Silicon carbide

Metal

Quantum mechanics

Engineering

Crystal (programming language)

Wide-bandgap semiconductor

Emissivity

Metallurgy

Materials science

Chromatography

Hot cathode

Cathode

Mineralogy

Carbide

Nuclear physics

Zirconium carbide

Single crystal

Computer science

Physical chemistry

Thermodynamics

Physics

Bismuth

Organic chemistry

Hafnium

Temperature measurement

Optics

Zirconium

Work function

Composite material

Analytical Chemistry (journal)

Crystallography

Chemistry

Programming language

Electron

Pyrometer

Thermal stability

Thermionic emission

Atmospheric temperature range

Optoelectronics

Electrical engineering

Engineering physics

IEEE Transactions on Electron Devices

Experiments to determine the feasibility of using transition metal carbides as stable thermionic cathodes at temperatures exceeding 2000 K are discussed. The primary emphasis here is electron emission and thermal stability properties of single crystals of ZrC. To obtain accurate emission versus temperature data, the spectral emissivity at 0.65 mu m of single-crystal ZrC specimens was measured in the temperature range 1200<T<2400 K. The spectral emissivity was determined to be isotropic with respect to crystalline orientation within the uncertainty of the measurements. Effective thermionic work function data are reported for three crystal faces of ZrC, within the temperature range 1800<T<2500 K. These results are plotted to show the temperature dependence of the work function. To date, the lowest work functions (3.2-3.4 eV) have been observed on the [210] plane. Volatility measurements on single-crystal specimens are reported. A figure of merit comparison with other cathode materials shows that if high current densities are desired and high temperatures are either mandated or are not a problem, ZrC would excel.<<ETX>>

Single-crystal zirconium carbide as a high-temperature thermionic cathode material