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Conjugated BaI2:Eu (5 at.%) nanocrystalline particles were synthesized, decorated with golden nanoparticles (GNP). GNP demonstrated some hydrophilic effect, leading to the BaI2·H2O phase creation. The Eu2+ luminescence intensity was reduced according to the GNP content. This was due to the decreased number of Eu2+ ions in the BaI2, most probably, arising from the Au substitution for Ba competing with Eu. Moreover, the decay time of luminescence was decreased upon GNP content. This was explained by the moderation of negative charge in the GNP, leading to the repulsion with an electron in the excited Eu2+. [ABSTRACT FROM AUTHOR]

The glass‐ceramics (GC) of gadolinium aluminum gallium garnets with the expected composition of Gd3Al3Ga2O12:Ce and Gd3Al3Ga2O12:Ce,Be (GAGG:Ce and GAGG:Ce,Be, respectively) are fabricated by crystallization from the Gd2O3–Al2O3–Ga2O3–CeO2–SiO2–BeO (Gd:Ga:Al ratio is close to 3:2:3) glasses. The influence of Be2+ co‐doping (including doping level) on the luminescent properties of the GAGG is demonstrated. In particular, Be co‐doping results in the suppression of the Ce3+‐related radioluminescence (RL) and as a consequence, the light yield is lowered as well. The conclusion is made that Be2+ creates effective electron or hole trapping centers. [ABSTRACT FROM AUTHOR]

Gadolinium oxychloride (GdOCl) powders doped with various concentrations of Ce3+ were synthesized via heat-treatment of hydrated gadolinium chloride. The reaction pathway to produce GdOCl by heat treating GdCl 3 · x H2O was explored through a combination of thermal analysis and X-Ray Diffraction (XRD) techniques, leading to the proposition of possible chemical reactions that describe the underlying mechanism of this complex process. The reversible hydration behavior observed in GdOCl:Ce has been leveraged to examine the possible impact of Gd(OH) 2 Cl:Ce on the optical characteristics of GdOCl:Ce. Studies comparing the luminescence properties of mixed GdOCl:Ce/Gd(OH) 2 Cl:Ce and pure GdOCl:Ce samples were conducted over a temperature range of 12–300K. These comparative analyses revealed analogous complex photoluminescence emissions between 350 and 600 nm, along with comparable lifetime characteristics for both GdOCl:Ce and Gd(OH) 2 Cl:Ce. The broad emission peak around 500 nm is likely associated with the oxide sublattice in GdOCl:Ce and may be attributed to emissions related to the host lattice or color center defects. These defects are likely responsible for the rapid decay components (<20 ns) observed in the luminescence decay. • GdOCl powders doped with different concentrations of Ce3+ were synthesized by annealing hydrated GdCl 3 :Ce in air. • Luminescence properties of GdOCl:Ce/Gd(OH) 2 Cl:Ce and GdOCl:Ce samples were investigated in the range 12–300K. • The rapid decay components in the luminescence are likely attributed to the defects in (GdO) n n + sublattice. [ABSTRACT FROM AUTHOR]

We report our investigation of the low-temperature optical properties of high-quality Cs 2 Cu 3 I 5 :In+ perovskite single crystals grown by the vertical Bridgman technique. Temperature-dependent radioluminescence in the range 15–300K reveals two main emissions for In+ doped samples at ∼450 nm and the other at ∼620 nm assigned to self-trapping exciton and In+ emissions respectively. Wavelength-resolved thermoluminescence reveals that In+ emission centers are the preferred recombination center for trapped charges. Further investigation of photoluminescence emission/excitation maps reveals a complex electronic structure that arises from spin-orbit coupling-related transitions in In+ and is only observable at low temperatures. Temperature-dependent photoluminescence decay measurements reveal some instances of charge transfer between the self-trapped excitons and In+ ions, as well as some thermally-assisted radiative recombination processes. • Transparent single crystals of undoped and In+-doped Cs 3 Cu 2 I 5 were grown via the Bridgman technique. • In addition to the STE emission, complex In + emission is registered in the PL at temperatures below 90K for In + -doped Cs 3 Cu 2 I 5. • In+ emission centers are the preferred recombination center for trapped charges in TSL for In+-doped Cs 3 Cu 2 I 5. [ABSTRACT FROM AUTHOR]

Glass ceramics based on Ce-doped garnets were fabricated by the controlled crystallization of CaO(MgO)–Y2O3–Al2O3–GeO2–SiO2–CeO2 glasses. The optimal conditions for transforming these glasses into ceramics by heat treatment were found by using differential scanning calorimetry: 1400 °C for MgO–Y2O3–Al2O3–GeO2–SiO2–CeO2 and 1500 °C for CaO–Y2O3–Al2O3–GeO2–SiO2–CeO2. The structure was characterized by X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy techniques, while the emission properties were studied by photoluminescence (PL) spectroscopy. The fine structure of XRD patterns evidences contributions from garnets of different compositions. Spatially-resolved PL spectroscopy using confocal microscopy shows that the garnet crystallites have a layered structure. The capability of tuning the PL peak position within the range from 530 to 580 nm by changing the excitation wavelength was demonstrated. This effect is caused by the localization of Ce3+ ions at the positions with different crystal fields, which varies due to a composition gradient in the crystallites. These glass ceramics have high potential for exploitation as phosphors in high-power white light sources. [ABSTRACT FROM AUTHOR]

Cerium doped gadolinium gallium aluminum garnet (Gd 3 Al 3 Ga 2 O 12 , GAGG) was synthesized in the glass ceramics form by the crystallization from Gd 2 O 3 –Al 2 O 3 –Ga 2 O 3 –SiO 2 –CeO 2 glass in the following weight proportion: 101 : 26: 47 : 25: 1. The spatial distribution and incorporation of Ce into the GAGG ceramic grains as well as the luminescence and scintillation performance are studied carrying out correlated experiments of photo-, radio- and cathodoluminescence including decay kinetics as well as energy dispersive X-ray spectroscopy combined with scanning electron microscopy. Optical absorption features were investigated using photothermal deflection spectroscopy. Cerium stays within the material mostly in the Ce3+ charge state. Its distribution in the bulk of the sample exhibits irregular trend indicating the tendency to coalesce in the middle. • The GAGG:Ce glass nanoceramics was fabricated. • Spatial distribution of Ce3+ in the batch of the glass nanoceramics was observed. • Hole trapping processes affect the luminescence in GAGG:Ce glass nanoceramics. [ABSTRACT FROM AUTHOR]

The search for engineering approaches to improve the scintillation properties of Gd3Al2Ga3O12 crystals and enable their production technology is of current interest. This crystal, while doped with Ce, is considered a good multi‐purpose scintillation material for detecting gamma‐quanta and neutrons. It is observed that co‐doping with Mg affected intrinsic defects in the crystal structure that create shallow electronic traps. Other point structure defects, which are based on local variations of the crystal stoichiometry, are significantly diminished by use of a co‐precipitated raw material. Nano‐structuring of the raw material enables production of a homogeneous precursor mixture for growing a crystal with minimal evaporation of Ga from the melt. The demonstrated nano‐engineering approach increased the light yield from the crystal by approximately 20%, enabling its applications in well logging. A technological approach to control defect formation in Gd3Al2Ga3O12:Ce crystalline material and minimize their effect on the crystal scintillation properties is successfully implemented. Co‐doping of the crystal with an aliovalent impurity acts as an efficient tool for reducing the crystal structure disordering, while use of co‐precipitated nanostructured raw material diminishes the effect of gallium evaporation from the melt during the crystal growth. [ABSTRACT FROM AUTHOR]