Cerium boride

CeB6 is a cathode material with high electron emissivity due to its low power function, which is more resistant to carbon pollution and has a longer life than lanthanum boride cathode. It is widely used in electron microscope, microwave tube, electron beam etching, electron beam welding, X-ray tube and free electron laser medium fields. At present, cerium hexaboride crystals have been successfully used in the desktop scanning electron microscope and become excellent and stable filament materials. Cerium hexaboride [1] (CeB6, also known as cerium boride, CeBix, CeBix, sometimes written CeB) is an inorganic compound. Cerium hexaboride (CeB6) has a CsCl structure (belonging to a simple cubic crystal system, whose crystal structure is shown in Figure 1, and the large ball represents the Ce element). The difference is that the B6 octahedral cluster occupies the position of Cl and the Ce occupies the position of Cs. It is a refractory ceramic material with a low work function which makes it one of the known cathode materials with high electron emissivity, and it is also very stable in vacuum. Cerium hexaboride normally operates at 1450°C. Cerium hexaboride, like lanthanum hexaboride, evaporates slowly while working at the cathode. CeB6 cathode can maintain its shape for a longer period of time at 1850 K operating temperature, so its life is longer. At the same time, because the evaporation rate is about 30% slower than lanthanum boride, cerium boride’s hot cathode coating is more difficult to remove than lanthanum boride.

Application
Cerium hexaboride is mainly used as coating for the hot cathode, or the hot cathode is directly composed of cerium hexaboride crystal. Cerium hexaboride (CeB6) and lanthanum hexaboride (LaB6) are often used as high current thermal cathodic coatings. Hexaboride has a low work function, about 2.5 eV, and has some tolerance to cathode pollution. Cerium boride cathodes have a lower evaporation rate than lanthanum boride at 1700 K, but they become uniform at 1850 K and even higher above this temperature. Cerium boride cathode has a 50% longer life than lanthanum boride due to its higher carbon pollution resistance. The boride cathode is ten times brighter and lasts ten to fifteen times longer than the tungsten cathode. Some laboratory tests have shown that CeB6 is more resistant to the negative effects of carbon pollution than LaB6. They are commonly used in electron microscopes, microwave tubes, electron beam etching, electron beam welding, X-ray tubes, and free electron lasers.