Tammann and Hüttig temperatures are important for considerations in catalytic activity, segregation and sintering of solid materials.
[1]: 152 [3]: 502 The bulk compounds should be contrasted with nanoparticles which exhibit melting-point depression, meaning that they have significantly lower melting points than the bulk material, and correspondingly lower Tammann and Hüttig temperatures.
The threshold temperature for activation and diffusion of atoms at surfaces was studied by de:Gustav Franz Hüttig, physical chemist on the faculty of Graz University of Technology, who wrote in 1948 (translated from German):[6][7] In the solid state the atoms oscillate about their position in the lattice.
Such an atom may become dislodged and switch places with another one (exchange reaction) or it may, for a time, travel about aimlessly.
The relationship between this temperature and the melting point in degrees K is constant for all metals.
... On the basis of these elementary processes, sintering is analyzed in relation to the coefficient α which is the fraction of the melting point in degrees K ...
Loosening or release of adsorbed gasses occurs simultaneously.The Hüttig temperature for a given material is where
is the absolute temperature of the material's bulk melting point (usually specified in Kelvin units) and
[4][8][9][10] It is an approximation to the temperature necessary for mobility and diffusion of atoms, ions, and defects within a bulk crystal.
The following table gives an example Tammann and Hüttig temperatures calculated from each compound's melting point Tmp according to: