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Optical, scintillation, and thermally and optically stimulated luminescence (TSL and OSL) properties of the undoped and Mn-doped MgGa 2 O 4 single crystals were investigated. All the crystals showed a luminescence peak at 500 nm caused by the 3d–3d transitions of Mn2+. The 0.03 %-Mn-doped crystal exhibited the highest OSL intensity, whereas the 0.3 %-Mn-doped crystal exhibited the highest photoluminescence quantum yield and scintillation intensity. There was an inverse relationship between the scintillation and OSL intensity in the 0.03–0.3 % Mn-doped crystals. The results indicated that the 0.03 % Mn-doped crystal exhibits the highest efficiency during carrier trapping. In the OSL dose response functions, the lower detection limit of the 0.03 % Mn-doped crystal was 0.01 mGy, which was comparable with that of a commercial product. • Optical, scintillation, and dosimetric properties of Mn-doped MgGa 2 O 4 single crystals were investigated. • The crystals showed the luminescence due to 3d-3d transitions of Mn2+. • The 0.03 % Mn-doped MgGa 2 O 4 single crystal showed the highest OSL intensity, and the detection limit was better than that of a commercial dosimeter. [ABSTRACT FROM AUTHOR]

This study provided the first in-depth investigation of the effects of large dopant incompatibility (Pr3+ and La3+ ions) on the small host lattice element (Lu3+) in Lu 3 Al 5 O 12 (LuAG) single crystal. The growth of such complex crystals from the melt presented many challenges. By engineering the ionic radius ratio of RE- and M-site cations, a single-crystal phase stabilized by configurational entropy was achieved. This investigation elucidated the crystallization behavior of configurationally disordered rare-earth aluminum garnet oxide (Lu 1−x−y Pr x La y) 3 Al 5 O 12 from the melt and characterized its functional properties, including microstructural, optical, photoluminescence, and scintillation properties, between 5 and 300 K. Relaxation of the imposed strain energy led to local perturbations and destabilization of the garnet structure. Multielemental EDS mapping, micro-Raman spectroscopy, and thermoluminescence revealed the mechanism by which atomic size mismatch drove a smooth transition from the garnet to the perovskite phase in high entropy garnets. The optical, photoluminescence, and scintillation measurements provided fundamental insights into property changes driven by incompatibility doping. Standard and modified Judd-Ofelt theory analysis of absorption spectra determined the phenomenological Judd-Ofelt parameters Ω λ and radiative lifetimes. Atomic size mismatch engineering offers a promising approach to overcoming the limitations of conventional eutectic synthesis methods. • Perovskite inclusions, driven by atomic size mismatch, extend from rim to core. • Controlled incompatible La3+,Pr3+ codoping in LuAG modify functional properties. • Scintillation light yield improved up to 30% in La3+ codoped LuAG:Pr crystals. • (La,Pr)AlO 3 perovskite forms due to size mismatch of La3+ and Pr3+ with Lu3+. • Lattice disorder affects the intensity ratio of Pr³⁺ 5d→4 f and 4 f→4 f emissions. [ABSTRACT FROM AUTHOR]

Several types of dislocations were found in CdWO 4 single crystals. In-grown dislocations slip on (100) plane parallel to [001]. Dislocation pits were revealed in mechanically polished samples on (100) and (010) planes. Based on the results of chemical etching, it was inferred that the lattice dislocations gliding along < 001 > and < 100 > can split into partial dislocations. In the samples annealed at T = 600ºC for 2 h dislocation density decreased noticeably. After annealing shape and sizes of helical etch pits on (100) and (001) planes transform to those typical of lattice dislocations. • Dislocations slip as (100)[001] and (010)[100] in CdWO 4. • Lattice dislocations a[001] or c[001] dissociate. • Partial dislocations ½<101> glide and climb simultaneously. • Dislocation density decreases due to annealing. • Lattice dislocations are restored during annealing. [ABSTRACT FROM AUTHOR]

High-quality lutetium aluminum garnet doped with various Pr3+ concentrations ((Lu 1- x Pr x) 3 Al 5 O 12 , abbreviated to Pr:LuAG) single crystals were grown by the optical floating zone method. The concentration of Pr3+ dependence on microstructure, luminescence and scintillation properties were systematically studied. Based on the results of Rietveld refinement, the doping of Pr3+ leads to lattice distortion and lowers its symmetry. The symmetry of the LuO 8 dodecahedron center is lowest at 0.010, as confirmed by the Raman spectra. When excited at 450 nm and X-rays, the primary emission peak at 614 and 300 nm, respectively, induced by Pr3+ 4 f 2-4 f 2 and 4 f 5 d -4 f 2 transitions. The optimal doping concentration is 0.010. The electric dipole-electric dipole interaction between adjacent Pr3+ was responsible for the concentration quenching in the Pr:LuAG single crystals. (Lu 0.990 Pr 0.010) 3 Al 5 O 12 shows the shortest average scintillation decay time (22.55 ns) and highest light yield (23,842 ± 2300 ph./MeV) under 662 KeV 137Cs gamma-ray irradiation. In terms of overall luminescence and scintillation performance, 0.010 doping was the best for Pr3+ doped LuAG single crystals. • High quality Pr:LuAG single crystal was grown by optical floating zone method. • Pr ions lead to the enhanced translational motion of rare earth ions in Pr:LuAG. • Electric dipole-electric dipole interaction induced concentration quenching of Pr3+. • 0.010 Pr:LuAG single crystal has the best scintillation and luminescence properties. [ABSTRACT FROM AUTHOR]

Bismuth silicate (Bi 4 Si 3 O 12 , BSO) crystal is considered as a promising candidate for fabricating dual-readout calorimeters. Ta 2 O 5 doped BSO crystals were successfully grown by the modified vertical Bridgman method. The crystals possessed about 80% transmittance in the region of 350–800 nm with an absorption edge at about 280 nm. The emission and excitation spectra only showed a wide band which could be ascribed to the typical peaks of Bi3+. The light yield of BSO crystals could be improved effectively by doping Ta 2 O 5 , and the optimized concentration was about 1 mol%, dramatically improving the light output to about 150% of pure BSO crystals. Both the experimental results and theoretical calculations showed that doping Ta5+ ion could reduce the band gap and effectively enhance the light absorption, which was beneficial to generate more electron-hole pairs and promote its emission and light yield. Ta5+ ion is an effective candidate among the transition metal ions for improving the light output of BSO crystals. [Display omitted] • Ta 2 O 5 : BSO crystals with 25 mm diameter and 80 mm length were successfully grown by the modified vertical Bridgman method. • It was showed that Ta5+ improves the light yield of BSO to about 150% of the pure one. • Ta5+ introduces defect levels in the band gap of BSO, which is beneficial to promote the emission and light yield. [ABSTRACT FROM AUTHOR]

Inorganic scintillation materials have been widely used in several fields, such as high energy physics, nuclear medical imaging and industrial nondestructive inspection. In this work, a novel scintillation material, (Ce x Lu 1-x) 3 Al 5 O 12 /Al 2 O 3 (Ce3+:LuAG/Al 2 O 3) eutectic with different Ce3+-doping concentrations, was successfully grown by the micropulling down method at different pulling speeds. The effects of Ce3+-doping concentration and pulling speed on the microstructure and luminescent properties of the Ce3+:LuAG/Al 2 O 3 eutectic were investigated. The eutectic has a typical garnet structure, and a "Chinese script" microstructure can be seen throughout the cross section. As the pulling speed increased, the grain size and the morphological appearance of the "Chinese script" microstructure decreases. The Ce3+:LuAG/Al 2 O 3 eutectic shows a characteristic Ce3+ emission band centered at 508 nm, and the emission intensity increases with increasing Ce3+-doping concentration until the Ce3+-doping concentration reaches x = 0.01. The eutectic grown at a pulling speed of 1.7 mm/min shows maximum emission intensity, and the light yield of the (Ce 0.01 Lu 0.99) 3 Al 5 O 12 /Al 2 O 3 eutectic excited with X-ray at room temperature is approximately 64% of that of the (Ce 0.01 Lu 0.99) 3 Al 5 O 12 single crystal. The results reveal that the Ce3+:LuAG/Al 2 O 3 eutectic has a potential application as an X-ray detector material. Image 1 • The Ce3+:LuAG/Al 2 O 3 eutectic was firstly grown by the micropulling down method. • The eutectic exhibits garnet structure and typical "Chinese script" microstructure. • The eutectic has high light-yield, short decay time and an X-ray detector material. [ABSTRACT FROM AUTHOR]

Abstract Single crystal scintillators of RE 2 O 3 :Eu (RE = Lu, Y, Sc) with high (8%) and low (1%) Eu doping concentration were grown by the optical floating zone method. The luminescence and scintillation properties have been investigated and compared thoroughly. Correlated measurements of afterglow curves, photoluminescence excitation and photoluminescence, photoluminescence decay curves and X-ray excitation curves were performed. Lu 2 O 3 :Eu and Y 2 O 3 :Eu present significant afterglow intensity decreasing after high Eu concentration doping. While for the Sc 2 O 3 :Eu, its afterglow intensity even increases slightly. The luminescence efficiencies of high doping concentration samples are weaker than that of the low concentration ones due to the concentration quenching. The integrated X-ray excitation luminescence reveals the scintillation luminescence efficiencies of samples with the high concentration or the low ones both have the following sequence:Lu 2 O 3 :Eu＞Y 2 O 3 :Eu＞Sc 2 O 3 :Eu. Highlights • RE 2 O 3 :Eu (RE = Lu,Y,Sc) single crystal scintillators are grown by optical FZ method. • Sc 2 O 3 :Eu present different afterglow behavior comparing with Lu 2 O 3 :Eu and Y 2 O 3 :Eu. • The relationship between afterglow and Eu(S 6).→Eu(C 2) energy transfer is discussed. [ABSTRACT FROM AUTHOR]

CaMoO 4 single crystal with high quality and large size was grown by Bridgman method. The as-grown CaMoO 4 crystal presents blue-black color, and the annealed CaMoO 4 crystal presents optically transparent. The mechanisms of crystal fading by thermal annealing were explained in detail. The annealing effects on the optical transmission, photoluminescence spectra, X-ray luminescence spectra and luminescence decay time were investigated. The results indicate that thermal annealing not only has positive effects on reducing oxygen vacancies and alleviating the self-absorption phenomenon, but also the luminescent intensity can be enhanced greatly. The annealed CaMoO 4 crystal has moderate Stokes shift (1.46 eV). The light output of annealed CaMoO 4 single crystal by the excitation of 662 KeV X-ray from a 137 Cs source was measured to be 57.9 p.e. per MeV. This work offers detailed and significant data of scintillation properties of CaMoO 4 single crystal, which are very helpful for potential applications in searching for rare events especially in neutrinoless double beta decay area. [ABSTRACT FROM AUTHOR]

Transparent and yellowish Ce-doped SrHfO 3 (Ce:SHO) single crystals were grown by the xenon lamp equipped floating zone method. The synthesized crystals were in the single phase of SHO crystal structure, and no impurity phases such as HfO 2 were evident by the X-ray diffraction analysis. The Ce:SHO shows blue luminescence peaking at 410 nm in both the PL and scintillation spectra, and the decay time constant was approximately 14 ns. The PL QY increases with the Ce concentration, which was confirmed up to 5%. The afterglow level is the lowest when the Ce concentration is 3%. The full energy peak can be demonstrated with all the Ce:SHO single crystals prepared in this study under 241Am alpha-ray irradiation, and the estimated light yield is 396 photons/MeV for the 3% Ce:SHO, which is the highest among the samples studied. • Transparent and yellowish Ce-doped SrHfO 3 (Ce:SHO) single crystals were synthesized by the xenon lamp equipped floating zone method. • Ce:SHO showed blue luminescence with the maximum peak at 410 nm in both the photoluminescence and X-ray-induced scintillation spectra. • The full energy peak was observed in all the Ce:SHO single crystals under 241Am alpha-ray irradiation. [ABSTRACT FROM AUTHOR]

The photoluminescence spectra of CuI crystals using synchrotron radiation as an excitation light source were obtained at 60 K. The emission peaks at 405, 415, 420 and 443 nm were observed. The possible origins of these peaks were discussed by the temperature dependence of luminescence spectra for CuI material. Meanwhile, the photoluminescence spectra of CuI powder with different excitation intensity were measured and the ultrafast luminescence component of CuI crystals was warranted to be attributed to the recombination of donor acceptor pair. Furthermore, the excitation process was studied by measuring the photoluminescence excitation spectra of CuI crystals and powder. [ABSTRACT FROM AUTHOR]

• Mg2+ codoping effect on the atoms segregation in GAGG:Ce single crystal studied. • The formation of defects in Mg2+ and Ce3+ codoped GAGG crystals discussed. • The luminescence quenching mechanism in Mg2+ codoped proposed. • The charge compensation mechanism discussed. • Mg2+ codoping influence on the scintillation and luminescence properties investigated. The undoped, Mg2+ doped, Ce3+ doped as well as Mg2+:Ce3+ codoped Gd 3 Al 2 Ga 3 O 12 crystals were grown from the melt by the micro-pulling down method. Ce3+ and Mg2+ ions were codoped in a wide concentration range. A study of Mg2+ ion concentration effect on the luminescence and scintillation properties as well as segregation of atoms and defects creation processes were carried out. Mg2+ doping in Gd 3 Al 2 Ga 3 O 12 led to the creation of O O • defects localized next to Mg2+ sites due to charge imbalance compensation. Consequently, neutral (Mg Ga/Al/Gd O O) x defects were formed. In Ce3+ doped crystals, Mg2+ codoping changed the valence state from Ce3+ to Ce4+ to maintain charge neutrality. Hence, additional neutral (Ce Gd • -Mg Ga/Al/Gd ′) x and (Ce Gd -Mg Ga/Al/Gd O O) x defects appeared. Moreover, Mg2+ induced charge imbalance in GAGG crystal might also be compensated by the formation of oxygen vacancies (V O •• ). The Mg2+ ions imposed defects deteriorated the segregation of atoms. Accordingly the radial inhomogeneity of the crystals was diminished. The presence of stable Ce4+ and defects imposed by Mg2+ ions codoping were proved by absorption, photoluminescence, and scintillation decay time analysis. Hence, Mg2+ codoping resulted in quenching of the Ce3+ luminescence, acceleration of scintillation response, reduction of light yield, and thermally stimulated luminescence. The mechanism explaining a strong luminescence quenching with increasing Mg2+ ions concentration was proposed. [ABSTRACT FROM AUTHOR]

• The optical constants of Lu 2 O 3 single crystals covering the UV–VIS–NIR spectral region are firstly investigated • The bandgap energy 5.541 ± 0.004 eV of Lu 2 O 3 single crystal is derived experimentally • Large-size and damage-free Lu 2 O 3 single crystal is obtained by chemical mechanical polishing Lu 2 O 3 has attracted widespread attention in high-power lasers, scintillators, and semiconductors due to its high thermal conductivity, high stability, and large band gap. Due to the limitations of the growth process, high-precision characterization of polished quality and optical properties for large-size Lu 2 O 3 single crystal is extremely scarce, which hinders the design and optimization of optics based on Lu 2 O 3. In this study, we design a systematic machining scheme for large-size Lu 2 O 3 single crystal thick chip to obtain polished crystal with virtually no surface and subsurface damage. The surface/subsurface quality was evaluated utilizing optical profilometer, scanning electron microscope, and transmission electron microscope. Variable-angle spectroscopic ellipsometer was employed to measure the optical constants over wide spectral region (210–1690 nm), removing the lack of optical constants of Lu 2 O 3 single crystal in the ultraviolet region. The band gap is analyzed based on the optical constants results. The consistency of the measured data with the relevant literature verifies the reliability and accuracy of the measurement method along with the data. The surface/subsurface damage inspection method provides an effective approach for ultra-precision machining mechanism research and process optimization of Lu 2 O 3 and other hard and brittle materials. The band gap and the optical constants in wide spectral region provide critical fundamental data for the design and performance optimization of related optics. [ABSTRACT FROM AUTHOR]

• LPS single crystals with Nd doping concentration of 0.1%, 0.5%, 1.0%, 2.0%, and 5.0% were synthesized by the FZ method. • Under X-ray irradiated, Sample exhibited scintillation emission at both UV and NIR ranged caused by Nd3+ 4–4f transitions. • X-ray induced scintillation decay time of Nd-doped LPS samples resulted in 3–4 μs. • Under 662 keV γ-ray, scintillation light yield of Nd-doped LPS reached up to 800 ph/MeV in the 2.0% Nd-doped sample. Lutetium pyrosilicate (Lu 2 Si 2 O 7 , LPS) single crystals were synthesized by the floating-zone method with different dopant concentration to investigate the Nd-concentration dependence on the photoluminescence (PL) and scintillation properties. The Nd-doped LPS presented PL peaking at 800–900 nm due to the 4–4f transitions with the PL quantum yield up to 34%. Under X-ray irradiation, the samples showed several sharp peaks in both UV–visible and NIR regions. The scintillation decay time constants were around 3–4 μs upon pulsed X-ray excitation, and the afterglow level at 20 ms after X-ray irradiation was 310–650 ppm. The scintillation light yields of the Nd-doped LPS under γ-rays from 137Cs were up to 800 ph/MeV. hMeV. [ABSTRACT FROM AUTHOR]

• Charge trapping processes were studied in LiCaAlF 6 :Eu,Na single crystals. • O- defect was detected in the undoped LiCaAlF 6 single crystals aged in air. • Perturbed F 2 - hole trapping centers were detected in LiCaAlF 6 :Eu,Na single crystals. • Eu2+ ions predominately stay at Ca and only partly at Li sites. • Na co-doping results in decrease of the number of Eu2+ ions at Li site. Single crystals of LiCaAlF 6 , undoped, Eu-doped and Na co-doped, were studied by electron paramagnetic resonance, radioluminescence and thermally stimulated luminescence techniques applied in a correlated manner. The undoped samples exposed to X-ray irradiation featured two hole-like charge trapping centers which were attributed to the perturbed F 2 − pseudomolecular ion and O− (as a result of the contact with air). Their trap depths (E t) and frequency factors (f 0) were determined as follows: E t Perturbed F 2 − = 1.1 ± 0.1 eV , E t ( O −) = 1.7 ± 0.1 eV , f 0 Perturbed F 2 − = f 0 O − ~ 10 13 s − 1 , respectively. Annealing in air caused the appearance of another defect, a new electron-like center as well. It was found that the europium dominating charge state is 2 + in the LiCaAlF 6 :Eu,Na samples, however, some amount of the Eu3+ is also present. Moreover, there were two Eu2+ centers: the dominating Eu 1 2 + = Eu Ca 2 + and the low-content Eu 2 2 + = Eu Li 2 + . The amount of the latter is easily governed by the sodium admixture while the former is insensitive to the Na co-doping. The Eu and Na co-doping affected the defects distribution and incorporation in the LiCaAlF 6 host. Thermally stimulated luminescence yielded up to 8 peaks within the 100–600 K temperature range in glow curves of the undoped and doped crystals signalizing the presence of deep trapping states in the bandgaps. Along with the obvious degradation of the crystal surface in air by creation of new trapping centers this can contribute to the decreased light yield and downgrade of timing characteristics. [ABSTRACT FROM AUTHOR]

The luminescence, scintillation, and photoconversion properties of the single crystals of Ce3+ doped Tb 3−x Gd x Al 5-y Ga y O 12 (х = 0–1.5; у = 2–2.5) mixed garnets, grown by the micro-pulling-down (μ-PD) method, are investigated as a function of the Tb/Gd ratio with the aim of development of phosphor-convertors of white LED and scintillators. The partial Tb3+ substitution by Gd3+ cations leads to the suitable change of the crystal field splitting of the 5d energy levels of Ce3 ions due to different sizes of the Gd3+ and Tb3+ cations. For this reason, the cation engineering enables to improve the luminescence and scintillation characteristics of Tb 3−x Gd x Al 3-2.5 Ga 2-2.5 O 12 crystals due to increasing the efficiency of Gd3+→ Tb3+→ Ce3+ cascade energy transfer observed in these solid solutions. We have shown that from all the crystals under study, the Tb 3-x Gd x Al 2.5 Ga 2.5 O 12 :Ce (х = 1–1.5) crystal is the best promising candidate for the photoconversion and scintillation applications. • Single crystals of TbGdAGG:Ce grown by the micro-pulling-down method. • Tb3+/Gd3+ ratio control improving the color rendering and scintillation properties. • The best photoconversion properties are shown by Tb 2-1.5 Gd 1-1.5 Al 2.5 Ga 2.5 O 12 :Ce. [ABSTRACT FROM AUTHOR]

Lutetium pyrosilicate (Lu 2 Si 2 O 7) single crystals were synthesized by using the floating-zone method with 0.1, 0.5, 1.0, 2.0 and 5.0% of Tm-doping concentration. After the phase confirmation by powder XRD, photoluminescence (PL) and scintillation properties were systematically measured, including PL emission map, PL decay time, scintillation spectra, scintillation decay time and pulse height spectra. When we irradiated X-rays, we observed the scintillation emission at 360 and 460 nm caused by Tm3+ 4f-4f transitions. Under 662 keV γ-ray irradiation, we determined absolute scintillation light yield of 2340 ph/MeV for the 2.0% Tm doped sample. Taking into account whole optical and scintillation properties, 2.0% doping was the best for Tm-doped LPS crystals. • We successfully synthesized LPS single crystals with Tm doping concentration of 0.1 to 5.0 % by the FZ method. • When we irradiated X-rays, we observed the scintillation emission at 360 and 460 nm caused by Tm3+ 4f-4f transitions. • Under 662 keV γ-ray, scintillation light yield of Tm doped LPS reached up to 2340 ph/MeV with the 2.0 % Tm doped sample. • The optimal Tm doping concentration in the LPS single crystal for a scintillator was determined to be around 2.0 %. [ABSTRACT FROM AUTHOR]

β-Ga 2 O 3 is an emerging ultra-wide bandgap (4.9 eV) oxide semiconductor that additionally scintillates under gamma excitation. A unique combination of transparency in the UV/visible spectrum, semiconducting, and scintillation properties makes that compound interesting for fundamental studies of underlying physics and design of novel devices, in particular compact detectors for gamma radiation. Undoped, and singly (Ce, Si, Al), doubly (Ce + Si, Ce + Al), and triply (Ce + Al + Si) doped bulk β-Ga 2 O 3 single crystals were grown by the Czochralski method under very similar conditions and systematically studied in terms of electrical and optical properties that were correlated with scintillation light yield under gamma excitation. A wide spectrum of doping enabled to control the free electron concentration in semiconducting β-Ga 2 O 3 crystals within almost three orders of magnitude (7 × 1015–6 × 1018 cm−3) with the Hall mobility approaching 150 cm2 V−1s−1. The maximum of light yield under gamma excitation was recorded for undoped and Ce-doped β-Ga 2 O 3 single crystals having the free electron concentration of mid 1016 cm−3. The light yield significantly decreases for both electrically insulating and highly conducting (Si-doped) crystals. None of the dopants (Ce, Si, Al) introduces any absorption bands in the spectral region of light emission (340–410 nm) under gamma excitation. The dopants in quest do not affect the structure of neither cathodoluminescence (CL) nor radioluminescence (RL) emissions, but modify their absolute intensity. A double-band structure of RL spectra corresponds to UV and blue emissions observed in CL spectra that are assigned to self-trapped excitons. Image 1 • Doped semiconducting β-Ga 2 O 3 was grown and studied for gamma radiation detection. • The crystals are fully transparent to scintillation emissions at 340–410 nm. • Maximum of light yield was found at free electron concentration of mid 1016 cm−3. • Luminescence spectra point to self-trapped excitons in scintillation mechanism. [ABSTRACT FROM AUTHOR]