Benas Beklešovas, Vytautas Stankus, Aleksandras Iljinas, Liutauras Marcinauskas
Cobalt-doped lead ferrite (Pb2Fe2O5) thin films were deposited by reactive magnetron sputtering. The influence of the cobalt concentration and synthesis temperature on the structure, phase composition and ferroelectric properties of Pb2Fe2O5 thin films was investigated. It was determined that the increase in deposition temperature increased the grain size and density of the Co-doped PFO thin films. The XRD data demonstrated that the Co-doped Pb2Fe2O5 thin films consisted of Pb2Fe2O5 and PbO phases with a low amount of CoO and Co3O4 phases. The increase in the cobalt concentration in the Pb2Fe2O5 films slightly enhanced the cobalt oxide phase content. Polarization dependence on electric field measurement demonstrated that the highest ferroelectric properties of the Co-doped Pb2Fe2O5 films were obtained when the synthesis was performed at 550 °C temperatures. The increase in the cobalt concentration in the films enhanced the remnant polarization and coercive field values. It was found that the Co-doped Pb2Fe2O5 film deposited at 550 °C temperature and containing 10% cobalt had the highest remnant polarization (72 µC/cm2) and coercive electric field (105 kV/cm).
{"title":"Ferroelectric and Structural Properties of Cobalt-Doped Lead Ferrite Thin Films Formed by Reactive Magnetron Sputtering","authors":"Benas Beklešovas, Vytautas Stankus, Aleksandras Iljinas, Liutauras Marcinauskas","doi":"10.3390/cryst14080721","DOIUrl":"https://doi.org/10.3390/cryst14080721","url":null,"abstract":"Cobalt-doped lead ferrite (Pb2Fe2O5) thin films were deposited by reactive magnetron sputtering. The influence of the cobalt concentration and synthesis temperature on the structure, phase composition and ferroelectric properties of Pb2Fe2O5 thin films was investigated. It was determined that the increase in deposition temperature increased the grain size and density of the Co-doped PFO thin films. The XRD data demonstrated that the Co-doped Pb2Fe2O5 thin films consisted of Pb2Fe2O5 and PbO phases with a low amount of CoO and Co3O4 phases. The increase in the cobalt concentration in the Pb2Fe2O5 films slightly enhanced the cobalt oxide phase content. Polarization dependence on electric field measurement demonstrated that the highest ferroelectric properties of the Co-doped Pb2Fe2O5 films were obtained when the synthesis was performed at 550 °C temperatures. The increase in the cobalt concentration in the films enhanced the remnant polarization and coercive field values. It was found that the Co-doped Pb2Fe2O5 film deposited at 550 °C temperature and containing 10% cobalt had the highest remnant polarization (72 µC/cm2) and coercive electric field (105 kV/cm).","PeriodicalId":10855,"journal":{"name":"Crystals","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141934668","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}
This study investigated the susceptible sites for pit nucleation in a transformation-induced plasticity (TRIP) Fe39Mn20Co20Cr15Si5Al1 (at.%) high-entropy alloy (HEA) in 3.5 wt.% NaCl solution. The investigation involved a constant-load stress corrosion cracking (SCC) experiment. The SCC testing was interrupted at different pre-determined time intervals to characterize the specimen surface using a scanning electron microscope (SEM), electron backscattered diffraction (EBSD), and a three-dimensional optical stereomicroscope. The EBSD results revealed pit nucleation at the susceptible γ–ε interphase and ε–ε interlath/plate boundaries. The three-dimensional profile and SEM results indicated an increase in pit depth with no change in pit diameter on the surface of the specimen as the experiment progressed over time. This study highlights the importance of microstructural features and mechanical loading in the corrosion behavior of TRIP HEAs, providing insights into the mechanisms of pit nucleation and growth under aggressive environmental conditions.
{"title":"Early Stages of Crack Nucleation Mechanism in Fe39Mn20Co20Cr15Si5Al1 High-Entropy Alloy during Stress Corrosion Cracking Phenomenon: Pit Initiation and Growth","authors":"Pranshul Varshney, Nilesh Kumar","doi":"10.3390/cryst14080719","DOIUrl":"https://doi.org/10.3390/cryst14080719","url":null,"abstract":"This study investigated the susceptible sites for pit nucleation in a transformation-induced plasticity (TRIP) Fe39Mn20Co20Cr15Si5Al1 (at.%) high-entropy alloy (HEA) in 3.5 wt.% NaCl solution. The investigation involved a constant-load stress corrosion cracking (SCC) experiment. The SCC testing was interrupted at different pre-determined time intervals to characterize the specimen surface using a scanning electron microscope (SEM), electron backscattered diffraction (EBSD), and a three-dimensional optical stereomicroscope. The EBSD results revealed pit nucleation at the susceptible γ–ε interphase and ε–ε interlath/plate boundaries. The three-dimensional profile and SEM results indicated an increase in pit depth with no change in pit diameter on the surface of the specimen as the experiment progressed over time. This study highlights the importance of microstructural features and mechanical loading in the corrosion behavior of TRIP HEAs, providing insights into the mechanisms of pit nucleation and growth under aggressive environmental conditions.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141934669","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}
Steponas Ašmontas, Maksimas Anbinderis, Aurimas Čerškus, Jonas Gradauskas, Andžej Lučun, Algirdas Sužiedėlis
Planar microwave bow-tie diodes on bases of selectively doped semiconductor structures are successfully used in the detection and imaging of electromagnetic radiation in millimeter and submillimeter wavelength ranges. Although the signal formation mechanism in these high-frequency diodes is said to be based on charge-carrier heating in a semiconductor in a strong electric field, the nature of the electrical signal across the bow-tie diodes is not yet properly identified. In this research paper, we present a comprehensive study of a series of various planar bow-tie diodes, starting with a simple asymmetrically shaped submicrometer-thick n-GaAs layer and finishing with bow-tie diodes based on selectively doped GaAs/AlGaAs structures of different electrical conductivity. The planar bow-tie diodes were fabricated on two different types of high-resistivity substrates: bulky semi-insulating GaAs substrate and elastic dielectric polyimide film of micrometer thickness. The microwave diodes were investigated using DC and high-frequency probe stations, which allowed us to examine a sufficient number of diodes and collect a large amount of data to perform a statistical analysis of the electrical parameters of these diodes. The use of probe stations made it possible to analyze the properties of the bow-tie diodes and clarify the nature of the detected voltage in the dark and under white-light illumination. The investigation revealed that the properties of various bow-tie diodes are largely determined by the energy states residing in semiconductor bulk, surface, and interfaces. It is most likely that these energy states are responsible for the slow relaxation processes observed in the studied bow-tie diodes.
{"title":"Microwave Bow-Tie Diodes on Bases of 2D Semiconductor Structures","authors":"Steponas Ašmontas, Maksimas Anbinderis, Aurimas Čerškus, Jonas Gradauskas, Andžej Lučun, Algirdas Sužiedėlis","doi":"10.3390/cryst14080720","DOIUrl":"https://doi.org/10.3390/cryst14080720","url":null,"abstract":"Planar microwave bow-tie diodes on bases of selectively doped semiconductor structures are successfully used in the detection and imaging of electromagnetic radiation in millimeter and submillimeter wavelength ranges. Although the signal formation mechanism in these high-frequency diodes is said to be based on charge-carrier heating in a semiconductor in a strong electric field, the nature of the electrical signal across the bow-tie diodes is not yet properly identified. In this research paper, we present a comprehensive study of a series of various planar bow-tie diodes, starting with a simple asymmetrically shaped submicrometer-thick n-GaAs layer and finishing with bow-tie diodes based on selectively doped GaAs/AlGaAs structures of different electrical conductivity. The planar bow-tie diodes were fabricated on two different types of high-resistivity substrates: bulky semi-insulating GaAs substrate and elastic dielectric polyimide film of micrometer thickness. The microwave diodes were investigated using DC and high-frequency probe stations, which allowed us to examine a sufficient number of diodes and collect a large amount of data to perform a statistical analysis of the electrical parameters of these diodes. The use of probe stations made it possible to analyze the properties of the bow-tie diodes and clarify the nature of the detected voltage in the dark and under white-light illumination. The investigation revealed that the properties of various bow-tie diodes are largely determined by the energy states residing in semiconductor bulk, surface, and interfaces. It is most likely that these energy states are responsible for the slow relaxation processes observed in the studied bow-tie diodes.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141934667","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}
Tetrasodium silicate (Na4SiO4) has emerged as a promising candidate for battery applications due to its favorable ionic transport properties. Atomic-scale simulations employing classical pair potentials have elucidated the defect mechanisms and ion migration dynamics in Na4SiO4. The Na Frenkel defect, characterized by the creation of a Na vacancy and an interstitial Na⁺ ion, is identified as the most energetically favorable defect process, facilitating efficient vacancy-assisted Na⁺ ion migration. This process results in three-dimensional ion diffusion with a low activation energy of 0.55 eV, indicating rapid ion movement within the material. Among monovalent dopants (Li⁺, K⁺, and Rb⁺), K⁺ was found to be the most advantageous for substitution on the Na site. For trivalent doping, Al is the most favorable on the Si site, generating additional Na⁺ ions and potentially enhancing ionic conductivity. Ge was identified as a promising isovalent dopant for the Si site. These theoretical findings suggest that Na4SiO4 could offer high ionic conductivity and stability when optimized through appropriate doping. Experimental validation of these predictions could lead to the development of advanced battery materials with improved performance and durability.
硅酸四钠（Na4SiO4）因其良好的离子传输特性而成为电池应用的理想候选材料。采用经典对电位进行的原子尺度模拟阐明了 Na4SiO4 中的缺陷机制和离子迁移动力学。Na Frenkel 缺陷的特征是产生一个 Na 空位和一个间隙 Na⁺ 离子，它被确定为能量上最有利的缺陷过程，可促进有效的空位辅助 Na⁺ 离子迁移。这一过程导致三维离子扩散，激活能低至 0.55 eV，表明离子在材料内快速移动。在单价掺杂剂（Li⁺、K⁺和Rb⁺）中，K⁺被认为是对 Na 位点最有利的替代物。对于三价掺杂，Al 对 Si 位点最有利，可产生额外的 Na⁺离子，并有可能提高离子导电性。Ge 被认为是对 Si 位点很有前途的异价掺杂剂。这些理论研究结果表明，如果通过适当的掺杂进行优化，Na4SiO4 可以提供高离子电导率和稳定性。对这些预测的实验验证将有助于开发出性能更好、更耐用的先进电池材料。
{"title":"Atomistic Simulation Studies of Na4SiO4","authors":"Mallikage Shalani Shanika, Poobalasingam Abiman, Poobalasuntharam Iyngaran, Navaratnarajah Kuganathan","doi":"10.3390/cryst14080718","DOIUrl":"https://doi.org/10.3390/cryst14080718","url":null,"abstract":"Tetrasodium silicate (Na4SiO4) has emerged as a promising candidate for battery applications due to its favorable ionic transport properties. Atomic-scale simulations employing classical pair potentials have elucidated the defect mechanisms and ion migration dynamics in Na4SiO4. The Na Frenkel defect, characterized by the creation of a Na vacancy and an interstitial Na⁺ ion, is identified as the most energetically favorable defect process, facilitating efficient vacancy-assisted Na⁺ ion migration. This process results in three-dimensional ion diffusion with a low activation energy of 0.55 eV, indicating rapid ion movement within the material. Among monovalent dopants (Li⁺, K⁺, and Rb⁺), K⁺ was found to be the most advantageous for substitution on the Na site. For trivalent doping, Al is the most favorable on the Si site, generating additional Na⁺ ions and potentially enhancing ionic conductivity. Ge was identified as a promising isovalent dopant for the Si site. These theoretical findings suggest that Na4SiO4 could offer high ionic conductivity and stability when optimized through appropriate doping. Experimental validation of these predictions could lead to the development of advanced battery materials with improved performance and durability.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141934671","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}
Four-dimensional-printed smart materials have a wide range of applications in areas such as biomedicine, aerospace, and soft robotics. Among 3D printing technologies, fused deposition molding (FDM) is economical, simple, and apply to thermoplastics. Cross-linked polyethylene (XLPE) forms a stable chemical cross-linking structure and shows good shape-memory properties, but the sample is not soluble or fusible, which makes it hard to be applied in FDM printing. Therefore, in this work, a new idea of printing followed by irradiation was developed to prepare 4D-printed XLPE. First, low-density polyethylene (LDPE) was used to print the products using FDM technology and then cross-linked by gamma irradiation was used. The printing parameters were optimized, and the gel content, mechanical properties, and shape-memory behaviors were characterized. After gamma irradiation, the samples showed no new peak in FTIR spectra. And the samples exhibited good shape-memory capabilities. Increasing the irradiation dose increased the cross-linking degree and tensile strength and improved the shape-memory properties. However, it also decreased the elongation at break, and it did not affect the crystallization or melting behaviors of LDPE. With 120 kGy of irradiation, the shape recovery and fixity ratios (Rr and Rf) of the samples were 97.69% and 98.65%, respectively. After eight cycles, Rr and Rf remained at 96.30% and 97.76%, respectively, indicating excellent shape-memory performance.
{"title":"Shape-Memory Effect of 4D-Printed Gamma-Irradiated Low-Density Polyethylene","authors":"Yunke Huang, Yongxiang Tao, Yan Wang","doi":"10.3390/cryst14080717","DOIUrl":"https://doi.org/10.3390/cryst14080717","url":null,"abstract":"Four-dimensional-printed smart materials have a wide range of applications in areas such as biomedicine, aerospace, and soft robotics. Among 3D printing technologies, fused deposition molding (FDM) is economical, simple, and apply to thermoplastics. Cross-linked polyethylene (XLPE) forms a stable chemical cross-linking structure and shows good shape-memory properties, but the sample is not soluble or fusible, which makes it hard to be applied in FDM printing. Therefore, in this work, a new idea of printing followed by irradiation was developed to prepare 4D-printed XLPE. First, low-density polyethylene (LDPE) was used to print the products using FDM technology and then cross-linked by gamma irradiation was used. The printing parameters were optimized, and the gel content, mechanical properties, and shape-memory behaviors were characterized. After gamma irradiation, the samples showed no new peak in FTIR spectra. And the samples exhibited good shape-memory capabilities. Increasing the irradiation dose increased the cross-linking degree and tensile strength and improved the shape-memory properties. However, it also decreased the elongation at break, and it did not affect the crystallization or melting behaviors of LDPE. With 120 kGy of irradiation, the shape recovery and fixity ratios (Rr and Rf) of the samples were 97.69% and 98.65%, respectively. After eight cycles, Rr and Rf remained at 96.30% and 97.76%, respectively, indicating excellent shape-memory performance.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141934670","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}
Fatih Uzun, Dominik Daisenberger, Konstantinos Liogas, Zifan Ivan Wang, Jingwei Chen, Cyril Besnard, Alexander M. Korsunsky
Polycrystalline diffraction is a robust methodology employed to assess elastic strain within crystalline components. The Extended Caking (exCaking) method represents a progression of this methodology beyond the conventional azimuthal segmentation (Caking) method for the quantification of elastic strains using Debye–Scherrer 2D X-ray diffraction rings. The proposed method is based on the premise that each complete diffraction ring contains comprehensive information about the complete elastic strain variation in the plane normal to the incident beam, which allows for the introduction of a novel algorithm that analyses Debye–Scherrer rings with complete angular variation using ellipse geometry, ensuring accuracy even for small eccentricity values and offering greater accuracy overall. The console application of the exCaking method allows for the accurate analysis of polycrystalline X-ray diffraction data according to the up-to-date rules presented in the project repository. This study presents both numerical and empirical examinations and error analysis to substantiate the method’s reliability and accuracy. A specific validation case study is also presented to analyze the distribution of residual elastic strains in terms of force balance in a Ti-6Al-4V titanium alloy bar plastically deformed by four-point bending.
多晶衍射是一种用于评估晶体成分内部弹性应变的可靠方法。在使用 Debye-Scherrer 二维 X 射线衍射环量化弹性应变的传统方位角分割（Caking）方法之外，扩展 Caking（exCaking）方法代表了这一方法的进步。所提出方法的前提是，每个完整的衍射环都包含入射光束法线平面上完整弹性应变变化的全面信息，因此可以引入一种新颖的算法，利用椭圆几何对具有完整角度变化的 Debye-Scherrer 衍射环进行分析，即使偏心值较小也能确保精确度，并提供更高的总体精确度。通过控制台应用 exCaking 方法，可以根据项目资料库中提供的最新规则对多晶 X 射线衍射数据进行精确分析。本研究通过数值和经验检验以及误差分析，证实了该方法的可靠性和准确性。本研究还介绍了一个具体的验证案例研究，分析了 Ti-6Al-4V 钛合金棒材通过四点弯曲发生塑性变形时的力平衡残余弹性应变分布。
{"title":"Extended Caking Method for Strain Analysis of Polycrystalline Diffraction Debye–Scherrer Rings","authors":"Fatih Uzun, Dominik Daisenberger, Konstantinos Liogas, Zifan Ivan Wang, Jingwei Chen, Cyril Besnard, Alexander M. Korsunsky","doi":"10.3390/cryst14080716","DOIUrl":"https://doi.org/10.3390/cryst14080716","url":null,"abstract":"Polycrystalline diffraction is a robust methodology employed to assess elastic strain within crystalline components. The Extended Caking (exCaking) method represents a progression of this methodology beyond the conventional azimuthal segmentation (Caking) method for the quantification of elastic strains using Debye–Scherrer 2D X-ray diffraction rings. The proposed method is based on the premise that each complete diffraction ring contains comprehensive information about the complete elastic strain variation in the plane normal to the incident beam, which allows for the introduction of a novel algorithm that analyses Debye–Scherrer rings with complete angular variation using ellipse geometry, ensuring accuracy even for small eccentricity values and offering greater accuracy overall. The console application of the exCaking method allows for the accurate analysis of polycrystalline X-ray diffraction data according to the up-to-date rules presented in the project repository. This study presents both numerical and empirical examinations and error analysis to substantiate the method’s reliability and accuracy. A specific validation case study is also presented to analyze the distribution of residual elastic strains in terms of force balance in a Ti-6Al-4V titanium alloy bar plastically deformed by four-point bending.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141934672","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}
Fatima Kainat, Nawishta Jabeen, Ali Yaqoob, Najam Ul Hassan, Ahmad Hussain, Mohamed E. Khalifa
Bismuth layered structure ferroelectrics (BLSFs), also known as Aurivillius phase materials, are ideal for energy-efficient applications, particularly for solar cells. This work reports the first comprehensive detailed theoretical study on the fascinating structural, electronic, and optical properties of XNb2Bi2O9 (X = Ca, Ba, Be, Mg, Sr). The Perdew–Burke–Ernzerhof approach and generalized gradient approximation (GGA) are implemented to thoroughly investigate the structural, bandgap, optical, and electronic properties of the compounds. The optical conductivity, band topologies, dielectric function, bandgap values, absorption coefficient, reflectivity, extinction coefficient, refractive index, and partial and total densities of states are thoroughly investigated from a photovoltaics standpoint. The material exhibits distinct behaviors, including significant optical anisotropy and an elevated absorption coefficient > 105 cm−1 in the region of visible; ultraviolet energy is observed, the elevated transparency lies in the visible and infrared regions for the imaginary portion of the dielectric function, and peaks in the optical spectra caused by inter-band transitions are detected. According to the data reported, it becomes obvious that XNb2Bi2O9 (X = Ca, Ba, Be, Mg, and Sr) is a suitable candidate for implementation in solar energy conversion applications.
{"title":"Effect of Ca, Ba, Be, Mg, and Sr Substitution on Electronic and Optical Properties of XNb2Bi2O9 for Energy Conversion Application Using Generalized Gradient Approximation–Perdew–Burke–Ernzerhof","authors":"Fatima Kainat, Nawishta Jabeen, Ali Yaqoob, Najam Ul Hassan, Ahmad Hussain, Mohamed E. Khalifa","doi":"10.3390/cryst14080710","DOIUrl":"https://doi.org/10.3390/cryst14080710","url":null,"abstract":"Bismuth layered structure ferroelectrics (BLSFs), also known as Aurivillius phase materials, are ideal for energy-efficient applications, particularly for solar cells. This work reports the first comprehensive detailed theoretical study on the fascinating structural, electronic, and optical properties of XNb2Bi2O9 (X = Ca, Ba, Be, Mg, Sr). The Perdew–Burke–Ernzerhof approach and generalized gradient approximation (GGA) are implemented to thoroughly investigate the structural, bandgap, optical, and electronic properties of the compounds. The optical conductivity, band topologies, dielectric function, bandgap values, absorption coefficient, reflectivity, extinction coefficient, refractive index, and partial and total densities of states are thoroughly investigated from a photovoltaics standpoint. The material exhibits distinct behaviors, including significant optical anisotropy and an elevated absorption coefficient > 105 cm−1 in the region of visible; ultraviolet energy is observed, the elevated transparency lies in the visible and infrared regions for the imaginary portion of the dielectric function, and peaks in the optical spectra caused by inter-band transitions are detected. According to the data reported, it becomes obvious that XNb2Bi2O9 (X = Ca, Ba, Be, Mg, and Sr) is a suitable candidate for implementation in solar energy conversion applications.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141934673","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 structure of the title compound (4d), unexpectedly obtained in the reaction between o-phenylenediamine and 2-benzoylcyclohexanone instead of the target 3H-benzo[b][1,4]diazepine derivative 3d, was determined spectroscopically in solution and by a single-crystal X-ray diffraction (XRD) study. It involves two enantiomeric rotamers, called forms D and U, of which the structure was elucidated based on NMR spectra measured and predicted in DFT-GIAO calculations. An averaging of δCs for all tautomeric positions in the benzimidazole part of the 4d hydrate studied in wet (probably slightly acidic) CDCl3 unambiguously indicates tautomeric exchange in its imidazole unit. An XRD analysis of this material confirms the existence of only one tautomer in the solid phase. The non-covalent interactions forming between molecules of water and benzimidazole derivative are shorter than the sum of van der Waals radii and create an infinite-chain hydrogen bond motif along the b-axis. A possible mechanism for the observed cyclocondensation is also proposed.
通过溶液光谱和单晶 X 射线衍射 (XRD) 研究，确定了在邻苯二胺和 2-苯甲酰基环己酮反应中意外得到的标题化合物 (4d) 的结构，而不是目标 3H-苯并[b][1,4]二氮杂卓衍生物 3d。该衍生物包含两种对映异构体，分别称为 D 型和 U 型，其结构是根据 DFT-GIAO 计算所测得和预测的核磁共振光谱而阐明的。在湿的（可能是微酸性的）CDCl3 中研究了 4d 水合物苯并咪唑部分的所有同分异构体位置的 δCs 平均值，结果明确表明其咪唑单元中存在同分异构体交换。对这种材料的 XRD 分析证实，固相中只存在一种同分异构体。水分子和苯并咪唑衍生物之间形成的非共价相互作用比范德华半径之和还要短，并沿着 b 轴形成了无限链氢键图案。此外，还提出了观察到的环缩合现象的可能机理。
{"title":"Unexpected Formation of 6-(1H-Benzo[d]imidazol-2-yl)-1-phenyl-hexan-1-one and Its Structure in Solution and Solid State Analyzed in the Context of Tautomerism","authors":"Ryszard B. Nazarski, Małgorzata Domagała","doi":"10.3390/cryst14080704","DOIUrl":"https://doi.org/10.3390/cryst14080704","url":null,"abstract":"The structure of the title compound (4d), unexpectedly obtained in the reaction between o-phenylenediamine and 2-benzoylcyclohexanone instead of the target 3H-benzo[b][1,4]diazepine derivative 3d, was determined spectroscopically in solution and by a single-crystal X-ray diffraction (XRD) study. It involves two enantiomeric rotamers, called forms D and U, of which the structure was elucidated based on NMR spectra measured and predicted in DFT-GIAO calculations. An averaging of δCs for all tautomeric positions in the benzimidazole part of the 4d hydrate studied in wet (probably slightly acidic) CDCl3 unambiguously indicates tautomeric exchange in its imidazole unit. An XRD analysis of this material confirms the existence of only one tautomer in the solid phase. The non-covalent interactions forming between molecules of water and benzimidazole derivative are shorter than the sum of van der Waals radii and create an infinite-chain hydrogen bond motif along the b-axis. A possible mechanism for the observed cyclocondensation is also proposed.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141882873","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}
Milena Jacinto da Silva Moura, Roberta Bastos Vasques, Saulo Jose de melo Magalhães, Francisco Wagner de Queiroz Almeida Neto, Pedro de Lima Neto, Luís Paulo Mourão dos Santos, Mauro Andres Cerra Florez, Gemma Fargas Ribas, Samuel Lucas Santos Medeiros, Francisco Carlos Carneiro Soares Salomão, Eduardo Bedê Barros, Walney Silva Araújo
The amino acid L-histidine, which has an imidazole ring, was investigated as a corrosion inhibitor for AISI 1018 carbon steel in chloride solution based on the effectiveness of inhibitors containing imidazole in their composition. A neutral environment was chosen for this study due to the scarcity of research on this amino acid in this environment type. Concentrations of 250, 500, and 1000 ppm were evaluated. Various methods were used to determine inhibition effectiveness, including mass loss, open circuit potential, linear potentiodynamic polarization, and electrochemical impedance spectroscopy. For mass loss, the inhibition efficiency varied from 83 to 88% according to the increase in concentration. For the electrochemical tests, the efficiency variation ranged from 62 to 90% with increasing amino acid concentration. Furthermore, a simulation analysis using quantum chemical calculations within the scope of Density Functional Theory (DFT) revealed that histidine’s nucleophilic character is crucial for its corrosion inhibitory capacity in an aqueous medium at pH 7. The inhibition efficiency increased with increasing concentration in a neutral medium, following the Langmuir isotherm for the adsorption of L-histidine. Additional studies were carried out using Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TGA). Analysis of the substrate surface by scanning electron microscopy (SEM) showed greater preservation with the addition of L-histidine, confirming its adsorption on the steel. Atomic Force Microscopy (AFM) also demonstrated an improvement in surface roughness in the presence of amino acids compared to the medium without an inhibitor.
{"title":"Assessment of the Amino Acid L-Histidine as a Corrosion Inhibitor for a 1018 Carbon Steel in Aqueous Sodium Chloride Solution","authors":"Milena Jacinto da Silva Moura, Roberta Bastos Vasques, Saulo Jose de melo Magalhães, Francisco Wagner de Queiroz Almeida Neto, Pedro de Lima Neto, Luís Paulo Mourão dos Santos, Mauro Andres Cerra Florez, Gemma Fargas Ribas, Samuel Lucas Santos Medeiros, Francisco Carlos Carneiro Soares Salomão, Eduardo Bedê Barros, Walney Silva Araújo","doi":"10.3390/cryst14080703","DOIUrl":"https://doi.org/10.3390/cryst14080703","url":null,"abstract":"The amino acid L-histidine, which has an imidazole ring, was investigated as a corrosion inhibitor for AISI 1018 carbon steel in chloride solution based on the effectiveness of inhibitors containing imidazole in their composition. A neutral environment was chosen for this study due to the scarcity of research on this amino acid in this environment type. Concentrations of 250, 500, and 1000 ppm were evaluated. Various methods were used to determine inhibition effectiveness, including mass loss, open circuit potential, linear potentiodynamic polarization, and electrochemical impedance spectroscopy. For mass loss, the inhibition efficiency varied from 83 to 88% according to the increase in concentration. For the electrochemical tests, the efficiency variation ranged from 62 to 90% with increasing amino acid concentration. Furthermore, a simulation analysis using quantum chemical calculations within the scope of Density Functional Theory (DFT) revealed that histidine’s nucleophilic character is crucial for its corrosion inhibitory capacity in an aqueous medium at pH 7. The inhibition efficiency increased with increasing concentration in a neutral medium, following the Langmuir isotherm for the adsorption of L-histidine. Additional studies were carried out using Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TGA). Analysis of the substrate surface by scanning electron microscopy (SEM) showed greater preservation with the addition of L-histidine, confirming its adsorption on the steel. Atomic Force Microscopy (AFM) also demonstrated an improvement in surface roughness in the presence of amino acids compared to the medium without an inhibitor.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141882832","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}
Employing the spin-wave formalism within and beyond the harmonic-oscillator approx-imation, we study the dynamic structure factors of spin-12 nearest-neighbor quantum Heisenberg antiferromagnets on two-dimensional quasiperiodic lattices with particular emphasis on a mag-netic analog to the well-known confined states of a hopping Hamiltonian for independent electrons on a two-dimensional Penrose lattice. We present comprehensive calculations on the C5v Penrose tiling in comparison with the C8v Ammann–Beenker tiling, revealing their decagonal and octagonal antiferromagnetic microstructures. Their dynamic spin structure factors both exhibit linear soft modes emergent at magnetic Bragg wavevectors and have nearly or fairly flat scattering bands, signifying magnetic excitations localized in some way, at several different energies in a self-similar manner. In particular, the lowest-lying highly flat mode is distinctive of the Penrose lattice, which is mediated by its unique antiferromagnons confined within tricoordinated sites only, unlike their itinerant electron counterparts involving pentacoordinated, as well as tricoordinated, sites. Bringing harmonic antiferromagnons into higher-order quantum interaction splits, the lowest-lying nearly flat scattering band in two, each mediated by further confined antiferromagnons, which is fully demonstrated and throughly visualized in the perpendicular as well as real spaces. We disclose superconfined antiferromagnons on the two-dimensional Penrose lattice.
{"title":"Magnon Confinement on the Two-Dimensional Penrose Lattice: Perpendicular-Space Analysis of the Dynamic Structure Factor","authors":"Shoji Yamamoto, Takashi Inoue","doi":"10.3390/cryst14080702","DOIUrl":"https://doi.org/10.3390/cryst14080702","url":null,"abstract":"Employing the spin-wave formalism within and beyond the harmonic-oscillator approx-imation, we study the dynamic structure factors of spin-12 nearest-neighbor quantum Heisenberg antiferromagnets on two-dimensional quasiperiodic lattices with particular emphasis on a mag-netic analog to the well-known confined states of a hopping Hamiltonian for independent electrons on a two-dimensional Penrose lattice. We present comprehensive calculations on the C5v Penrose tiling in comparison with the C8v Ammann–Beenker tiling, revealing their decagonal and octagonal antiferromagnetic microstructures. Their dynamic spin structure factors both exhibit linear soft modes emergent at magnetic Bragg wavevectors and have nearly or fairly flat scattering bands, signifying magnetic excitations localized in some way, at several different energies in a self-similar manner. In particular, the lowest-lying highly flat mode is distinctive of the Penrose lattice, which is mediated by its unique antiferromagnons confined within tricoordinated sites only, unlike their itinerant electron counterparts involving pentacoordinated, as well as tricoordinated, sites. Bringing harmonic antiferromagnons into higher-order quantum interaction splits, the lowest-lying nearly flat scattering band in two, each mediated by further confined antiferromagnons, which is fully demonstrated and throughly visualized in the perpendicular as well as real spaces. We disclose superconfined antiferromagnons on the two-dimensional Penrose lattice.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141882831","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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