Normal and anomalous heating rate effects on thermoluminescence of Ce-doped ZnB2O4
Introduction
Borates, Sulphates, Fluorides, Oxides and Silicates are some of the important Thermoluminescence (TL) materials that have been developed and used over many decades. Especially, the borate based phosphors among them are preferred to be studied. Borate based phosphors are popular to study their TL characteristics due to neutron and gamma sensitivity, near tissue equivalence, basic structure of glow curve, synthesis feasibility in bulk quantities and simple thermal treatment procedure.
Several studies have been performed to determine the TL properties of borates using various preparation techniques, different modifiers and activators. Lately, ZnB2O4 has started to draw increasing research interest because it can be used as a host in phosphor applications (Li et al., 2007, Li et al., 2008, Zheng et al., 2009, Liu et al., 2010, Kucuk et al., 2013). Kucuk et al. (2015) reported the TL dosimetry properties of Lanthanum doped ZnB2O4 phosphor synthesized by nitric acid method. Yazici et al. (2006) reported that Ce doped BaB4O7 compounds could be used in dosimetric applications. Li et al., 2007, Juan et al., 2008) reported photoluminescence (PL) and TL dosimetry properties of Terbium and Dysprosium doped ZnB2O4 phosphors synthesized by using solid state technique. Dogan and Yazıcı (2009) reported fading and reusability properties in dose linearity region of Ce doped MgB4O7.
Heating rate (HR) is one of the important factors affecting the dosimetric characteristics of many TL materials. The various heating rate (VHR) method considers how the traps are emptied at different HRs while all other parameters are held constant (Topaksu et al., 2015). There are lots of studies in the literature which prove that the glow peak height decreases with an increase in HR as a normal behavior under the constant dose (Jiang et al., 2008) whereas there are also studies indicating the opposite interpretation (Akselrod et al., 1990). It is called as anomalous HR effect which the area under the normalized TL signal (TL/β) against temperature increases when the HR increases. This anomalous HR effect has been explained by Mandowski and Bos (Mandowski and Bos, 2011) using the semi-localized transition (SLT) model developed by Mandowski (Mandowski, 2005). According to SLT model, the localized transition from the excited state into the recombination center and the delocalized transition from the conduction band into the center are assumed to produce measurable TL (Chen et al., 2012). On the other hand, there are some studies having different aspects to this effect (Kitis et al., 2006, Bos et al., 2010, Chen and Pagonis, 2016). In two-stage model, it appears similar the above mentioned SLT model, but the concentration is given only on recombination of electrons going through the conduction band (Chen et al., 2012). Recently, the approach of non-localized Schön – Klasens model draws attention to both a decrease and increase on normalized TL intensity and the area under the glow peak to explain two presentations of TL in their simulation study (Chen and Pagonis, 2016). The model presents one electron trap and one recombination with one reservoir as two centers in the model to clarify the normal and anomalous HR effects.
The aim of the present study is to understand the HR effects on TL peaks of Ce3 + doped ZnB2O4 phosphors. For this purpose, we present TL glow curves, normalized TL peak area, the change of the full width at the half maximum (FWHM) as a function of HR and the reusability results of 1%, 4%, and 10% Ce3 + doped ZnB2O4 phosphors. In addition, E and s have been calculated with the VHR method for Ce3 + doped ZnB2O4 phosphors.
Section snippets
Material and methods
The nitric acid method (NAM) was applied for the synthesis of ZnB2O4: Ce3 + doped at various ratios. Zinc oxide (99.99% pure ZnO), boric acid (99.99% pure H3BO3) and cerium oxide (99.99% pure CeO2) were used to form ZnB2O4:Ce3 + phosphors. The preparation of ZnB2O4:Ce3 + powders is described as follows: stoichiometric amounts of ZnO, H3BO3 and CeO2 powders were separately weighted. The initial materials were mixed using a magnetic stirrer at 80 °C in 1 M nitric acid solution (HNO3). Boric acid
Heating rate (HR)
Linear HR responses of 1%, 4%, and 10% Ce3 + doped ZnB2O4 phosphors were studied. The irradiated Ce3 + doped ZnB2O4 samples were read out with nine different linear HRs between 2 and 10 °C/s to determine the dependence of the TL intensities to HR values. TL glow curves of Ce3 + doped ZnB2O4 phosphors are shown respectively in Fig. 1. As seen in Fig. 1, the TL glow curves of all Ce3 + doped ZnB2O4 have two strong peaks with maxima at around 75 and 150 °C called as peak 1 and peak 2, respectively,
Conclusion
In this study, normal and anomalous HR effect of TL is presented for various amount of Ce3 + doped ZnB2O4 phosphors to investigate the change in the TL intensity, the peak area and FWHM with increasing HR. Additionally, reusability test is applied to see whether the phosphors are useful for dosimetric purposes or not. Two situations are observed in the measurements: The first peaks of all phosphors are compatible with the TL theory as well as the second peak of 10% Ce3 + doped one where the TL
Acknowledgements
Authors would like to thank Dr. Yeter Göksu and Dr. Nurdoğan Can for their valuable contributions to this study.
References (35)
- et al.
Kinetic parameters and TL mechanism in cadmium tetra borate phosphor
J. Lumin.
(2014) Determination of thermoluminescence parameters from glow curves – I. A review
Nucl. Tracks
(1986)- et al.
Energy levels in YPO4:Ce + 3, Sm + 3 studied by thermally and optically stimulated luminescence
Radiat. Meas.
(2010) - et al.
Model explaining the anomalous heating-rate effect in thermoluminescence as an inverse thermal quenching based on simultaneous thermal release of electrons and holes
Radiat. Meas.
(2016) - et al.
Two-stage thermal stimulation of thermoluminescence
Radiat. Meas.
(2012) - et al.
Thermoluminescence glow curve analysis of natural onyx from Turkey
Appl. Radiat. Isot.
(2015) - et al.
Impact of non-ideal heat transfer on the determination of thermoluminescent kinetic parameters
J. Lumin.
(1997) - et al.
Thermoluminescence characteristics of rare-earth-doped LiCaBO3 phosphor
J. Lumin.
(2008) - et al.
Determination of thermoluminescence kinetic parameters of thulium doped lithium calcium borate
Radiat. Meas.
(2011) - et al.
Effect on thermoluminescence parameters of biotite mineral due to thermal quenching
J. Lumin.
(2012)
Estimation of band gap of muscovite mineral using thermoluminescence (TL) analysis
Phys. B: Condens. Matter
Heating rate effects on the TL glow-peaks of three thermoluminescent phosphors
Nucl. Instrum. Methods B
Effect of annealing temperature on determining trap depths of quartz by various HR method
Radiat. Meas.
Synthesis, thermoluminescence and dosimetric properties of La-doped zinc borates
J. Lumın.
Thermoluminescence kinetic parameters of different amount La-doped ZnB2O4
Appl. Radiat. Isot.
Dependence of peak height of glow curves on heating rate in Thermoluminescence
J. Lumın.
Synthesis, photoluminescence, thermoluminescence and dosimetry properties of novel phosphor Zn(BO2)2:Tb
J. Phys. Chem. Solids
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