Enhanced Thermionic Emission and Thermal Stability of C12A7:e − Electride via In Situ Mo 2 C Formation
Jingjing Liu, Xin Zhang, Yanjie Guo, Ziquan Liu, Shenlin Zhou, Qingmei Lu, Guanrong HangABSTRACT
C12A7:e − , as a low‐work‐function inorganic electride, exhibits considerable potential for thermionic emission applications. However, it is prone to softening, melting collapse, and deformation under high‐temperature operating conditions, which severely limits its long‐term emission stability. In this work, graphene oxide‐like residual carbon species generated during the preparation of C12A7:e − by the sol–gel method combined with spark plasma sintering (SPS) were utilized as in situ carbon sources. During the secondary SPS process, introduced metallic Mo reacted in situ with the residual carbon species to form uniformly dispersed Mo 2 C second phases, thereby preparing Mo 2 C/C12A7:e − composites. The results indicate that the localized reducing atmosphere generated by the deoxygenation of residual carbon species promoted the removal of cage oxygen ions, increasing the electron concentration from 0.89 × 10 21 − to 1.94 × 10 21 cm −3 . With increasing Mo 2 C content, the relative density, microhardness, and high‐temperature stability of the composites were all improved. In particular, the 20 wt.% Mo 2 C/C12A7:e − composite exhibited an increase in the onset temperature of weight loss from 904°C to 1257°C and achieved a maximum emission current density of 3.14 A/cm 2 at 1100°C, while the average effective work function decreased to 1.88 eV.