Nano metal fluorides: small particles with great properties
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Nano metal fluorides: small particles with great properties Erhard Kemnitz1,2 · Stefan Mahn1,2 · Thoralf Krahl1,2 Received: 23 April 2020 / Accepted: 24 June 2020 © The Author(s) 2020
Abstract The recently developed fluorolytic sol–gel route to metal fluorides opens a very broad range of both scientific and technical applications of the accessible high surface area metal fluorides, many of which have already been applied or tested. Specific chemical properties such as high Lewis acidity and physical properties such as high surface area, mesoporosity and nanosize as well as the possibility to apply metal fluorides on surfaces via a non-aqueous sol make the fluorolytic synthesis route a very versatile one. The scope of its scientific and technical use and the state of the art are presented. Keywords Non-aqueous fluorolytic sol–gel synthesis · Nanoscopic metal fluorides · Mechanism · Applications
Introduction Although nanomaterials have played a role in science and technology for many years, it was only in the 1990s that a consensus was established among the scientific and industrial community that nanoscience will start a new kind of industrial and technological revolution. Not surprisingly, a drastic jump in the number of publications dealing in general with nanomaterials can be observed.
A short excursion into the nano world Nanotechnology is science, engineering and technology conducted at nanoscale, which is about 1–100 nm. The ideas and concepts behind nanoscience and nanotechnology started with a talk given by the physicist Richard Feynman (1918–1988) at an American Physical Society meeting at the California Institute of Technology (CalTech) on December 29, 1959. The title of his talk was “There’s Plenty of Room at the Bottom” and this was long before the term nanotechnology was used. More than a decade later, Professor Norio Taniguchi created the term nanotechnology. It is hard to imagine how small nano really is. One * Erhard Kemnitz [email protected]‑berlin.de 1
Institut für Chemie, Humboldt-Universität zu Berlin, Brook‑Taylor‑Str. 2, 12489 Berlin, Germany
Nanofluor GmbH, Rudower Chaussee 29, 12489 Berlin, Germany
2
nanometre is a billionth of a metre, 10–9 m. A few examples will illustrate this: • • • • •
The diameter of a hair is about 50 µm = 50,000 nm. A bacterium is about 100 nm. A virus is about 10 nm. A protein is about 1 nm. A molecule is about 0.1 nm.
Thus, nanoscience and nanotechnology involve the ability to see and to control individual atoms and molecules. But something as small as an atom is impossible to see with the naked eye. In fact, it is impossible to see it with microscopes typically used in school education. It was not until 1981, with the development of the scanning tunneling microscope (STM), that one could “see” individual atoms, and shortly after that the atomic force microscope (AFM), that the age of nanotechnology was born. Because of making materials smaller and smaller up to the nanoscale, their chemical and physical properties may change
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