Defects and Impurities
Real crystals feature defects or irregularities in the ideal arrangements described above and it is these defects that critically determine many of the electrical and mechanical properties of real materials. When one atom substitutes for one of the principal atomic components within the crystal structure, alteration in the electrical and thermal properties of the material may ensue. Impurities may also manifest as spin impurities in certain materials. Research on magnetic impurities demonstrates that substantial alteration of certain properties such as specific heat may be affected by small concentrations of an impurity, as for example impurities in semiconducting ferromagnetic alloys may lead to different properties as first predicted in the late 1960s. Dislocations in the crystal lattice allow shear at lower stress than that needed for a perfect crystal structure.
Read more about this topic: Crystal Structure
Famous quotes containing the words defects and, defects and/or impurities:
“All conservatives are such from personal defects. They have been effeminated by position or nature, born halt and blind, through luxury of their parents, and can only, like invalids, act on the defensive. But strong natures, backwoodsmen, New Hampshire giants, Napoleons, Burkes, Broughams, Websters, Kossuths, are inevitable patriots, until their life ebbs, and their defects and gout, palsy and money, warp them.”
—Ralph Waldo Emerson (1803–1882)
“The East is the hearthside of America. Like any home, therefore, it has the defects of its virtues. Because it is a long-lived-in house, it bursts its seams, is inconvenient, needs constant refurbishing. And some of the family resources have been spent. To attain the privacy that grown-up people find so desirable, Easterners live a harder life than people elsewhere. Today it is we and not the frontiersman who must be rugged to survive.”
—Phyllis McGinley (1905–1978)
“In order for the wheel to turn, for life to be lived, impurities are needed, and the impurities of impurities in the soil, too, as is known, if it is to be fertile. Dissension, diversity, the grain of salt and mustard are needed: Fascism does not want them, forbids them, and that’s why you’re not a Fascist; it wants everybody to be the same, and you are not. But immaculate virtue does not exist either, or if it exists it is detestable.”
—Primo Levi (1919–1987)