Tungsten Work Function

Working function means electrons escape from nucleus and the minimum energy needed to escape from surface of material. Generally speaking, electrons escape from metal need to add electron energy so as to make it active. 

For example, by sunlight, or photoelectric effect can make electrons escape, or activate electron by heating to let it escape from metal.

Working function of metal material is important property of electronic device. Tungsten working function is 4.55eV. In the early days, pure tungsten is the main raw material of electronic valve and electrode. Until 1913, scientists synthesized thorium and tungsten, new material tungsten thorium alloy came into being. Thus brought great changes to electronic valve and electrode.

Tungsten has good property of heat resistance and low vapor pressure, but its working function is normal. However, disperse ThO2 grain evenly on tungsten base can lower its electronic working function as well as inherit other good property of tungsten. Research shows that thorium tungsten alloy working function is 2.66eV, 40% lower than pure tungsten. It enhances emission efficiency of cathode tube. Thorium tungsten then replaces pure tungsten as the raw material of electrode.

Since thorium has radioactivity, recently scientists found rare earth tungsten alloy to replace thorium tungsten alloy. Transmitting tube with high power, microwave cathode tube and LED are all made of rare earth tungsten alloy. No matter it is thorium tungsten or rare earth tungsten alloy, both of them are consisted of tungsten.

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