ABSTRACT Among the undoped metal sulfates, on sintering at high temperatures, only BaSO4 was found to exhibit TL glow peaks in the region of radiation dosimetric interest i.e. ∼200°C (peak I) and 250°C (peak II). The TL intensity of peak I is very weak in purified BaSO4 but increased 4 times on 500°C, 1 h sintering. The intensity of peak II and the peak II/I height ratio increased with sintering temperature between 500°C and 1000°C. NaCl flux enhances the TL sensitivity of BaSO4 unlike that of Na2SO4. TL response of BaSO4 is in general linear below 1 kGy but unlike other phosphors, the TL response in the high dose region (> 1 kGy) does not saturate but increases sublinearly with dose (1–15 kGy) as a result of slow creation of traps by radiolysis. XRD shows that BaSO4 made with NaCl flux corresponding to a single phase of orthorhombic Barite crystal. The oxygen interstitial ions, are envisioned to be the hole traps and the radicals/anion vacancies formed by thermal dissociation of ions constitute the electron traps for peaks I and II, respectively. During TL, in the absence of dopants, the electron–hole recombination energy is observed under relaxed anion exciton emission in the 380–410 nm region. The phosphor is reusable after irradiation and TL readout. High dose irradiations, however, causes sensitization of TL after 400°C, 1 h post-irradiation anneal but a 700°C, 1 h anneal reduced the TL sensitivity. The creation of TL traps causing peak I precede that of peak II and a trap conversion between them occurs during high-temperature sintering. The study thus reveals for the first time that the defects causing TL peaks I and II are both thermally induced. Further studies to extend the saturation dose limit are proposed.

中文翻译：

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重晶石中的陷阱产生、陷阱转换和热释光过程——通量的影响

摘要 在未掺杂的金属硫酸盐中，在高温烧结时，只有 BaSO4 在辐射剂量学感兴趣的区域显示出 TL 辉光峰，即约 200°C（峰 I）和 250°C（峰 II）。在纯化的 BaSO4 中峰 I 的 TL 强度非常弱，但在 500°C、1 h 烧结时增加了 4 倍。随着烧结温度在 500°C 到 1000°C 之间，峰 II 的强度和峰 II/I 的高度比增加。与 Na2SO4 不同，NaCl 通量增强了 BaSO4 的 TL 敏感性。BaSO4 的 TL 响应在 1 kGy 以下通常是线性的，但与其他磷光体不同，高剂量区域 (> 1 kGy) 的 TL 响应不会饱和，而是随着剂量 (1–15 kGy) 的缓慢产生而呈亚线性增加通过辐射分解的陷阱。XRD 表明用 NaCl 熔剂制成的 BaSO4 对应于单相正交重晶石晶体。氧间隙离子被设想为空穴陷阱，而由离子热解离形成的自由基/阴离子空位分别构成峰 I 和 II 的电子陷阱。在 TL 期间，在没有掺杂剂的情况下，在 380-410 nm 区域的松弛阴离子激子发射下观察到电子 - 空穴复合能。荧光粉在照射和 TL 读出后可重复使用。然而，高剂量照射会在 400°C、照射后 1 小时退火后引起 TL 敏化，但 700°C、1 小时退火会降低 TL 敏感性。引起峰 I 的 TL 陷阱的产生先于峰 II，并且它们之间的陷阱转换发生在高温烧结过程中。因此，该研究首次揭示了导致 TL 峰 I 和 II 的缺陷都是热诱导的。提出了进一步研究以扩展饱和剂量限制。