Transport properties Hall effect

We shall briefly discuss the electrical properties of the metal oxides. Thermal conductivity, electrical conductivity, the Seebeck effect, and the Hall effect are some of the electron transport properties of solids that characterize the nature of the charge carriers. On the basis of electrical properties, the solid materials may be classified into metals, semiconductors, and insulators as shown in Figure 2.1. The range of electronic structures of oxides is very wide and hence they can be classified into two categories, nontransition metal oxides and transition metal oxides. In nontransition metal oxides, the cation valence orbitals are of s or p type, whereas the cation valence orbitals are of d type in transition metal oxides. A useful starting point in describing the structures of the metal oxides is the ionic model.5 Ionic crystals are formed between highly electropositive... 

In crystalline semiconductors, the most common technique for the measurement of carrier mobility involves the Hall effect. However, in noncrystalline materials, experimental data are both fragmentary and anomalous (see, for example. Ref. [5]). Measured HaU mobility is typically of the order of 10 - 10 cm A /s and is frequently found to exhibit an anomalous sign reversal with respect to other properties providing information concerning the dominant charge carrier. Thus, apart from some theoretical interest, the Hall effect measurements are of minimal value in the study of macroscopic transport in amorphous semiconductors. 

Special attention is paid to transport properties (resistance and Hall effect) because they are very sensitive to external parameters being the base for working mechanisms in many types of sensors and devices. The magnetic field and temperature dependences of resistance and Hall effect are considered in the framework of the percolation theory. Various types of magnetoresistances such as giant and anisotropic ones as well as their mechanisms are under discussion. 

The devices, based on variation of electronic transport properties (mainly, resistance and Hall effect) under action of an external magnetic field, are very popular now and their production is one of the most successful areas of the modern instrument-making industry. In this area, many types of micro... 

The final transport measurement to be considered is the Hall effect. This is the most intriguing transport property, but has been so difiicult to imderstand that it has not contributed much towards the elucidation of the conduction mechanisms. The reason is that the Hall effect is anomalous and has the opposite sign from that which is normally expected. Thus holes give a negative Hall voltage and... 

Before leaving the subject of the mechanism of metal-ion transport across membranes, a cautionary result and a by-product of these investigations might be reported. Hall has found that the antibiotic monamycin forms complexes in solution with K+, Rb+, and Cs+, but not with Na+ or Li+. However, it seems that their antibacterial action is due to their lytic effects on cell membranes rather than to any ion-transporting properties they may possess. The metal-ion selectivity of nonactin and valino-mycin has been put to use in the design of potassium-selective membrane electrodes. These contain the antibiotics as components of the membrane, and can be used to estimate K+ in the presence of Na+, for example in human serum. 

Seeger, K., W.D. Gill, T.C. Clarke, and G.B. Street. 1978. Conductivity and hall effect measurements in doped polyacetylene. Solid State Commun 28 (10) 873 (b) Kwak, J.F., T.C. Clarke, R.L. Greene, and G.B. Street. 1979. Transport properties of heavily ASF5 doped polyacetylene. Solid State Commun 31 (5) 355. 

The atomic disorder associated with the amorphous state leads to completely different transport properties from those encountered in the crystalline state. Experimental results of the electrical resistivity, the Hall effect, magnetoresistance, thermoelectric power and the occurrence of. superconductivity are discussed in section 8. The main emphasis is placed on the electrical resistivity. The occurrence of negative temperature coefficients of the resistivity is related to models based on the extended Ziman theory. In the low temperature regime the resistivity often shows a In T... 

This chapter reviews the available knowledge of the bulk magnetic and transport properties of the rare earth metals with a particular emphasis on the ways in which these macroscopic properties may be interpreted to improve our understanding of the fundamental microscopic interactions. The review comprises five basic components in section 2 we discuss the magnetization and susceptibility of these metals followed by their magnetic anisotropy in section 3 and magnetostriction in section 4. Section 5 considers the electrical resistivity, whilst section 6 deals with magnetoresistance and the Hall effect. 

The rare earth metals display a rich variety of transport phenomena, which we shall discuss in the remaining sections. Transport properties were last reviewed by Legvold (1972), who presented data for the resistivity, thermal conductivity and Seebeck coefficient of almost all the rare earth metals together with Hall effect results for the elements Gd-Er. Since 1972 little attention has been given to the thermal conductivity and Seebeck coefficient and, accordingly, we shall concentrate on the resistivity, magnetoresistivity and Hall effect measurements, with particular attentiM to recent studies. 

Among the normal-state transport properties of the high-temperature cuprate superconductors, the Hall effect remains one of the most difflcult to explain. In the majority of the cuprates, the Hall coefficient Jin falls monotonically with increasing temperature. The... 

In the next chapter (115), J.M. Fournier and E. Gratz have reviewed the transport properties of lanthanide/actinide compounds. These include the electrical resistivity, thermal conductivity, thermoelectric power, magnetoresistance and the Hall effect. As expected, most of this review deals with the electrical resistivity because of the preponderance of data oa this property, relative to the other four. Throughout this chapter the authors attempt to use the available information on the transport properties to help improve our understanding of the differences and similarities of... 

Hall effect is the most widely used technique to measure the transport properties and assess the quality of epitaxial layers. For semiconductor materials, it yields the carrier concentration, its type, and carrier mobility. More specifically, experimental data on Hall measurements over a wide temperature range (4.2-300 K) provide quantitative information on impurities, imperfections, uniformity, scattering mechanisms, and so on. The Hall coefficient and resistivity (p) are experimentally determined and then related to the electrical parameters through (for n-type conduction) ffn = fulne and M-h = f n/P. where n is the free electron concentration, e is the unit electronic charge, Ph is the Hall mobility, and Th is the Hall scattering factor that depends on the particular scattering mechanism. The drift mobility is the average velocity per unit electric field in the limit of zero electric field and is related to the Hall mobility... 

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