Pub Date : 2025-02-01DOI: 10.1016/j.omx.2024.100392
Kuat K. Kumarbekov , Askhat B. Kakimov , Zhakyp T. Karipbayev , Murat T. Kassymzhanov , Mikhail G. Brik , Chong-geng Ma , Michał Piasecki , Yana Suchikova , Meldra Kemere , Marina Konuhova
This study explores the synthesis and luminescent properties of europium-doped gallium oxide (Ga₂O₃:Eu) ceramics fabricated via electron beam-assisted synthesis (EBAS) at 1.4 MeV. The resulting Ga₂O₃:Eu ceramics exhibit a nanocrystalline structure with an average crystallite size of ∼30 nm, high crystallinity, and minimal lattice strain (<0.5 %). Luminescence analysis from 4 K to 300 K reveals both intrinsic and europium-induced emissions. While intrinsic Ga₂O₃ emission exhibits thermal quenching above 100 K, Eu³⁺-related emissions, notably the 611 nm red emission, show thermal stability, retaining ∼90 % of their intensity at 300 K. Additionally, a novel low-temperature emission peak at 1.74 eV, potentially associated with electron beam-induced defects, was detected, meriting further exploration. These findings indicate that Ga₂O₃:Eu ceramics synthesized via EBAS hold promise for optoelectronic, radiation detection, and high-temperature applications, given their rapid production and enhanced thermal stability.
{"title":"Temperature-dependent luminescence of europium-doped Ga₂O₃ ceramics","authors":"Kuat K. Kumarbekov , Askhat B. Kakimov , Zhakyp T. Karipbayev , Murat T. Kassymzhanov , Mikhail G. Brik , Chong-geng Ma , Michał Piasecki , Yana Suchikova , Meldra Kemere , Marina Konuhova","doi":"10.1016/j.omx.2024.100392","DOIUrl":"10.1016/j.omx.2024.100392","url":null,"abstract":"<div><div>This study explores the synthesis and luminescent properties of europium-doped gallium oxide (Ga₂O₃:Eu) ceramics fabricated via electron beam-assisted synthesis (EBAS) at 1.4 MeV. The resulting Ga₂O₃:Eu ceramics exhibit a nanocrystalline structure with an average crystallite size of ∼30 nm, high crystallinity, and minimal lattice strain (<0.5 %). Luminescence analysis from 4 K to 300 K reveals both intrinsic and europium-induced emissions. While intrinsic Ga₂O₃ emission exhibits thermal quenching above 100 K, Eu³⁺-related emissions, notably the 611 nm red emission, show thermal stability, retaining ∼90 % of their intensity at 300 K. Additionally, a novel low-temperature emission peak at 1.74 eV, potentially associated with electron beam-induced defects, was detected, meriting further exploration. These findings indicate that Ga₂O₃:Eu ceramics synthesized via EBAS hold promise for optoelectronic, radiation detection, and high-temperature applications, given their rapid production and enhanced thermal stability.</div></div>","PeriodicalId":52192,"journal":{"name":"Optical Materials: X","volume":"25 ","pages":"Article 100392"},"PeriodicalIF":0.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.omx.2025.100401
Ibrahim Oksuz , Sabin Neupane , Yanfa Yan , Lei R. Cao
A nuclear photovoltaic battery uses scintillator to convert radiation into visible light, which is then collected by a photovoltaic (PV) cell to generate electricity. If the radiation is gamma-rays emitted from external sources, the battery may also be referred as gammavoltaic battery. In this study, a polycrystalline CdTe solar cell was optically coupled with a 2.0 cm × 2.0 cm × 1.0 cm Gadolinium Aluminum Gallium Garnet (GAGG) scintillator, and the resulting device was tested using intense gamma radiation fields from a Cs-137 (1.5 kRad/h) and a Co-60 (10 kRad/h) irradiator. Measurements with Cs-137 provided a maximum power output (Pmax) of ∼288 nW, with a short-circuit current density (Jsc) of ∼1.22 μA/cm2 and an open-circuit voltage (Voc) of ∼0.34 V. In contrast, Co-60 irradiator gave a Pmax of 1.5 μW, with a Jsc of ∼4.73 μA/cm2 and a Voc of ∼0.38 V. The CdTe was also paired with a Lutetium-Yttrium Oxyorthosilicate (LYSO) crystal and tested with the Cs-137 source. The experiment presents a scalable option to reach to higher power outputs by harvesting gamma radiation fields in many cases where high radiation field demands heavy shielding and is often regarded as unwanted waste.
{"title":"Scintillator based nuclear photovoltaic batteries for power generation at microwatts level","authors":"Ibrahim Oksuz , Sabin Neupane , Yanfa Yan , Lei R. Cao","doi":"10.1016/j.omx.2025.100401","DOIUrl":"10.1016/j.omx.2025.100401","url":null,"abstract":"<div><div>A nuclear photovoltaic battery uses scintillator to convert radiation into visible light, which is then collected by a photovoltaic (PV) cell to generate electricity. If the radiation is gamma-rays emitted from external sources, the battery may also be referred as gammavoltaic battery. In this study, a polycrystalline CdTe solar cell was optically coupled with a 2.0 cm × 2.0 cm × 1.0 cm Gadolinium Aluminum Gallium Garnet (GAGG) scintillator, and the resulting device was tested using intense gamma radiation fields from a Cs-137 (1.5 kRad/h) and a Co-60 (10 kRad/h) irradiator. Measurements with Cs-137 provided a maximum power output (P<sub>max</sub>) of ∼288 nW, with a short-circuit current density (J<sub>sc</sub>) of ∼1.22 μA/cm<sup>2</sup> and an open-circuit voltage (V<sub>oc</sub>) of ∼0.34 V. In contrast, Co-60 irradiator gave a P<sub>max</sub> of 1.5 μW, with a J<sub>sc</sub> of ∼4.73 μA/cm<sup>2</sup> and a V<sub>oc</sub> of ∼0.38 V. The CdTe was also paired with a Lutetium-Yttrium Oxyorthosilicate (LYSO) crystal and tested with the Cs-137 source. The experiment presents a scalable option to reach to higher power outputs by harvesting gamma radiation fields in many cases where high radiation field demands heavy shielding and is often regarded as unwanted waste.</div></div>","PeriodicalId":52192,"journal":{"name":"Optical Materials: X","volume":"25 ","pages":"Article 100401"},"PeriodicalIF":0.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.omx.2024.100387
Dmitriy I. Shlimas , Daryn B. Borgekov , Artem L. Kozlovskiy
The aim of this study is to determine the differences in the damaged layer degradation kinetics in two-phase lithium-containing ceramics based on Li2ZrO3 and Li4SiO4 compounds in the case of irradiation with protons and helium ions, simulating the gas swelling and blistering processes, as well as the accumulation of radiolysis products in the damaged layer. During the conducted studies it was established that in the case of proton irradiation, the dominant role at fluences of 1015–1017 cm−2 is played by oxygen vacancies, the change in the concentration of which upon reaching critical values causes a decrease in the thermophysical properties, and disordering of the damaged layer. In this case, the accumulation of radiolysis products in the form of HC2 – and Zr3+ -defects in the structure of the damaged layer is observed at fluences of 5 × 1017 cm−2, while when irradiated with He2+ ions, the formation of these types of HC2 – and Zr3+ -defects is observed at a fluence of 1017 cm−2. Comparison of the concentration dependences of defects in the damaged layer on the atomic displacement value under irradiation with protons and He2+ ions revealed that the formation of oxygen vacancies under irradiation with He2+ ions is more intense than in the case of irradiation with protons, which in turn results in more pronounced processes of accumulation of radiolysis products in the case of high-dose irradiation.
{"title":"Application of EPR spectroscopy method for comparative analysis of structural damage accumulation kinetics in two-phase lithium-containing ceramics","authors":"Dmitriy I. Shlimas , Daryn B. Borgekov , Artem L. Kozlovskiy","doi":"10.1016/j.omx.2024.100387","DOIUrl":"10.1016/j.omx.2024.100387","url":null,"abstract":"<div><div>The aim of this study is to determine the differences in the damaged layer degradation kinetics in two-phase lithium-containing ceramics based on Li<sub>2</sub>ZrO<sub>3</sub> and Li<sub>4</sub>SiO<sub>4</sub> compounds in the case of irradiation with protons and helium ions, simulating the gas swelling and blistering processes, as well as the accumulation of radiolysis products in the damaged layer. During the conducted studies it was established that in the case of proton irradiation, the dominant role at fluences of 10<sup>15</sup>–10<sup>17</sup> cm<sup>−2</sup> is played by oxygen vacancies, the change in the concentration of which upon reaching critical values causes a decrease in the thermophysical properties, and disordering of the damaged layer. In this case, the accumulation of radiolysis products in the form of HC<sub>2</sub> – and Zr<sup>3+</sup> -defects in the structure of the damaged layer is observed at fluences of 5 × 10<sup>17</sup> cm<sup>−2</sup>, while when irradiated with He<sup>2+</sup> ions, the formation of these types of HC<sub>2</sub> – and Zr<sup>3+</sup> -defects is observed at a fluence of 10<sup>17</sup> cm<sup>−2</sup>. Comparison of the concentration dependences of defects in the damaged layer on the atomic displacement value under irradiation with protons and He<sup>2+</sup> ions revealed that the formation of oxygen vacancies under irradiation with He<sup>2+</sup> ions is more intense than in the case of irradiation with protons, which in turn results in more pronounced processes of accumulation of radiolysis products in the case of high-dose irradiation.</div></div>","PeriodicalId":52192,"journal":{"name":"Optical Materials: X","volume":"25 ","pages":"Article 100387"},"PeriodicalIF":0.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work the influence of a short-pulsed ion irradiation with a high flux (∼5.5∙1019 cm−2s−1) on structure, optical and photo-electrical properties of gallium oxide thin films have been investigated. The films were produced by the radio-frequency magnetron sputtering method. A part of deposited films was annealed in the air environment (900 °C, 2 h) for synthesis of β-Ga2O3 phase. Obtained films were subjected to the short-pulsed ion irradiation (ion energy - up to 200 keV, pulse duration - 90 ns, current density on the target - up to 15 A/cm2). The influence of the annealing and the irradiation on spectral dependences of absorption, the bandgap width and the Urbach energy have been determined. It was found that irradiation leads to amorphization of crystalline β-Ga2O3 films and a significant change in optical characteristics. In addition, we measured the magnitude of surface dark and photoconductivity of the films. Also, the field and spectral dependences of the photosensitivity of the films were researched. As a result, it was established that short-pulsed irradiation improves the photoelectric properties of amorphous gallium oxide films. The reasons of it are discussed.
{"title":"Influence of short-pulsed Ion irradiation on optical and photoelectrical properties of thin gallium oxide films","authors":"Zhanymgul Koishybayeva , Fedor Konusov , Sergey Pavlov , Dmitrii Sidelev , Artur Nassyrbayev , Dmitry Cheshev , Ruslan Gadyrov , Vladislav Tarbokov , Abdirash Akilbekov","doi":"10.1016/j.omx.2024.100394","DOIUrl":"10.1016/j.omx.2024.100394","url":null,"abstract":"<div><div>In this work the influence of a short-pulsed ion irradiation with a high flux (∼5.5∙10<sup>19</sup> cm<sup>−2</sup>s<sup>−1</sup>) on structure, optical and photo-electrical properties of gallium oxide thin films have been investigated. The films were produced by the radio-frequency magnetron sputtering method. A part of deposited films was annealed in the air environment (900 °C, 2 h) for synthesis of β-Ga<sub>2</sub>O<sub>3</sub> phase. Obtained films were subjected to the short-pulsed ion irradiation (ion energy - up to 200 keV, pulse duration - 90 ns, current density on the target - up to 15 A/cm<sup>2</sup>). The influence of the annealing and the irradiation on spectral dependences of absorption, the bandgap width and the Urbach energy have been determined. It was found that irradiation leads to amorphization of crystalline β-Ga<sub>2</sub>O<sub>3</sub> films and a significant change in optical characteristics. In addition, we measured the magnitude of surface dark and photoconductivity of the films. Also, the field and spectral dependences of the photosensitivity of the films were researched. As a result, it was established that short-pulsed irradiation improves the photoelectric properties of amorphous gallium oxide films. The reasons of it are discussed.</div></div>","PeriodicalId":52192,"journal":{"name":"Optical Materials: X","volume":"25 ","pages":"Article 100394"},"PeriodicalIF":0.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.omx.2024.100382
G.A. Kaptagay , B.M. Satanova , A.U. Abuova , M. Konuhova , Zh.Ye. Zakiyeva , U. Zh Tolegen , N.O. Koilyk , F.U. Abuova
By means of DFT oxygen evolution reaction on Rh-doped BaTiO3 (001) surface has been modeled. Gibbs free energies for each step of the reaction as well as the values of overpotential have been calculated, taking into account the solvation effect. The position of Rh-induces defect energy levels have been determined. Our findings indicated a substantial reduction in overpotential for the Rhodium-modified TiO2 surface compared to the bare surface. The high overpotential on the bare BaTiO3 surface suggests low OER efficiency, making Rh doping a promising strategy for enhancement.
{"title":"Effect of rhodium doping for photocatalytic activity of barium titanate","authors":"G.A. Kaptagay , B.M. Satanova , A.U. Abuova , M. Konuhova , Zh.Ye. Zakiyeva , U. Zh Tolegen , N.O. Koilyk , F.U. Abuova","doi":"10.1016/j.omx.2024.100382","DOIUrl":"10.1016/j.omx.2024.100382","url":null,"abstract":"<div><div>By means of DFT oxygen evolution reaction on Rh-doped BaTiO<sub>3</sub> (001) surface has been modeled. Gibbs free energies for each step of the reaction as well as the values of overpotential have been calculated, taking into account the solvation effect. The position of Rh-induces defect energy levels have been determined. Our findings indicated a substantial reduction in overpotential for the Rhodium-modified TiO<sub>2</sub> surface compared to the bare surface. The high overpotential on the bare BaTiO<sub>3</sub> surface suggests low OER efficiency, making Rh doping a promising strategy for enhancement.</div></div>","PeriodicalId":52192,"journal":{"name":"Optical Materials: X","volume":"25 ","pages":"Article 100382"},"PeriodicalIF":0.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.omx.2024.100396
Dmitriy I. Shlimas , Ainagul A. Khametova , Artem L. Kozlovskiy , Maxim V. Zdorovets
The article presents the results of experimental studies of the effect of the stabilizing MgO dopant using the electron spin resonance (ESP) method on enhancement of the stability of Li2ZrO3 ceramics to defect formation processes and accumulation of radiolysis products in the near-surface layer in the case of high-dose irradiation with protons simulating the hydrogenation effects characteristic of processes associated with tritium production. During the conducted studies, it was established that the addition of the stabilizing MgO dopant results in formation of inclusions in the form of the tetragonal MgLi2ZrO4 phase, which leads to an increase in the resistance of the near-surface layers to destructive damage due to the accumulation of structural damage (oxygen vacancies and point defects), as well as products of the physicochemical processes of radiolysis, characteristic of high irradiation fluence values. It was found that in the case of unmodified Li2ZrO3 ceramics, the formation of HC2 – centers is observed at a fluence of 1016 proton/cm2, while for two-phase ceramics, the formation of HC2 – centers is observed at higher fluences, while the intensity of the bands is significantly less than in the case of single-phase unmodified ceramics. The difference in the nature of changes in the intensities of singlet bands responsible for the presence of vacancy defects in the damaged layer, as well as HC2 – centers for single-phase and two-phase ceramics is a direct confirmation of the inhibition of structural degradation mechanisms in two-phase ceramics.
{"title":"Study of defect formation mechanisms in Li2ZrO3/MgLi2ZrO4 ceramics using EPR spectroscopy","authors":"Dmitriy I. Shlimas , Ainagul A. Khametova , Artem L. Kozlovskiy , Maxim V. Zdorovets","doi":"10.1016/j.omx.2024.100396","DOIUrl":"10.1016/j.omx.2024.100396","url":null,"abstract":"<div><div>The article presents the results of experimental studies of the effect of the stabilizing MgO dopant using the electron spin resonance (ESP) method on enhancement of the stability of Li<sub>2</sub>ZrO<sub>3</sub> ceramics to defect formation processes and accumulation of radiolysis products in the near-surface layer in the case of high-dose irradiation with protons simulating the hydrogenation effects characteristic of processes associated with tritium production. During the conducted studies, it was established that the addition of the stabilizing MgO dopant results in formation of inclusions in the form of the tetragonal MgLi<sub>2</sub>ZrO<sub>4</sub> phase, which leads to an increase in the resistance of the near-surface layers to destructive damage due to the accumulation of structural damage (oxygen vacancies and point defects), as well as products of the physicochemical processes of radiolysis, characteristic of high irradiation fluence values. It was found that in the case of unmodified Li<sub>2</sub>ZrO<sub>3</sub> ceramics, the formation of HC<sub>2</sub> – centers is observed at a fluence of 10<sup>16</sup> proton/cm<sup>2</sup>, while for two-phase ceramics, the formation of HC<sub>2</sub> – centers is observed at higher fluences, while the intensity of the bands is significantly less than in the case of single-phase unmodified ceramics. The difference in the nature of changes in the intensities of singlet bands responsible for the presence of vacancy defects in the damaged layer, as well as HC<sub>2</sub> – centers for single-phase and two-phase ceramics is a direct confirmation of the inhibition of structural degradation mechanisms in two-phase ceramics.</div></div>","PeriodicalId":52192,"journal":{"name":"Optical Materials: X","volume":"25 ","pages":"Article 100396"},"PeriodicalIF":0.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.omx.2024.100391
M.L. Chithambo , I.A. Ferreira , N.M. Trindade
Phototransferred thermoluminescence (PTTL) of rose quartz induced by 470 nm blue-, 525 nm green- and 405 nm UV-light is reported. Although its conventional TL glow curve measured at 1 °C s−1 during heating to 500 °C has five peaks (labelled I–V), only peaks I-IV are reproduced under phototransfer. All four peaks re-appear owing to phototransfer by 405 nm illumination whereas only peaks I-II are regenerated by 470 nm and 525 nm light. The dependence of PTTL intensity on duration of illumination for peaks I and II is analysed using phenomenological and kinetics models as systems of acceptor and donors with the number of the latter determined by experiment. The intensity of PTTL induced from deep electron traps increases with temperature of illumination with an activation energy of thermal assistance of 0.20 ± 0.01 eV irrespective of the illumination wavelength but decreases at elevated temperatures with an activation energy of thermal quenching whose value depends on the illumination wavelength. The extent to which electron traps affect the PTTL as acceptors or donors has also been studied.
{"title":"Phototransferred thermoluminescence of rose quartz: Measurement and analysis","authors":"M.L. Chithambo , I.A. Ferreira , N.M. Trindade","doi":"10.1016/j.omx.2024.100391","DOIUrl":"10.1016/j.omx.2024.100391","url":null,"abstract":"<div><div>Phototransferred thermoluminescence (PTTL) of rose quartz induced by 470 nm blue-, 525 nm green- and 405 nm UV-light is reported. Although its conventional TL glow curve measured at 1 °C s<sup>−1</sup> during heating to 500 °C has five peaks (labelled I–V), only peaks I-IV are reproduced under phototransfer. All four peaks re-appear owing to phototransfer by 405 nm illumination whereas only peaks I-II are regenerated by 470 nm and 525 nm light. The dependence of PTTL intensity on duration of illumination for peaks I and II is analysed using phenomenological and kinetics models as systems of acceptor and donors with the number of the latter determined by experiment. The intensity of PTTL induced from deep electron traps increases with temperature of illumination with an activation energy of thermal assistance of 0.20 ± 0.01 eV irrespective of the illumination wavelength but decreases at elevated temperatures with an activation energy of thermal quenching whose value depends on the illumination wavelength. The extent to which electron traps affect the PTTL as acceptors or donors has also been studied.</div></div>","PeriodicalId":52192,"journal":{"name":"Optical Materials: X","volume":"25 ","pages":"Article 100391"},"PeriodicalIF":0.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ce3+-doped compounds are typically the preferred materials for the development of inorganic phosphors for white LEDs, displays, and scintillators. In this study, pump-probe absorption spectroscopy was performed for Gd3Ga5O12:Ce and Gd3Al1Ga4O12:Ce crystals using ultraviolet (UV) and visible (VIS) pump light, and infrared (IR) probe light. A change in the IR-absorption was observed owing to the generation of free carrier plasma via photoexcitation. Through a simple analysis, the excitation spectra of this change determined the energy at the bottom of the conduction band relative to that at the Ce3+ 4f level. The transient response of the IR-absorption change suggested different relaxation processes for excited electrons in Gd3Ga5O12:Ce and Gd3Al1Ga4O12:Ce. Analysis of the thermally stimulated luminescence (TSL) glow curve determined the trap depth of the electrons in Gd3Al1Ga4O12:Ce. Based on positron annihilation lifetime spectroscopy (PALS), the generation of electron traps was linked to the introduction of vacancy complexes or vacancy aggregates with a negative charge, namely nonstoichiometric compositions. This helps achieve high-quality Ce3+-doped multicomponent oxides.
{"title":"Relationship between Ce3+ 5d1 level, conduction-band bottom, and shallow electron trap level in Gd3Ga5O12:Ce and Gd3Al1Ga4O12:Ce crystals studied via pump-probe absorption spectroscopy","authors":"Mamoru Kitaura , Heishun Zen , Shinta Watanabe , Hirokazu Masai , Kei Kamada , Kyoung-Jin Kim , Akira Yoshikawa , Jumpei Ueda","doi":"10.1016/j.omx.2024.100398","DOIUrl":"10.1016/j.omx.2024.100398","url":null,"abstract":"<div><div>Ce<sup>3+</sup>-doped compounds are typically the preferred materials for the development of inorganic phosphors for white LEDs, displays, and scintillators. In this study, pump-probe absorption spectroscopy was performed for Gd<sub>3</sub>Ga<sub>5</sub>O<sub>12</sub>:Ce and Gd<sub>3</sub>Al<sub>1</sub>Ga<sub>4</sub>O<sub>12</sub>:Ce crystals using ultraviolet (UV) and visible (VIS) pump light, and infrared (IR) probe light. A change in the IR-absorption was observed owing to the generation of free carrier plasma via photoexcitation. Through a simple analysis, the excitation spectra of this change determined the energy at the bottom of the conduction band relative to that at the Ce<sup>3+</sup> 4f level. The transient response of the IR-absorption change suggested different relaxation processes for excited electrons in Gd<sub>3</sub>Ga<sub>5</sub>O<sub>12</sub>:Ce and Gd<sub>3</sub>Al<sub>1</sub>Ga<sub>4</sub>O<sub>12</sub>:Ce. Analysis of the thermally stimulated luminescence (TSL) glow curve determined the trap depth of the electrons in Gd<sub>3</sub>Al<sub>1</sub>Ga<sub>4</sub>O<sub>12</sub>:Ce. Based on positron annihilation lifetime spectroscopy (PALS), the generation of electron traps was linked to the introduction of vacancy complexes or vacancy aggregates with a negative charge, namely nonstoichiometric compositions. This helps achieve high-quality Ce<sup>3+</sup>-doped multicomponent oxides.</div></div>","PeriodicalId":52192,"journal":{"name":"Optical Materials: X","volume":"25 ","pages":"Article 100398"},"PeriodicalIF":0.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.omx.2024.100393
K. Lamonova , A. Prokhorov , M. Schmidbauer , A. Kwasniewski , Yu Kazarinov , M. Konuhova , A. Platonenko , Z. Remeš , K. Ridzoňová , M. Buryi
The luminescence properties of two co-doped ZnSe:(Cr, Fe) single crystals, grown by the Bridgman method, have been studied using photoluminescence techniques. Structural characterization by high-resolution X-ray diffraction (HR-XRD), electron paramagnetic resonance (EPR) and scanning electron microscopy (SEM) has revealed that the samples differ in terms of dopant concentration and intrinsic native defects. Analysis of the VIS and near-IR photoluminescence spectra, based on the modified crystal field theory and DFT calculations has shown that Fe and Cr exist in two charge states (+2/+3) and can be located in both tetrahedral and octahedral positions. In the blue light region, quantum dots (QDs) appear. These represent clusters of three Cr-containing octahedral complexes accompanied by Zn vacancies, anticipating the formation of spinel ZnCr2Se4 inclusions in the host chalcogenide ZnSe matrix.
{"title":"Luminescence properties of ZnSe single crystals co-doped with Fe and Cr","authors":"K. Lamonova , A. Prokhorov , M. Schmidbauer , A. Kwasniewski , Yu Kazarinov , M. Konuhova , A. Platonenko , Z. Remeš , K. Ridzoňová , M. Buryi","doi":"10.1016/j.omx.2024.100393","DOIUrl":"10.1016/j.omx.2024.100393","url":null,"abstract":"<div><div>The luminescence properties of two co-doped ZnSe:(Cr, Fe) single crystals, grown by the Bridgman method, have been studied using photoluminescence techniques. Structural characterization by high-resolution X-ray diffraction (HR-XRD), electron paramagnetic resonance (EPR) and scanning electron microscopy (SEM) has revealed that the samples differ in terms of dopant concentration and intrinsic native defects. Analysis of the VIS and near-IR photoluminescence spectra, based on the modified crystal field theory and DFT calculations has shown that Fe and Cr exist in two charge states (+2/+3) and can be located in both tetrahedral and octahedral positions. In the blue light region, quantum dots (QDs) appear. These represent clusters of three Cr-containing octahedral complexes accompanied by Zn vacancies, anticipating the formation of spinel ZnCr<sub>2</sub>Se<sub>4</sub> inclusions in the host chalcogenide ZnSe matrix.</div></div>","PeriodicalId":52192,"journal":{"name":"Optical Materials: X","volume":"25 ","pages":"Article 100393"},"PeriodicalIF":0.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.omx.2024.100395
K. Shunkeyev , А. Kenzhebayeva , A. Krasnikov , V. Nagirnyi , Sh Sagimbayeva , D. Sergeyev , А. Tilep , Zh Ubaev , A. Lushchik
The study is focused on luminescence features of bound excitons (exciton-like formations, ELFs) in KCl:Na single crystals created in the field of sodium impurity ions either directly at photoexcitation or via the recombination of electron-hole pairs. The intensity of the X-ray luminescence (XRL) bands peaked at 2.8 and 3.1 eV (emission of recombinationally formed and relaxed ELFs) increases with both, the concentration of sodium impurity ions (10 → 1000 ppm) and the detection temperature (85 → 350 K). It is worth noting that at room temperature, the light yield of these XRL bands in KCl:Na practically coincides with that for the luminescence measured in the same way in classical scintillators, CsI and CsI:Na crystals. The lifetime of the fast component of cathodoluminescence at 2.8 and 3.1 eV equals 2.4 and 1.7 ns, respectively, at 6 K and even shortens to approximately τ ≈ 0.3 ns at room temperature. At 10 K, photons of 7.6 and 6.7 eV directly form ELFs in the field of single or paired Na+ impurity ions with typical luminescence bands peaked, respectively, at 2.8 eV ( (Na+)) and 3.1 eV ( (Na+-Na+)). These photoluminescence bands undergo complete thermal quenching by 200–300 K, whereas relevant XRL bands are not quenched up to 350 K, their intensity even noticeably increases at 200 → 350 K.
研究的重点是 KCl:Na 单晶中结合激子（类激子形成，ELFs）的发光特征，这些结合激子是在钠杂质离子场中直接通过光激发或电子-空穴对重组产生的。峰值为 2.8 和 3.1 eV 的 X 射线发光（XRL）带（重组形成和弛豫 ELF 的发射）强度随着钠杂质离子浓度（10 → 1000 ppm）和检测温度（85 → 350 K）的增加而增加。值得注意的是，在室温下，KCl:Na 中这些 XRL 波段的光产率实际上与在经典闪烁体、CsI 和 CsI:Na 晶体中以同样方式测量的发光光产率相吻合。在 6 K 时，2.8 和 3.1 eV 的阴极荧光快速分量的寿命分别为 2.4 和 1.7 ns，在室温下甚至缩短至约 τ ≈ 0.3 ns。在 10 K 时，7.6 和 6.7 eV 的光子直接在单个或成对 Na+ 杂质离子场中形成 ELF，典型的发光带分别在 2.8 eV （el0 (Na+)）和 3.1 eV （el0 (Na+-Na+)）处达到峰值。这些光致发光带在 200-300 K 时会完全热淬灭，而相关的 XRL 发光带在 350 K 时不会被淬灭，其强度甚至在 200 → 350 K 时会明显增加。
{"title":"Luminescence of bound excitons created near sodium impurity ions in KCl:Na single crystals","authors":"K. Shunkeyev , А. Kenzhebayeva , A. Krasnikov , V. Nagirnyi , Sh Sagimbayeva , D. Sergeyev , А. Tilep , Zh Ubaev , A. Lushchik","doi":"10.1016/j.omx.2024.100395","DOIUrl":"10.1016/j.omx.2024.100395","url":null,"abstract":"<div><div>The study is focused on luminescence features of bound excitons (exciton-like formations, ELFs) in KCl:Na single crystals created in the field of sodium impurity ions either directly at photoexcitation or via the recombination of electron-hole pairs. The intensity of the X-ray luminescence (XRL) bands peaked at 2.8 and 3.1 eV (emission of recombinationally formed and relaxed ELFs) increases with both, the concentration of sodium impurity ions (10 → 1000 ppm) and the detection temperature (85 → 350 K). It is worth noting that at room temperature, the light yield of these XRL bands in KCl:Na practically coincides with that for the luminescence measured in the same way in classical scintillators, CsI and CsI:Na crystals. The lifetime of the fast component of cathodoluminescence at 2.8 and 3.1 eV equals 2.4 and 1.7 ns, respectively, at 6 K and even shortens to approximately <em>τ</em> ≈ 0.3 ns at room temperature. At 10 K, photons of 7.6 and 6.7 eV directly form ELFs in the field of single or paired Na<sup>+</sup> impurity ions with typical luminescence bands peaked, respectively, at 2.8 eV (<span><math><mrow><msubsup><mi>e</mi><mi>l</mi><mn>0</mn></msubsup></mrow></math></span> (Na<sup>+</sup>)) and 3.1 eV (<span><math><mrow><msubsup><mi>e</mi><mi>l</mi><mn>0</mn></msubsup></mrow></math></span> (Na<sup>+</sup>-Na<sup>+</sup>)). These photoluminescence bands undergo complete thermal quenching by 200–300 K, whereas relevant XRL bands are not quenched up to 350 K, their intensity even noticeably increases at 200 → 350 K.</div></div>","PeriodicalId":52192,"journal":{"name":"Optical Materials: X","volume":"25 ","pages":"Article 100395"},"PeriodicalIF":0.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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