SrSO4:Eu磷光体的光释光特性

研究了通过掺杂得到的SrSO4:Eu(0.1mol%)的粉末样品的光释光(OSL)特性.用90Sr的β射线辐照0.116-1.16kGy后,测定了恒定光源激发的光释光发光曲线(CW-OSL)和线性光源激发的光释光发光曲线(LW-OSL),对发光曲线分析均得到了四种陷阱成分.采用复合作用响应函数得到SrSO4:Eu辐射剂量响应为线性-亚线性.测量了温度对OSL信号的影响,结果表明OSL信号的温度稳定性很好,最灵敏读出温度约为180℃,说明这时OSL信号来自热激发和光激发的共同作用.用60Coγ辐照100Gy后,测量了热释光(TL)三维光谱,确定了发光波长主要位于375nm,可以确定这是来自于Eu2+能级跃迁的发光.     

热释光和光释光发光谱的测量

介绍了自行研制的计算机化热释光和光释光三维光谱测量装置的系统结构及其工作原理.在计算机的控制下,通过精密加热器或激发光源以热激发或光激发的方式使样品发光.从样品发出的光经过光路和光栅分光系统后,形成光谱,被高灵敏度的CCD采集,再将光谱图像模拟信号变为可以直接用计算机进行数据处理的数据信号.波长范围200~800nm,波长分辨率优于2nm,人机界面友好,操作方便.利用热释光和光释光三维光谱测量装置测量了SrSO₄:Eu(0.1%,摩尔分数)和CaSO₄:Eu(0.1%,摩尔分数)的光释光发光谱和热释光发光谱,得到SrSO₄:Eu的光释光发光波长与热释光发光波长均为375nm,而CaSO₄:Eu的光释光发光波长与热释光发光波长均为385nm,说明热释光和光释光具有相同的发光中心,均来自于Eu²⁺的能级跃迁.同时在CaSO₄:Eu的热释光发光谱中还观察到了Eu³⁺的发光.与二维发光曲线相比较,通过对三维热释光和光释光发光谱的研究,可以得到更丰富的信息,这有助于对热释光和光释光发光机制进行更深入的研究.     

LiMgPO_4:Tm,Tb的热释光和光释光陷阱参数

采用高温固相法合成了LiMgPO_4:Tm,Tb粉末样品,测定了热释光陷阱参数激发能E和频率因子s.用脉冲退火和多次退火方法研究了其光释光陷阱参数E和s,并与用多速法得到的热释光的结果进行了比较.对不同β射线剂量照射的样品发光曲线的研究表明,300°C高温峰属于一级动力学发光峰.通过对热释光和光释光陷阱的相关性研究表明,经200°C预热的热释光信号(对应于300°C高温峰)和光释光信号很有可能来自于同一深度的陷阱.     

α-Al2O3单晶的热释光和光释光特性

研究了纯α-Al2O3单晶的热释光发光曲线和三维发光谱,以及光释光衰变曲线,对它们的发光机理和剂量学特性进行了分析和讨论.实验观察到α-Al2O3单晶β射线照射后立即测量的热释光发光曲线,有峰温为76℃和207℃两个发光峰.经γ射线照射数小时后测量的三维发光谱,只有峰温207℃波长为416 nm发光峰,它与α-Al2O3:C晶体的发光波长基本相同,是受热激发到导带的电子与F+心复合所生成的F心激发态3P跃迁至基态1S发的光.用热释光动力学方程拟合不同照射剂量的发光曲线,207 ℃发光峰的峰温基本不随剂量而变化,形状因子μg的平均值为0.415±0.001,该发光峰的剂量响应为线性-亚线性,表明它基本符合一级动力学模型所预言的发光峰.实验还测定了纯α-Al2O3单晶辐照不同剂量后,470 nm波长激发的光释光衰变曲线.用两个指数衰变函数拟合光衰变曲线得到的衰变时间常数τ1(平均值为2.63±0.07s)基本不随剂量而变化,而τ2则在0.12至12 Gy范围内有明显下降趋势,大于12 Gy时无明显变化,约75s.时间常数τ1对应的光释光强度和吸收剂量的关系为线性-亚线性.     

不同退火温度的Al_2O_3:C薄膜热释光和光释光性能

α-Al_2O_3:C晶体的热释光和光释光性能优越,但其制备要求高,需高温和高还原气氛.与α-Al_2O_3:C晶体性能接近的α-Al_2O_3:C陶瓷,热释光峰不单一.本文采用两次阳极氧化法在0.5 mol/L的草酸溶液中5℃恒温制备高度均匀有序的多孔Al_2O_3:C薄膜,主要研究不同退火温度对其热释光和光释光特性的影响.结果表明,经不同温度退火后的Al_2O_3:C薄膜均为非晶结构;不同退火温度的Al_2O_3:C薄膜热释光的主发光峰约在310℃左右,符合通用级动力学模型.600℃退火后的Al_2O_3:C薄膜热释光灵敏度最强,其热释光剂量曲线在1-10 Gy范围内具有很好的线性响应,在剂量10-120 Gy范围内出现超线性响应;在相同的辐照剂量下,随着退火温度的升高(≤600℃)光释光的初始发光强度逐渐增强.不同退火温度的Al_2O_3:C薄膜光释光衰减曲线都呈典型的指数衰减且快衰减速率相比α-Al_2O_3:C晶体显著加快.600℃退火后的Al_2O_3:C薄膜光释光灵敏度最强,其光释光剂量响应曲线在1-200 Gy整体上都具有很好的剂量线性关系.与热释光相比,Al_2O_3:C薄膜的光释光具有更宽的线性剂量响应范围.此研究为Al_2O_3:C薄膜作为光释光辐射剂量材料做出了有益的探索.     

CaSO4∶Eu磷光体的热释光特性研究

用热释光三维发光谱仪和蓝色滤光片的热释光仪测定了CaSO4:Eu2+的辐照后的发光曲线,得到峰温为107和144℃波长390nm的发光峰.辐照50d后,107℃发光峰已衰退,发光曲线呈现144℃单个发光峰.经一级力学方程式拟合得到的激活能E=(1.02±0.03)eV与初始升温法(1.07±0.01)eV和峰形法(1.02±0.01)eV的非常符合.用通用级动力学模型拟合发光曲线,得到陷阱能级E=(1.04±0.01)eV,频率因子s=(2.07±0.8)×1012s-1和动力学级数b=1.05±0.02 关键词： CaSO4∶Eu 剂量响应 动力学参量 热释光     

α-Al2O3单晶的热释光和光释光特性

研究了纯α-Al₂O₃单晶的热释光发光曲线和三维发光谱，以及光释光衰变曲线，对它们的发光机理和剂量学特性进行了分析和讨论.实验观察到α-Al₂O₃单晶β射线照射后立即测量的热释光发光曲线，有峰温为76℃和207℃两个发光峰.经γ射线照射数小时后测量的三维发光谱，只有峰温207℃波长为416 nm发光峰，它与α-Al₂O₃:C晶体的发光波长基本相同，是受热激发到导带的电子与F< 关键词： 2O₃')" href="#">α-Al₂O₃ 三维发光谱 TL/OSL剂量响应     

BaCl2:Eu和BaCl2·2H2O:Eu微晶的发光特性

本文研究了用还原气氛法在箱式炉内制得的BaCl2:Eu2+微晶及进一步处理后得到的BaCl2·2H2O:Eu2+微晶的发光特性,包括发射光谱、激发光谱、热释光、光激励发光(存贮效应)及其温度依赖,就这些特性对BaCl2:Eu与BaCl2·2H2O:Eu进行了比较.根据发光光谱与激发光谱分析了它们具有良好光致发光特性的原因,讨论了这两种材料在热释光性能及光激励发光(存贮效应)上的明显不同,并对BaCl2·2H2O:Eu2+中Eu2+发光的增强提出了可能的解释.     

一种天然正长石的释光特性

应用RGB-3B型热释光仪和BG2003释光谱仪对一种正长石矿物的热释光和选频释光发光曲线进行测定,获得正长石的释光特性。研究表明：天然正长石的三个热释光峰峰温为148,197,310 ℃,辐照一定剂量后,出现197 ℃和263 ℃两个稳定的热释光峰。正长石的峰位温度随着增温速率的减小,向左移动。选频热释光290, 300, 310, 340, 400, 480 nm存在释光响应,选频绿光释光280, 290, 300, 310, 320, 400, 460, 480 nm存在释光响应,400 nm频道的光子计数随剂量的变化具有一定的线性关系,具有辐射剂量计的特性,具备释光测年的应用潜力。     

Sr3SiO5:Eu2+和Sr3SiO5:Eu2+, Dy3+荧光粉的黄色长余辉性质

用高温固相法制备了Sr3SiO5:Eu2 和Sr3SiO5:Eu2 , Dy3 荧光粉.在紫外光辐照后, Sr3SiO5:Eu2 和Sr3SiO5:Eu2 , Dy3 荧光粉具有明亮的黄色长余辉,源于Eu2 的4f65d - 4f7的跃迁.紫外光激发停止后,Sr3SiO5:Eu2 的余辉时间是4 h以上.余辉衰减曲线和热释光曲线说明了引入Dy3 离子可以产生大量的深陷阱和浅陷阱.产生的深陷阱使余辉时间延长到6 h以上.由热释发光曲线,根据热释光的通用级公式拟合了陷阱深度.Sr3SiO5:Eu2 和Sr3SiO5:Eu2 , Dy3 荧光粉是有应用前景的黄色长余辉材料.     

Investigations of OSL properties of LiMgPO4:Tb,B based dosimeters

Lithium magnesium phosphate LiMgPO₄ (LMP) doped with Tb and B is one of new materials intended for use in optically stimulated luminescence (OSL) dosimetry. LMP doped with Tb and B luminophors were synthetized at IFJ PAN in Krakow. The investigations were carried out on self-developed dosimeters consisting of a slide with four LMP detectors and a light tight cover. LMP detectors were investigated in regard to their OSL properties using OSL reader named HELIOS adopted to the readouts of dosimetric cards. New LMP detectors showed high sensitivity to the ionizing radiation, good repeatability of OSL signal and good dose response, 25% of fading in the first two weeks after irradiation. Also, the pronounced dependence of OSL response on the energy of the measured radiation requires to apply the compensation filters.     

纳米Zn0.6CoxFe2.4－xO4晶粒的结构相变与磁性研究

采用溶胶 凝胶自燃烧法制备了纳米尺度的锌钴铁氧体Zn06CoxFe24-  xO4(x=0—030)粉体,分别在不同温度下进行了热处理，利用x射线衍射仪(XRD) 和振动样品磁强计(VSM)对其物 相结构和磁性进行了测量和分析.实验结果表明，锌钴铁氧体Zn06Co015Fe 225O4在550—800℃温度区间出现α Fe2O3过渡相，在高于800℃温度时生 成 单一尖晶石相锌钴铁氧体；随钴含量的增加，Zn06CoxFe2 关键词： 锌钴铁氧体 磁性 结构 相变 溶胶 凝胶     

Thermoluminescence and optically stimulated luminescence studies on LiMgPO4 crystallized by micro pulling down technique

LiMgPO₄ (LMP) crystals were grown by micro pulling down technique. Samples were irradiated with different β-particle doses of the ⁹⁰Sr/⁹⁰Y source. Thermally and optically stimulated luminescence spectra were measured with the automatic Risø TL/OSL-DA20 reader under the different modes of stimulation. The dose–response dependence, reproducibility, the lowest measurable dose and short-time fading were investigated. TL and OSL dose–response of LiMgPO₄ crystals was found to be linear up to around 1 kGy, what makes this material suitable for high dose measurements. Discrepancies between successive measurements did not exceed 10%, regardless of the applied growth parameters. The lowest measurable dose, defined as three standard deviations of the signal of unexposed detector, was determined around 0.5 mGy. About 73% of the initial OSL signal value was measured 24 h after the irradiation. For longer periods of time the level of signal stabilizes so that there was no further loss of signal observed. In case of TL, the level of signal does not stabilize and decreases to 69% within 2 weeks after the irradiation. The obtained results tend to suggest that LiMgPO₄ crystals may be considered as promising dosimeters for both personal and high dose dosimetry.     

Real-time luminescence from Al2O3 fiber dosimeters

The real-time luminescence signal from Al₂O₃ single crystal fibers, monitored during simultaneous irradiation and optical stimulation, was investigated using computer simulations and experimental measurements. Both radioluminescence (RL) and optically stimulated luminescence (OSL) signals were studied. The simulations were performed initially using a simple one-trap/one-recombination-center energy band model, and then extended to include shallow and deep electron traps as well. Real-time luminescence experiments were performed for different radiation dose rates and optical stimulation powers using periodic laser stimulation of the samples through a fiber optic cable, and the experimental results were compared with the predictions from the computer simulations. The luminescence signal was observed, both theoretically and experimentally, to increase from its initial value to a steady-state level. The steady-state RL and OSL levels were found to be dependent on dose rate, the steady-state level of the real-time OSL being independent of laser power. It was also shown that the total integrated absorbed dose throughout the irradiation period can be determined by correcting the real-time OSL signal for depletion caused by each laser stimulation pulse. The effects of the shallow and deep traps on the time-dependence of the real-time luminescence signal were studied comparing the experimental data from several Al₂O₃ fibers known to have different trapping state concentrations. The additional traps were found to slow the response of the real-time luminescence such that the time to reach steady state was increased as the additional traps were added.     

Radiation effects in KMgF 3 crystals

Effects of x, g and UV irradiation on Tb 3+ and Eu 2+ doped KMgF 3 crystals were studied. Thermoluminescence (TL) excited by VUV radiation was compared to that induced by x and g rays. TL excitation spectra showed maxima at 125, 140, 155 and 180 v nm. The main TL peaks appeared after VUV irradiation at about the same temperatures and with the same thermal activation energies as after x or g irradiation, indicating that these peaks are due to the same trapping levels. In samples, which had previously been exposed to ionizing radiation, TL could also be excited with longer wavelengths that could not excite any TL in un-irradiated crystals; this is attributed to a process of phototransfer (PTTL). The x and UV excited luminescence was measured at LNT and RT and showed essentially the same main emission bands that appeared in the TL and PTTL peaks of these crystals. The dose dependence of the 730 v K TL peak in of KMgF 3 :Eu 2+ was linear up to about 2000 v Gy. The TL sensitivity of KMgF 3 :Eu 2+ was by an order of magnitude higher than that of KMgF 3 :Tb 3+ , which was by a factor of two greater than that of the known TLD-l00 phosphor.     

Influence of thermal treatment on OSL regeneration in potassium chloride

Optically stimulated luminescence (OSL) of pure analytical potassium chloride (KCl) prepared in two different forms (crystals and pellets) was studied. The occurrence of regeneration effect (self-renewal of the OSL signal) in the material was examined. The experiments using the variable delay OSL (VD-OSL) method were carried out. Performed measurements allowed to determine time scale of the phenomenon, as well as quantitative changes of regeneration depending on thermal treatment before and after irradiation. Significant increase of the OSL regeneration was noticeable for pellets after the application of the annealing before irradiation, while for crystals a substantial decrease of regeneration was observed. Preheating applied after irradiation caused that self-renewal of OSL signal was drastically reduced or completely suppressed depending on the form of KCl samples.     

Luminescence sensitivity changes of polymineral fine grains during IRSL and [post-IR] OSL measurements

Sensitivity changes during measurement sequences of infra-red-stimulated luminescence (IRSL) and post-IR optically stimulated luminescence (OSL) are presented for a sample of loess from northwestern China. Together with a dose recovery experiment, the results are used to investigate the ratio of 2.4 found for the D_e values (for IRSL and [post-IR] OSL) obtained when using a single-aliquot regenerative-dose (SAR) protocol in which both D_e values are obtained in a single sequence of measurements. Responses to test doses for both the IRSL and [post-IR] OSL show progressive luminescence sensitivity changes with repeated measurement cycles, with a slight dose dependence for the IRSL. In addition, five modified SAR procedures were used, varying preheats, filter combinations and method of measuring the luminescence signal. The D_e values for all IRSL measurements were at least 50% greater than those for the [post-IR] OSL signal. A modified SAR sequence was also applied in which 0.1 s stimulations (using both IR and blue light sources) were made between all sample treatments. A lack of consistency in the measured luminescence sensitivity of the natural IRSL signal suggests that the [post-IR] OSL signal provides the more reliable value of D_e.