Sum Rule for Lattice Vibrations in Ionic Crystals

1959 ◽  
Vol 113 (1) ◽  
pp. 43-44 ◽  
Author(s):  
R. Brout
Keyword(s):  
Lattice Vibrations ◽  
Ionic Crystals ◽  
Sum Rule

Lattice Vibrations and Optical Waves in Ionic Crystals

Nature ◽  
1951 ◽  
Vol 167 (4254) ◽  
pp. 779-780 ◽  
Author(s):  
KUN HUANG
Keyword(s):  
Lattice Vibrations ◽  
Ionic Crystals ◽  
Optical Waves

scholarly journals Energy distribution and stability of electrons in electric fields

1947 ◽  
Vol 188 (1015) ◽  
pp. 532-541 ◽  
Keyword(s):  
External Field ◽  
Energy Distribution ◽  
Electric Current ◽  
Electric Fields ◽  
Stationary State ◽  
Usual Method ◽  
Lattice Vibrations ◽  
Ionic Crystals ◽  
Free Electrons ◽  
Stationary Conditions

The behaviour of free electrons in ionic crystals in the presence of an external field is studied. It is shown that the usual method of calculating the electric current is incorrect. The correct solution shows that—on the usual assumption that electrons are scattered by the lattice vibrations only—a stationary state is impossible. Stationary conditions can probably be obtained by considering collisions between electrons as well. For very small electron density, however, these latter collisions are negligible. It is shown that in this case the possibility of reaching stationary conditions depends on the behaviour of electrons whose energy is large enough to ionize or excite ions of the lattice.

scholarly journals Theory of electrical breakdown in ionic crystals. II

1939 ◽  
Vol 172 (948) ◽  
pp. 94-106 ◽  
Keyword(s):  
Kinetic Energy ◽  
Field Strength ◽  
External Field ◽  
Thermal Equilibrium ◽  
Ionic Crystal ◽  
Electrical Breakdown ◽  
The Other ◽  
Lattice Vibrations ◽  
Ionic Crystals ◽  
Electrical Fields

Recently a theory of electrical breakdown in solids has been developed (Fröhlich 1937). This theory is based on the idea that electrical breakdown is a phenomenon due to the acceleration of electrons, as has been suggested by von Hippel (1935) and others. The critical field strength at which the breakdown occurs has been calculated in the following way: In strong external electrical fields, there are always some electrons in the conduction levels of an ionic crystal. These electrons, which are not in thermal equilibrium with the lattice, may be brought into these levels by cold emission or by some similar “pulling out” mechanism. Such an electron will make collisions with the lattice vibrations and thus lose per second a certain energy B ( E ), which depends upon its kinetic energy E . On the other hand, it will gain per second an energy A ( E, F ) from the external field F . Now it has been shown in I that B decreases but that A increases with increasing energy E . Thus there exists always an energy E' for which A = B . An electron with energy E less than E' will, on the average over several collisions, lose energy, whereas an electron with E greater than E' will gain more and more energy.

Sign in / Sign up

Export Citation Format

Share Document