Evidence of a Periodic Deviation from the Schottky Line. I

A periodic deviation from the Schottky line has been observed for tungsten and for tantalum. For fields less than 4 × ${10}^4$ volts ${\mathrm{cm}}^{-1\mathrm{}}$ the deviations are of the order of the experimental error. For fields greater than this the sign and magnitude of the peak deviations may be seen from the following series, the first number in each case being the value of $E^{\frac{1}{2}}$ in ${\mathrm{volt}}^{\mathrm{½}}$ ${\mathrm{cm}}^{-\mathrm{½}}$, and the second being the percent deviation from a least-squares reference line: 200, +0.03 (±0.01); 265, -0.07(±0.01); 365, +0.12(±0.01); 501, -0.11(±0.01). The data refer to a 1-mil tungsten wire at 1610°K. There is no appreciable effect of temperature upon the positions of the peaks along the $E^{\frac{1}{2}}$ axis. The magnitude of the deviations decreases with increasing temperature. The results with tantalum agree within experimental error with those for tungsten.