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Lithium–magnesium fluorophosphate with the formula Li9Mg3[PO4]4F3 has recently been proposed as a new thermoluminescent material capable of storing ionizing radiation energy and emitting photons after additional thermal stimulation. Pure and sodium-doped fluorophosphates were obtained by microwave-assisted synthesis. Using X-ray and neutron diffraction methods, it was shown that sodium occupies only one of the three nonequivalent lithium positions. This conclusion was confirmed by a MAS NMR study and ab initio calculations. A significant increase in the thermoluminescence intensity of sodium-containing fluorophosphates in comparison to the undoped compound was found. Analysis of the kinetic parameters obtained from glow curves showed that they are similar for the undoped and sodium-doped samples. This indicates that the addition of sodium does not result in the emergence of novel types of traps, but rather in a change in their number. The effect of sodium on the formation of intrinsic defects, which can be responsible for the enhanced thermoluminescence, is considered using ab initio modelling. [ABSTRACT FROM AUTHOR]

Lithium magnesium phosphate LiMgPO4 is one of the most promising materials for luminescence dosimetry. In this paper, we consider methods for the synthesis or additional processing of this material, such as microwave, hydrothermal, and flux techniques, as well as melting followed by quenching, which makes it possible to enhance its thermoluminescence by increasing the crystallinity of the samples and improving grain contacts. The best properties are shown by the LiMgPO4–Na2B4O7 composite. [ABSTRACT FROM AUTHOR]

Fluorine-doped lithium magnesium phosphate has been studied for the first time. It has been shown that fluorine significantly enhances the intensity of thermally stimulated luminescence. To find the preferred positions of fluorine and structural distortions caused by aliovalent substitution, ab initio calculations have been performed, which demonstrate that fluorine is not included into the (PO4)3– anion; rather, it promotes the formation of clusters simultaneously containing lithium and fluorine ions. [ABSTRACT FROM AUTHOR]

The phosphates LiMgPO4:RE (RE – Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm) with an olivine-type orthorhombic structure were synthesized by the conventional solid state reaction route and their optical properties were examined by the experimental and theoretical methods. In this work, we showed that the radioluminescence and thermoluminescence spectra of irradiated LiMgPO4:RE (RE = Sm, Gd, Tb, Dy, Tm) consist of lines reflecting 4f–4f transitions in the rare-earth element. For LiMgPO4:RE (RE = Nd, Ho, Er), they coincide with the spectrum of the phosphate matrix with two broad bands at 360 nm and 650 nm but are much more intense. A model of energy transfer is proposed to explain this phenomenon. It is shown that the model is confirmed by the features of photoluminescence in doped LiMgPO4 and by the results of ab initio calculations. [ABSTRACT FROM AUTHOR]

The 13C and 19F NMR spectra of the original and irradiated polytetrafluoroethylene samples were studied in the range of gamma radiation doses of up to 50 kGy. In this range, the 19F NMR spectrum width increases linearly with an increase in the absorbed dose. It is concluded that it is possible to monitor technological doses by the NMR method using polytetrafluoroethylene as a detector. [ABSTRACT FROM AUTHOR]

Olivine-type phosphate LiMgPO4 doped with rare-earth elements is currently considered as a new dosimetric material suitable for both OSL and TSL applications and able to compete with top commercial detectors. In this work, the samples of LiMgPO4:Er3+ were synthesized by the conventional solid state reaction method. We first studied X-ray luminescence and thermally and optically stimulated luminescence in LiMgPO4:Er3+ in detail. Our studies included the structure refinement, DFT calculations, which predicted the preferred positions of both erbium and charge-compensating vacancies, and UV-vis spectroscopy. We showed that the thermoluminescence spectrum of irradiated LiMgPO4:Er3+ does not contain components caused by the 4f–4f transitions in erbium, but coincides with the spectrum of the phosphate matrix with two broad bands at 360 nm and 650 nm. We discovered a high OSL and TSL output in LiMgPO4:Er3+, despite the nonradiative deexcitation of erbium ions. [ABSTRACT FROM AUTHOR]

A brief list of the main directions in radiation processes using ionizing radiation in a wide range of doses and energies is given. The necessity of monitoring doses in irradiated objects and diagnosing radiation fields is substantiated. It is noted that in world practice, these problems are solved with the help of dosimetric EPR systems and detectors based on L-α-alanine. Using the example of sterilizing medical devices by radiation from an electron accelerator, a series of experimental results have been obtained that confirm the possibility of using polytetrafluoroethylene as a detector in dosimetric EPR systems for monitoring radiation processes. [ABSTRACT FROM AUTHOR]

It is established that simple color centers of the F+ and F type (anion vacancies with one or two electrons, respectively) in anion-deficient corundum (α-Al2O3-δ) crystals can be transformed into complex centers (including divacancy centers of the F2 type) using a special thermo-optical treatment. A fine structure of the photoluminescence bands of complex centers of both the known and unknown natures was recorded in these crystals at helium temperatures in the near-IR range. A comparison with the photoluminescence bands in neutron-irradiated α-Al2O3 samples with the initial stoichiometric composition reveals their complete similarity, which indicates the possibility of nonradiative formation of complex centers in α-Al2O3. [ABSTRACT FROM AUTHOR]

Lithium–magnesium fluorophosphate with the formula Li9Mg3[PO4]4F3 has recently been proposed as a new thermoluminescent material capable of storing ionizing radiation energy and emitting photons after additional thermal stimulation. Pure and sodium-doped fluorophosphates were obtained by microwave-assisted synthesis. Using X-ray and neutron diffraction methods, it was shown that sodium occupies only one of the three nonequivalent lithium positions. This conclusion was confirmed by a MAS NMR study and ab initio calculations. A significant increase in the thermoluminescence intensity of sodium-containing fluorophosphates in comparison to the undoped compound was found. Analysis of the kinetic parameters obtained from glow curves showed that they are similar for the undoped and sodium-doped samples. This indicates that the addition of sodium does not result in the emergence of novel types of traps, but rather in a change in their number. The effect of sodium on the formation of intrinsic defects, which can be responsible for the enhanced thermoluminescence, is considered using ab initio modelling. [ABSTRACT FROM AUTHOR]

Olivine-type phosphate LiMgPO4 doped with rare-earth elements is currently considered as a new dosimetric material suitable for both OSL and TSL applications and able to compete with top commercial detectors. In this work, the samples of LiMgPO4:Er3+ were synthesized by the conventional solid state reaction method. We first studied X-ray luminescence and thermally and optically stimulated luminescence in LiMgPO4:Er3+ in detail. Our studies included the structure refinement, DFT calculations, which predicted the preferred positions of both erbium and charge-compensating vacancies, and UV-vis spectroscopy. We showed that the thermoluminescence spectrum of irradiated LiMgPO4:Er3+ does not contain components caused by the 4f-4f transitions in erbium, but coincides with the spectrum of the phosphate matrix with two broad bands at 360 nm and 650 nm. We discovered a high OSL and TSL output in LiMgPO4:Er3+, despite the nonradiative deexcitation of erbium ions.