Microstructure of mayenite 12CaO·7Al₂O₃ and electron emission characteristics

Abstract

Electron emission characteristic, electrical conductivity of polycrystalline mayenite (12CaO•7Al 2 O 3 ) electride, formation of [Ca 24 Al 28 O 64 ] 4+ (e − ) 4 framework as a function of phase content, and microstructure have been investigated. The mayenite microstructure was investigated using high-resolution transmission microscopy which revealed the type cage structure of 12CaO•7Al 2 O 3 partially filled by extraframework oxygen ions. Incorporation of electrons by means of carbon C 2 − 2 ion template 12CaO•7Al 2 O 3 produces complex structure, and an incomplete C 2 − 2 ion template 12CaO•7Al 2 O 3 structure consisting of mixture of a [Ca 24 Al 28 O 64 ] 4+ (e − ) 4 and [Ca 24 Al 28 O 64 ] 4+ (O 2− ) 2 framework had a direct effect on the electron emission. Surface chemistry and stability of the 12CaO•7Al 2 O 3 electride have been studied using x-ray photoelectron spectroscopy. The work function of phase pure 12CaO•7Al 2 O 3 electride was determined from direct thermionic emission data and compared to the measurement from ultraviolet photoelectron spectroscopy (UPS). Depending on the extent of C 2 −2 ion template of 12CaO•7Al 2 O 3 structure, a work function of 0.9-1.2 eV and 2.1-2.4 eV has been measured and thermionic emission initiating at 600°C.

Tunable interstitial anionic electrons in layered MXenes

“…It is sometimes considered as defects if the density is very low, such as F-center, where unpaired electrons are bonded with vacancies, leading to the color change of the crystal [3,4]. When the intensity of the cavity electrons increases significantly and distributes uniformly, we can obtain the electrides and observe many intriguing properties, such as advanced light absorption ability [5,6], low work function [7,8], high electron mobility [9,10], and high carrier concentration [11,12], which can be applied in non-linear optical devices [13,14], electron emitter devices [15,16], high-speed electronic devices [17], superconductors [18,19], and chemical applications such as catalysis [20][21][22]. Since the * Authors to whom any correspondence should be addressed.…”