Nano- Nanocrystalline” materials

H.E. Schaefer, H. Kisker, H. Kronmiiller, and R. Wiirschum, Magnetic Properties of Nanocrystalline Nickel, Nano structural Materials, Vol.l, 1992, pp.523-529. 

This article focuses on a specific class of such novel nano-scaled materials, nanocrystalline Ti02, and its photocatalytic properties. The title of this article encompasses three main terms ( (photo)catalysis, nanocrystalline, and Ti02 ) which, individually, stand for very important areas of scientific research and of, perhaps even more important, technological applications. Their synergistic combination, as... 

We expect particularly interesting phenomena in the nanosize range, when the distance between the two interfaces (e.g. grain boundaries in nanocrystalline material) is of the order of magnitude of the Debye length or smaller. If we ignore structmal effects just mentioned (see however Fig. 5.108, page 261) we expect the thermodynamic profiles shown in Fig. 5.82. Nano-size effects will be considered explicitly in Example c. 

Films of materials deposited at or near room temperature (and in this respect 100°C is considered to be near room temperature) tend to have a small crystal size. This is not surprising since high temperatures are normally required to impart sufficient mobility to a freshly deposited species in order for recrystallization to occur. This small crystal size, which at one time was almost universally considered to be a disadvantage, is increasingly considered to be an advantage as interest in nanocrystalline and nanoparticle materials grows. The term nano crystalline usually refers to materials with a crystal size from a nanometer up to hundreds of nanometers (at this upper limit, the term microcrystalline starts to take over). 

Biomimetic nanocrystalline apatite coatings were deposited on titanium substrates by matrix-assisted pulsed laser evaporation (MAPLE), a technique with potential application in tissue engineering (Visan et al., 2014 Caricato etal., 2014). The targets were prepared from nano-sized, poorly crystalline apatite powders, analogous in composition to mineral bone. For the deposition of thin films, a KrF excimer laser source was used (A = 248 nm,rFWHM < 25 ns). Analyses of the deposited films showed that the structural and chemical nature of the nanocrystalline precursor apatite was preserved. Hence, MAPLE may be a suitable technique for the congruent transfer of a delicate material such as nanohydroxyapatite. 

A new nanocrystaUine Ga—Al—Zn complex-oxide (designated here as nano-GAZ) has been synthesized by a hydrothermal method, with uniform nanocrystalline particles of size around 5-lOnm and very uniform 3.8nm mesopores [123]. This new material was designed for the elimination of N-containing polycyclic aromatic compounds (NPACs) present in diesel-engine emissions, which are known to be carcinogenic and need now to be removed. For instance, the concentration of 1-nitropyrene, which is the most abundant NPAC in diesel emission extracts, is... 

Jamnik, ]., and Maier, J. (2003]. Nanocrystallinity effects in lithium battery materials Aspects of nano-ionics. Part IV. Phys. Chem. Chem. Phys., 5(23] pp. 5215-5220. 

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