The invention discloses a preparation method of a multicomponent large-size
rare earth boride La*Ce1-xB6 monocrystalline block
cathode material, belonging to the technical field of
rare earth boride thermionic
cathode and
cold cathode materials. At present, little research has been done into multicomponent
rare earth boride monocrystals, the preparation technology in the prior art is complicated, and the prepared monocrystals in the prior art has bad quality and small size and is difficult for practical application. The
cathode material disclosed herein is represented as LaxCe1-xB6, wherein, x ranges from 0.2-0.6. The method disclosed herein is characterized in that: a
discharge plasma sintering method is adopted, a LaxCe1-xB6 polycrystalline rod is prepared in a high vacuum environment, and then the prepared polycrystalline rod is smelted in a
smelting furnace of an optic zone. In the process of
crystal growth, for effectively inhibiting the volatilization and oxidation of La and Ce, high-purity flow
argon is introduced to a
quartz tube, wherein, the gas flow velocity is 1-2 L / min, and the
gas pressure is 0.5-0.7 MPa. For making a melting zone more uniform, a
seed crystal and a charge bar are reversely rotated, wherein, the rotating speed is 30-40 rpm, and the
growth speed is 7-10 mm / h. The prepared monocrystal has the advantages of
large size, high purity, and good quality.