Study of TiO on the Voltage Holdoff Capacity of Cr/Mn-Doped AlO Ceramic in Vacuum.

With the development of vacuum electronic devices toward high power, high frequency, and miniaturization, the voltage holdoff capacity of the insulation materials in devices has also been raised to a higher demand. Cr/Mn/Ti-doped AlO ceramics were prepared, and the bulk density, micromorphology, phase composition, resistivity, secondary electron emission coefficient, and surface flashover threshold in the vacuum of the AlO were characterized. The results show that the addition of TiO to the AlO ceramic can promote the sintering of the ceramic. The Cr/Mn/Ti-doped AlO ceramic with a homogeneous microstructure can be obtained by an appropriate amount of TiO addition. In the process of the heat treatment, the TiO in the ceramics was reduced to a certain degree, which had an impact on the microstructure of the AlO ceramic. Adding a small amount of TiO can improve the voltage holdoff performance in the vacuum. The value of the surface flashover threshold in the vacuum of the Cr/Mn/Ti-doped AlO ceramic containing 1 wt.% TiO reached a value of 33 kV, which is 32% higher than that of the basic AlO ceramic. The preparation of AlO ceramics with a high voltage holdoff capacity in a vacuum provides fundamental technical support for the development of vacuum electronic devices.