Modak Pampa, Modak Brindaban
RSD, Atomic Energy Regulatory Board, Mumbai 400 094, India and Homi Bhabha National Institute, Mumbai 400 094, India.
Homi Bhabha National Institute, Mumbai 400 094, India and Theoretical Chemistry Section, Bhabha Atomic Research Centre, Mumbai 400 085, India.
Phys Chem Chem Phys. 2020 Jul 22;22(28):16244-16257. doi: 10.1039/d0cp02425b.
Linearity in dose response up to very high radiation doses and sufficient sensitivity to even low radiation doses are extremely important for the measurement of radiation dose in the field of radiation technology, ranging from medical to industrial applications. Olivine type LiMgPO4 has been shown immense interest as a phosphor material in the fields of thermoluminescence and optically stimulated luminescence dosimetry. In the present study, we have explored the role of different vacancy defects in the optical properties of LiMgPO4 aiming at enhancing its sensitivity for the measurement of radiation dose. For this purpose, we have systematically investigated the electronic structure of LiMgPO4 in the absence and presence of various vacancy defects using density functional theory as a tool. The present study considers all possible vacancy defects including neutral, charged and mixed lattice vacancy defects in LiMgPO4. To find the most energetically favourable vacancy defect, we have compared the defect formation energy of all the vacancy defects. We have also calculated vacancy formation energy in different chemical environments to investigate how the formation of different types of vacancy defect can be controlled by tuning the chemical environment. Finally, the origin of the different optical properties of LiMgPO4 has been explained by using a possible mechanism based on our detailed electronic structure calculations. Thus, the present study is believed to provide valuable insight for the development of materials with improved features for the measurement of radiation dose.
在从医学到工业应用的辐射技术领域中，直至非常高的辐射剂量的剂量响应线性以及对甚至低辐射剂量的足够灵敏度对于辐射剂量的测量极其重要。橄榄石型LiMgPO4作为热释光和光激励发光剂量测定领域的磷光体材料已引起极大关注。在本研究中，我们探索了不同空位缺陷在LiMgPO4光学性质中的作用，旨在提高其对辐射剂量测量的灵敏度。为此，我们使用密度泛函理论作为工具，系统地研究了在不存在和存在各种空位缺陷的情况下LiMgPO4的电子结构。本研究考虑了LiMgPO4中所有可能的空位缺陷，包括中性、带电和混合晶格空位缺陷。为了找到能量上最有利的空位缺陷，我们比较了所有空位缺陷的缺陷形成能。我们还计算了不同化学环境中的空位形成能，以研究如何通过调整化学环境来控制不同类型空位缺陷的形成。最后，基于我们详细的电子结构计算，通过一种可能的机理解释了LiMgPO4不同光学性质的起源。因此，本研究被认为为开发具有改进特性的用于辐射剂量测量的材料提供了有价值的见解。
