Rachel Boillat-Newport, Sriram Praneeth Isanaka, Frank Liou
As high-strength aluminum alloys present several processability issues with additive manufacturing (AM), Scalmalloy®, an Al-Mg-Sc-Zr-based alloy, has been developed. This alloy is age-hardenable, allowing it to precipitate out a strengthening precipitate phase, Al3(Sc,Zr). The manufacturer recommends a single-stage aging treatment at 325 °C for 4 h; however, the majority of the literature studies utilize a powder bed processing known as selective laser melting (SLM) over powder-fed processing directed energy deposition (DED). This study addresses the lack of information on heat treatments for DED fabrication by exploring the application of artificial aging temperatures of 300–400 °C for 2, 4, and 6 h to: 1. determine the impact on the microstructural evolution and mechanical performance and 2. determine whether the recommended treatment for Scalmalloy® is appropriate for DED fabrication. Tensile testing determined that low-temperature treatments exhibited no visible dependence on time (2–6 h); however, time becomes influential at higher temperatures starting at 350 °C. The temperature plays a considerable role in the mechanical and microstructural behaviors of DED Scalmalloy®. The highest tensile strength was noted at 300 °C (384 MPa, 21.6% increase), but all heat-treated cases resulted in an improvement over the as-built case. This investigation established that increasing the treatment temperature resulted in a decreasing trend for the tensile strength that held over time. Elongation at 2 h displayed a near parabolic trend that peaks at 350 °C (20%) and falls with higher temperatures. At the 4 h treatment, a slight decreasing trend was noticed for elongation. No visible change was observed for elongation at 6 h, with elongation values remaining fairly consistent. The microstructural evolution, including micron-sized and nano-sized Al3(Sc,Zr) and grain size, was examined, and coarsening effects were noted with the increase in the temperature. It is recommended that treatment be conducted at 300 °C to achieve the precipitation of the strengthening Al3(Sc,Zr) phase while minimizing coarsening.
由于高强度铝合金在增材制造（AM）中存在一些可加工性问题，因此开发了一种 Al-Mg-Sc-Zr 基合金 Scalmalloy®。这种合金具有时效硬化性，可析出强化沉淀相 Al3(Sc,Zr)。制造商建议在 325 °C 下进行 4 小时的单级时效处理；然而，大多数文献研究采用的是一种称为选择性激光熔化（SLM）的粉末床加工方法，而不是粉末馈送加工的定向能沉积（DED）方法。本研究探讨了 300-400 °C 人工老化温度下持续 2、4 和 6 小时的应用，以解决定向能沉积制造热处理信息缺乏的问题：1. 确定对微观结构演变和机械性能的影响；2. 确定推荐的 Scalmalloy® 处理方法是否适合 DED 制造。拉伸测试表明，低温处理对时间（2-6 小时）没有明显的依赖性；但是，从 350 °C 开始，温度越高，时间越有影响。温度对 DED Scalmalloy® 的机械和微观结构行为起着重要作用。拉伸强度在 300 ℃ 时最高（384 兆帕，增加 21.6%），但所有热处理情况都比坯料情况有所改善。这项研究表明，提高处理温度会导致拉伸强度呈下降趋势，而且这种趋势会随着时间的推移而持续。2 小时后的伸长率呈现近似抛物线的趋势，在 350 °C 时达到峰值（20%），温度越高，伸长率越低。在 4 小时的处理过程中，伸长率呈轻微下降趋势。6 小时后，伸长率没有明显变化，伸长率值保持相当一致。对微观结构演变（包括微米级和纳米级 Al3（Sc，Zr）和晶粒大小）进行了研究，发现随着温度的升高，微观结构会发生粗化效应。建议在 300 °C 下进行处理，以实现强化 Al3（Sc，Zr）相的析出，同时尽量减少粗化。
{"title":"Heat Treatment Post-Processing for the Improved Mechanical Properties of Scalmalloy® Processed via Directed Energy Deposition","authors":"Rachel Boillat-Newport, Sriram Praneeth Isanaka, Frank Liou","doi":"10.3390/cryst14080688","DOIUrl":"https://doi.org/10.3390/cryst14080688","url":null,"abstract":"As high-strength aluminum alloys present several processability issues with additive manufacturing (AM), Scalmalloy®, an Al-Mg-Sc-Zr-based alloy, has been developed. This alloy is age-hardenable, allowing it to precipitate out a strengthening precipitate phase, Al3(Sc,Zr). The manufacturer recommends a single-stage aging treatment at 325 °C for 4 h; however, the majority of the literature studies utilize a powder bed processing known as selective laser melting (SLM) over powder-fed processing directed energy deposition (DED). This study addresses the lack of information on heat treatments for DED fabrication by exploring the application of artificial aging temperatures of 300–400 °C for 2, 4, and 6 h to: 1. determine the impact on the microstructural evolution and mechanical performance and 2. determine whether the recommended treatment for Scalmalloy® is appropriate for DED fabrication. Tensile testing determined that low-temperature treatments exhibited no visible dependence on time (2–6 h); however, time becomes influential at higher temperatures starting at 350 °C. The temperature plays a considerable role in the mechanical and microstructural behaviors of DED Scalmalloy®. The highest tensile strength was noted at 300 °C (384 MPa, 21.6% increase), but all heat-treated cases resulted in an improvement over the as-built case. This investigation established that increasing the treatment temperature resulted in a decreasing trend for the tensile strength that held over time. Elongation at 2 h displayed a near parabolic trend that peaks at 350 °C (20%) and falls with higher temperatures. At the 4 h treatment, a slight decreasing trend was noticed for elongation. No visible change was observed for elongation at 6 h, with elongation values remaining fairly consistent. The microstructural evolution, including micron-sized and nano-sized Al3(Sc,Zr) and grain size, was examined, and coarsening effects were noted with the increase in the temperature. It is recommended that treatment be conducted at 300 °C to achieve the precipitation of the strengthening Al3(Sc,Zr) phase while minimizing coarsening.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":"25 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141775270","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}
Peridot has a long history and is deeply loved by people for its unique olive-green color. The Yiqisong peridot deposit in Jilin Province is a newly discovered peridot deposit that still deserves systematic research. In this study, gemological and chemical analyses of thirty-three Yiqisong peridot samples were carried out to investigate the gemological characteristics, as well as the mantle properties and formation conditions of the Yiqisong. In addition, we identified gemological differences in peridot between Yiqisong, Tanzania, and Arizona. The Yiqisong peridot samples have typical peridot gemological characteristics. The UV–visible spectrum indicated that Fe is the chromogenic element. The infrared spectra and Raman spectra of different samples are consistent, which indicates that the Yiqisong peridot belongs to forsterite. The contents of Ni and V in Yiqisong peridot are generally low, distinguishing it from peridot found in Tanzania and Arizona. The major and trace elements of samples show that the Yiqisong peridot is derived from the spinel lherzolite xenoliths with the P–T formation conditions of 813–1087 °C and 21–22 kbar. The Yisqisong peridot samples have relatively high Fo values (up to 91.6), supporting their origin from a moderate refractory lithosphere mantle. Therefore, this study provides gemological, mineralogical, and chemical evidence that fills the research gap in peridot deposit studies and lays the foundation for follow-up investigations of gem-grade peridot deposits.
{"title":"Gemological and Chemical Characterization of Gem-Grade Peridot from Yiqisong, Jilin Province","authors":"Jina Li, Yi Zhao, Bo Xu","doi":"10.3390/cryst14080689","DOIUrl":"https://doi.org/10.3390/cryst14080689","url":null,"abstract":"Peridot has a long history and is deeply loved by people for its unique olive-green color. The Yiqisong peridot deposit in Jilin Province is a newly discovered peridot deposit that still deserves systematic research. In this study, gemological and chemical analyses of thirty-three Yiqisong peridot samples were carried out to investigate the gemological characteristics, as well as the mantle properties and formation conditions of the Yiqisong. In addition, we identified gemological differences in peridot between Yiqisong, Tanzania, and Arizona. The Yiqisong peridot samples have typical peridot gemological characteristics. The UV–visible spectrum indicated that Fe is the chromogenic element. The infrared spectra and Raman spectra of different samples are consistent, which indicates that the Yiqisong peridot belongs to forsterite. The contents of Ni and V in Yiqisong peridot are generally low, distinguishing it from peridot found in Tanzania and Arizona. The major and trace elements of samples show that the Yiqisong peridot is derived from the spinel lherzolite xenoliths with the P–T formation conditions of 813–1087 °C and 21–22 kbar. The Yisqisong peridot samples have relatively high Fo values (up to 91.6), supporting their origin from a moderate refractory lithosphere mantle. Therefore, this study provides gemological, mineralogical, and chemical evidence that fills the research gap in peridot deposit studies and lays the foundation for follow-up investigations of gem-grade peridot deposits.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":"5 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141775271","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}
Jana Chrappová, Yogeswara Rao Pateda, Lenka Bartošová, Erik Rakovský
Three hybrid compounds based on decavanadates, i.e., (NH4)2[Co(H2O)5(β-HAla)]2[V10O28]·4H2O (1), (NH4)2[Ni(H2O)5(β-HAla)]2[V10O28]·4H2O (2), and (NH4)2[Cd(H2O)5(β-HAla)]2[V10O28]·2H2O (3), (where β-Hala = zwitterionic form of β-alanine) were prepared by reactions in mildly acidic conditions (pH ~ 4) at room temperature. These compounds crystallise in two structure types, both crystallising in monoclinic P21/n space group but with dissimilar cell packing, i.e., as tetrahydrates (1 and 2) and as a dihydrate (3). An influence of crystal radii and spin state of the central atom in [M(H2O)5(β-HAla)]2+ complex cations on the crystal packing leading to the formation of different crystallohydrate forms was investigated together with previously prepared (NH4)2[Zn(H2O)5(β-HAla)]2[V10O28]·4H2O (4) and (NH4)2[Mn(H2O)5(β-HAla)]2[V10O28]·2H2O (5) and spin states of [M(H2O)5(β-HAla)]2+ (M = Co2+, Ni2+, and Mn2+) cations in solution were confirmed by 1H-NMR paramagnetic effects. FT-IR and FT-Raman spectra for 1–5 are in agreement with the X-ray structure analysis results.
{"title":"Investigating the Formation of Different (NH4)2[M(H2O)5(NH3CH2CH2COO)]2[V10O28]·nH2O (M = CoII, NiII, ZnII, n = 4; M = CdII, MnII, n = 2) Crystallohydrates","authors":"Jana Chrappová, Yogeswara Rao Pateda, Lenka Bartošová, Erik Rakovský","doi":"10.3390/cryst14080685","DOIUrl":"https://doi.org/10.3390/cryst14080685","url":null,"abstract":"Three hybrid compounds based on decavanadates, i.e., (NH4)2[Co(H2O)5(β-HAla)]2[V10O28]·4H2O (1), (NH4)2[Ni(H2O)5(β-HAla)]2[V10O28]·4H2O (2), and (NH4)2[Cd(H2O)5(β-HAla)]2[V10O28]·2H2O (3), (where β-Hala = zwitterionic form of β-alanine) were prepared by reactions in mildly acidic conditions (pH ~ 4) at room temperature. These compounds crystallise in two structure types, both crystallising in monoclinic P21/n space group but with dissimilar cell packing, i.e., as tetrahydrates (1 and 2) and as a dihydrate (3). An influence of crystal radii and spin state of the central atom in [M(H2O)5(β-HAla)]2+ complex cations on the crystal packing leading to the formation of different crystallohydrate forms was investigated together with previously prepared (NH4)2[Zn(H2O)5(β-HAla)]2[V10O28]·4H2O (4) and (NH4)2[Mn(H2O)5(β-HAla)]2[V10O28]·2H2O (5) and spin states of [M(H2O)5(β-HAla)]2+ (M = Co2+, Ni2+, and Mn2+) cations in solution were confirmed by 1H-NMR paramagnetic effects. FT-IR and FT-Raman spectra for 1–5 are in agreement with the X-ray structure analysis results.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":"55 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141775268","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}
Tim Korschinsky, Benjamin Möller, Marvin Kiel, Matthias Hecht
Due to its good conductive properties, unalloyed (pure) aluminum, such as EN AW-1050A H24, finds new fields of application in electromobility. To optimize components, the cyclic material behavior must be understood and described precisely as a foundation of a proper fatigue life estimation. Various cyclic tests were performed to not only derive the cyclic parameters to describe the material but also to find the most suitable procedure to deal with the challenges faced during the experiments. The main point of interest is the comparison between a surface-mounted clip-on extensometer and an optical system both used for strain control in cyclic tests. For the analysis of the anisotropic behavior of EN AW-1050A H24, un-notched flat specimens were extracted from sheet metal lengthways and crossways in respect to the rolling direction. While the cyclic material behavior for specimens of both directions of extraction is characterized by cyclic softening in general, the specimens extracted crossways show a strain-amplitude-dependent cyclic softening with strong strain localization especially at the contact points of the knives of the clip-on extensometer leading to an increased quantity of invalid experiments as well as sudden fractures. In the study, it was possible to show the benefits of a contactless optical strain control system when dealing with very soft metallic materials such as EN AW-1050A H24.
由于具有良好的导电性能，非合金（纯）铝（如 EN AW-1050A H24）在电动汽车中找到了新的应用领域。为了优化组件，必须准确理解和描述材料的循环行为，以此作为正确估算疲劳寿命的基础。我们进行了各种循环试验，不仅要得出描述材料的循环参数，还要找到最合适的程序来应对试验过程中面临的挑战。主要关注点是表面贴装夹式拉伸计和光学系统之间的比较，两者都用于循环测试中的应变控制。为了分析 EN AW-1050A H24 的各向异性行为，从轧制方向相对于纵向和横向的金属板上提取了未切口的扁平试样。两个方向提取的试样的材料循环行为一般都表现为循环软化，而横向提取的试样则表现为随应变振幅变化的循环软化，特别是在夹式拉伸计刀具的接触点处，应变局部性很强，导致无效实验和突然断裂的数量增加。在这项研究中，我们可以看到非接触式光学应变控制系统在处理 EN AW-1050A H24 等非常软的金属材料时的优势。
{"title":"Analysis of the Anisotropic Cyclic Material Behavior of EN AW-1050A H24 Derived from Strain-Controlled Testing Using a Clip-On Extensometer and an Optical System","authors":"Tim Korschinsky, Benjamin Möller, Marvin Kiel, Matthias Hecht","doi":"10.3390/cryst14080686","DOIUrl":"https://doi.org/10.3390/cryst14080686","url":null,"abstract":"Due to its good conductive properties, unalloyed (pure) aluminum, such as EN AW-1050A H24, finds new fields of application in electromobility. To optimize components, the cyclic material behavior must be understood and described precisely as a foundation of a proper fatigue life estimation. Various cyclic tests were performed to not only derive the cyclic parameters to describe the material but also to find the most suitable procedure to deal with the challenges faced during the experiments. The main point of interest is the comparison between a surface-mounted clip-on extensometer and an optical system both used for strain control in cyclic tests. For the analysis of the anisotropic behavior of EN AW-1050A H24, un-notched flat specimens were extracted from sheet metal lengthways and crossways in respect to the rolling direction. While the cyclic material behavior for specimens of both directions of extraction is characterized by cyclic softening in general, the specimens extracted crossways show a strain-amplitude-dependent cyclic softening with strong strain localization especially at the contact points of the knives of the clip-on extensometer leading to an increased quantity of invalid experiments as well as sudden fractures. In the study, it was possible to show the benefits of a contactless optical strain control system when dealing with very soft metallic materials such as EN AW-1050A H24.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":"37 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141775269","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}
S. M. Nourin Sultana, Emna Helal, Giovanna Gutiérrez, Eric David, Nima Moghimian, Nicole R. Demarquette
This work demonstrates the potentials of a commercially available few-layer graphene (FLG) in enhancing the electro-dissipative properties, mechanical strength, and UV protection of polyolefin blend composites; interesting features of electronic packaging materials. Polyethylene (PE)/ polypropylene (PP)/ FLG blend composites were prepared following two steps. Firstly, different concentrations of FLG were mixed with either the PE or PP phases. Subsequently, in the second step, this pre-mixture was melt-blended with the other phase of the blend. FLG-filled composites were characterized in terms of electrical conductivity, morphological evolution upon shear-induced deformation, mechanical properties, and UV stability of polyolefin blend composites. Premixing of FLG with the PP phase has been observed to be a better mixing strategy to attain higher electrical conductivity in PE/PP/FLG blend composite. This observation is attributed to the influential effect of FLG migration from a thermodynamically less favourable PP phase to a favourable PE phase via the PE/PP interface. Interestingly, the addition of 4 wt.% (~2 vol.%) and 5 wt.% (~2.5 vol.%) of FLG increased an electrical conductivity of ~10 orders of magnitude in PE/PP—60/40 (1.87 × 10−5 S/cm) and PE/PP—20/80 (1.25 × 10−5 S/cm) blends, respectively. Furthermore, shear-induced deformation did not alter the electrical conductivity of the FLG-filled composite, indicating that the conductive FLG network within the composite is resilient to such deformation. In addition, 1 wt.% FLG was observed to be sufficient to retain the original mechanical properties in UV-exposed polyolefin composites. FLG exhibited pronounced UV stabilizing effects, particularly in PE-rich blends, mitigating surface cracking and preserving ductility.
{"title":"The Influence of a Commercial Few-Layer Graphene on Electrical Conductivity, Mechanical Reinforcement and Photodegradation Resistance of Polyolefin Blends","authors":"S. M. Nourin Sultana, Emna Helal, Giovanna Gutiérrez, Eric David, Nima Moghimian, Nicole R. Demarquette","doi":"10.3390/cryst14080687","DOIUrl":"https://doi.org/10.3390/cryst14080687","url":null,"abstract":"This work demonstrates the potentials of a commercially available few-layer graphene (FLG) in enhancing the electro-dissipative properties, mechanical strength, and UV protection of polyolefin blend composites; interesting features of electronic packaging materials. Polyethylene (PE)/ polypropylene (PP)/ FLG blend composites were prepared following two steps. Firstly, different concentrations of FLG were mixed with either the PE or PP phases. Subsequently, in the second step, this pre-mixture was melt-blended with the other phase of the blend. FLG-filled composites were characterized in terms of electrical conductivity, morphological evolution upon shear-induced deformation, mechanical properties, and UV stability of polyolefin blend composites. Premixing of FLG with the PP phase has been observed to be a better mixing strategy to attain higher electrical conductivity in PE/PP/FLG blend composite. This observation is attributed to the influential effect of FLG migration from a thermodynamically less favourable PP phase to a favourable PE phase via the PE/PP interface. Interestingly, the addition of 4 wt.% (~2 vol.%) and 5 wt.% (~2.5 vol.%) of FLG increased an electrical conductivity of ~10 orders of magnitude in PE/PP—60/40 (1.87 × 10−5 S/cm) and PE/PP—20/80 (1.25 × 10−5 S/cm) blends, respectively. Furthermore, shear-induced deformation did not alter the electrical conductivity of the FLG-filled composite, indicating that the conductive FLG network within the composite is resilient to such deformation. In addition, 1 wt.% FLG was observed to be sufficient to retain the original mechanical properties in UV-exposed polyolefin composites. FLG exhibited pronounced UV stabilizing effects, particularly in PE-rich blends, mitigating surface cracking and preserving ductility.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":"94 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141775023","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}
Foamed ceramics with high closed porosity were prepared using granite scrap as the raw material and silicon carbide as a foaming agent, and the effects of Na2O, K2O, and MgO on the pore structure and properties of the foamed ceramics were investigated. The results show that both Na2O and K2O could reduce the viscosity of the melt and promote the formation of the liquid phase, and the increase in content could enhance the foaming ability of the blank. When the dosage of Na2O was 4–6 wt% and the dosage of K2O was 6–8 wt%, the homogeneity of the pore structure of the foamed ceramics could be effectively improved, and the samples exhibited an optimal performance, including a bulk density of 510.36–593.33 kg/m3, a closed porosity of 68.24–78.04%, a compressive strength of 1.33–2.66 MPa, and a water absorption capacity of 0.57–1.31%. A further increase in the Na2O and K2O dosages destroyed the uniformity of the pore structure, resulting in a large number of irregular macropores. MgO had a slight effect on regulating the pore structure of the foamed ceramics, and the increase in dosage promoted the precipitation of forsterite crystals, creating conditions suitable for the preparation of foamed ceramics with small pores.
{"title":"The Effect of Flux on a Waste-Derived Foamed Ceramic: Analysis of Microstructure and Properties","authors":"Zhiwu Zuo, Minghao Mu, Xue Liu, Congcong Jiang","doi":"10.3390/cryst14080682","DOIUrl":"https://doi.org/10.3390/cryst14080682","url":null,"abstract":"Foamed ceramics with high closed porosity were prepared using granite scrap as the raw material and silicon carbide as a foaming agent, and the effects of Na2O, K2O, and MgO on the pore structure and properties of the foamed ceramics were investigated. The results show that both Na2O and K2O could reduce the viscosity of the melt and promote the formation of the liquid phase, and the increase in content could enhance the foaming ability of the blank. When the dosage of Na2O was 4–6 wt% and the dosage of K2O was 6–8 wt%, the homogeneity of the pore structure of the foamed ceramics could be effectively improved, and the samples exhibited an optimal performance, including a bulk density of 510.36–593.33 kg/m3, a closed porosity of 68.24–78.04%, a compressive strength of 1.33–2.66 MPa, and a water absorption capacity of 0.57–1.31%. A further increase in the Na2O and K2O dosages destroyed the uniformity of the pore structure, resulting in a large number of irregular macropores. MgO had a slight effect on regulating the pore structure of the foamed ceramics, and the increase in dosage promoted the precipitation of forsterite crystals, creating conditions suitable for the preparation of foamed ceramics with small pores.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":"62 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141775274","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}
Matthias Zschornak, Christian Wagner, Melanie Nentwich, Muthu Vallinayagam, Karl F. Fischer
The Parameter Space Concept (PSC) is an alternative approach to solving and refining (partial) crystal structures from very few pre-chosen X-ray or neutron diffraction amplitudes without the use of Fourier inversion. PSC interprets those amplitudes as piecewise analytic hyper-surfaces, so-called isosurfaces, in the Parameter Space, which is spanned by the spatial coordinates of all atoms of interest. The intersections of all isosurfaces constitute the (possibly degenerate) structure solution. The present feasibility study investigates the La and Sr split position of the potential high-temperature super-conductor (La0.5Sr1.5)MnO4, I4/mmm, with a postulated total displacement between La and Sr of a few pm by theoretical amplitudes of pre-selected 00l reflections (l=2,4,…,20). The revision of 15-year-old results with state-of-the-art computing equipment enhances the former simplified model by varying the scattering power ratio ferrortypeceLa/ferrortypeceSr, as exploitable by means of resonant scattering contrast at synchrotron facilities, and irrevocably reveals one of the two originally proposed solutions as being a “blurred” pseudo-solution. Finally, studying the resolution limits of PSC as a function of intensity errors by means of Monte-Carlo simulations shows both that the split can only be resolved for sufficiently low errors and, particularly for the resonant scattering contrast, a theoretical precision down to ±0.19pm can be achieved for this specific structural problem.
参数空间概念（PSC）是另一种无需使用傅立叶反演即可通过预先选择的极少量 X 射线或中子衍射振幅求解和完善（部分）晶体结构的方法。PSC 将这些振幅解释为参数空间（Parameter Space）中的片断解析超曲面（即所谓的等值面），参数空间由所有相关原子的空间坐标跨越。所有等值面的交点构成（可能是退化的）结构解。本可行性研究调查了潜在高温超导体 (La0.5Sr1.5)MnO4, I4/mmm 的 La 和 Sr 分裂位置，通过预选的 00l 反射（l=2,4,..,20）的理论振幅，推测 La 和 Sr 之间的总位移为几个 pm。利用最先进的计算设备对 15 年前的结果进行修正，通过改变散射功率比 ferrortypeceLa/ferrortypeceSr （可通过同步加速器设施的共振散射对比进行利用），增强了之前的简化模型，并无可挽回地揭示了最初提出的两个解决方案之一是一个 "模糊 "的伪解决方案。最后，通过蒙特卡洛模拟研究了 PSC 分辨率极限与强度误差的函数关系，结果表明只有在误差足够小的情况下才能分辨出分裂，尤其是共振散射对比度，对于这个特定的结构问题，理论精度可以低至 ±0.19pm。
{"title":"Advances in the Parameter Space Concept towards Picometer Precise Crystal Structure Refinement—A Resolution Study","authors":"Matthias Zschornak, Christian Wagner, Melanie Nentwich, Muthu Vallinayagam, Karl F. Fischer","doi":"10.3390/cryst14080684","DOIUrl":"https://doi.org/10.3390/cryst14080684","url":null,"abstract":"The Parameter Space Concept (PSC) is an alternative approach to solving and refining (partial) crystal structures from very few pre-chosen X-ray or neutron diffraction amplitudes without the use of Fourier inversion. PSC interprets those amplitudes as piecewise analytic hyper-surfaces, so-called isosurfaces, in the Parameter Space, which is spanned by the spatial coordinates of all atoms of interest. The intersections of all isosurfaces constitute the (possibly degenerate) structure solution. The present feasibility study investigates the La and Sr split position of the potential high-temperature super-conductor (La0.5Sr1.5)MnO4, I4/mmm, with a postulated total displacement between La and Sr of a few pm by theoretical amplitudes of pre-selected 00l reflections (l=2,4,…,20). The revision of 15-year-old results with state-of-the-art computing equipment enhances the former simplified model by varying the scattering power ratio ferrortypeceLa/ferrortypeceSr, as exploitable by means of resonant scattering contrast at synchrotron facilities, and irrevocably reveals one of the two originally proposed solutions as being a “blurred” pseudo-solution. Finally, studying the resolution limits of PSC as a function of intensity errors by means of Monte-Carlo simulations shows both that the split can only be resolved for sufficiently low errors and, particularly for the resonant scattering contrast, a theoretical precision down to ±0.19pm can be achieved for this specific structural problem.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":"50 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141775276","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}
Liquid crystals, which have both liquid and solid properties, inevitably exhibit fluctuations. Some frustrated liquid-crystalline phases with a hierarchical structure, such as cybotactic nematic, modulated smectic, and bicontinuous cubic phases, are fascinating fluctuation-induced phases. In addition to these equilibrium phases, a pattern formation that is a nonequilibrium order through fluctuation is one of the most attractive research areas in soft matter. In this review, the studies on producing these fluctuation-induced orders in liquid crystals are described. Liquid-crystalline supermolecules in which several mesogens are connected via a flexible spacer have been designed. They have not only a characteristic shape but also an intra-molecular dynamic order. The supermolecules induce the fluctuations in layer structures at a molecular level, producing from the frustrated hierarchical to dynamic dissipative structures. In addition to reviewing molecular design for the hierarchical structures, the pattern propagation in a smectic phase is discussed based on the rotation of smectic blocks through Rayleigh–Bénard convection.
{"title":"Liquid-Crystalline Supermolecules Inducing Layer Fluctuations: From Hierarchical to Dissipative Structures","authors":"Atsushi Yoshizawa","doi":"10.3390/cryst14080681","DOIUrl":"https://doi.org/10.3390/cryst14080681","url":null,"abstract":"Liquid crystals, which have both liquid and solid properties, inevitably exhibit fluctuations. Some frustrated liquid-crystalline phases with a hierarchical structure, such as cybotactic nematic, modulated smectic, and bicontinuous cubic phases, are fascinating fluctuation-induced phases. In addition to these equilibrium phases, a pattern formation that is a nonequilibrium order through fluctuation is one of the most attractive research areas in soft matter. In this review, the studies on producing these fluctuation-induced orders in liquid crystals are described. Liquid-crystalline supermolecules in which several mesogens are connected via a flexible spacer have been designed. They have not only a characteristic shape but also an intra-molecular dynamic order. The supermolecules induce the fluctuations in layer structures at a molecular level, producing from the frustrated hierarchical to dynamic dissipative structures. In addition to reviewing molecular design for the hierarchical structures, the pattern propagation in a smectic phase is discussed based on the rotation of smectic blocks through Rayleigh–Bénard convection.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":"15 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141775273","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}
Tzu-Yi Chang, Gavin Vandenbroeder, David M. Frazer, Dewen Yushu, Stephanie Pitts, Tianyi Chen
This work reports a new methodology using indentation stress relaxation to characterize the dislocation velocity–stress exponent. Through the indentation stress relaxation process, the dislocation structure builds up at the rate governed by dislocation velocity, which is a function of the externally applied stress. The relationship between the dislocation velocity and stress can thus be derived from the indentation stress relaxation data of the stress as a function of time. In this study, instrumented nanoindentation stress relaxation experiments were performed on pure aluminum samples, following three different initial displacement rates of 100, 400, and 800 nm/s. Based on the scaling properties of dislocation kinetics, the data were interpreted to derive a dislocation velocity–stress exponent of 2.5 ± 0.5 for room-temperature aluminum. Crystal plasticity finite-element simulations were performed to illustrate the sensitivity of the proposed nanoindentation stress relaxation methodology to the dislocation velocity–stress exponent value.
{"title":"Nanoindentation Stress Relaxation to Quantify Dislocation Velocity–Stress Exponent","authors":"Tzu-Yi Chang, Gavin Vandenbroeder, David M. Frazer, Dewen Yushu, Stephanie Pitts, Tianyi Chen","doi":"10.3390/cryst14080680","DOIUrl":"https://doi.org/10.3390/cryst14080680","url":null,"abstract":"This work reports a new methodology using indentation stress relaxation to characterize the dislocation velocity–stress exponent. Through the indentation stress relaxation process, the dislocation structure builds up at the rate governed by dislocation velocity, which is a function of the externally applied stress. The relationship between the dislocation velocity and stress can thus be derived from the indentation stress relaxation data of the stress as a function of time. In this study, instrumented nanoindentation stress relaxation experiments were performed on pure aluminum samples, following three different initial displacement rates of 100, 400, and 800 nm/s. Based on the scaling properties of dislocation kinetics, the data were interpreted to derive a dislocation velocity–stress exponent of 2.5 ± 0.5 for room-temperature aluminum. Crystal plasticity finite-element simulations were performed to illustrate the sensitivity of the proposed nanoindentation stress relaxation methodology to the dislocation velocity–stress exponent value.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":"31 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141775272","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 Malysheva emerald mine (Urals, Russia) boasts a long history and extraordinary emerald output. However, recent studies indicate that Malysheva emeralds share highly similar inclusion varieties, UV-visible-near infrared (UV-Vis-NIR) spectra, and compositional characteristics with other tectonic-magmatic-related (type I) emeralds from Zambia, Brazil, and Ethiopia. This similarity poses challenges for determination of the emeralds’ origin. This paper systematically investigates the microscopy, spectroscopy, and trace element chemistry of Malysheva emerald samples and compiles previously reported compositional data for the aforementioned Type I emeralds. Based on this dataset, principal component analysis (PCA) and machine learning methods are employed to construct models for emerald provenance discrimination. The results have updated the provenance characteristics of Malysheva emeralds, confirming the solid phase component of their three-phase inclusions as siderite and revealing two UV-Vis-NIR spectral patterns. Furthermore, the unique infrared absorptions related to HDO and D2O molecules within the 2600–2830 cm−1 range were discovered, which can be indicative of the origin of Malysheva. The prediction results of the machine learning model demonstrate an accuracy rate of 98.7%, and for an independent validation set of Malysheva emeralds, the prediction accuracy reached 100%. The feature importance ranking of the model highlights trace elements and parameters strongly correlated with the emeralds’ origin. These results illustrate the enormous potential of machine learning in the field of emerald origin determination, offering new insights into the traceability of precious gemstones.
{"title":"Characterizing Malysheva Emeralds (Urals, Russia) by Microscopy, Spectroscopy, Trace Element Chemistry, and Machine Learning","authors":"Yu-Yu Zheng, Xiao-Yan Yu, Bo Xu, Yu-Jie Gao","doi":"10.3390/cryst14080683","DOIUrl":"https://doi.org/10.3390/cryst14080683","url":null,"abstract":"The Malysheva emerald mine (Urals, Russia) boasts a long history and extraordinary emerald output. However, recent studies indicate that Malysheva emeralds share highly similar inclusion varieties, UV-visible-near infrared (UV-Vis-NIR) spectra, and compositional characteristics with other tectonic-magmatic-related (type I) emeralds from Zambia, Brazil, and Ethiopia. This similarity poses challenges for determination of the emeralds’ origin. This paper systematically investigates the microscopy, spectroscopy, and trace element chemistry of Malysheva emerald samples and compiles previously reported compositional data for the aforementioned Type I emeralds. Based on this dataset, principal component analysis (PCA) and machine learning methods are employed to construct models for emerald provenance discrimination. The results have updated the provenance characteristics of Malysheva emeralds, confirming the solid phase component of their three-phase inclusions as siderite and revealing two UV-Vis-NIR spectral patterns. Furthermore, the unique infrared absorptions related to HDO and D2O molecules within the 2600–2830 cm−1 range were discovered, which can be indicative of the origin of Malysheva. The prediction results of the machine learning model demonstrate an accuracy rate of 98.7%, and for an independent validation set of Malysheva emeralds, the prediction accuracy reached 100%. The feature importance ranking of the model highlights trace elements and parameters strongly correlated with the emeralds’ origin. These results illustrate the enormous potential of machine learning in the field of emerald origin determination, offering new insights into the traceability of precious gemstones.","PeriodicalId":10855,"journal":{"name":"Crystals","volume":"81 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141775275","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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