Bin Feng, Sena Hoshino, Bin Miao, Jiake Wei, Yu Ogura, Atsutomo Nakamura, Eita Tochigi, Katsuyuki Matsunaga, Yuichi Ikuhara, Naoya Shibata
Mobility of dislocations in compound semiconductor materials can be changed by light illumination because the core structure of dislocations is supposed to be reconstructed by photoexcited carriers. However, the atomic structure of such dislocation cores has not been observed and is still poorly understood. In this study, we introduced dislocations in ZnS, one of the typical II–VI type compound semiconductors, by deformation under darkness, and investigated the atomic structure of the dislocation cores using scanning transmission electron microscopy (STEM) combined with theoretical calculations. Direct observation of the Zn core partial dislocation revealed that its atomic structure is in good agreement with the theoretically predicted dislocation core without electron trapping. Moreover, the dislocations were observed to move along a slip plane during the observation. These results indicate that the electron-trap-free dislocation is mobile and could be the origin of plasticity in the dark.
{"title":"Direct observation of intrinsic core structure of a partial dislocation in ZnS","authors":"Bin Feng, Sena Hoshino, Bin Miao, Jiake Wei, Yu Ogura, Atsutomo Nakamura, Eita Tochigi, Katsuyuki Matsunaga, Yuichi Ikuhara, Naoya Shibata","doi":"10.2109/jcersj2.23065","DOIUrl":"https://doi.org/10.2109/jcersj2.23065","url":null,"abstract":"Mobility of dislocations in compound semiconductor materials can be changed by light illumination because the core structure of dislocations is supposed to be reconstructed by photoexcited carriers. However, the atomic structure of such dislocation cores has not been observed and is still poorly understood. In this study, we introduced dislocations in ZnS, one of the typical II–VI type compound semiconductors, by deformation under darkness, and investigated the atomic structure of the dislocation cores using scanning transmission electron microscopy (STEM) combined with theoretical calculations. Direct observation of the Zn core partial dislocation revealed that its atomic structure is in good agreement with the theoretically predicted dislocation core without electron trapping. Moreover, the dislocations were observed to move along a slip plane during the observation. These results indicate that the electron-trap-free dislocation is mobile and could be the origin of plasticity in the dark.","PeriodicalId":17246,"journal":{"name":"Journal of the Ceramic Society of Japan","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135372803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Our understanding on how dislocation textures quantitatively affect thermal conductivity has been limited. We investigate the impact of kink dislocations on phonon thermal conduction in MgO by molecular dynamics, through changing edge and screw components in kink dislocations. The thermal conductivity is almost independent of the length of the edge component, but is rather reduced significantly with increasing the length of screw component, resulting in lower thermal conductivity than perfect edge dislocations. This reveals the combined effect of the edge and screw components on thermal conductivity beyond the simple description as one-dimensional obstacles and linear elastic strain field. Atomic contributions to thermal conductivity show that not only atoms in the vicinity of the kink dislocation cores but also those away from the cores exhibit suppressed thermal conductivity compared to the perfect edge dislocations. These results indicate that it is possible to efficiently reduce thermal conductivity in complex dislocation textures in real materials.
{"title":"Enhanced reduction of thermal conductivity across kink dislocation textures in magnesium oxide","authors":"Wataru Sekimoto, Susumu Fujii, Masato Yoshiya","doi":"10.2109/jcersj2.23066","DOIUrl":"https://doi.org/10.2109/jcersj2.23066","url":null,"abstract":"Our understanding on how dislocation textures quantitatively affect thermal conductivity has been limited. We investigate the impact of kink dislocations on phonon thermal conduction in MgO by molecular dynamics, through changing edge and screw components in kink dislocations. The thermal conductivity is almost independent of the length of the edge component, but is rather reduced significantly with increasing the length of screw component, resulting in lower thermal conductivity than perfect edge dislocations. This reveals the combined effect of the edge and screw components on thermal conductivity beyond the simple description as one-dimensional obstacles and linear elastic strain field. Atomic contributions to thermal conductivity show that not only atoms in the vicinity of the kink dislocation cores but also those away from the cores exhibit suppressed thermal conductivity compared to the perfect edge dislocations. These results indicate that it is possible to efficiently reduce thermal conductivity in complex dislocation textures in real materials.","PeriodicalId":17246,"journal":{"name":"Journal of the Ceramic Society of Japan","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135372977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Artificial-neural-network (ANN) interatomic potentials for Al–Y–O and Al–Hf–O systems are constructed using density-function-theory (DFT) data and combined with Monte Carlo (MC) simulations in order to predict Y and Hf segregation behavior at the ∑7(4510)/[0001] grain boundary (GB) in α-Al2O3. The ANN potentials are demonstrated to accurately predict preferential substitutional sites of not only an isolated but also multiple dopant ions. This enables us to circumvent DFT calculations for MC trial moves, thereby greatly reducing computational cost. There is a tendency that both Y and Hf ions substitute for 6-fold Al ions with elongated Al–O bonds at the GB and have coordination numbers greater than 6 after structural relaxation. This may suggest that even at the GB, Y and Hf ions prefer atomic environments in Y- and Hf-containing oxides with 7- and 8-fold coordination. Furthermore, effects of dopant species and concentrations on band-gap reduction at the GB are elucidated by analyzing partial density of states for the dopant-segregated GBs. The ANN-MC method with DFT analysis will pave the way for systematically determining atomic and electronic structures of GBs involving dopants, as demonstrated in this work.
{"title":"Grain boundary segregation of Y and Hf dopants in α-Al<sub>2</sub>O<sub>3</sub>: A Monte Carlo simulation with artificial-neural-network potential and density-functional-theory calculation","authors":"Tatsuya Yokoi, Akihiro Hamajima, Yu Ogura, Katsuyuki Matsunaga","doi":"10.2109/jcersj2.23044","DOIUrl":"https://doi.org/10.2109/jcersj2.23044","url":null,"abstract":"Artificial-neural-network (ANN) interatomic potentials for Al–Y–O and Al–Hf–O systems are constructed using density-function-theory (DFT) data and combined with Monte Carlo (MC) simulations in order to predict Y and Hf segregation behavior at the ∑7(4510)/[0001] grain boundary (GB) in α-Al2O3. The ANN potentials are demonstrated to accurately predict preferential substitutional sites of not only an isolated but also multiple dopant ions. This enables us to circumvent DFT calculations for MC trial moves, thereby greatly reducing computational cost. There is a tendency that both Y and Hf ions substitute for 6-fold Al ions with elongated Al–O bonds at the GB and have coordination numbers greater than 6 after structural relaxation. This may suggest that even at the GB, Y and Hf ions prefer atomic environments in Y- and Hf-containing oxides with 7- and 8-fold coordination. Furthermore, effects of dopant species and concentrations on band-gap reduction at the GB are elucidated by analyzing partial density of states for the dopant-segregated GBs. The ANN-MC method with DFT analysis will pave the way for systematically determining atomic and electronic structures of GBs involving dopants, as demonstrated in this work.","PeriodicalId":17246,"journal":{"name":"Journal of the Ceramic Society of Japan","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135372986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ti1−2x(FeNb)xO2 solid solutions were prepared as visible-light-active photocatalysts using a conventional solid-state reaction method. Ti1−2x(FeNb)xO2 solid solutions were obtained below x = 0.25 without any secondary phase. They exhibited light absorption in the visible region. The strong absorption corresponding to the bandgap shifted to the lower energies with increasing x. Because the valence band maxima of the samples remained unchanged, the conduction band minima shifted to lower energies. The photocatalytic activity was evaluated based on the degradation of methylene blue under UV–visible light irradiation. The photocatalytic activity of Ti1−2x(FeNb)xO2 solid solutions tends to improve with increasing x. Clear visible light photocatalytic activity corresponding to the band gap was also observed. Thus, these materials are promising candidates for environmental applications.
{"title":"Synthesis and characterization of Ti<sub>1−2</sub><i><sub>x</sub></i>(FeNb)<i><sub>x</sub></i>O<sub>2</sub> solid solutions for visible-light-active photocatalyst","authors":"Takuya Nishio, Hidenobu Murata, Yasuaki Tokudome, Atsushi Nakahira","doi":"10.2109/jcersj2.23013","DOIUrl":"https://doi.org/10.2109/jcersj2.23013","url":null,"abstract":"Ti1−2x(FeNb)xO2 solid solutions were prepared as visible-light-active photocatalysts using a conventional solid-state reaction method. Ti1−2x(FeNb)xO2 solid solutions were obtained below x = 0.25 without any secondary phase. They exhibited light absorption in the visible region. The strong absorption corresponding to the bandgap shifted to the lower energies with increasing x. Because the valence band maxima of the samples remained unchanged, the conduction band minima shifted to lower energies. The photocatalytic activity was evaluated based on the degradation of methylene blue under UV–visible light irradiation. The photocatalytic activity of Ti1−2x(FeNb)xO2 solid solutions tends to improve with increasing x. Clear visible light photocatalytic activity corresponding to the band gap was also observed. Thus, these materials are promising candidates for environmental applications.","PeriodicalId":17246,"journal":{"name":"Journal of the Ceramic Society of Japan","volume":"115 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135372993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Soft and hard magnetic materials are becoming increasingly important for energy efficiency in transformers, motors, and inductors. To reveal the microscopic origins of their magnetic properties, it is crucial to observe magnetic domain structures with an external magnetic field at high spatial resolution. Differential-phase-contrast scanning transmission electron microscopy (DPC STEM) is expected to be a powerful technique for directly visualizing electromagnetic fields inside materials even down to atomic dimensions. In this study, we investigated the capability of DPC STEM for in-situ observation of soft magnetic materials. We observed three different soft magnetic materials with various coercivities and found clear differences in the observation results. These results suggest that DPC STEM has a great capability to directly reveal the microscopic origin of magnetic properties in magnetic materials.
{"title":"In-situ observation of magnetic domain structures in nanocrystalline soft magnetic materials by differential-phase-contrast scanning transmission electron microscopy","authors":"Takehito Seki, Masaya Takamoto, Masayuki Ishihara, Haruhito Ishio, Yuichi Ikuhara, Naoya Shibata","doi":"10.2109/jcersj2.23061","DOIUrl":"https://doi.org/10.2109/jcersj2.23061","url":null,"abstract":"Soft and hard magnetic materials are becoming increasingly important for energy efficiency in transformers, motors, and inductors. To reveal the microscopic origins of their magnetic properties, it is crucial to observe magnetic domain structures with an external magnetic field at high spatial resolution. Differential-phase-contrast scanning transmission electron microscopy (DPC STEM) is expected to be a powerful technique for directly visualizing electromagnetic fields inside materials even down to atomic dimensions. In this study, we investigated the capability of DPC STEM for in-situ observation of soft magnetic materials. We observed three different soft magnetic materials with various coercivities and found clear differences in the observation results. These results suggest that DPC STEM has a great capability to directly reveal the microscopic origin of magnetic properties in magnetic materials.","PeriodicalId":17246,"journal":{"name":"Journal of the Ceramic Society of Japan","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135372995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The good correlation between the speed of oxygen-release versus the oxygen-ion conductivity was found in ceria-zirconia under 33 mol % of Ce content. The crystal lattice expansion was also found to affect the speed of oxygen-release in ceria-zirconia with Ce content of 33–66 mol %. Because these properties can be controlled by rare-earth trivalent cation M3+-doping in ceria-zirconia, the state of M3+ and vacancies formed by substituting with M3+ has been investigated in typical model samples of M3+-doped ceria-zirconia using X-ray powder diffraction and X-ray absorption fine structure. It was experimentally clear that the lattice constant increased with increasing the ionic radius of M3+-doped in (Ce0.5Zr0.4M0.1)O1.95. It was also found that M3+ with higher ligand-field stabilization energy of f-orbitals tended to be fully octahedral-coordinated by eight oxygen ions and form free oxygen vacancies un-associated with M3+, possibly leading to the high speed of oxygen-release.
{"title":"Design of oxygen-storage/release materials with high-speed of oxygen-release in rare-earth trivalent cation M<sup>3+</sup>-doped ceria-zirconia system","authors":"Keigo Aihara, Hiroki Uede, Kyouhei Kitagawa, Masasuke Yamaba, Yusuke Hidaka, Tomoharu Itoh, Kenji Okamoto, Shingo Katayama","doi":"10.2109/jcersj2.23078","DOIUrl":"https://doi.org/10.2109/jcersj2.23078","url":null,"abstract":"The good correlation between the speed of oxygen-release versus the oxygen-ion conductivity was found in ceria-zirconia under 33 mol % of Ce content. The crystal lattice expansion was also found to affect the speed of oxygen-release in ceria-zirconia with Ce content of 33–66 mol %. Because these properties can be controlled by rare-earth trivalent cation M3+-doping in ceria-zirconia, the state of M3+ and vacancies formed by substituting with M3+ has been investigated in typical model samples of M3+-doped ceria-zirconia using X-ray powder diffraction and X-ray absorption fine structure. It was experimentally clear that the lattice constant increased with increasing the ionic radius of M3+-doped in (Ce0.5Zr0.4M0.1)O1.95. It was also found that M3+ with higher ligand-field stabilization energy of f-orbitals tended to be fully octahedral-coordinated by eight oxygen ions and form free oxygen vacancies un-associated with M3+, possibly leading to the high speed of oxygen-release.","PeriodicalId":17246,"journal":{"name":"Journal of the Ceramic Society of Japan","volume":"307 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135372814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fumitaka Hayashi, Yongsu Kim, Masaki Moriwaki, Yosuke Moriya, Katsuya Teshima
Layered sodium titanates are extremely advantageous for use in the energy and environmental fields. Herein, submicron-sized layered sodium titanate crystals were synthesized at low temperatures via solid-state reaction using trisodium citrate as the Na source. Characterization results including in situ observations showed that the decomposition of trisodium citrate proceeded at 300–350 °C, and the resulting activated Na species reacted with TiO2 at temperatures of 520 °C and above. This study therefore provides an economically viable method for the synthesis of layered titanate materials.
{"title":"Low-temperature synthesis of submicron-sized layered sodium titanate crystals using citrate salts","authors":"Fumitaka Hayashi, Yongsu Kim, Masaki Moriwaki, Yosuke Moriya, Katsuya Teshima","doi":"10.2109/jcersj2.23112","DOIUrl":"https://doi.org/10.2109/jcersj2.23112","url":null,"abstract":"Layered sodium titanates are extremely advantageous for use in the energy and environmental fields. Herein, submicron-sized layered sodium titanate crystals were synthesized at low temperatures via solid-state reaction using trisodium citrate as the Na source. Characterization results including in situ observations showed that the decomposition of trisodium citrate proceeded at 300–350 °C, and the resulting activated Na species reacted with TiO2 at temperatures of 520 °C and above. This study therefore provides an economically viable method for the synthesis of layered titanate materials.","PeriodicalId":17246,"journal":{"name":"Journal of the Ceramic Society of Japan","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135372815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tin sulfide (SnS) is a semiconductor composed of abundant and non-toxic elements and has potential applications as a light absorbing layer in thin-film solar cells and a thermoelectric material. While controlling the carrier type (n- or p-type conduction) and carrier concentration of SnS by impurity doping has been intensively studied both experimentally and theoretically since 2010s, no comprehensive discussion of them has been made. This review is motivated to provide researchers with an overview of SnS doping techniques including following topics. The importance and effects of carrier control on the performance of SnS-based photovoltaics and thermoelectric devices are at first discussed. Subsequently, the electrical property of the undoped SnS resulting from its intrinsic defects are summarized. Also, the characteristics of p- and n-type dopings to SnS with various dopants are summarized and compared with the doping systems to other IV–VI group semiconductors, particularly SnSe. The final section presents a perspective on the current status of research in SnS carrier control and potential future research directions.
{"title":"Carrier control in SnS by doping: A review","authors":"Issei Suzuki","doi":"10.2109/jcersj2.23098","DOIUrl":"https://doi.org/10.2109/jcersj2.23098","url":null,"abstract":"Tin sulfide (SnS) is a semiconductor composed of abundant and non-toxic elements and has potential applications as a light absorbing layer in thin-film solar cells and a thermoelectric material. While controlling the carrier type (n- or p-type conduction) and carrier concentration of SnS by impurity doping has been intensively studied both experimentally and theoretically since 2010s, no comprehensive discussion of them has been made. This review is motivated to provide researchers with an overview of SnS doping techniques including following topics. The importance and effects of carrier control on the performance of SnS-based photovoltaics and thermoelectric devices are at first discussed. Subsequently, the electrical property of the undoped SnS resulting from its intrinsic defects are summarized. Also, the characteristics of p- and n-type dopings to SnS with various dopants are summarized and compared with the doping systems to other IV–VI group semiconductors, particularly SnSe. The final section presents a perspective on the current status of research in SnS carrier control and potential future research directions.","PeriodicalId":17246,"journal":{"name":"Journal of the Ceramic Society of Japan","volume":"149 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135372637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Binjie Chen, Jinghuang Lin, Bin Feng, Yuichi Ikuhara, Hiromichi Ohta
Tin dioxide (SnO2) is a semiconductor with significant potential for use in the electronic industry, including sensors, transparent electrodes, and thin film transistors among other purposes. To realize these applications, the synthesis of high-quality thin films is a prerequisite. Here, we show the epitaxial growth of SnO2 films on (1100) α-Al2O3 (M-sapphire) by pulsed laser deposition method. The epitaxial relationship was clarified to be (001)[100]SnO2 || (1100)[0001] α-Al2O3 with 4-fold symmetry, consistent with that grown on (001) TiO2 single crystal. Orthorhombic distortion was absent, possibly owing to a combination of high strain relaxation due to a large lattice mismatch along [0001] α-Al2O3, coupled with a negligible mismatch-induced strain absence along [1120] α-Al2O3. The mobility increases up to ∼57 cm2 V−1 s−1 with increasing film thickness while the density of states (DOS) effective mass keeps a constant around the theoretical value of ∼0.3 m0. Furthermore, the trend of carrier concentration versus mobility is analogous to those of single crystal SnO2, thereby indicating the applicability of M-sapphire substrates in facilitating the epitaxial growth of high-quality SnO2 films.
{"title":"High-mobility rutile SnO<sub>2</sub> epitaxial films grown on (1−100) α-Al<sub>2</sub>O<sub>3</sub>","authors":"Binjie Chen, Jinghuang Lin, Bin Feng, Yuichi Ikuhara, Hiromichi Ohta","doi":"10.2109/jcersj2.23035","DOIUrl":"https://doi.org/10.2109/jcersj2.23035","url":null,"abstract":"Tin dioxide (SnO2) is a semiconductor with significant potential for use in the electronic industry, including sensors, transparent electrodes, and thin film transistors among other purposes. To realize these applications, the synthesis of high-quality thin films is a prerequisite. Here, we show the epitaxial growth of SnO2 films on (1100) α-Al2O3 (M-sapphire) by pulsed laser deposition method. The epitaxial relationship was clarified to be (001)[100]SnO2 || (1100)[0001] α-Al2O3 with 4-fold symmetry, consistent with that grown on (001) TiO2 single crystal. Orthorhombic distortion was absent, possibly owing to a combination of high strain relaxation due to a large lattice mismatch along [0001] α-Al2O3, coupled with a negligible mismatch-induced strain absence along [1120] α-Al2O3. The mobility increases up to ∼57 cm2 V−1 s−1 with increasing film thickness while the density of states (DOS) effective mass keeps a constant around the theoretical value of ∼0.3 m0. Furthermore, the trend of carrier concentration versus mobility is analogous to those of single crystal SnO2, thereby indicating the applicability of M-sapphire substrates in facilitating the epitaxial growth of high-quality SnO2 films.","PeriodicalId":17246,"journal":{"name":"Journal of the Ceramic Society of Japan","volume":"2013 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135372809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sena Hoshino, Tatsuya Yokoi, Yu Ogura, Katsuyuki Matsunaga
II–VI semiconductors, including Cd compounds, become brittle under light illumination. This phenomenon is known as the photoplastic effect (PPE) and is thought to arise from interactions between glide dislocations and photoexcited carriers. The present study investigated atomic structures of 30° Shockley-partial dislocations with and without excess carriers in CdX (X = S, Se and Te), by density-functional-theory (DFT) calculations. It was found that both Cd and anion cores favor unreconstructed atomic structures when excess carriers are absent. In the presence of excess carriers, on the other hand, reconstructed atomic structures were more stable at the anion cores while the unreconstructed ones were still energetically more favorable at the Cd cores. It is thus expected that only the anion cores change their atomic structures by light illumination, which can retard glide-dislocation motion by forming like-atom bonds. Analyses of local densities of states (LDOSs) revealed that the reconstructed Cd and anion cores form shallow and deep defect states within the band gaps, respectively. This determines the possible atomic reconstructions at the dislocation cores in the presence of excess carriers excited by external light.
{"title":"Electronic and atomic structures of Shockley-partial dislocations in CdX (X = S, Se and Te)","authors":"Sena Hoshino, Tatsuya Yokoi, Yu Ogura, Katsuyuki Matsunaga","doi":"10.2109/jcersj2.23055","DOIUrl":"https://doi.org/10.2109/jcersj2.23055","url":null,"abstract":"II–VI semiconductors, including Cd compounds, become brittle under light illumination. This phenomenon is known as the photoplastic effect (PPE) and is thought to arise from interactions between glide dislocations and photoexcited carriers. The present study investigated atomic structures of 30° Shockley-partial dislocations with and without excess carriers in CdX (X = S, Se and Te), by density-functional-theory (DFT) calculations. It was found that both Cd and anion cores favor unreconstructed atomic structures when excess carriers are absent. In the presence of excess carriers, on the other hand, reconstructed atomic structures were more stable at the anion cores while the unreconstructed ones were still energetically more favorable at the Cd cores. It is thus expected that only the anion cores change their atomic structures by light illumination, which can retard glide-dislocation motion by forming like-atom bonds. Analyses of local densities of states (LDOSs) revealed that the reconstructed Cd and anion cores form shallow and deep defect states within the band gaps, respectively. This determines the possible atomic reconstructions at the dislocation cores in the presence of excess carriers excited by external light.","PeriodicalId":17246,"journal":{"name":"Journal of the Ceramic Society of Japan","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135372982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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