Vacuum and solid-state thermionic emission have long been proposed as a means of converting heat or solar energy directly into electrical power. However, low work function materials must be developed before a reasonably efficient power generation device can be realized. In this work, thermionic emission energy distributions were measured for four samples including a single-crystal tungsten (100) sample, a pristine CNT mat, and two potassium-intercalated CNT mats. One of the potassium-intercalated CNT mats was composed largely of randomly oriented CNTs while the other CNT sample was grown in templated anodized alumina to align the growth pattern. Thermionic emission data obtained from the tungsten sample validated the experimental apparatus and method. The pristine CNT mat exhibited an emission distribution with a work function of 4.7 eV, while the potassium-intercalated samples exhibited work functions of approximately 3.1 and 3.4 eV for the randomly oriented and the templated meshes, respectively. The differences in the measured work function values for intercalated samples may be due to emitter tip differences. Both intercalated CNT samples showed some degradation after cooling from 510°C and reheating to the same temperature.

This content is only available via PDF.
You do not currently have access to this content.