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Nano research 2024年第6期17卷 5336-5348页

作者： Alevtina Smekhova Daniel Gaertner Alexei Kuzmin Ana Guilherme Buzanich Goetz Schuck Ivo Zizak Gerhard Wilde Kirill V.Yusenko Sergiy Divinski Helmholtz-Zentrum Berlin für Materialien und Energie(HZB) D-12489 BerlinGermany Institute of Materials Physics University of MünsterD-48149 MünsterGermany Institute of Solid State Physics University of LatviaLV-1063 RigaLatvia bundesanstalt für materialforschung und–prüfung(bam) D-12489 BerlinGermany

Multi-edge extended X-ray absorption fine structure(EXAfS)spectroscopy combined with reverse Monte Carlo(rMC)simulations was used to probe the details of element-specific local coordinations and component-dependent structure relaxations in single crystalline equiatomic CrMnfeCoNi high-entropy alloy as a function of the annealing *** representative states,namely a high-temperature state,created by annealing at 1373 K,and a low-temperature state,produced by long-term annealing at 993 K,were compared in *** features identified in atomic configurations of particular principal components indicate variations in the local environment distortions connected to different degrees of compositional disorder at the chosen representative *** detected changes provide new atomistic insights and correlate with the existence of kinks previously observed in the Arrhenius dependencies of component diffusion rates in the CrMnfeCoNi high-entropy alloy.

关键词： high-entropy alloys diffusion short-range order extended X-ray absorption fine structure(EXAfS) reverse Monte Carlo

A New Kind of Atomic force Microscopy Scan Control Enabled by Artificial Intelligence:Concept for Achieving Tip and Sample Safety Through Asymmetric Control

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Nanomanufacturing and Metrology 2024年第2期7卷 50-59页

作者： Johannes Degenhardt Mohammed Wassim Bounaim Nan Deng rainer Tutsch Gaoliang Dai Physikalisch-Technische bundesanstalt Bundesallee 10038116 BrunswickGermany Institut für prozessmess-und Sensortechnik Technische Universität Ilmenau EhrenbergstraBe 2998693 IlmenauGermany Institute of production Metrology TU Braunschweig SchleinitzstraBe 2038106 BrunswickGermany

This paper introduces a paradigm shift in atomic force microscope(AfM)scan control,leveraging an artificial intelligence(AI)-based *** contrast to conventional control methods,which either show a limited performance,such as proportional integral differential(PID)control,or which purely focus on mathematical optimality as classical optimal control approaches,our proposed AI approach redefines the objective of control for achieving practical *** presented AI controller minimizes the root-mean-square control deviations in routine scans by a factor of about 4 compared to PID control in the presented setup and also showcases a distinctive asymmetric response in complex situations,prioritizing the safety of the AfM tip and sample instead of the lowest possible control *** development and testing of the AI control concept are performed on simulated AfM scans,demonstrating its huge potential.

关键词： Atomic force microscopy Artificial intelligence Deep reinforcement learning Optimal control

Excitation and relaxation dynamics in ultrafast laser irradiated optical glasses

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High Power Laser Science and Engineering 2016年第4期4卷 1-8页

作者： C.Mauclair A.Mermillod-Blondin K.Mishchik J.Bonse A.rosenfeld J.P.Colombier r.Stoian Laboratoire Hubert Curien UMR 5516 CNRSUniversité de LyonUniversité Jean Monnet Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie bundesanstalt für materialforschung und-prüfung (bam)

We discuss the dynamics of ultrashort pulsed laser excitation in bulk optical silica-based glasses(fused silica and borosilicate BK7) well-above the permanent modification threshold. We indicate subsequent structural and thermomechanical energy relaxation paths that translate into positive and negative refractive index changes, compression and rarefaction zones. If fast electronic decay occurs at low excitation levels in fused silica via self-trapping of excitons,for carrier densities in the vicinity of the critical value at the incident wavelength, persistent long-living absorptive states indicate the achievement of low viscosity matter states manifesting pressure relaxation, rarefaction, void opening and compaction in the neighboring domains. An intermediate ps-long excited carrier dynamics is observed for BK7 in the range corresponding to structural expansion and rarefaction. The amount of excitation and the strength of the subsequent hydrodynamic evolution is critically dependent on the pulse time envelope, indicative of potential optimization schemes.

关键词： carrier plasmas glasses pulse shaping refractive index engineering ultrafast laser excitation

Al-driven peculiarities of local coordination and magnetic properties in single-phase Al_(x)-CrfeCoNi high-entropy alloys

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Nano research 2022年第6期15卷 4845-4858页

作者： Alevtina Smekhova Alexei Kuzmin Konrad Siemensmeyer Chen Luo Kai Chen florin radu Eugen Weschke Uwe reinholz Ana Guilherme Buzanich Kirill V.Yusenko Helmholtz-Zentrum Berlin für Materialien und Energie(HZB) D-12489Germany Institute of Solid State Physics University of LatviaLV-1063Latvia bundesanstalt für materialforschung und-prüfung(bam) D-12489Germany

Modern design of superior multi-functional alloys composed of several principal components requires in-depth studies of their local structure for developing desired macroscopic ***,peculiarities of atomic arrangements on the local scale and electronic states of constituent elements in the single-phase face-centered cubic(fcc)-and body-centered cubic(bcc)-structured high-entropy Alx-CrfeCoNi alloys(x=0.3 and 3,respectively)are explored by element-specific X-ray absorption spectroscopy in hard and soft X-ray energy *** based on the reverse Monte Carlo approach allow to perform a simultaneous fit of extended X-ray absorption fine structure spectra recorded at K absorption edges of each 3d constituent and to reconstruct the local environment within the first coordination shells of absorbers with high *** revealed unimodal and bimodal distributions of all five elements are in agreement with structure-dependent magnetic properties of studied alloys probed by magnetometry.A degree of surface atoms oxidation uncovered by soft X-rays suggests different kinetics of oxide formation for each type of constituents and has to be taken into account.X-ray magnetic circular dichroism technique employed at L2,3 absorption edges of transition metals demonstrates reduced magnetic moments of 3d metal constituents in the sub-surface region of in situ cleaned fcc-structured Al0.3-CrfeCoNi compared to their bulk *** to nanostructured versions of multicomponent alloys,such studies would bring new insights related to effects of high entropy mixing on low dimensions.

关键词： high-entropy alloys reverse Monte Carlo magnetism element-specific spectroscopy extended X-ray absorption fine structure(EXAfS) X-ray magnetic circular dichroism(XMCD)

Influence of test procedure on dielectric breakdown strength of alumina

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Journal of Advanced Ceramics 2019年第2期8卷 247-255页

作者： Bjoern MIELLEr bundesanstalt fuer materialforschung und-pruefung (bam) Division Advanced Technical Ceramics

Dielectric strength testing of ceramics can be performed with various setups and parameters. Comparisons of results from different sources are often not meaningful, because the results are strongly dependent on the actual testing procedure. The aim of this study is to quantify the influence of voltage ramp rate, electrode size, electrode conditioning, and sample thickness on the measured AC dielectric strength of a commercial alumina. Mean values, Weibull moduli, and failure probabilities determined in standardized short time tests are evaluated and related to withstand voltage tests. Dielectric strength values in the range from 21.6 to 33.2 kV·mm–1 were obtained for the same material using different testing procedures. Short time tests resulted in small standard deviations(round 30, while withstand tests at voltage levels with low and virtual zero failure probability in short time tests resulted in large scatter of withstand time and Weibull moduli rong decrease in Weibull moduli is attributed to progressive damage from partial discharge and depolarization during AC testing. These findings emphasize the necessity of a thorough documentation of testing procedure and highlight the importance of withstand voltage tests for a comprehensive material characterization.

关键词： dielectric strength dielectric breakdown withstand voltage test high AC voltage testing

Efficiency Evaluation of Extraction Methods for Analysis of OCPs and PCBs in Soils of Varying TOC

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Journal of Environmental protection 2017年第6期8卷 693-713页

作者： Ulrike Mülow-Stollin Petra Lehnik-Habrink Stephanie Kluge Wolfram Bremser Christian Piechotta bundesanstalt für materialforschung und-prüfung (bam) Berlin Germany

Organochlorine pesticides and polychlorinated biphenyls are toxic, carcinogenic, and have a high potential for bioaccumulation. Due to their stability, they are still considered an environmental problem even though the use of most of them has been phased out several decades ago. Soil is a matrix which can retain these contaminants to a great extent. This ability is often associated with the total organic carbon content (TOC). In order to judge the pollution status of soil and to make monitoring data more easily comparable a simple, yet robust extraction method is needed. Agitation solid-liquid-extraction is well suited for this purpose. However, the influence of TOC on the analyte recovery has to be known. for the presented study, 12 organochlorine pesticides and 7 polychlorinated biphenyls were spiked into four model soils with organic carbon contents between 1.6% - 13.3%. The matrices were extracted using solid-liquid extraction between 45 minutes and 16 hours. for comparison, all soils were also extracted using pressurised liquid extraction and Soxhlet extraction. After clean-up the extracts were measured using a gas chromatography-mass spectrometry (GC-MS) system. Statistical analysis of the results implied that the TOC content of the soils did not have significant influence on the extraction efficiency. A longer solid-liquid extraction time did not necessarily increase analyte recovery: Extraction for one hour resulted in 88% recovery while 16 hour extraction led to 89%. Thus, the efficiency of all the methods was comparable for all model soils. Additional investigations regarding GC liner performance highlighted the need for isotopically labelled standards during the analysis of thermolabile pesticides.

关键词： POP Soil Organic Matter Solid-Liquid Extraction pressurised Liquid Extraction

The NMr core analyzing tomograph:a multi-functional tool for non-destructive testing of building materials

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Magnetic resonance Letters 2023年第3期3卷 207-219,I0003页

作者： Sabine Kruschwitz Sarah Munsch Melissa Telong Wolfram Schmidt Thilo Bintz Matthias fladt Ludwig Stelzner bundesanstalt für materialforschung und-prüfung Unter den Eichen 87Berlin12205Germany Technische Universitat Berlin Gustav-Meyer-Allee 25Berlin13355Germany

NMr is becoming increasingly popular for the investigation of building materials as it is a non-invasive technology that does not require any sample preparation nor causes damage to the *** on the specific application it can offer insights into properties like porosity and spatial saturation degree as well as pore *** it enables the determination of moisture transport properties and the(re-)distribution of internal moisture into different reservoirs or chemical phases upon damage and ***,as yet most investigations were carried out using devices originally either designed for geophysical applications or the analysis of rather homogeneous small scale(r describes the capabilities of an NMr tomograph,which has been specifically optimized for the investigation of larger,heterogeneous building material samples(diameters of up to 72 mm,length of up to 700 mm)with a high flexibility due to interchangeable coils allowing for a high SNr and short echo times(50-80 ms).

关键词： Natural stone Concrete Sensitivity Moisture transport Cement hydration Supplementary cementitious materials frost and salt attack fire spalling

Zeolite Synthesis under Insertion of Silica rich filtration residues from Industrial Wastewater reconditioning

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Advances in Chemical Engineering and Science 2014年第2期4卷 120-134页

作者： Andrea Hartmann V.Petrov J.-C.Buhl K.rübner M.Lindemann C.prinz A.Zimathies Institut für Mineralogie Universitat HannoverHannoverGermany fachgruppe VII.1 Baustoffe Bundesanstalt für Materialforschung und-prüfung(BAM)BerlinGermany fachbereich 1.3 Strukturanalytik richard-Willstätter Bundesanstalt für Materialforschung und-prüfung(BAM)BerlinGermany

Zeolite synthesis was studied using two silica rich filtration residues (fr 1 and fr 2) as Si-source and sodium aluminate in a direct synthesis at 60°C at strong alkaline conditions (8 M - 16 M NaOH). In addition to these one-pot syntheses, a two-step process was investigated. Here, an alkaline digestion of fr at 60°C was followed by gel precipitation with sodium aluminate and gel crystallization under usual conditions of 80°C - 90°C. The results show that the substitution of chemical reagent sodium silicate by a waste material like fr as Si-source is possible but requires fine tuning of the reaction conditions as zeolite crystallization is a process under kinetic control. The solubility behaviour and impurities of the inserted filtration residues strongly influenced the course of reaction. Thus zeolites like hydrosodalite or intermediate zeolite between cancrinite and sodalite, or zeolite NaA or Z-21 in cocrystallization with hydrosodalite could be observed in the one pot syntheses already in a short time interval between 1 - 4 h depending on the alkalinity. The two step process yield to zeolites NaA and NaX in very good quality. The reaction process of fr in both reaction methods was characterized by chemical analyses, X-ray powder diffraction, fourier transform infrared spectroscopy as well as scanning electron microscopy. Surface area and water content of selected products were further characterized by the BET-method and by thermogravimetry. Summing up the results, we can show that zeolite formation from filtration residues is possible by several reaction procedures as model cases for a re-use of industrial waste materials. Beside the importance for environmental protection, the reactions are of interest for zeolite chemistry as the re-use of fr is possible under economically conditions of low energy consumption at 60°C and short reaction periods.

关键词： Zeolites Superalkaline Conditions filtration residues re-Use of Industrial Waste reaction Kinetics Silica residue

Scattering on scattering

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Light(Science & Applications) 2017年第1期6卷 328-329页

作者： Jörn Bonse fachbereich 6.4 Technologien mit Nanowerkstoffen Bundesanstalt für Materialforschung und-prüfung(BAM)Unter den Eichen 87Berlin D-12205Germany

Ultrafast experiments can reveal the spatiotemporal dynamics of nanostructure formation via scattering in background-free optical dark-field *** of electromagnetic radiation is used in many scientific,industrial and daily *** time-resolved experiments using ultrafast lasers,the spatial and temporal coherence of the radiation is of crucial importance for visualizing scattering *** the macro-scale,an ultrafast video recording at 100 billion frames per second can impressively visualize even the Mach cone superluminal propagation of light in scattering media1;however,imaging objects at the micro-scale via ultrafast microscopy is often challenging:the fact that the coherence of the illuminating laser radiation is manifested in undesired speckle patterns can limit the spatial resolution and thus the single-shot imaging capabilities2.

关键词： scattering Scattering speckle

单通道和多通道毛细管光学元件-技术发展水平和应用(英文)

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光学精密工程 2007年第12期15卷 1932-1945页

作者： A Bjeoumikhov r Wedell S Bjeoumikhova IfG Institute for Scientific Instruments GmbH 12489 BerlinRudowerChaussee 29/31Germany Institut für angewandte Photonik e.V. 12489 BerlinRudowerChaussee 29/31Germany bundesanstalt für materialforschung und-prüfung 12200 BerlinGermany

毛细管光学元件在X射线分析中的应用已有20多年的历史,在这段时间里,毛细管光学元件的制作技术发生了很大的变化。上世纪90年代初,使用的是组装的毛细管光学元件,目前,集成的多通道毛细管光学元件已广泛地应用于市场销售的X射线分析设... 详细信息

毛细管光学元件在X射线分析中的应用已有20多年的历史,在这段时间里,毛细管光学元件的制作技术发生了很大的变化。上世纪90年代初,使用的是组装的毛细管光学元件,目前,集成的多通道毛细管光学元件已广泛地应用于市场销售的X射线分析设备中。这些元件的毛细管直径在微米量级,其光学性质可以根据几何光学的光线追迹计算进行描述。最近,由于多通道毛细管制作技术的改进,已成功制成了200 nm及以下通道尺寸的毛细管光学元件。在这样小的通道尺寸下,观察到了X射线辐射的波动效应。最后文章介绍了毛细管光学元件在X射线微荧光分析和微衍射方面的应用。

关键词： X射线毛细管光学元件波动特性纳米毛细管 X射线分析