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This line has been called the amphoteric line, [2] the metal-nonmetal line, [3] the metalloid line, [4] [5] the semimetal line, [6] or the staircase. [2] [n 1] While it has also been called the Zintl border [8] or the Zintl line [9] [10] these terms instead refer to a vertical line sometimes drawn between groups 13 and 14.
The Kirkendall effect is the motion of the interface between two metals that occurs due to the difference in diffusion rates of the metal atoms. The effect can be observed, for example, by placing insoluble markers at the interface between a pure metal and an alloy containing that metal, and heating to a temperature where atomic diffusion is reasonable for the given timescale; the boundary ...
Under most definitions the radii of isolated neutral atoms range between 30 and 300 pm (trillionths of a meter), or between 0.3 and 3 ångströms. Therefore, the radius of an atom is more than 10,000 times the radius of its nucleus (1–10 fm ), [ 2 ] and less than 1/1000 of the wavelength of visible light (400–700 nm ).
Schematic representations of a tilt boundary (top) and a twist boundary between two idealised grains. The simplest boundary is that of a tilt boundary where the rotation axis is parallel to the boundary plane. This boundary can be conceived as forming from a single, contiguous crystallite or grain which is gradually bent by some external force ...
The bonding between adjacent atoms in a chain is covalent, but there is evidence of a weak metallic interaction between the neighbouring atoms of different chains. [387] Tellurium is a semiconductor with an electrical conductivity of around 1.0 S•cm −1 [ 388 ] and a band gap of 0.32 to 0.38 eV. [ 389 ]
The small radius of the aluminium ion combined with its high charge make it a strongly polarizing species, prone to covalency. [77] Aluminium in pure form is a soft metal (MH 3.0) with low mechanical strength. [78] It has a close-packed structure (BCN 12) showing some evidence of partially directional bonding.
Ionic radius, r ion, is the radius of a monatomic ion in an ionic crystal structure. Although neither atoms nor ions have sharp boundaries, they are treated as if they were hard spheres with radii such that the sum of ionic radii of the cation and anion gives the distance between the ions in a crystal lattice.
From these equations it becomes clear that the boundary between boundary diffusion and lattice diffusion is heavily dependent on grain size. For systems with larger grains, the Nabarro-Herring lattice diffusion region of the deformation mechanism map will be larger than in maps with very small grains.