Roesch, Louis C. (1963) The influence of temperature and preferred orientation on Hall coefficient and resistivity of pure titanium. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:10032012-143956761
An experimental apparatus capable of measuring voltages in the microvolt region with an accuracy of ± 5.10^(-9) volts is used to determine the temperature variation of resistivity and Hall coefficient of three specimens of iodide titanium. These specimens are of comparable purity (room temperature to liquid helium temperature resistance ratio near 30) and possess a high degree of preferred orientation. The measurements are made at temperatures between 4.2 and 300°K.
The Hall coefficient is found to depend strongly on temperature and crystalline texture. At room temperature it has a value of -1.8 x 10^(-11) m^3/coulomb in two specimens, whereas in the third it equals + 1.2.10^(-11) m^3/coulomb. Several factors including impurities, changes in the scattering mechanism, size effects, crystallographic anisotropy, which could account for the observed differences, are discussed and it is proposed that crystallographic orientation is the most influential factor. From the measured data and a phenomenological theory of the Hall effect developed in the case of single crystals, values of the components of the galvanomagnetic tensor, which replaces the scalar Hall coefficient of isotropic media, are calculated and discussed in connection with a possible model of the Fermi surface of titanium.
Only tentative conclusions can be drawn from the present experimental investigation and no definite explanation can be offered for the difference in the signs of the two principal galvanomagnetic coefficients. Additional measurements on single crystals and extension of these measurements to higher temperatures, as well as investigations of other properties of titanium (topological measurements in particular) must be made before a more comprehensive band model of titanium metal can be established.
|Item Type:||Thesis (Dissertation (Ph.D.))|
|Subject Keywords:||Mechanical Engineering|
|Degree Grantor:||California Institute of Technology|
|Division:||Engineering and Applied Science|
|Major Option:||Mechanical Engineering|
|Thesis Availability:||Public (worldwide access)|
|Defense Date:||1 January 1963|
|Default Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Benjamin Perez|
|Deposited On:||04 Oct 2012 18:26|
|Last Modified:||26 Dec 2012 04:45|
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