Some Special Applications

We have learned from the preceding chapters that the chemical and physical state of a Mossbauer atom in any kind of solid material can be characterized by way of the hyperfine interactions which manifest themselves in the Mossbauer spectrum by the isomer shift and, where relevant, electric quadrupole and/or magnetic dipole splitting of the resonance lines. On the basis of all the parameters obtainable from a Mossbauer spectrum, it is, in most cases, possible to identify unambiguously one or more chemical species of a given Mossbauer atom occurring in the same material. This - usually called phase analysis by Mossbauer spectroscopy - is nondestructive and widely used in various kinds of physicochemical smdies, for example, the studies of 

Phase transitions Spin and magnetic transitions Dynamic solid-state phenomena Solid-state reactions (e.g., thermolysis, radiolysis) 

Problems of metallurgy Surface phenomena Catalysis Corrosion 

After effects of nuclear transformations in solids Biological systems Minerals 

Because of the limited scope of this monograph, it is impossible to give a rigorous account of the work that has been accomplished in these fields. By the end of 2008, about 60,000 publications dealing with the use of Mossbauer spectroscopy had been documented in the literature. Excellent review articles on Mossbauer Spectroscopy Applied to Inorganic Chemistry (3 volumes) are given in [30, 34-35] in Chap. 1 and on Mossbauer Spectroscopy Applied to Magnetism and Materials Science (2 volumes) in [38, 40] in Chap. 1. 

---

Some heat pumps, called thermoelectric heat pumps, employ the Peltier effect, using thermocouples. The Peltier effect refers to the evolution or absorption of heat produced by an electric current passing across junctions of two suitable, dissimilar metals, alloys, or semiconductors. Presently, thermoelectric heat pumps are used only in some specialized applications. They have not been developed to a point to make them practical for general heating and cooling of buildings. 

Hub bores are usually straight, although for some special applications taper bores are sometimes specified. For smaller diameters, bores are designed for clearance fits and a set screw is used over the key. The major advantage of a clearance fit is that hubs can be easily assembled and disassembled. For larger diameters, the bores are designed for interference fits without setscrews. For rapid-reversing applications, interference fits are required. 

With increasing purity of aluminium, greater resistance to corrosion is developed. On high-purity materials, however, any pits which develop are likely to be deeper though fewer in number than those formed in more impure metal. In some special applications, notably in contact with ammonia solutions or pure water at elevated temperatures and pressures, the iron and silicon present in commercial-purity metal are beneficial and retard corrosion. Up to about 5% magnesium improves the corrosion resistance to sea-water. 

Regarding the specific energy, i.e., the electric energy per mass, a major distinction can be made between today s aqueous and nonaqueous battery systems [15]. Apart from batteries for some special applications, there are... 

---