A thin film dispenser or micro-dispenser cathode can be generated using standard RF sputtering deposition technology. These films are compositionally modulated structures based on W and a multi-component Ba oxide. Annealing to temperatures from 900 to 1300 K results in Ba reduction, transport and diffusion across the emitter surface. A finite temperature range exists (<1200 K) where a uniform Re coating can be retained at the emitter surface. The metallic coating results in a nearly homogeneous work function based on emission characteristics. These films produce stable emission at higher temperatures (⩾1200 K) where the uniform Re coating is lost. Analysis of emission properties yield a work function of 2.2 eV and an apparent emission coefficient of 6 A⋅cm−2⋅K−2 after annealing to 1200 K. This high apparent emission coefficient yields a film suitable for milliwatt power generation applications. Microminiature Thermionic Converters (MTCs) are one potential application for these films.

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