Work Function of NiW Alloys for Use in Thermionic Energy Converters

Abstract

The material properties of electroplated NiW alloys with potential for use as emitters in thermionic energy converters were investigated. NiW alloy films with W content ranging from 11 to 25 at% were electroplated and the material properties of the alloy films including their surface morphologies, and crystallinities, were determined. The work functions of the NiW films were also evaluated using photoemission yield spectroscopy and were found to be independent of the W content. In addition, heat treatment up to 700°C in a vacuum chamber of a NiW film with 21.4 at% W content decreased the electron yield with increasing its work function.