Binary composite La2O3 and Ta2O5-doped molybdenum negative electrode material and preparation method thereof

Abstract

The invention provides a binary composite La2O3 and Ta2O5-doped molybdenum negative electrode material and a preparation method thereof, and belongs to the technical field of rare-earth refractory metal negative electrode materials. The total additive amount of active materials La2O3 and Ta2O5 in a negative electrode substrate is 3-5wt%, wherein the additive amount of the Ta2O5 is 0.05%-0.5%; and the balance is Mo. The method comprises the steps of mixing a lanthanum nitrate solution, an ammonium heptamolybdate solution and a citric acid solution, adding tantalum oxide powder and then carrying out water-bath heating, mechanical stirring and drying to finally form dried gel; decomposing the dried gel to obtain La2O3 and Ta2O5-doped MoO3 powder; doping the La2O3 and the Ta2O5 obtained from the mixed oxide powder through a secondary reduction process into molybdenum powder; carrying out pressing, sintering, carbonizing, activating and seasoning treatment on the powder to obtain the negative electrode material with good emission property. The material is excellent in thermionic emission property and meets the operating requirements of a negative electrode in a microwave oven magnetron.

Description

technical field [0001] A binary compound La 2 o 3 、 Ta 2 o 5 The doped molybdenum cathode material and its preparation method belong to the technical field of rare earth refractory metal cathode materials. technical background [0002] In addition to being used in military fields such as radar, guidance, navigation, and electronic countermeasures, magnetrons also play an important role in the civilian market, such as medical treatment, radar, and industrial heating; among them, the most closely related to people's livelihood That's household microwave ovens. Since the magnetron is a microwave generator, it is the core device of the microwave oven; the cathode is known as the "heart" of the magnetron, and its working characteristics and life affect and restrict the performance of the magnetron. At present, the cathode material used in household microwave ovens worldwide is thoriated tungsten (ThO 2 -W) Cathode. But Th is a radioactive element with a half-life of 1.4×10...

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Problems solved by technology

[0003] Predecessors have doped unit or compound doped La 2 o 3 , Y 2 o 3 、Gd 2 o 3 、Lu 2 o 3 A lot of research has been done on the preparation process and properties of molybdenum cathodes such as rare earth oxides [1-8] However, due to the fact that these cathodes still have problems such as poor emission stability and evaporation of rare earth active materials in actual magnetrons, this restricts the promotion and use of these researches.

to La 2 o 3 doped Mo cathode as an example, although La 2 o 3 The doped Mo cathode has good thermal electron emission performance, but the electrons emitted from the cathode surface in the magnetron will bombard the active material on the cathode surface and the Mo matrix under the action of an external magnetic field, resulting in a large amount of La and Mo elements evaporating. As a result, the emission current of the cathode decreases sharply, resulting in poor cathode emission stability

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