Polymorphic Phases of Metal Chlorides in the Confined 2D Space of Bilayer Graphene

• Published in: Advanced materials (Weinheim) Vol. 33; no. 52; pp. e2105898 - n/a
• Main Authors: Lin, Yung‐Chang, Motoyama, Amane, Kretschmer, Silvan, Ghaderzadeh, Sadegh, Ghorbani‐Asl, Mahdi, Araki, Yuji, Krasheninnikov, Arkady V., Ago, Hiroki, Suenaga, Kazu
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.12.2021
• Subjects: Aluminum chloride; Bilayers; Chlorine; Copper chloride; Density functional theory; EELS; Electron beams; Graphene; graphene intercalation; Heterostructures; Hybrid systems; Insulators; Intercalation; Materials science; metal chloride; Metal chlorides; Metalloids; phase transitions; Phases; Scanning transmission electron microscopy; Sheets; Two dimensional materials; graphene intercalation; phase transitions; metal chloride; EELS
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.202105898

Unprecedented 2D metal chloride structures are grown between sheets of bilayer graphene through intercalation of metal and chlorine atoms. Numerous spatially confined 2D phases of AlCl3 and CuCl2 distinct from their typical bulk forms are found, and the transformations between these new phases under the electron beam are directly observed by in situ scanning transmission electron microscopy (STEM). The density functional theory calculations confirm the metastability of the atomic structures derived from the STEM experiments and provide insights into the electronic properties of the phases, which range from insulators to semimetals. Additionally, the co‐intercalation of different metal chlorides is found to create completely new hybrid systems; in‐plane quasi‐1D AlCl3/CuCl2 heterostructures are obtained. The existence of polymorphic phases hints at the unique possibilities for fabricating new types of 2D materials with diverse electronic properties confined between graphene sheets. Metal chlorides intercalated in the van der Waals gap of bilayer graphene are found to have polymorphic phases. New phases and phase transformation of AlCl3, as well as new hybrid alloy of quasi‐1D AlCl3 and CuCl2 are directly observed by scanning transmission electron microscopy.