Sr-doping enhanced electrical transport and thermionic emission of single crystal 12CaO·7Al2O3 electride

Enhancing the injected electron concentration and thermionic emission property in C12A7:e− ceramic via Al site Zr doping

“…The larger size of the cage cavity structure will also facilitate the escape of electrons during the thermal emission. 21 The surface of the C12(Al 0.86 Zr 0.14 )7:e − block sample was polished to remove all scratches before backscattered electron (BSE) photomicrographs and EDS test. As The injected electron concentration and electron mobility of the different Zr-doped C12A7:e − at 300 K are shown in Figure 7A.…”

“…10 The free e − can replace the free O 2− to form [Ca 24 Al 28 O 64 ] 4+ (4e − ) (C12A7:e − ) electride, and the free e − can travel between the nano-cages, so the electrides become electrical conducting. 11 Complete removal of free O 2− from the C12A7 cage can achieve a high inject electron density of 2.3×10 21 /cm 3 and maximum conductivity of about 1500 S/cm. 12,13 Khan et al significantly improved the conductivity and catalytic performance of C12A7:e − by doping Fe, Ga, Si, Sn, and V. [14][15][16][17] Xiao et al enlarged the size of the cage of polycrystalline C12A7 using the partial substitution of Sr and Ba on the Ca site, which facilitated the replacement of internal free O 2− and the migration of free e − .…”

“…12,13 Khan et al significantly improved the conductivity and catalytic performance of C12A7:e − by doping Fe, Ga, Si, Sn, and V. [14][15][16][17] Xiao et al enlarged the size of the cage of polycrystalline C12A7 using the partial substitution of Sr and Ba on the Ca site, which facilitated the replacement of internal free O 2− and the migration of free e − . [18][19][20][21][22] Thus, homovalent cationic substitution helped to improve electrical transport properties and reduce the work function of the C12A7:e − . To better understand the doping phenomenon, Huang et al used density functional theory (DFT) to explore the effect of cationic (Mg 2+ , Cu 2+ , Sr 2+ , Fe 3+ , Ir 4+ , P 5+ , and V 5+ ) substitution on C12A7:e − structure, electronic characteristics, and electrical properties.…”

[Ca24Al28O64]4+(4e−) are directly and quickly synthesized by self‐reduction of C12H10Ca3O14 + Al2O3 without any reducing agent

“…This makes it easier for the electrons in C12A7:e − to achieve energy band transitions 11,13 . The unique crystal and electronic structure of C12A7:e − gives it excellent chemical stability, 16 and extremely low work function (2.4 eV) 17,18 . Therefore, it has great application potential in cold cathode fluorescent lamps and catalyst carriers 19…”

“…11,13 The unique crystal and electronic structure of C12A7:e − gives it excellent chemical stability, 16 and extremely low work function (2.4 eV). 17,18 Therefore, it has great application potential in cold cathode fluorescent lamps and catalyst carriers. 19 At present, the effective synthesis methods of C12A7:e − include sol-gel method, 3,20,21 metal vapor reduction, 13,22,23 reducing atmosphere reduction (CO), 24 thermite reduction, 11,25 and calcium thermal reduction.…”