Synthesis of [Ca24Al28O64]4+(4e−)+LaB6 composite ceramic bulk and its electron emission properties

The C12A7:e− + LaB6 mixed powder was used as the precursor, and high-quality C12A7:e− + LaB6 composite ceramic blocks were synthesized by spark plasma sintering (SPS) at 1200 °C, 50 MPa, and 20 min. The relative density of the sample reaches 99.6%. C12A7:e− and LaB6 phases coexist with a size of 0.1–10 μm and are relatively uniformly distributed in the sample. The current emission density of the sample reaches 2.92 A/cm2, the zero-field emission current density reaches 2.39 A/cm2, and the effective work function reaches 2.17 eV when the anode voltage is 4000 V, and the temperature is 1200 °C. Also, no melting phenomenon appeared in the samples, and the bulk had excellent emission stability during emission performance testing. These results provide a new idea for solving the melting phenomenon of C12A7:e− in high-temperature cyclic ignition. This provides the basis for the practical application of C12A7:e− in electron emission and vacuum electronic technology.