First-principles study of organically modified muscovite mica with ammonium (NH${}_4^{+}$) or methylammonium (CH${}_3$NH${}_3^{+}$) ion

Abstract

Using density functional theory calculations, we have investigated the interlayer cation exchange phenomena in muscovite mica, which is motivated by a necessity to develop flexible high-insulating covering materials. The crystalline structures, chemical bonding properties, energetics, and electronic properties of muscovites before and after exchange of interlayer K${}^{+}$ cation with ammonium (NH${}_4^{+}$) or methylammonium (CH${}_3$NH${}_3^{+}$) ion were calculated. It was found that the unit cell volume changes are negligibly small upon exchange with NH${}_4^{+}$ ion, while the unit cells are expanded with about 4 \% relative rate when replacing the interlayer K${}^{+}$ cation with CH${}_3$NH${}_3^{+}$ ion. The energy band gap of pre-exchanged muscovite was calculated to be about 5 eV, which hardly changes upon interlayer cation exchange with either NH${}_4^{+}$ or CH${}_3$NH${}_3^{+}$ ion, indicating the preservation of high insulating property of muscovite. The exchange energies were found to be about -100 kJ/mol for NH${}_4^{+}$ and about -50 kJ/mol for CH${}_3$NH${}_3^{+}$ exchange, indicating that the exchange reactions are exothermic. A detailed analysis of atomic resolved density of states and electron density redistribution was provided.

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Cited by in corpus (1)

• Ab initio study of sodium cointercalation with diglyme molecule into graphite