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This study focuses on the chemistry, thermal stability, and electrical conductivity of low/intermediate pyrolysis temperature (700−900 °C) polysiloxane derived ceramics. These ceramics were modified with additional carbon derived from divinylbenzene (DVB) added to the precursor. Their electrical properties were investigated for potential uses in micro-electrical mechanical systems (MEMS) and anodes for lithium batteries. The microstructure and chemical composition was investigated by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS); thermogravimetric analysis (TGA) provided insight into the thermal stability; and electrochemical impedance spectroscopy (EIS) into the electrical properties of the material. The increase of pyrolysis temperature and carbon content lead to an enhancement of the electrical conductivity, higher than previously reported values for intermediate pyrolysis temperature SiOC polymer derived ceramics. A limit of the amount of DVB that can be added to PHMS to produce a hybrid precursor has also been obtained.

The radioluminescence (RL) of a Lu3Al5O12:Ce (LuAG:Ce) single crystal and a transparent polycrystalline ceramic was investigated at high temperatures, up to 600 °C. Two bands were observed, one within 1.8–2.8 eV attributed to Ce3+, and another within 2.8–4.5 eV attributed to the collective behavior of different types of defects. The integrated RL intensity of the Ce3+ band normalized to the respective value at RT increased by a factor of 1.4x from room temperature (RT) up to 450 °C for the single crystal, and by a factor of 1.9x up to 300 °C for the polycrystalline ceramic. Comparison between the integrated RL intensity and glow curves suggested the radiative recombination of electrons thermally released from traps to account for the increase in RL intensity. Beyond these respective temperatures, integrated RL intensity decreased linearly with a rate ~1.4x higher for the single crystal. At about 500/530 °C the normalized integrated RL intensity was the same as at RT for the polycrystalline ceramic and the single crystal, respectively, showing that LuAG:Ce scintillators can be effectively used over a broad range of temperatures.

A series of new ternary lanthanide-based chlorides, Cs2EuCl5(H2O)10, Cs7LnCl10(H2O)8 (Ln = Gd or Ho), Cs10Tb2Cl17(H2O)14(H3O), Cs2DyCl5(H2O)6, Cs8Er3Cl17(H2O)25, and Cs5Ln2Cl11(H2O)17 (Ln = Y, Lu, or Yb), were prepared as single crystals via a facile solution route. The compounds with compositions of Cs7LnCl10(H2O)8 (Ln = Gd or Ho) and Cs5Ln2Cl11(H2O)17 (Ln = Y, Lu, or Yb) crystallize in a monoclinic crystal system in space groups C2 and P21/c, respectively, whereas Cs2EuCl5(H2O)10, Cs10Tb2Cl17(H2O)14(H3O), and Cs8Er3Cl17(H2O)25 crystallize in orthorhombic space groups Pbcm, Pnma, and P212121, respectively. Cs2DyCl5(H2O)6 crystallizes with triclinic symmetry in space group P1. All of these compounds exhibit complex three-dimensional structures built of isolated lanthanide polyhedral units that are linked together by extensive hydrogen bonds. Cs2EuCl5(H2O)10 and Cs10Tb2Cl17(H2O)14(H3O) luminesce upon irradiation with 375 nm ultraviolet light, emitting intense orange-red and green color, respectively, and Cs10Tb2Cl17(H2O)14(H3O) scintillates when exposed to X-rays. Radioluminescence (RL) measurement of Cs10Tb2Cl17(H2O)14(H3O) in powder form shows that the RL emission integrated in the range of 300-750 nm was ∼16% of BGO powder.

The effects of BaO network modifier on the structure, optical properties and luminescence of Ce-doped aluminophosphate glasses were investigated. Glasses were prepared by the melt quenching method in air with different chemical compositions: 50 or 60 mol% P2O5 + 5, 15 or 25 mol% SiO2 + 4–19 mol% BaO + 15 mol% Al2O3 + 1–6 mol% Ce2O3 such the total summed up to 100 mol%. Density was determined to be within 2.7–3.0 g/cm3, while the index of refraction was estimated using the Gladstone-Dale relation using the experimentally-obtained density values to be around 1.48. For each glass series, Raman spectra varied according to the BaO and/or Ce2O3 content. For 1 mol% Ce-doped glasses, the ultraviolet (UV) transparency cutoff was within 317–328 nm, with the cutoff wavelength increasing to 367–373 nm for 6 mol% doped glasses. Scintillation was characterized by radioluminescence (RL) measurements under X-ray excitation, and luminescence by photoluminescence emission (PL), excitation, and fluorescence lifetime measurements. PL and RL results showed a broad band centered around 3.3–3.6 eV with a fluorescence lifetime of about 30 ns. The highest RL output was observed from the 60P2O5·14BaO·5SiO2·15Al2O3·6Ce2O3 glass.

The effects of the sintering temperature on the microsctruture and luminescence of Lu 3 Al 5 O 12 :Pr (LuAG:Pr) ceramics was investigated by density, X-ray diffraction (XRD), scanning electron microscopy (SEM), grain size, attenuated total reflection Fourier transform infrared spectroscopy (ATR FTIR), photoluminescence (PL), radioluminescence (RL), and thermoluminescence (TL) measurements. A Czochralski-grown single crystal was used as reference. The increase of the sintering temperature promoted progressive structural modifications toward the characteristics of the single crystal. The presence of an amorphous phase was strongly detrimental to the luminescence of LuAG:Pr, with its elimination leading to enhanced RL and reduced TL emission. Evidence of synergism between the F-related defects and the Pr 3+ 4f - 4f and 4f - 5d transitions was also found with the presence of these defects being detrimental to the 5 d - 4 f scintillation.

The optically stimulated luminescence (OSL) and thermoluminescence (TL) signals of an Al2O3:C,Mg single crystal were investigated as a function of the heating temperature and illumination time before readout, respectively. The TL and OSL results were analyzed in complementary ways, including the area under the curve, whole range and partial integration, and peak intensity. A correlation between the continuous decay of the main TL peak intensity (at 185 °C at a heating rate of 1 °C/s) against blue light (470 nm) illumination times and the decay of the OSL signal for higher temperatures was found. Both these results showed that the emptying of the OSL active trap was closely related to the emptying of the trap related to the main TL peak, indicating a correlation of both phenomena.

The thermoluminescence (TL) of natural alexandrite (BeAl2O4) was investigated using different methods, namely Tm-Tstop, Tm as a function of beta irradiation dose, glow curve best fitting, variable heating rate, and TL fading as a function of time after irradiation, in addition to radioluminescence (RL) measurements under X-ray excitation as a function of the temperature. The chemical composition and the concentration of secondary mineral phases were determined by scanning electron microscopy and Energy-dispersive X-ray spectroscopy. TL measurements with heating rate = 1 K/s revealed five individual TL peaks at about 355 (peak I), 405 (peak II), 435 (peak III), 530 (peak IV), and 580 K (peak V). The activation energy E and the frequency factor s associated with each of them were determined by different methods. Within irradiation doses from 1 to 10 Gy, analysis of the Tm position indicated that all glow peaks exhibited a first-order kinetics TL mechanism. TL fading at room temperature was 15% for peak IV and 5% for peak V within 2 days after irradiation. RL measurements revealed luminescence centers attributed to Cr3+, Mn4+ and Fe3+ impurities. Overall, the results suggest that natural alexandrite has a potential use in dosimetry.

This work focuses on the fabrication and luminescent characterization of Tb-doped yttrium aluminum garnet (Y3Al5O12:Tb; YAG:Tb) ceramics produced using the laser sintering technique. In this technique, a CO2 laser is employed as the main heating source to promoting the sintering. YAG powders with different Tb concentrations were prepared by the polymeric precursor method and presented single cubic crystalline phase after calcination at 1000 °C in air for 2 h. Ceramic bodies were fabricated by laser sintering of uniaxially pressed pellets using a CO2 laser at a power level of 3.3 ± 0.1 W/mm2 for 90 s. To sintering, the green sample were put inside a sample holder, that improved the density, microstructure and avoided ablation effect. The resultant ceramics exhibited a high relative density of about 98–99 ± 1%, good microstructural homogeneity as verified by scanning electron microscopy, and a single cubic crystalline phase as determined by X-ray diffraction. X-ray absorption near edge structure measurements taken at the Tb LIII edge showed Tb to be exclusively in the trivalent state.

This contribution describes the fabrication of an ultrafiltration membrane scintillator based on ZnS:Ag. A solid state reaction method was used for the synthesis of ZnS:Ag, with particular emphasis on investigating the effects of the reaction temperature on the ZnS host, and of the Ag concentration on the radioluminescence (RL) output. The reaction temperature was found to control the crystallite size between 3 and 10 nm for temperatures between 75 and 500 °C, while the RL output was maximized for an Ag concentration of 0.2 mol%. Modified membranes were coated with ZnS:Ag powders via ultrafiltration and their response to ionizing radiation was characterized by means of RL measurements.

A α-Al2O3:C,Mg single crystal was investigated by means of optical absorption and photoluminescence measurements aimed at the identification of defects involved in the luminescence process. It was also investigated by thermoluminescence (TL) measurements as a function of the spectral emission in the 1.7–5.0 eV range. Radioluminescence measurements under X-ray excitation as a function of the temperature, from room temperature up to 400 °C were executed. These measurements revealed the presence of F, F-type, F-aggregate, and Mg-perturbed F-type and F-aggregate centers, and their thermal quenching behavior. Further, the role of these defects as recombination centers in the TL process was revealed.

This work aims at demonstrating the fabrication of a new composite material based on the micron-sized powder of the alexandrite mineral (BeAl2O4:Cr3+) dispersed in a fluorinated polymer for OSL dosimetric applications. Composites with 50 wt% alexandrite powders were obtained and characterized in their chemical composition, mechanical, and luminescent properties. Energy dispersive X-ray spectroscopy mapping measurements of the pellets revealed a homogeneous distribution of alexandrite particles throughout the organic matrix. PL measurements showed the signal related to Cr3+ ions in alexandrite remained active besides all fabrication steps, and tensile tests showed the pellets to have good ductility and tensile strength. The OSL results showed the integrated intensity signal varied linearly with the beta irradiation dose and that the pellets were stable at room temperature over time of 28 days. Nevertheless, improvements in the fabrication process are necessary toward obtaining the same OSL intensity from different pellets.

In this work, fluorophosphate glass samples with the composition 35NaPO3-30Ba(PO3)2-25MgF2-(10- x)YF3–x[EuF3 or Dy2O3] with x = 0–4.0 mol% EuF3, or x = 0–1.0 mol% Dy2O3, were fabricated by the melt quenching technique. The glasses were characterized from the structural, thermal and optical-spectroscopic points of view. Emission spectra were measured in the visible range upon UV excitation. Luminescence decay curves were registered by monitoring the most intense emissions of Eu3+ (5D0→7F2) and of Dy3+ (4F9/2→6H13/2) in the red and green, respectively, and from them the average lifetime values of the excited states 5D0 of Eu3+ (2.5 ms) and 4F9/2 of Dy3+ (0.71 ms) were determined. Emission spectra measured under variable excitation power yielded calibration curves for Eu3+ and Dy3+-doped glasses. The response to X-ray excitation was evaluated through radioluminescence measurements. The results indicate the promising application of these glasses in scintillators and for X-ray sensing devices.

Understanding the mechanisms of proton conduction at the interface of materials enables the development of a new generation of protonic ceramic conductors at low temperatures (150 °C) through water absorption and proton transport on the surface and grain boundaries. Conductivity measurements under Ar-3% H

The effects of ultraviolet (UV) radiation exposure on the thermoluminescence (TL) of aluminium oxide co-doped with carbon and magnesium (Al2O3:C,Mg) are reported. An Al2O3:C,Mg single crystal was investigated as a potential UV TL dosimeter after exposure to a Hg lamp radiation. The TL peak intensity and area under the curve signals were investigated as a function of the UV exposure time. Intense TL signal was obtained after UV radiation, and the area of the main TL peak at 456 K exponentially increasing with UV exposure time (within 10–120 s), with a trend for saturation for long irradiation times These results were interpreted against similar measurements using beta radiation, showing that the same defects are involved in the TL response for both types of radiation, while the different irradiation response to the two types of radiation was related to the differences in the energy dissipation characteristics, and how they affect the concentration of F-type/F-aggregate centers.

Motivated by the search of new materials for optically stimulated luminescence (OSL) dosimeters, magnesium aluminum spinels with different Mg:Al ratios were investigated. Powders were prepared via the co-precipitation method with Mg:Al ratios 1:2 (stoichiometric), 1.5:2 (MgO-rich) and 1:3 (Al2O3-rich) and calcined at 1000 °C in air for 2 h. A higher level of structural disorder was found in the powders than in the single crystal as determined by X-ray diffraction and Raman spectroscopy measurements, while the same luminescence centers were present in all materials as shown by X-ray induced radioluminescence measurements. Among the different Mg:Al ratios, stoichiometric spinel presented superior OSL dose response, being linear within 0.16 Gy and 2 Gy, presenting 1% reproducibility of the dosimetric response after repeated exposure to the same dose, having the least fading, and with a minimum detectable absorbed dose (MDD) of 0.65 mGy.

An investigation of the luminescent properties of undoped and rare earth (RE) singly- and co-doped YF 3 was carried out by means of radioluminescence (RL) and thermoluminescence (TL) measurements. Materials were obtained by ligand-free co-precipitation with Ce, Tm, Tb or Eu substituting for Y, followed by calcination in air at 500 °C for 1 h. RL measurements confirmed the effective luminescence activation of the host. TL measurements revealed a relatively intense contribution of the host, with Tm doping yielding the strongest signal among the singly-doped samples. Co-doping with Ce and Tm was investigated within the 0.5–5 mol% range for each RE, with the 0.5,0.5 (Ce,Tm) mol% co-doping yielding the strongest luminescence signal. However, a clear correlation between the RE dopant(s) and TL peaks was not found.

Continuous wave optically stimulated luminescence (CW-OSL) of an Al2O3:C, Mg single crystal was investigated after irradiation with ultraviolet C radiation (UVC; peak emission at 254 nm) as well as with a beta source under different doses (100 mGy – 3 Gy). Analysis of the OSL decay curves provided experimental evidence that: i) UVC- and beta-irradiated Al2O3:C, Mg single crystal showed similar OSL decay curves, and that ii) a same fast ( τ ~ 2.9 s) and a same slow ( τ ~ 29 s) components were identified in the OSL decay curves for both types of radiation. On the other hand, analysis of the results suggested that radiation type generated distinct initial concentration of charges trapped at these two traps. The differences in the OSL decay curves were attributed either to differences in the initial population of the traps or to a balance of trapping-detrapping during UV irradiation.

An investigation of Ce-activated borate-rich borosilicate glasses was performed in a composition range previously unexplored, with high B 2 O 3 :SiO 2 ratios from 4.83:1 to 8.75:1. Glass samples were prepared by the melt quenching method in air. Samples were individually heated for 15 min at 1000 °C, evaluated for weight loss due to the release of volatile species, followed by a final melt for 15 min at 1000 °C, and then annealed at 350 °C for one hour to enhance stability. Particular emphasis was placed on the luminescence of the glasses investigated under X-ray and ultraviolet excitation. Luminescence was interpreted in terms of defects and Ce 3 + in different environments. The results indicated it was possible to achieve a composition of the host matrix that exhibited ultraviolet transparency cutoff at 326 nm and a well-defined emission from Ce 3 + , especially under X-ray excitation.

In this work, we demonstrated the fabrication of crack-free luminescent Er-doped silica coatings sintered using a CO2 laser. The silica sol-gel precursor with controllable rheology was developed using tetraethyl orthosilicate (TEOS) and hexamethyldisiloxane (HMDS). Luminescence activation was achieved through doping with Er ions. Coatings sintered at 1100 °C presented green photoluminescence at ∼550 nm and strong radioluminescence as well. After dip-coating, crack-free Er-doped silica thin films were obtained using a CO2 laser. Films sintered by laser had similar microstructure as the films sintered in a furnace. However, laser sintering extended the thickness range for making crack free sintered films. Using laser sintering, the thickness of crack-free silica films could be extended to above 1 μm, which is important for scintillation and optical waveguide applications. In order to understand the cracking control mechanism, a finite element (FEM) model was developed to analyze the stress distribution within the laser-sintered thin film. The model showed that the localized nature of sintering by laser heating allows for constrained sintering stress relaxation by the softer surrounding region of the film, effectively suppressing cracking.

This work focuses on demonstrating the fabrication of miniaturized scintillators based on rare earth activated YAG ceramics using the direct inkjet printing method. Erbium was chosen as the activator, and YAG sol-gel precursor inks were prepared under precise hydrolysis and polycondensation reactions. The precursors showed excellent control over rheology and surface tension, resulting in good printability. One of the most important challenges of inkjet printing of lines is the stability of lines. Line stability during printing is highly dependent on the printing frequency, drop spacing and substrate temperature. When a line was printed drop by drop, bulges were always observed during printing at 25 °C. This instability was significantly suppressed when the substrates were slightly heated. Adding polyvinylpyrrolidone to the precursor helped eliminate pores and cracks during firing. Crack-free YAG lines with ∼200 nm thickness were obtained after firing. The photoluminescence of YAG:Er heat-treated at 1200 °C for 1 h was optimized for an Er concentration of 2 wt%. X-ray induced radioluminescence was dominated by emission lines at 398 and 567 nm.

The effects of the incorporation of Ce on the luminescence of tetragonal garnet-type Li 7 La 3 Zr 2 O 12 (LLZO) were examined. Undoped and Ce-doped LLZO powders with nominal compositions of Li 7 (La 1-x Ce x ) 3 Zr 2 O 12 with x = 0, 0.005, 0.01, 0.03, and 0.05 were synthesized via conventional solid state reaction. X-ray diffraction (XRD) revealed the structural evolution from tetragonal to cubic LLZO, together with Li 2 ZrO 3 and Ce 4 O 7 minor phases upon Ce incorporation. Undoped LLZO exhibited a single luminescence band centered at 2.84 eV that was quenched by the incorporation of Ce. A Gaussian band deconvolution analysis of the radioluminescence (RL) spectra suggested that Ce occupied two distinct crystallographic sites when replacing for La, with emission bands centered at 2.41 and 2.78 eV. The Gaussian band deconvolution analysis of RL spectra up to ∼250 °C revealed thermal quenching reduced the intensity by about half at 50–60 °C, with negligible emission detected at about 250 °C.

Described herein is the use of a laser sintering technique to produce persistent luminescence CaAl 2 O 4 :Eu 2+ Dy 3+ ceramics exhibiting enhanced translucency in the visible/near infrared spectral range. In this technique, a CO 2 laser was used as the main heating source for sintering with no atmospheric control. The ceramics sintered at a power density of 1.2 W/mm 2 yielded single monoclinic CaAl 2 O 4 phase, homogeneous grain size distributions and transmittance up to 45% in the range of 400 nm–900 nm. Upon conventional sintering in air, the ceramics exhibited the characteristic blue emission from the Eu 2+ ions corresponding to the 5d → 4f transition at 440 nm, and weak emission from Eu 3+ ions between 550 nm and 700 nm, corresponding to the 5 D 0 → 7 F J transitions.

High-density scintillating glasses are proposed for a novel proton-imaging device that can improve the accuracy of the hadron therapy. High-density scintillating glasses are needed to build a cost effective, compact calorimeter that can be attached to a gantry. This report summarizes the study on Europium, Terbium, and Cerium-doped scintillating glasses that were developed containing heavy elements such as Lanthanum, Gadolinium, and Tungsten. The density of the samples reach up to 5.9 g/cm 3 , and their 300–600 nm emission overlaps perfectly with the peak cathode sensitivity of the commercial photo detectors. The developed glasses do not require any special quenching and can be poured easily, which makes them a good candidate for production in various geometries. Here, the glass making conditions, preliminary tests on optical and physical properties of these scintillating, high-density, oxide glasses developed for a novel medical imaging application are reported.

An electrospinning method for fabrication of the YAG:Er3+ fibrous membrane is developed and the scintillation properties of the obtained membranes were examined. A homogeneous precursor YAG sol was synthesized allowing to control the sol–gel transition. The synthesized precursor allows one to achieve the 5 wt.% level of fiber doping with Er without formation of any undesired crystalline phases. It was found that the relative humidity had a strong impact on the fiber microstructure. The fibers obtained at the low relative humidity level (~30%) had almost straight cylindrical shape with an average diameter of ~590 nm, their surface was smooth. The shape of fibers obtained at the high relative humidity level (~50%) deviated from the straight cylindrical shape and the average diameter was larger, ~1.12 µm. The fluid permeability of membranes, K, obtained at the low relative humidity level was measured using an upward wicking experiment to give K~10−13 m2. The YAG:Er membrane presented a strong green photoluminescence under ultraviolet excitation and intense radioluminescence dominated by emission lines at 398 and 467 nm under the X-ray excitation. The properties of these materials make them promising candidates as porous scintillators for the detection of ionizing radiation of flowing fluids.

Undoped and Ce-doped hexagonal BiPO4 were synthesized by a precipitation method and characterized on their structure, Ce spatial distribution and chemical state, together with detailed luminescence spectroscopy investigation through systematic variation of the excitation wavelength (λexc) over the broad range 250–460 nm combined with radioluminescence measurements and extensive literature review. Up to five distinct emission bands were observed, depending on λexc and on the presence or not of the activator. The host presented three emission bands: the 350 nm (3.54 eV) band was ascribed to a defect, the 405 nm (3.06 eV) band was ascribed to metal-to-metal charge transfer (MMCT), and the 570 nm (2.18 eV) band was ascribed to the Bi3+ 3P1 → 1S0 transition. The presence of Bi3+ ions perturbed by oxygen vacancies in the coordination polyhedron at varying distances to the Bi3+ ions created states with lower energies than the states of unperturbed Bi3+. Ce-incorporation led to the creation of two partially superimposing bands at about 445 nm (2.79 eV) and 490 nm (2.53 eV). Strong interaction between Ce3+ and the host was observed. These results led to enhanced understanding of the intrinsic and extrinsic luminescence of this material that presents considerable controversy in the literature.

The effects of different processing steps and processing conditions for the fabrication of Y2O3 and Lu2O3 ceramics were investigated, particularly the effects of calcination, and sintering temperature on the content of open-volume and electronic defects. Ceramic bodies were prepared from calcined powders by sintering from 1400°C to 1700°C for 20 h. Density was determined by the Archimedes method and showed pellets reached about 99% of Y2O3 density for temperatures ≥1450°C, and reached 98% for sintering at 1700°C for Lu2O3. The content of open-volume defects was followed by positron annihilation lifetime (PAL) measurements. For both materials, two lifetimes were obtained. The faster lifetime, 211 ps for Y2O3 and 204 ps for Lu2O3, was assigned to bulk annihilation with possible contribution of grain boundaries. The longer lifetime was assigned to positronium annihilation in open-volume defects with radii of 2–4 A. Doppler broadening analysis revealed the same type of defect in Lu2O3 ceramics for all sintering temperatures. PAL analysis results showed that densification was achieved through the elimination and agglomeration of open-volume defects. Thermoluminescence (TL) measurements of Y2O3 showed that sintering is beneficial in eliminating traps and/or recombination centers, and that higher sintering temperatures increase TL signal.

Alexandrite mineral (BeAl2O4:Cr3+) powder incorporated in a fluorinated polymer was prepared in the form of pellets. A mixture with 20 wt% of the alexandrite in the pellet had the luminescence behavior evaluated as a function of exposure to ionizing radiation using the optically stimulated luminescence (OSL) technique. The OSL measurements were evaluated in terms of dose-response (beta dose from 0.1 to 5 Gy), repeatability, reproducibility, and fading. The results showed that the OSL intensity signal varied linearly with the irradiation dose and that the OSL intensity suffered a strong reduction during the first five days of storage in the dark but remained stable for at least the following 30 days. Radioluminescence (RL) measurements under X-ray excitation revealed a weak luminescence within the ultraviolet–visible spectral region, while optical absorption (OA) measurements revealed the presence of Cr3+ impurities.

ZnS:Ag was synthesized by the hydrothermal reaction method with different Ag concentrations, from 0.05 to 5 mol%, Ag, Al co-doping concentrations, from 0.025 to 0.5 mol% ea., and under broad ranges of reaction temperature, from 60 to 200 °C, and reaction time, from 2 to 10 h. Samples were characterized on their structure, morphology, and luminescence by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL), and radioluminescence under X-ray excitation (RL) measurements, respectively. SEM results suggested that nucleation and growth of ZnS:Ag occurred on the surface of microbubbles. XRD results also revealed the samples to have single cubic structure, and that crystallite size could be controlled within ca. 2–11 nm through specific combinations of reaction temperature and time. PL measurements revealed the contribution of distinct luminescence centers, and that blue/red emission could be tuned by the reaction conditions. It was found that PL and RL output was maximized with nominal 0.l-0.2 mol% Ag, and with nominal 0.1 mol% ea. Ag, Al co-doping.

The structure, ultraviolet (UV) transparency, luminescence, and scintillation of CeO2-doped (0.1 mol%) borosilicate glasses containing Sb2O3, SnO2 or P2O5 were investigated. Glasses were prepared by melt quenching in air and characterized by several spectroscopy techniques: Raman scattering, optical absorption, photoluminescence (PL), fluorescence lifetime, thermoluminescence, and radioluminescence. Raman scattering results presented three major groups of vibrational modes, within 230–850 cm−1, 850-1250 cm−1, and 1250-1600 cm−1. Luminescence was dominated by a broad band centered at around 360–380 nm, depending on the chemical composition of the glass. Photoluminescence presented a dominant (96–98%) fast decay time of 36–40 ns that was ascribed to Ce3+. The P2O5-containing glass showed the highest scintillation output under X-ray excitation.

The effects of post-fabrication thermal processing in O2 flux on the luminescence and scintillation of a Y2O3:Tm transparent ceramic were investigated. The results showed that the strategy of post-fabrication processing can be beneficial to the performance of the ceramics, depending on the cumulative processing time. After the first hour of processing, about 40% enhancement in the luminescence output together with about 20% enhancement in the scintillation light yield were obtained. The enhancements were tentatively assigned to the incorporation of oxygen into vacancy sites. Longer cumulative processing times lead to the incorporation of oxygen as interstitials that is detrimental to scintillation light yield but not to luminescence output. This work also revealed that thermoluminescence measurements are a useful tool to predict scintillation light yield of Y2O3:Tm.

The present article focuses on the influence of gamma irradiation on nanoscale polymer grafted films and explores avenues for improvements in their stability toward the ionizing radiation. In terms of applications, we concentrate on enrichment polymer layers (EPLs), which are polymer thin films employed in sensor devices for the detection of chemical and biological substances. Specifically, we have studied the influence of gamma irradiation on nanoscale poly(glycidyl methacrylate) (PGMA) grafted EPL films. First, it was determined that a significant level of cross-linking was caused by irradiation in pure PGMA films. The cross-linking is accompanied by the formation of conjugated ester, carbon double bonds, hydroxyl groups, ketone carbonyls, and the elimination of epoxy groups as determined by FTIR. Polystyrene, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, dimethylphenylsilanol, BaF2, and gold nanoparticles were incorporated into the films and were found to mitigate different aspects of the radiation damage.

Transparent Y 2 O 3 ceramics singly-doped with either Eu 3+ or Tm 3+ were fabricated by means of sequential consolidation steps at high pressure and temperature. These ceramics were characterized for their luminescence and thermal lensing behaviors, and the results compared to data on single crystals reported in literature. Thermal diffusivity, D , and conductivity, K , values of D =26×10 −3 cm 2 /s and K =5.8 W/m K, respectively, for 1.0 mol% Eu 3+ and 0.5 mol% Tm 3+ singly-doped Y 2 O 3 transparent ceramics were obtained. These values are about half of those for single crystal analogs. A small temperature coefficient of the optical path length change, ds / dT =3×10 −6 K −1 , was determined, making these materials suitable for applications requiring nearly athermal response. Selected spectroscopic properties were obtained by means of Judd–Ofelt analysis and together with thermal lens results provided absolute values for the fluorescence quantum efficiency of several levels, particularly 62% for the 5 D 0 level of Eu 3+ and 84% for the 3 F 4 level of Tm 3+ .

0.25 at.% Er-doped Sc2O3 transparent ceramics fabricated using the two-step sintering method with different combinations of sintering temperatures were investigated by positron annihilation spectroscopy. Analysis of the broadening of the annihilation photopeak revealed the presence of the same type of defect in all samples. The lack of long lifetimes (τ ≥ 2 ns) suggested no positronium formation or the lack of trapping sites large enough to trap positronium for long enough time for the annihilation to be observed. Analysis of positron annihilation lifetime revealed the presence of a single lifetime that ranged from 208 to 219 ps, depending on the sintering conditions. These results also suggest the absence of a significant presence of vacancy clusters and other larger open-volume defects, and that the dominant open-volume defect corresponds to monovacancies and/or complex defects associated with monovacancies. The bulk lifetime of Er-doped scandia is estimated to be equal or lower than 208 ps.

The detection of neutrons above background levels is an indication of nuclear materials, creating significant applications for handheld neutron detectors in homeland security. For such applications, a 10B and 6Li enriched, scintillating glass neutron detector was designed. The model is compact enough to be used as a handheld detector and is equipped with machine learning capabilities to determine the location of the source and discriminate a neutron from a gamma. Lithium Borosilicate glass samples, with up to 70% 10B and 6Li content, and doped with Tb and Eu, were engineered to optimize the performance of the detector. The scintillation properties and neutron/gamma detection capabilities of the glass samples were tested. The model detector's performance was simulated in Geant4 and the simulation data was utilized for machine learning to predict the location of the source with an Artificial Neural Network (ANN). The reported handheld neutron detector design with the implemented artificial intelligence capability can achieve 99.9% accuracy in neutron/gamma discrimination, 8.9% error in radial angle estimates, and 2.9% error in azimuthal angle estimates.