The chapter provides useful information about synthesis and characterization of dysprosium doped oxide and fluoride-based phosphors such as SrGd2O4, CaSO4, and CaF2. Various techniques (e.g., acid-recrystallization, chemical co-precipitation, and homogenous precipitation cum auto-combustion methods) were adopted to synthesize these phosphors for large-scale production. All the prepared phosphors were characterized by x-ray diffraction analysis, scanning electron microscopy, and transmission electron microscopy techniques. The thermoluminescence (TL) studies were performed after different irradiation sources such as gamma rays, thermal neutrons, and low energy ions (H, Ar, and N), respectively. Linear dose responses were observed in a wide range of doses for all the samples. Various trapping parameters, namely order of kinetics, activation energy, and frequency factors, were calculated by using computerized glow curve deconvolution (CGCD) method.
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The phenomenon of thermoluminescence (TL) takes place when the radiation incident on insulating crystals and a fraction of deposited energy is stored at the defect centres or colour centres in the crystal lattice. After heating the respective crystal, this stored energy is released in the form of visible light (Bull, 1985, pp 105-113). Under certain limitations, the radiation dose absorbed through the crystal is directly proportional to the amount of light emitted. In the radiation dosimetry, the TL phosphors are utilized as a passive dosimeter for monitoring the integrated radiation doses obtained from various sources (Bull, 1985, pp 105-113). Linear dose response, low fading, radiation resistant, simple TL profile, less dependence on the energy of irradiation, high chemical robustness, and high sensitivity are essential requirements for materials used for dosimetric applications (Jayasudha et al., 2017; Gupta et al., 2016; Manam et al., 2010; Reddy et al., 2016). An appropriate combination of host-dopant and optimization of luminescent centres incorporated in the host lattice plays an important role in making sensitive phosphors because a single host does not hold all the characteristics of TLD phosphors very often (Jayasudha et al., 2017; Gupta et al., 2016; Manam et al., 2010; Reddy et al., 2016; Kumar et al., 2016; Wang et al., 2005).
TL responses of rare-earth doped oxide and fluoride based matrices are extensively studied due to their high chemical stability, wide range radiation dose response, less fading and high sensitivity to very small doses (Gupta et al., 2016; Wanget et al., 2005; Manam & Das, 2008; Dubey et al., 2016; Sun et al., 2014; Lakshmanan, 2001). These materials are mainly applicable in radiation dosimetry for environmental and personnel monitoring. A lot of researches have been done to develop such synthetic materials which exhibit all the characteristics of a good TLD material (Jayasudha et al., 2017; Gupta et al., 2016; Manam et al., 2010; Reddy et al., 2016; Kumar et al., 2016; Wang et al., 2005; Manam & Das, 2008; Dubey et al., 2016; Sun et al., 2014). On the basis of these researches, it is found that mixed alkali/alkaline oxide and sulphate matrices constitute a class of good TL phosphors and their TL performances improved when an appropriate amount of activators are incorporated (Manam & Das, 2008; Dubey et al., 2016; Sun et al., 2014; Lakshmanan, 2001; Salah et al., 2006; Shinsho et al., 2008; Salah N., 2008; Bhadane et al., 2016; Wagiran et al., 2012; Mondragon et al., 2008; Lakshmanan et al., 2008). As a novel luminescent host, the structural and thermoluminescence properties of SrY2O4 (Dubey et al., 2016) and BaGd2O4 (Sun et al., 2014) have been extensively investigated. However, no research work has been claimed so far concerning to TL studies of SrGd2O4: Dy3+ host synthesized via homogeneous precipitation cum auto-combustion method.