Precipitation kinetics of superparamagnetic nickel and cobalt crystals in silicate glasses controlled by redox potential

采用氧化还原电位诱导沉淀法在硅酸盐玻璃中合成了高密度过渡金属钴和镍的胶体（>1E20 m-3）。本研究的最初重点是这些过程的动力学，以及对微观结构-性能关系的分析。由于沉淀金属相的纳米尺度，等离子体共振现象，特别是超顺磁行为可以从这些新型金属-玻璃复合材料中得到。为了定制材料的微观结构，必须控制所涉及的沉淀和结晶过程的动力学。初步研究表明，采用复合氧化还原反应制备纳米级微结构是可行的。因此，预计在本项目中，可以建立一种不同于通常使用的合成方案（如化学沉淀反应或水热合成）的磁性Co-和Ni-纳米颗粒的替代合成路线。如果纳米颗粒通过设想的沉淀路线建立，它们本质上嵌入在二氧化硅基体中，因此可以防止腐蚀（氧化），并且具有很高的潜力，例如信息存储应用。由于控制Ni和Co金属的溶解、降解和沉淀反应的因素尚未在文献中报道，因此该项目有望获得巨大的科学知识。这一科学的“新领域”是通过结合玻璃技术（在玻璃合成方面）和微观结构诊断（在纳米分析方面）的工作包来打破的，以获得对相关沉淀现象的基于知识的理解。计划中的项目可能会导致玻璃陶瓷化的推广，因为通过控制玻璃组分的氧化还原状态，有望合成硅酸盐网络中的纳米级金属相。标准的最先进的玻璃陶瓷技术依赖于通过成核剂的初步沉淀功能氧化物相的结晶，与之相反，这种方法是完全新颖的。可望为新型功能复合材料的开发提供基础。

Colloids of the transition metals cobalt and nickel of high number densities (>1E20 m-3) shall be synthesized via redox potential induced precipitation in silicate glasses. The initial focus of this research is constituted by the kinetics of these processes, as well as by the analysis of microstructure-property relationships. Due to the nanosized scale of the precipitated metal phases, plasmon resonance based phenomena and, in particular, super-paramagnetic behavior can be expected from these novel metal-glass composites. In order to tailor the materials' microstructure, the kinetics of the involved precipitation and crystallization processes have to be controlled. Preliminary work showed a feasible path to produce a nanoscaled microstructure via complex redox reactions, which has been adopted from enamel technology. Therefore, it is anticipated that within this project, an alternative synthesis route for the generation of magnetic Co- and Ni- nanoparticles can be established, which is different from the usually used synthesis schemes (e.g., chemical precipitation reac-tion or hydrothermal synthesis). If nanoparticles are established via the envisioned precipitation route, they are intrinsically embedded in the silica matrix, thus protected against corrosive attack (oxidation), and bear a high potential e.g. for information storage applications. A huge level of scientific knowledge gain is expected by the project, since the factors which control the involved solution, degradation and precipitation reactions of Ni and Co metals are not reported in literature yet. This scientific "new ground" is broken via a combination of work packages considering both glass technology - on the side of glass syntheses - and micro-structural diagnostics - on the side of nanoanalytics - to gain a knowledge-based understanding of the relevant precipitation phenomena. The planned project may lead to a generalization of the ceramization of glasses, since through a control of the redox state of glass constituents, nanoscaled metal phases in a silicate network are expected to be synthesized. In contrast to the standard state-of-the-art glass ceramming technologies that rely on the crystallization of functional oxide phases via the preliminary precipitation of nucleation agents, this approach is entirely novel. It can be expected that it can provide a basis for the development of novel functional composite materials.