Nanotechnology and The Solid State

The higher-purity compound may undergo solid state reactions somewhat differently than those considered normal for the compound. If we reflect but a moment, we realize that this is what we might expect to occur as we obtain compounds (crystals) containing far fewer intrinsic defects. 

It is undoubtedly true that many of the descriptions of physical and solid state reaction mechanisms now existing in the literature are only partially correct. It seems that part of the fi-ontier of knowledge for Chemistry of The Solid State lies in measurement of physical and chemical properties of inorganic compounds as a function of purity. A case in point is that of the so-called Nano-Technology , the vanguard of research into chemical and ph Tsical properties of materials in the research community today. 

Current research defines nano-technology as the use of materials and systems whose structures and components exhibit novel and significantly changed properties when control is achieved at the atomic and/or molecular level. What this means is that when a given material is produced having particle sizes at fractions of a m (micron), it displays novel properties not found in the same material whose particles are larger than 1.0 nm (micron). Nanotechnology involves dimensions where atoms and molecules, and interactions between them, influence their chemical 

Consider that atoms have a size range of about 1-2 A. Most inorganic solids, with the exception of halides, sulfides (and other pnictides), are based upon the oxygen atom, i.e.- oxide = O , whose atomic radius does not change even when sulfates, phosphates and silicates are formed. Oxide has an atomic diameter of 1.5 A or 0.15 nm. = 0.00015 (om. Nanoparticles are clumps of 1000 to 10,000 atoms. The latter would be a particle of 0.15 (om. in diameter. They can be metal oxides, semiconductors, or metals with novel properties useful for electronic, optical, magnetic and/or catalytic uses. 

As we shall see in the next chapter, particles are formed first as embryos which are minute particles of the nano-particle class. These then grow into nuclei which then grow into particles. The science of particle growth has been a major source of our understanding of pcU ticles. As we have already shown, lattice defects, due to thermal effects, are the norm when a crystal grows to sizable proportions. However, when nano- 

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