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Initial nucleation of amorphous Si–B–C–N ceramics derived from polymer-precursors

Journal of Materials Science & Technology 2019年第12期35卷 2851-2858页

作者： Ling-yan Li Hui Gu Vesna Srot Peter van Aken joachim bill Materials Genome Institute School of Materials Science and EngineeringShanghai University99 Shangda RoadShanghai200444China Stuttgart Center for Electron Microscopy Max-Planck-lnstitute for Solid-State ResearchHeisen bergs trasse 370569StuttgartGermany Institute of Materials Science University of StuttgartHeisenbergstrasse 570569StuttgartGermany

Nucleation behavior of amorphous Si–B–C–N ceramics derived from boron-modified polyvinylsilazane procusors was systematically investigated by transmission electron microscopy(TEM) combined with spatially-resolved electron energy-loss spectroscopy(EELS) analysis. The ceramics were pyrolyzed at1000℃ followed by further annealing in N2, and SiC nano-crystallites start to emerge at 1200℃ and dominate at 1500℃. Observed by high-angle annular dark-field imaging, bright and dark clusters were revealed as universal nano-structured features in ceramic matrices before and after nucleation, and the growth of cluster size saturated before reaching 5 nm at 1400℃. EELS analysis demonstrated the gradual development of bonding structures successively into SiC, graphetic BNCxand Si3N4 phases, as well as a constant presence of unexpected oxygen in the matrices. Furthermore, EELS profiling revealed the bright SiC clusters and less bright Si3N4-like clusters at 1200–1400℃. Since the amorphous matrix has already phase separated into SiCN and carbon clusters, another phase separation of SiCN into SiC and Si3N4-like clusters might occur by annealing to accompany their nucleation and growth, albeit one crystallized and another remained in amorphous structure. Hinderance of the cluster growth and further crystallization was owing to the formation of BNCxlayers that developed between SiC and Si3N4-like clusters as well as from the excessive oxygen to form the stable SiO2.

关键词： Precursor derived ceramics Si–B–C–N Nucleation High-angle annular dark-field imaging Electron energy-loss spectroscopy

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前驱体制备Si-B-C-N陶瓷材料析晶过程的透射电镜研究

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无机材料学报 2010年第10期25卷 1076-1080页

作者：李凌燕顾辉 bill joachim 中国科学院上海硅酸盐研究所高性能陶瓷和超微结构国家重点实验室上海200050 Institute for Materials Science University of Stuttgart

以透射电镜的先进分析方法为主要手段,对前驱体制备Si-B-C-N陶瓷(T2-1)材料纳米尺度的微结构及其晶化过程进行了研究.结果表明,在直接经过1400℃热解后,所得到的T2-1样品出现了非均匀的SiC和Si3N4的结晶以及石墨化或BCN的团簇.为了有效... 详细信息

以透射电镜的先进分析方法为主要手段,对前驱体制备Si-B-C-N陶瓷(T2-1)材料纳米尺度的微结构及其晶化过程进行了研究.结果表明,在直接经过1400℃热解后,所得到的T2-1样品出现了非均匀的SiC和Si3N4的结晶以及石墨化或BCN的团簇.为了有效保持材料强度并抑制高温易分解Si3N4相的析出,对T2-1在1000℃热解以进行对比实验.显微结构的观察表明,经过低温热解的基体出现了均匀成分分相;即使再经过1400℃下的退火,仍能有效抑制Si3N4纳米晶的析出,从而增进了材料的高温稳定性.

关键词：前驱体陶瓷热解结晶透射电子显微学

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Recent Advances in Nano‑Enabled Seed Treatment Strategies for Sustainable Agriculture:Challenges,Risk Assessment,and Future Perspectives

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Nano-Micro Letters 2023年第4期15卷 153-189页

作者： Amruta Shelar Shivraj Hariram Nile Ajay Vikram Singh Dirk Rothenstein joachim bill Jianbo Xiao Manohar Chaskar Guoyin Kai Rajendra Patil Department of Technology Savitribai Phule Pune UniversityPuneMaharashtra 411007India Zhejiang Provincial International S&T Cooperation Base for Active Ingredients of Medicinal and Edible Plants and Health School of Pharmaceutical ScienceJinhua AcademyZhejiang Chinese Medical UniversityHangzhou 310053ZhejiangPeople’s Republic of China Department of Chemical and Product Safety German Federal Institute for Risk Assessment(BfR)Max‑Dohrn‑Strasse10589 BerlinGermany Institute for Materials Science University of Stuttgart70569 StuttgartGermany International Research Center for Food Nutrition and Safety Jiangsu UniversityZhenjiang 212013People’s Republic of China Faculty of Science and Technology Savitribai Phule Pune UniversityPuneMaharashtra 411007India Department of Biotechnology Savitribai Phule Pune UniversityPuneMaharashtra 411007India

Agro seeds are vulnerable to environmental stressors,adversely affecting seed vigor,crop growth,and crop *** agrochemical-based seed treatments enhance seed germination,but they can also cause damage to the environment;therefore,sustainable technologies such as nano-based agrochemicals are urgently *** can reduce the dose-dependent toxicity of seed treatment,thereby improving seed viability and ensuring the controlled release of nanoagrochemical active ingredients However,the applications of nanoagrochemicals to plants in the field raise concerns about nanomaterial safety,exposure levels,and toxicological implications to the environment and human *** the present comprehensive review,the development,scope,challenges,and risk assessments of nanoagrochemicals on seed treatment are ***,the implementation obstacles for nanoagrochemicals use in seed treatments,their commercialization potential,and the need for policy regulations to assess possible risks are also *** on our knowledge,this is the first time that we have presented legendary literature to readers in order to help them gain a deeper understanding of upcoming nanotechnologies that may enable the development of future generation seed treatment agrochemical formulations,their scope,and potential risks associated with seed treatment.

关键词： Agro seeds Environmental seed stressors Nanoagrochemicals Toxicological implications Risk regulations

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Formation of Calcium Carbonate Polymorphs Induced by Living Microalgae

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Journal of Biomaterials and Nanobiotechnology 2012年第4期3卷 413-420页

作者： Giulia Santomauro Johannes Baier Wanjing Huang Stefan Pezold joachim bill Institute for Materials Science University of Stuttgart Stuttgart Germany

Calcium carbonate (CaCO3) occurs in the three polymorphs calcite, aragonite and vaterite. The formation of these crystals in inorganic solutions is influenced by parameters like pH, temperature or impurities. Living freshwater microalgae can also induce the formation of CaCO3 when they live in a suitable environment containing saturated amounts of Ca2+. Through this biologically induced biomineralization only the formation of the polymorph calcite has been reported yet. We investigated the precipitates which have been formed in solutions containing the freshwater microalgae Scenedesmus obliquus and different zinc amounts (0, 3.27 and 6.53 mg Zn2+/l) by XRD and SEM. As references precipitates from the same solutions but without algae were investigated. We could show that the presence of living microalgae has a great influence on the precipitation of calcium carbonate crystals. In algae-containing media without or with a low zinc amount always calcite and aragonite are formed. In the corresponding medium with 6.53 mg Zn2+/l pure aragonite crystals were built. In contrast, in the inorganic, algae-free solutions without zinc, pure calcite is precipitated. Both inorganic solutions with zinc show major calcite precipitation and weak aragonite precipitation. Thus the algae cells advance significantly the formation of aragonite, which is enhanced by the presence of zinc cations in the media. Possible mechanisms are discussed.

关键词： CaCO3 Polymorphs Biomineralization Zinc Microalgae XRD

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Biomineralization of Zinc-Phosphate-Based Nano Needles by Living Microalgae

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Journal of Biomaterials and Nanobiotechnology 2012年第3期3卷 362-370页

作者： Giulia Santomauro Vesna Srot Birgit Bussmann Peter A. van Aken Franz Brümmer Horst Strunk joachim bill Institute for Biology Depart- ment of Zoology University of Stuttgart Stuttgart Germany 4Institute for Materials Science Chair in Material Physics University of Stuttgart Stuttgart Germany. Institute for Materials Science Chair in Chemical Material Synthesis University of Stuttgart Stuttgart Germany Institute for Materials Science University of Stuttgart Stuttgart Germany Stuttgart Center for Electron Microscopy – StEM Max Planck Institute for Intelligent Systems Stuttgart Germany Stuttgart Center for Electron Microscopy–StEM Max Planck Institute for Intelligent Systems Stuttgart Germany

Up to now, chemical synthesis routes only provide restricted opportunities for the formation of structured nano particles. In contrast, living microorganisms generate nano materials of well defined shapes by the precise control of biomineralization. Here we reveal new principles for the generation of functional nano materials through the process of biomineralization. We used the detoxification mechanism of the unicellular alga Scenedesmus obliquus to generate a techno logically interesting zinc-phosphate-based nano material. The algae were incubated in media with a sublethal zinc concentration (6.53 mg Zn dm-3) for 4 weeks. Using BF-and ADF-STEM imaging combined with analytical XEDS we could show that nano needles containing phosphorus and zinc were formed inside the living cells. Further more, the cells incubated with zinc show a strong fluorescence. Our findings indicate that the algae used polyphosphate bodies for detoxification of the zinc ions, leading to the generation of intracellular zinc-phosphate-based nano needles. Beside the technological application of this material, the fluorescent cells can be used for labeling of e.g. biological probes. This new experimental protocol for the production of an inorganic functional material can be applied also for other substances.

关键词： Nano Needles Biomineralization Zinc Phosphate Microalgae Fluorescence

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Formation of Calcium Carbonate Polymorphs Induced by Living Microalgae

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Journal of Biomaterials and Nanobiotechnology（生物材料与纳米技术） 2012年第4期

作者： Giulia Santomauro Johannes Baier Wanjing Huang Stefan Pezold joachim bill

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