制备条件对铽掺杂硅酸镁磷光体热释光特性的影响

Magnesium silicate doped with terbium was reported as one of the most sensitive thermoluminescence dosimetry materials. However, Mg2SiO4: Tb has not been widely used in application because its thermoluminescence characteristics are not stable and vary with preparation conditions. The project here aims to figure out how the thermoluminescence characteristics change with preparation conditions, such as chemical components, baking temperature, particle size and annealing temperature etc. In order to obtain the information, we will prepare the samples by high temperature solid phase and sol-gel method respectively and then collect glow curves to see the difference among the samples. Meanwhile, thermoluminescence spectra of both low and high temperature range would be obtained together with X-ray and electron crystallography. The optimized process of sample preparation would be selected and we will try to build up a full image of thermoluminescence mechanic model of magnesium silicate. The project seeks to provide information for the preparation of the excellent performance of high sensitivity thermoluminescence dosimeter so that it can be widely used in radiation monitoring, especially low dose radiation range.

铽掺杂的硅酸镁剂量计是已知灵敏度最高的热释光剂量计之一，但是由于其热释光特性不稳定，受制备条件影响大，从而使这种热释光剂量计并没有受到足够的重视。本项目拟采用高温固相法和溶胶-凝胶两种方法制备铽掺杂的硅酸镁磷光体，研究化学组分、焙烧温度、粒径、退火温度等因素对铽掺杂的硅酸镁热释光剂量计发光特性的影响规律，找到影响其稳定性的关键因素，并结合高低温范围内的热释光光谱和微观表征手段来研究影响热释光发光的具体机理，从而给出最优化的制备方案。本项目的研究结果将为制备性能优良的高灵敏度热释光剂量计提供实验数据和理论依据，使其能够广泛应用于辐射监测，尤其是低剂量辐照监测。

铽掺杂的硅酸镁剂量计的灵敏度高，但是其热释光特性受制备条件影响大。针对这一问题，本项目采用高温固相法，通过改变制备条件，研究了焙烧温度，焙烧时间，掺杂量等因素对铽掺杂的硅酸镁热释光剂量材料发光特性的影响规律，测量了样品的微观结构，收集了样品在20-673K范围内的热释光三维光谱和X射线激发光谱，全面研究了铽掺杂硅酸镁的热释光发光特性，并给出了理论解释。研究表明，焙烧温度是影响样品灵敏度最关键的因素，掺杂浓度过多会出现浓度猝灭现象。另外，在研究过程中，本项目通过比较了铕掺杂硅酸镁和铽掺杂硅酸镁的热释光峰温出现的位置，找到了稀土离子尺寸和热释光峰温变化的规律，发现不同能级跃迁产生的稀土特征峰在热释光发光曲线中出现的位置有差异，而且找到这种差异和具体的跃迁能级之间的对应关系。这些研究结果对于制备优质的铽掺杂硅酸镁剂量计有很好的实际借鉴意义，对研究稀土掺杂发光材料的发光机理都有着重要的理论意义。