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Article Dans Une Revue Journal of the American Ceramic Society Année : 2021

Microstructure of mayenite 12CaO·7Al 2 O 3 and electron emission characteristics

Marie-Hélène Berger
Tyson Back
Jonathan Mackey

Résumé

Abstract Electron emission characteristic, electrical conductivity of polycrystalline mayenite (12CaO·7Al2O3) electride, formation of [Ca24Al28O64]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·7Al2O3 partially filled by extra-framework oxygen ions. Incorporation of electrons by means of carbon C_2^−2 ion template 12CaO·7Al2O3 produces complex structure, and an incomplete C_2^−2 ion template 12CaO·7Al2O3 structure consisting of mixture of a [Ca24Al28O64]4+(e−)4 and [Ca24Al28O64]4+(O2−)2 framework had a direct effect on the electron emission. Surface chemistry and stability of the 12CaO·7Al2O3 electride have been studied using x-ray photoelectron spectroscopy. The work function of phase pure 12CaO·7Al2O3 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·7Al2O3 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.

Domaines

Matériaux
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Dates et versions

hal-03616636 , version 1 (22-03-2022)

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Ali Sayir, Marie-Hélène Berger, Tyson Back, Jonathan Mackey. Microstructure of mayenite 12CaO·7Al 2 O 3 and electron emission characteristics. Journal of the American Ceramic Society, 2021, 104 (11), pp.5750-5763. ⟨10.1111/jace.17925⟩. ⟨hal-03616636⟩
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