Electrical breakdown paths in the lithium halide crystals form star patterns consisting of 12 paths of the type [$\mathrm{xxy}$] where $x>~y$. The paths lie within the acute sectors of the (110) planes bounded by the directions [110] and [111]. The star assumes the [110] orientation at low temperatures and tends to approach the [111] position as the temperature increases. Under overvoltage conditions, complex [$\mathrm{xxy}$] patterns are obtained; they show abrupt changes in orientation as the paths proceed through the crystal, but follow a definite sequence of directions. It is shown that, although the breakdown paths seem to mark those directions in which electrons can be accelerated most rapidly to the ionization potential of the lattice, the star paths apparently do not follow simply from an electron wave interaction with the lattice or from a statistical competition between breakdown in the [110] and [111] directions.

• Received 22 January 1948

DOI:https://doi.org/10.1103/PhysRev.73.1194