X射线影像存储材料BaF_xCl_（2－x）Eu~（2＋）的制备及其热释发光和

本文采用了不同温度下两次烧结的新方法，制备了系列Ｘ射线影象存储材料ＢａＦ＿ｘＣｌ＿（２－ｘ）：Ｅｕ￣（２＋）（ｘ＝０．９０，０．９５，１．００，１．０５，１．１０１．１５）。通过改变Ｆ／Ｃｌ比值，研究了在Ｘ射线辐照后ＢａＦ＿ｘＣｌ＿（２－ｘ）：Ｅｕ￣（２＋）的热释发光性质，给出了热释发光峰的温度与缺陷种类的关系。最后，我们研究了ＢａＦ＿ｘＣｌ＿（２－ｘ）：Ｅｕ￣（２＋）的光激励发光性质，给出了Ｆ／Ｃｌ比值与光激励发光强度的关系。     

Luminescence of Eu in some fluorides prepared by reactive atmosphere processing

When phosphors are prepared by conventional solid-state route by heating in air, usually unwanted impurities like OH⁻, O₂⁻, etc., get incorporated. Such impurities can be quite harmful to the luminescence processes. Especially, fluorides are highly susceptible to hydrolysis. It is necessary to use highly sophisticated procedures like high vacuum and HF or CF₄ atmosphere for preparation of fluoride based phosphors. It is shown that using a simple wet chemical process and a modified reactive atmosphere processing (RAP) technique, fluorides showing intense Eu²⁺ photoluminescence can be prepared.     

Structural characterization and optical properties of dysprosium doped strontium calcium magnesium di-silicate phosphor by solid state reaction method

Dysprosium doped strontium calcium magnesium di-silicate phosphor namely: SrCaMgSi₂O₇:Dy³⁺ was prepared by the solid state reaction method. The crystal structure of the prepared phosphor was an akermanite type structure, which belongs to the tetragonal crystallography with space group P${\overline{42}}_1$m. From field emission scanning electron microscopy (FESEM), agglomerations of particles were observed due to the high temperature synthesis process. The chemical composition of the sintered SrCaMgSi₂O₇:Dy³⁺ phosphor was confirmed by energy dispersive X-ray spectroscopy (EDX). Under the ultra-violet (UV) excitation, the characteristic emission of Dy³⁺ ions peaking at 478, 580 and 674 nm, originating from the transitions of ⁴F_9/2 → ⁶H_15/2, ⁴F_9/2 → ⁶H_13/2 and ⁴F_9/2 → ⁶H_11/2 in the 4f⁹ configuration of Dy³⁺. Commission International de I’Eclairage (CIE) color coordinates of SrCaMgSi₂O₇:Dy³⁺ are suitable as white light emitting phosphor. Decay graph indicate that this phosphor contains fast decay and slow decay process. The mechanoluminescence (ML) intensity of SrCaMgSi₂O₇:Dy³⁺ phosphor increases linearly with increasing impact velocity of the moving piston, which suggests that this phosphor can be used as sensors to detect the stress of an object. Thus the present investigation indicates that the piezo-electrically induced de-trapping model is responsible to produce ML in SrCaMgSi₂O₇:Dy³⁺ phosphor. The possible mechanism of white light emitting long lasting phosphor is also investigated.     

Luminescence properties of near-UV excitable yellow-orange light emitting warm CaSrAl2SiO7:Sm3+ phosphors

Single-phase CaSrAl_2 SiO_7:Sm~(3+) phosphors were synthesized by traditional high temperature solid state reaction method. Formation of samples and phase analysis were confirmed by X-ray diffraction technique. Morphology was done by field emission scanning electron microscopy and elemental compositions were confirmed by energy dispersive X-ray analysis. Present phosphors have tetragonal crystallography with space group P42_1 m. Average crystallite size was calculated by using Scherrer and Williamson-Hall method. Photoluminescence study of CaSrAl_2 SiO_7:Sm~(3+) phosphor was investigated.Under different excitation wavelengths, PL spectra consist of four emission bands at 564, 570, 601 and650 nm. The emission bands located at 564 and 570 nm are associated with the transition ~4 G_(5/2)→~6 H_(5/2)while emission bands at 601 and 650 nm are due to ~4 G_(5/2)→~6 H_(7/2) and ~4 G_(5/2)→~6 H_(9/2),respectively.Intense emission was obtained when phosphor was excited under 404 nm wavelength. Non-radiative energy transfer process involved in concentration quenching, was also discussed. CIE coordinate is found in yellow-orange region, hence CaSrAl_2SiO_7:Sm~(3+) phosphors emit yellow-orange light when efficiently excited by near UV(～400 nm) LED chip. Color purity and CCT of the phosphor were determined; CCT suggests that present phosphor is a good candidate as a warm yellow-orange color emitting phosphor. Effect of different heating rates and different UV exposure time on the TL glow curve of the phosphor was investigated. Activation energies and kinetic parameters for different traps were calculated by using peak shape method. TL emission spectrum was also recorded. Present article explains all the possible mechanisms associated with luminescence process in CaSrAl_2 SiO_7:Sm~(3+) phosphors.     

The effects of Ce3+ doping on the structural and optical properties of SrS nanoparticles synthesized by solid state diffusion method

A solid state diffusion method (SSDM) is employed to synthesize the nanocrystalline SrS phosphors doped with varying concentrations of Ce³⁺ ions. The surface morphology and structural properties of as prepared phosphors are characterized by various techniques including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction pattern (SAED) and energy dispersive X-ray spectroscopy (EDX). The optical properties are investigated and discussed in terms of absorption spectra, photoluminescence (PL) and thermoluminescence (TL) measurements. The cubical crystal structure and average crystallite size estimated by X-ray diffractograms are found to lie in nano-range is also supported by HRTEM analysis. FESEM is used to describe the surface morphology and confirm the crystallite size of as-prepared nanophosphors. The absorption spectra and corresponding Tauc׳s plots confirm the wide band-gap nature of prepared samples. When excited with 375 nm wavelength of ultraviolet (UV) light at room temperature, the SrS:Ce³⁺ nanophosphors exhibit two emission bands at around 459 (blue region) and 551 nm (green region) originating from the ²T_2g(5d)→²F_5/2(4f) and ²T_2g(5d)→²F_7/2(4f) transitions respectively. The results of thermoluminescence (TL) studies in terms of TL glow curves, corresponding kinetic parameters and dopant concentration dependence of intensity for nanocrystalline SrS:Ce³⁺ phosphor are presented and discussed.     

一种简便的热释光剂量仪联机接口

介绍了一种在热释光剂量仪上进行数据采集并实时显示，同时具有数据平滑、拟合、数据格式转换、打印等处理功能的微机接口系统，系统由微机和设有计数器的A/D转换电路的接口板，以及系统软件等组成，该系统大大提高了剂量仪在热释光的测量功能，扩大了应用范围，并已用于热释光剂量学和热释光材料的研究。     

Near infrared emitting Cr3+ doped Zn3Ga2Ge2O10 long persistent phosphor for night vision surveillance and anti-counterfeit applications

The Cr³⁺ doped Zn₃Ga₂Ge₂O₁₀ long persistent phosphor materials were synthesized by solid state reaction method. The crystal structure of the synthesized phosphors are cubic with space group Fd3m. The band gap of the undoped host is about 4.48 eV. The materials show three photoluminescence excitation bands peaked at 260 nm, 412 nm and 580 nm. Due to the broad excitation band, the phosphors can be excited by UV light or visible light or sunlight. The phosphors shows a photoluminescence emission band peaked at 698 nm when excited by UV light. The afterglow emission shows a broad emission band with maximum at 700 nm. The detection of NIR light from the sample was observed by Night Vision Monocular for 24 h after switch off the excitation source. A mechanism is introduced to describe afterglow phenomenon and trap depth was calculated from thermoluminescence curve. As the material emit NIR persistent light, it was used as a secret light source for night vision devices. The developed material was used for tagging, tracking and locating purposes in defence application. The acrylic based paint was prepared to develop long persistent near infrared (NIR) paint, which can be coated on combat vehicle, ship, weapon, helmet, cloth, tent, rock for defence application. The NIR security ink was prepared and demonstrated to prevent counterfeit. Encryption and decryption method of confidential information was presented by using NIR security ink.     

Thermoluminescence as a new research tool for the evaluation of geothermal activity of the Kakkonda geothermal system, northeast Japan

The thermoluminescence glow-curve of quartz in volcanic and pyroclastic rocks of the Miocene and Quaternary in the Kakkonda geothermal field was divided into L (low), M (medium) and H (high) peaks in order of increasing temperature. Thermoluminescence emission is independent of stratigraphic boundaries but it is closely related to surface geothermal manifestations. Thermally stimulated processes of thermoluminescence caused by natural annealing occurred in the Quaternary after the eruption of the Tamagawa Welded Tuffs; radiation storage processes then began, as a consequence of the temperature drop. Thermoluminescence behavior indicates natural temperature manifestations, together with the paleo-temperature history.The H peak was thermally stable compared to the L and M peaks, and the area within which the relative intensity of the H peak is less than 5% coincides with the surface zone where dominant fluid flow is convective. In addition, L and M peaks indicate that a relatively low-temperature fluid mixes with the hot upflow around the western margin of the ascending flow zone.Thermoluminescence characteristics reflect paleo-temperature history and are related to geothermal fluid flow. Thermoluminescence is an effective exploration technique for evaluating natural temperature manifestations and subterranean heat flow in geothermal systems.     

Thermoluminescence study of Eu3+ doped Na2Sr2Al2PO4Cl9 phosphor via doping of singly,doubly and triply ionized ions

We report here thermoluminescence properties of Eu³⁺ doped Na₂Sr₂Al₂PO₄Cl₉ phosphor via doping of singly, doubly and triply ionized ions on the basis of PL studies done for this sample. The proposed sample was synthesized using solid state reaction method. Vibrational feature of this phosphor was confirmed by FT-IR spectra. This sample shows high degrees of crystallinity. All subseries are irradiated with ⁶⁰Co- γ (gamma) source and thermoluminescence studies were done for all subseries formed by doping of singly, doubly and triply ionized ions. The result shows that all the series give highest TL intensity at low dose rate. On doping of triply doped ionized ion (Y³⁺), TL intensity is enhanced to some extent. Deconvolution of broad TL glow data formed for some sample were done by using TLAnal computerized software. Thermoluminescence studies of these Eu³⁺ doped SrYAl₃O₇ phosphor were done by Nucleonix TL 1009I thermoluminescence (TL) reader. Trapping parameters of each phosphor such as activation energy (E), order of kinetics (b) and frequency factor (s) were calculated by Chen's peak shape method, Initial rise method and Ilich method. Thus, the singly, doubly and triply ionized ions co-doped with Na₂Sr₂Al₂PO₄Cl₉: Eu³⁺phosphor may be used in high dose thermoluminescence dosimetric application in various fields.