Materials science electrical resistivity

One of the most exciting developments in materials science in recent years involves mixed oxides containing rare earth metals. Some of these compounds are superconductors, as described in our Chemistry and Technology Box. Below a certain temperature, a superconductor can carry an immense electrical current without losses from resistance. Before 1986, it was thought that this property was limited to a few metals at temperatures below 25 K. Then it was found that a mixed oxide of lanthanum, barium, and copper showed superconductivity at around 30 K, and since then the temperature threshold for superconductivity has been advanced to 135 K. 

The microsystems may also serve potential applications in material science and in the growing field of nanotechnology. Microhotplates can be used for material processing, and, at the same time, for the monitoring of material properties such as the electrical resistance [10]. Moreover, the microsystems can be applied to determine thermal properties of new materials such as the melting point, especially when only small quantities of material are available [145], so that monolithic microhotplate-based devices are not only powerful sensor systems for a broad range of applications, but also new research tools for sensor science and nanotechnology. 

Light is electromagnetic radiation, and electricity and magnetism, along with optics, are extremely important in science, engineering, and industry. Smart materials and adaptive systems that respond to some aspect of electricity and magnetism are in high demand. A circuit based on electrical resistance was mentioned earlier in the chapter. 

A major scientific breakthrough in the area of material science involving copper occurred in late 1986 and early 1987 the discovery of the so-called high-temperature cuprate superconductors (see Superconductivity). These copper-oxide containing materials hold the record for the highest transition temperature (Tc, the temperature at which all resistance to electricity is lost), currently 133 K, which is sigiuficant... 

FIGURE 1.23 Communicating with a conducting polymer PPy/Cl in solution (a) cyclic voltammetry—a plot of current flow versus the electrical (potential) stimulus applied (b) the electrochemical quartz crystal mircobalance readout—mass polymer versus electrical (potential) stimulus applied (c) the resistometry readout—resistance of the polymer versus the electrical (potential) stimulus applied. (Printed with permission from Materials Science Forum, Vol. 189-190, Characterization of conducting polymer-solution interfacial processes using a new electrochemical method, A. Talaie, G. G. Wallace, 1995, p. 188, Trans Tech Publications, Switzerland.)... 

Superconductivity is a phenomenon of exactly zero electrical resistance occurring in certain materials when cooled below some critical temperatures Tc- Superconductivity attracts attention of physicists and engineers because of prospects of its applications in industry. The matter is of research applications, defense and space, instruments for science and medicine, machine tools, materials processing, transportation, and energy. 

It is general experience in materials science that alloy can exhibit qualities that are unobtainable with parent metals. This is particularly true for electrodeposited alloys, mainly due to formation of metastable phases and intermediate layers. Some important properties of materials, such as hardness, ductility, tensile strength. Young s modulus, corrosion resistance, solderability, wear resistance, antifriction service, etc., may be enhanced. At the same time, some properties that are not characteristic for parent metals, such as high magnetic permeability, other magnetic and electrical properties, amorphous structure, etc., can also be obtained. In some cases, alloy coatings may be more suitable for subsequent electroplate overlayers and conversion chemical treatments [1],... 

Kaddour, A.S., Al-Salehi, F.A.R., Al-Hassani, S.T.S., Hinton, M.J., 1994. Electrical resistance measurement technique for detecting failure in CFRP materials at high strain rates. Composites Science and Technology 51, 377—385. 

Barometry measures a broad variety of pressures using an equally broad variety of measurement techniques, including liquid column methods, elastic element methods, and electrical sensors. Electrical sensors include resistance strain gauges, capacitances, piezoresistive instruments, and piezoelectric devices. The technologies range from those developed by French mathematician Blaise Pascal, Greek mathematician Archimedes, and Torricelli to early twenty-first century MEMS sensors and those used to conduct nanoscale materials science. 

One of the most important qualities that a medium must possess to be useful in electrochemical science is an ability to support current flow. Electrochemical reactions always produce or consume ions at electrodes, and the electrolyte provides the pathway for ions to flow between and among electrodes in the cell to maintain charge balance. The ability of a phase to support current flow by motion of charged particles (ions in an electrolyte) when an electric field exists within the phase is called the conductivity, usually abbreviated as K. Conductivity has units of ohm cm sometimes called siemens cm Conductivity is a property of a phase or material for an electrolyte phase of uniform cross-section of area A and length L, whose electrical resistance is R, the ionic conductivity is given by K = (1IR)(L/A). Conductivity is the inverse of resistivity, usually abbreviated as p, with units of ohm cm. Representative values for ionic conductivity for some commonly used solvent-electrolyte combinations in electrochemistry are presented in Table 3.1. 

Chung, D.D.L. (2003) Damage in cement-based materials, studied by electrical resistance measurement, Materials, Science and Engineering, R52(l) pp. 1—40. 

Mikrajuddin, A., Shi, F. G., Kim, H. K., and Okuyama, K. 1999. Size-dependent electrical constriction resistance for contacts of arbitrary size from Sharvin to Holm limits. Materials Science in Semiconductor Processing 2 321-327. 

Electric resistance, R, of either electron or ion (or mixed) conductive material is an important characteristic in electrochemical science and engineering and is defined... 

The Industrial Revolution would introduce into the field of ceramics radical and ceaseless changes during the entire 20 centuiy, in the modes of preparation, manufacture, decorations, coloring and firing and especially with the use of the electric power, advances in chemistiy and material sciences. New applications that take advantage of the resistance of the material to thermal shocks (insulators, heat shields, etc.) as well as the inalterability and harmlessness of bioceramics would be implemented. 

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