660KeV)和60Co(1025KeV)热释光和光释光灵敏度相差不大；且α-Al2O3:C陶瓷的光释光(OSL)响应性能优于α-Al2O3:C晶体,其制备更简单,所需时间更短,在剂量学领域具有潜在的应用前景。与提拉法生长的α-Al2O3:C晶体相比,导模法生长的α-Al2O3:C晶体具有生长速度快、成本低的优点。真空烧结法制备的α-Al2O3:C陶瓷作为一种新型探测器材料,采用陶瓷工艺,可以在低于熔点的温度下进行烧结,同时可以很方便地实现C的掺杂,探测器一致性好,生产成本低、效率高、激活离子掺杂浓度高且可控并可以制造大尺寸和形状复杂的样品,适宜批量生产。导模法生长α-Al2O3:C晶体生长时间约为2天,而真空烧结法制备的α-Al2O3:C陶瓷需36小时。
[Abstract]:A -Al2O3:C crystal has excellent thermoluminescent and photoluminescent properties, especially in the field of radiation dosimetry, photoluminescent dosimetry field application is very important. At present, alpha -Al2O3:C release optical detector research there are two main problems: first, the market of the single crystal growth method (Tirafa). The crystal detector is expensive, to promote the use of influence; secondly, the academic, carbon atoms in the alpha -Al2O3 lattice position and valence differences still exist, the real effect of carbon in the dosimetric performance in the current research work is still controversial. There are few growth and development related to alpha -Al2O3:C crystal dosimetric aspects. This thesis from the actual needs of alpha -Al2O3:C crystal detector materials at home and abroad and starting to study the problem as a starting point, mainly carried out the following two materials luminescence detector research work: (1) crystal The detector body prepared by EFG method (EFG method) the rapid growth of 450 x 120 x 10mm alpha -Al2O3:C crystal, directed by cutting, grinding and polishing to obtain alpha crystal -Al2O3:C detector a 5x5 * LMM. The direction of crystal growth by 6N high pure 5N powder and high purity aluminum oxide powder as raw material, long life success carbon doped alpha -Al2O3:C 5000ppm crystal. The effects of different kinds of radiation sources (beta, 241Am, 137Cs, 60Co) light and release effect of light on the performance of crystal pyroelectric. Using our own system of alpha crystal -Al2O3:C detector were measured 1 Gy thermoluminescence dose response signal in Chinese measurement Academy of Sciences, the highest accuracy of the world currently known; low energy X-ray irradiation at alpha -Al2O3:C crystal shows higher TL sensitivity for the current widespread use of LiF (Mg, Cu, P) 3.5 times; high concentration carbon doping (detection of carbon content is more than 5000ppm) main heat alpha -Al2O3: C crystal The luminescence peak temperature of 255 degrees (518K) near the TL peak temperature with the increase of radiation dose to the low temperature direction, two power peaks, low concentration of carbon doping (detection of carbon content of about 3000ppm) alpha -Al2O3:C crystal when the main thermoluminescence peak temperature of 190 degrees (463K) near the peak temperature of TL does not vary with the change of radiation dose, a kinetic peak; crystal lattice of carbon doped high concentration of distortion, the trap level crystal is changed. At low doses of radiation, different radiation ray alpha -Al2O3:C crystal TL and OSL response curves showed good linearity, low energy ray 241Am (58KeV when the crystal irradiated) thermoluminescence sensitivity is high energy X-ray 137Cs (660KeV) and 60Co (1025KeV) 3 times, 137Cs (660KeV) and 60Co (1025KeV) Tl and OSL sensitivity were similar. (2) ceramics preparation: alpha -Al2O3:C ceramics prepared by vacuum sintering after cutting by method. The 5x5xlmm alpha -Al2O3:C ceramic detector. The experimental results show that the alpha -Al2O3:C ceramic C 1850 degrees sintering has the best TL and OSL performance, the dosimetric performance is about 60%. alpha -Al2O3:C alpha -Al2O3:C main heat ceramic crystal growth method of the guided mode luminescence peak temperature is 200 DEG C (473K) near the peak temperature of TL does not vary with the change of radiation dose, a kinetic peak; OSL attenuation curve decays exponentially, the early decay quickly, 10s attenuation in more than 50%, but the decay rate of 10s crystal as attenuation in more than 90%, while the late decline rate gradually slows down; OSL intensity increases with the increasing of irradiation dose and the enhancement; low radiation dose (100-1000 Gy), different radiation ray alpha -Al2O3:C ceramics TL and OSL response curves showed good linearity, low energy X-ray 241Am (58KeV) irradiation ceramic thermoluminescence sensitivity is high energy X-ray 137Cs (660KeV) and 60Co (1025KeV) 2-2.5 times. Right, 137Cs (660KeV) and 60Co (1025KeV) Tl and OSL sensitivity difference; and a -Al2O3:C ceramic photoluminescent (OSL) response performance is better than that of alpha -Al2O3:C crystal, its preparation is simpler, shorter time, has a potential application prospect in the field of -Al2O3:C. Compared to alpha crystal dosimetry with the growth of Czochralski crystal growth, a -Al2O3:C guided mode method has a fast growth rate, and low cost advantages. Prepared by vacuum sintering of alpha -Al2O3:C ceramics as a new type of detector materials, using ceramic technology, can be sintered at temperatures below the melting point, and can easily achieve the doping of C detector good consistency, low production cost, high efficiency, high concentration doped and controllable and complex manufacturing large size and shape of the sample, suitable for mass production. EFG growth alpha -Al2O3:C crystal growth time is about 2 days, and vacuum Alpha -Al2O3:C ceramics prepared by 36 hours.

【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O614.31;TQ174.7

【共引文献】