Solid-state chemistry defined

The following defines particle ranges that we usualfy encounter in solid state chemistry ... 

As a starting point in the description of the solid intermetallic phases it is useful to recall that their identification and classification requires information about their chemical composition and structure. To be consistent with other fields of descriptive chemistry, this information should be included in specific chemical and structural formulae built up according to well-defined rules. This task, however, in the specific domain of the intermetallic phases, or more generally in the area of solid-state chemistry, is much more complicated than for other chemical compounds. This complexity is related both to the chemical characteristics (formation of variable composition phases) and to the structural properties, since the intermetallic compounds are generally non-molecular in nature, while the conventional chemical symbolism has been mainly developed for the representation of molecular units. As a consequence there is no complete, or generally accepted, method of representing the formulae of intermetallic compounds. 

Almost all the crystalline materials discussed earlier involve only one molecular species. The ramifications for chemical reactions are thereby limited to intramolecular and homomolecular intermolecular reactions. Clearly the scope of solid-state chemistry would be vastly increased if it were possible to incorporate any desired foreign molecule into the crystal of a given substance. Unfortunately, the mutual solubilities of most pairs of molecules in the solid are severely limited (6), and few well-defined solid solutions or mixed crystals have been studied. Such one-phase systems are characterized by a variable composition and by a more or less random occupation of the crystallographic sites by the two components, and are generally based on the crystal structure of one component (or of both, if they are isomorphous). 

At present, the most widely used definition of fractional ionic character in solid state chemistry is that of Phillips (1970), based on a spectroscopic approach. Phillips defined fractional ionic character as... 

In 1975, Cohen introduced the concept of the reaction cavity in solid state chemistry (2. The reaction cavity was defined as the space occupied by the reacting species and bounded by the surrounding, stationary molecules. Cohen viewed the topochemical principle as resulting from the preference for chemical processes to occur with minimal distortion of the reaction cavity, either in the formation of voids within it or extrusions from it (Figure 1). 

We are accustomed to speak of both a molecular chemistry and of a solid-state chemistry. Molecules are understood to be finite and concrete particles in all states of aggregation, consisting of a defined number of atoms, whereas the so-called solid is characterized by its - in atomic dimensions - infinite extension and it normally does not... 

With the development of diffraction techniques, an increasing number of crystal structures has become available. Thus the modes in which various functional groups interact with each other, and the role of these interactions in defining molecular arrangements, are becoming clearer. We now outline some of the properties of molecular architecture in the crystal that can be of value in solid-state chemistry. 

We are ourselves engaged in such a synthetic endeavour and we report here on some typical structural problems encountered in coordination and solid state chemistry of these low-dimensional materials. Indeed, the properties of these compounds are very sensitive to order and disorder, purity and defects and chemical modifications such as doping, insertion or intercalation their understanding needs careful structural characterization. Extended X-Ray Absorption Fine Structures (EXAFS) spectroscopy possesses some unique features which can contribute to the solution of well-defined cases to set up correlations between structural and physical properties. 

We can now define a phosphor as a solid state material which emits in the visible part of the electromagnetic spectrum (this is not strictly true since some phosphors emit ultraviolet light and some emit infira-red light). Let us now examine the configurational aspects of phosphors and then the energy transfer mechanisms which occur once the phosphor is excited. Later In the following chapter, we will examine the solid state chemistry of phosphors. 

Our next step is define the conditions in which we would expect to obtain a phosphor having a luminescent process of high quantum efficiency. We then will be able to discuss how to design a phosphor, the experimental parameters involved, and the solid state chemistry of these defect-controlled materials. 

There is a close relationship between the solution-based syntheses of the naked clusters, as described above, and pure solid state chemistry. This relationship stems from the fact that homonuclear bonding and discrete clusters in many cases also exist within alloys of the type used in the synthesis of Zintl ions in solution. Indeed, such alloys are often to be regarded as well-defined intermetallic compounds. ... 

Transition metal clusters, however, need still to be tested in the engineering of crystalline materials. Crystal engineering has been defined as the capacity to make crystals with a purpose. In transition metal cluster chemistry this purpose is that of utilizing the distinct characteristics mentioned above to construct crystals that can function as the result of the inter-cluster interactions. To do this the experimentalist needs to conceive ways of directing the crystal-building process towards given architectures, i. e. needs to learn how to make non-covalent crystal synthesis. Clearly, the growth and success of a solid-state chemistry of transition metal clusters depends crucially on a close interaction between synthesis, theory, solid state characterization, and evaluation of properties. 

Nanoscience is the natural progression of science exploring the nature of matter between atoms and molecules (defined by quantum mechanics) and condensed matter (defined by solid state chemistry/physics). Thus, one of the central questions in nanoscience is at what point in diminishing the size of a material does it begin to act more like an atom or molecule or, conversely, how many atoms (in a cluster) does it take to begin observing bulk-like (solid state) behavior ... 

Solid state chemistry has many facets, and one of the purposes of this treatise is to help define the field."... 

Over the last decades, the concept of bond-valence calculations has been widely applied in solid state chemistry for prediction of bond lengths, as well as for determination of coordination numbers in corresponding compoimds. Besides, this concept serves as a criterion to verify the reliability of structure determinations (Brown, 1978 Brown and Altermatt, 1985 Altermatt and Brown, 1987). According to their approach, the atomic valence of an atom, Vi, is defined as the sum of bond valences z>ij... 

Mossbauer spectroscopy in solid state chemistry under in situ conditions at high temperatures and at defined oxygen partial pressures have been made by Becker (2001) for order-disorder processes and their kinetics in nickel alu-minate spinel and magnetite. The study has also been carried out for heterogeneous solid olid and solid-gas reactions which relate to the formation of cobalt aluminate spinel and to redox processes in fayalite, Fe2Si04, respectively. The diffusion of the iron cations in Fc2Si04 has also been observed by means of Mossbauer spectroscopy. 

The dimensionless quantity called electronegativity is an important concept that is extremely useful both in inorganic and solid-state chemistry because it allows one to understand and explain qualitatively the molecular and crystal structure of various compounds. Basically, the electronegativity of a chemical element can be defined as the ability of an atom to gain electrons by contrast, electropositivity is the ability to capture electrons. 

Nernst, Walther (1864-1941 ) A German physical chemist, physicist, and inventor, Nernst discovered the Third Law of Thermodynamics—defining the chemical reactions affecting matter as temperatures drop toward absolute zero—for which he was awarded the 1920 Nobel Prize in Chemistry. He also invented an electric lamp, and developed an electric piano and a device using rare-earth filaments that significantly advanced infrared spectroscopy. He made numerous contributions to the specialized fields of electrochemistry, solid-state chemistry, and photochemistry. 

The first part of the book examines the crystal and electronic structure, stoichiometry and composition, redox properties, acid-base character, and cation valence states, as well as new approaches to the preparation of ordered TMO with extended structure of texturally defined systems. The second part compiles practical aspects of TMO applications in materials science, chemical sensing, analytical chemistry, solid-state chemistry, microelectronics, nanotechnology, environmental decontamination, and fuel cells. The book examines many types of reactions — such as dehydration, reduction, selective oxidations, olefin metathesis, VOC removal, photo- and electrocatalysis, and water splitting — to elucidate how chemical composition and optical, magnetic, and structural properties of oxides affect their surface reactivity in catalysis. 

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