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Trivalent Eu-activated MNb2O6 (M = Sr, Cd, Ni) ceramic phosphors were produced using the molten salt route, which involves a low sintering temperature and provides improved homogeneity. The photoluminescence (PL) and radioluminescence (RL) spectra of phosphors exhibited characteristic Eu3+ emissions with 5F0 → 7Fj transitions, and strong peaks occurred at the 5D0 → 7F2 transition. The PL and RL emissions of SrNb2O6:Eu3+ decreased over 3 mol%, while both emissions for CdNb2O6:Eu3+ and NiNb2O6:Eu3+ increased with increasing Eu3+ concentration. The spectral properties of phosphors were evaluated by determining Judd–Ofelt intensity parameters (Ω2, Ω4) from the PL emission spectrum. The quantum efficiencies (ηQE%) of MNb2O6:Eu3+ (M = Sr, Cd, Ni) phosphors with the highest emission were found as 61.87%, 41.89%, and 11.87% respectively. Bandwidths (σe × Δλeff) and optical gains (σe × τ) of MNb2O6:Eu3+ (M = Sr, Cd, Ni) phosphors with highest emissions were found as follows; 24.182 × 10−28, 28.674 × 10−28, 38.647 × 10−28 cm3 and 20.441 × 10−25, 13.790 × 10−25, 3.987 × 10−25 cm2 s, respectively, corresponding to the 5D0 → 7F2 transition.

In this work, Dy3+-doped SrNb2O6 phosphors were fabricated by the molten salt process, which avoids high sintering temperatures, prolonged reaction time and poor compositional homogeneity. All samples crystallized to the orthorhombic columbite structure with space group, P21/c, while a rod-like morphology was observed by scanning electron microscopy (SEM). PL (photoluminescence) and RL (radioluminescence) spectra of SrNb2O6:Dy3+ exhibited a strong blue emission peak at 576.0 nm related to 4F9/2 → 6H15/2 transition of Dy. The high RL emission of the 4F9/2 → 6H15/2 (electric dipole) transition upon X-ray-induced excitation led to a decrease in Dy3+ local environmental symmetry. The Judd–Ofelt (J–O) theory was applied to the PL excitation spectra for the calculation of optical data such as Ω2, Ω4, and Ω6 parameters, radiative transition probability (Ar), branching ratios (β, βexp) and stimulated emission cross-section (σe). The quantum efficiencies (ηQE) varied between 35.47 and 31.93%, which are compatible with theoretical quantum efficiencies based on the Einstein relation. The CIE chromaticity coordinates (x, y) and CCT (correlated color temperature) parameter for 3 mol% phosphor were defined (0.385, 0.432) and 4209 K, respectively.

CdS quantum dots (QDs) which have unique luminescence efficiency were synthesized by two-phase method using oleic acid (OA) as a surfactant. The nanocomposites have been obtained by blended CdS quantum dots with low-density polyethylene (LDPE) in different ratios. Primarily, radioluminescence (RL) properties were investigated as well as their structural (FT-IR, XRD), morphological (TEM, SEM), thermal (TG-DTA) and absorption (UV–Vis) properties of these nanocomposites. The RL peaks of OA-capped CdS QD were observed at 456 nm and 655 nm. As a consequence of the nanocomposites being doped with powder CdS QD, a significant blue shift was observed in the absorption bands. The optical band gap of CdS was calculated as 2.3 eV. The nanocomposites blended with CdS QD, this value increased to 2.7 eV. It has also been observed that nanoparticles cause nanocomposites to have lower melting temperatures.

In this study Sr0.985Al2O4:0.005Eu(2+)/0.01Dy(3+) luminescent materials with long afterglow and high intensity were synthesized by flame spray pyrolysis (FSP) method for the first time. Precursor solution was divided into two separate part. One of the parts was used FSP process, the other one was dried to simulate sol- gel process. Thermal properties and organic content of FSP derived particles and dried gel were compared using DTA-TG and FTIR devices. FSP derived particles were sintered in argon medium at 1200 degrees C. Phase and elemental analysis of the final phosphors were carried out by X-Ray Diffraction (XRD) and X-Ray Photo electron Spectroscopy (XPS) measurements. Scanning electron microscopy (SEM) images were obtained to observe particle morphology. Optical properties of phosphor were determined by Photoluminescence (PL), thermoluminescence (TL) and radioluminescence (RL) measurements. The emission spectra of Sr0.985Al2O4: 0.005Eu(2+)/0.01Dy(3+) were composed by a green band at 525 nm at room temperature when it was excited by 350 nm light, assigned to anomalous luminescence originated by Eu2+ and Dy3+ in the host lattice. There were estimated peaks at around 90, 130, 170 and 200 degrees C under the main glow curve in the sample irradiated by X- ray and He- Ne laser (lambda(exc) = 632 nm). RL spectrum of Sr0.985Al2O4 : 0.005Eu(2+)/0.01Dy(3+) powders have four distinct emission peaks at around 527 nm, 576 nm, 667 nm, 753; nm and a comparatively weak emission band at about 846 nm.

Tb3+/Dy3+ co-doped CaLa2(WO4)4 (CLW: Tb3+/Dy3+) and its derivatives were synthesized by the sol-gel method. The morphology, thermal, structure and luminescent-optical properties the as-prepared light-emitting phosphors were characterized by utilizing scanning electron microscopy (SEM), differential thermal analysis (DTA)-thermogravimetric analysis (TG), X-ray diffraction (XRD) and radioluminescence (RL or X-ray luminescence) - photoluminescence (PL) –thermoluminescence (TL or TSL) - optical absorption spectrometry. The Tb3+ and Dy3+ ions were singly or doubly doped and the results were examined in detail. Moreover, for these phosphors, the energy transfer mechanisms which depend on RL and PL spectra were determined. The samples excited by X-ray demonstrate characteristic luminescence peaks of Dy3+ (422, 480, 575, 663 and 747 nm) and Tb3+ (489, 544, 586, 620, 652 and 675 nm). These emissions are similar for RL and PL measurements. It could be said that the energy transfer efficiency of the host material is perfect for rare-earth ions. The synthesized phosphors exhibit various colors from yellow to blue under UV excitation. The optical band gaps of host CLW, CLW: Tb3+, CLW: Dy3+ and co-doped CLW: Tb3+/Dy3+ were calculated at values 3.83 eV, 3.44 eV, 3.64 eV and 3.52 eV, respectively. From the results obtained, the CaLa2(WO4)4: Tb3+, Dy3+phosphors may be one of the potential candidates for light-emitting diode.

Nanotechnology has become one of the most popular areas of interdisciplinary research. In the vast majority of nanotechnology applications, polymer-based matrices were used as the dispersing medium of nanoparticles. The combination of polymer–zeolite nanocomposite has the potential to come out with the advantages of polymers and zeolites while coping with the deficiencies of both materials. In this study, the synthesis and properties of low-density polyethylene (LDPE) composites with nanozeolite + Y2O3 are investigated. Polyethylene nanocomposite fibers containing nanozeolite + Y2O3 at 5% by mass using a melt extrusion method were composed in a laboratory type twin screw extruder. The thermal properties of the composite fibers were determined by analysis of both thermal gravimetric and differential thermal spectra. Their structural properties were enlightened by scanning electron microscopy, Fourier transform infrared, and ultraviolet absorption. According to the results of X-ray diffraction tests, the samples contain crystals in semicrystalline and α form. The mechanical properties of LDPE matrices increased with the addition of nanoparticles. In addition, radioluminescence properties of the polymer were also improved after composing with nanozeolite and Y2O3.

The un-doped, Tb3+ and, Dy3+ doped LiMgPO4 phosphors were successfully synthesized by the sol-gel method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize the light-emitting phosphors. The XRD spectra verify the phase formation of samples. The luminescence properties were analyzed by radioluminescence (RL), photoluminescence (PL), cathodoluminescence (CL) and, thermoluminescence (TL) spectra. Also, the effect of Tb3+, Dy3+ ions in LiMgPO4 was determined on the luminescence intensity in detail. The RL spectrum of un-doped LiMgPO4 consists of two broad emission bands in the 310–450 nm and 575–850 nm range. The maximum intensities of these bands were observed at 360 nm and 655 nm. The emission spectrum of Dy3+ doped LiMgPO4 under X-ray excitation show characteristic emissions of Dy3+ corresponds to 4F9/2→6Hj transitions. In addition to the 5D4→7Fj (j:6–1) transitions of Tb3+ doped LiMgPO4 phosphor, strong emissions derived from 5D3→7Fj (j:6–3) transitions were observed in the blue region. Also, these blue emissions were seen at RL, PL and, CL spectra. The optical absorption spectra were recorded and the energy band gaps were calculated 3.62 eV, 3.30 eV and, 4,01 eV for un-doped, Dy3+ and, Tb3+ doped LiMgPO4 phosphors, respectively. The phosphors irradiated with UV (254 nm) light. The main TL glow peak was observed at 288 °C for the Dy3+ doped phosphor, and the peaks at 198, 283 °C were observed for the Tb3+ doped phosphor. © 2020 Elsevier B.V.

For investigate spectroscopic properties, Eu3+ doped columbite type CdTa2O6 phosphors were synthesized using the solid state reaction method. The synthesized ceramic phosphors were investigated by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), photoluminescence (PL), radioluminescence (RL) and thermoluminescence (TL) analyses. CdTa2O6:Eu3+ phosphors exhibited emissions at 591.8 nm and 612.1 nm because of the characteristic band transitions of the Eu3+ ion. Phosphor emission increased with increasing Eu3+ ion dopant up to 1.5 mol%, and then decreased owing to concentration quenching. The decay times decreased with increasing Eu3+ dopant, while they were varied from 711 to 534 μm. The scintillation emissions of Eu3+ doped samples from the UV to near-IR spectral region were monitored by RL measurements. The high RL emission may be attributed to the good scintillation property of phosphor. TL glow curves were monitored for different Eu3+ concentrations in the range of 50 °C to 400 °C at a heating rate of 2 °C s-1, after being irradiated under short-wave UV light (254 nm). © 2018 The Royal Society of Chemistry.

In this work, highly luminescent alloyed CdSeS QDs are successfully synthesized by two phase route method by using oleic acid (OA) as a surfactant. OA capped CdSeS QDs prepared in two different synthesis duration were compared in terms of luminescence and optical properties. The nanocomposites blended with CdSeS QDs which have highly luminescent efficiency in different ratios by Low Density Polyethylene (LDPE) and these nanocomposites were mainly investigated radioluminescence (RL) and optical properties (UV/VIS absorption). Structural, morphological, thermal properties of the nanocrystal and nanocomposites were examined using; XRD, FT-IR, TEM, SEM, TG-DTA techniques. OA capped CdSeS and also nanocomposites were showed two RL spectrum peaks in green and red region at around 528 nm and 710 nm respectively. Also, it is seen that the radioluminescence intensity changes linearly with the particle size of the QDs and about 12% size change of quantum dot led to a threefold increase in RL intensity. The luminescence glow curves are in compliance with absorption and fluorescence spectra. The absorption bands showed a significant blue shift for the nanocomposites as compare to powder CdSeS. The optical band gap of the OA capped CdSeS calculated as 1.77 eV. It was observed that the optical band gap of LDPE was decreased by the adding ratio of CdSeS from 3.71 eV to 2.25 eV. © 2017 Elsevier B.V.

Tb3+/Eu3+ co-doped SrLa2(MoO4)(4) have been synthesized using the sol-gel process. The as-produced light-emitting phosphors were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA)/thermogravimetric analysis (TG), optical absorption spectra, radioluminescence (RL), and photoluminescence (PL) spectra. The effect of Tb(3+)and Eu(3+)doping concentrations on the RL and PL intensity of host material was analyzed in details. Furthermore, the energy transfer mechanism based on RL spectra were determined of Tb3+/Eu(3+)co-doped SrLa2(MoO4)(4) phosphors. When the samples excited by X-ray, the SrLa2(MoO4)(4) phosphors exhibit characteristic emissions of Tb3+ (489, 544, 586, 620 and 675 nm) and Eu(3+)d (545, 592, 614, 650 and 700 nm). Also, similar emissions are observed in the results of PL spectra, when the samples excited by 488 nm. The host material has excellent energy transfer efficiency for lanthanide ions. In addition, the luminescence spectra indicated that the energy transfer is also effective between from Tb3+ to Eu(3+)and vice versa. The CIE parameters are calculated to characterize the color emission. Under UV excitation, the synthesized materials display different color from green to red. Based on the results, the SrLa2(MoO4)(4:Eu)(3+)(3+)(,Tb) phosphors may be potential candidates for light-emitting diode. (C) 2019 Elsevier B.V. All rights reserved.

In this study, the structural and spectroscopic properties of orthorhombic PbNb2O6 doped with different concentrations of Eu3+ were studied. Interestingly, XRD analysis of undoped PbNb2O6 showed rhombohedral phase while Eu3+ doped structures exhibited an orthorhombic phase at 1250 °C. This difference was also observed in the morphology and composition of grains by SEM-EDS analysis. PL and RL emissions occurred between 550 and 850 nm owing to the 4f–4f transitions of Eu3+. The Judd-Ofelt theory was applied to the experimental data for determination of the Judd-Ofelt parameters (Ω2, Ω4), radiative transition rates (Ar) and radiative lifetimes (τr). TL glow curves were monitored by the peaks of 98 and 250 °C while emission increased up to 6 mol%. TL emission of 6 mol% phosphor depending on X-ray irradiation dose exhibited the highest intensity for 1200 Gy and appeared new peaks. Moreover, the TL emission of phosphor showed a linear relation with X-ray irradiation. The deconvolution peaks of 1200 Gy irradiated samples were determined by the CGCD method. Kinetic data of first peak (98 °C) depending on the dose increase were calculated by the PS method.

ZnO single crystals has been implanted with 400 keV Cu ions at fluences of 2,5 x 1016 ions/cm2 at room temperature. The cathodoluminescence (CL) measurements of pure and Cu implanted samples has been reported at UV-visible range at both room and different temperatures. After the implantation process, the samples were annealed for 1 hour at 1000ºC. The effects of ion implantation and annealing temperature and on the CL signals were researched with the data obtained. The CL spectrum of pure ZnO exhibited two emission bands at 385 nm and 550 nm. There are some changes in the emission bands in the CL spectrum that are thought to be due to the presence of Cu ions. Also it is possible to say that the annealing temperature can strongly influence CL intensity.

The luminescence properties of septarian have been investigated for the first time in this study, which has been the subject of many studies in both geological and geophysical fields. This sediment with a calcium carbonate structure exhibited high luminescence properties with X-ray excitation. The radioluminescence (RL) and thermoluminescence (TL) properties were investigated as well as their structural (FT-IR, XRD), morphological (SEM), thermal (TG-DTA) and absorption (UV-Vis-NIR) properties of this sediment. The broad RL peak of septarian was observed at 640 nm. There was a significant increase in the RL intensities of the sifted samples compared with the bulk sample. The TL glow curves of septarian irradiated with X-rays exhibited intense main TL glow peak having the maximum temperatures at 116 degrees C and about 390 degrees C with a heating rate of 2 degrees C/s. Also; the TL kinetic parameters were reported; activation energy (E), frequency factor (s) and the order of kinetics (b) of the first peak have been determined in detail by using peak shape (PS) and Computerized Glow Curve Deconvolution (CGCD) methods. SEM and EDS analysis were performed for the two different layers of septarian. The light colored side with the amorphous structure of the sample has more impurities (such as Fe, Al, Zr, K) than the crystallized and darker side.

Barium tantalate phosphors activated with different concentrations of Nd3+ ion were synthesized via conventional solid state reaction method. The synthesized ceramic powders were characterized by X–ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), laser diode (LD) excited near infrared (NIR) photoluminescence and X-ray induced radioluminescence (RL) analyses. In XRD results, Nd3+ doped BaTa2O6 structure with tetragonal tungsten bronze (TTB) symmetry was observed to continue up to 10 mol%. In the examination of ceramic powders by SEM, grain size decreased with the increasing doping concentration. By using laser diode excited NIR photoluminescence of BaTa2O6:Nd3+ phosphor exhibited characteristic emissions at 877, 1080, and 1376 nm wavelengths due to 4F3/2 → 4I11/2, 4F3/2 → 4I11/2, and 4F3/2 → 4I11/2 band transitions respectively. Scintillation properties of Nd3+ doped samples from UV to near-IR spectral region were carried out by the radioluminescence analysis. NIR and scintillation emissions initially increased by the doping concentration, and then decreased due to concentration quenching effect. © 2018 The American Ceramic Society

The study reveals the thermoluminescence (TL) properties of white and blue chalcedony minerals which this mineral mined two different regions (Edirne and Eskişehir, respectively) of Turkey. With the help of various characterization techniques (such as X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR)), the gem-quality of the samples was tested. The TL glow curves of the samples irradiated with X-rays show intense main TL glow peak having the maximum temperatures at 100 °C and 121 °C with a heating rate of 2 °C/s, respectively. The TL kinetic parameters of the samples are reported here for the first time. Activation energy (E), frequency factor (s) and the order of kinetics (b) of these peaks have been determined in detail by using various heating rates (VHR) and peak shape (PS) methods and verified by Computerized Glow Curve Deconvolution (CGCD). The CGCD method was used to determine the number of peaks associated with the TL glow curves. The values of E calculated with these three methods are a good agreement. © 2018 Elsevier Ltd

This study aims to find out usage of zinc oxide (ZnO) and 2-hydroxy-4-methoxybenzophenone (BP-3) for getting better optical and structural properties of nanocomposites. Polymer nanocomposites were prepared by adding zinc oxide for minimizing UV rays effects of the sun with the particle size of nanometer in different ratios to a low density polyethylene (LDPE). The polymer mixtures were synthesized by mixing nanocomposite samples with BP-3 featuring UV stabilizer. Besides making tensile testing measurements, in order to find out the optical, structural, mechanical and thermal changes, the new polymer nanocomposites were characterized by XRD, TG-DTA spectra, and SEM images. The samples with zinc oxide which show luminescent properties were examined in terms of radioluminescence features. Radioluminescence spectrum showed characteristic peaks of zinc oxide dispersed nanocomposites prepared with LDPE. The intensity of the characteristic peaks at 530 and 390 nm (exciton) increased by increasing rates of nanopowder zinc oxide while adding BP-3 to the composites caused a decrease in intensity of radioluminescence. © 2018, Pleiades Publishing, Ltd.