Strategies for chemical modification of transition metal halides MX3 (M = Cr, Mo, Rh, Ru; X = Cl, Br, I) as 2D layered materials: rational synthesis planning, crystal growth and chemical/physical properties

• Applicants: Dr. Silke Hampel; Professor Dr. Peer Schmidt
• Subject Area: Solid State and Surface Chemistry, Material Synthesis
• Term: from 2020 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 437046793

The project addresses the evaluation of solid solution systems of two-dimensional layered compounds of the transition metal halides MX3 (M = Cr, Mo, Rh, Ru; X, Y = Cl, Br, I). To this end, systematic investigations are to be carried out on the formation and existence ranges of solid solution phases M1−xM´xX3 and M(X1−yYy)3, respectively. A rational pre-selection of suitable systems is carried out on the basis of thermodynamic analyses (electromotive series of the halides), so that the formation of solid solution crystals in the combination of the cations (Cr, Mo, Rh, Ru) is expected with a high degree of probability. The systems CrCl3-RuCl3 and CrX3-CrY3 (X, Y = Cl, Br, I) serve as model systems for the evaluation of the method spectrum and for the further development of thermodynamic concepts for the rational prediction of the existence ranges as well as suitable synthesis conditions for crystal growth.The main objective is the experimental realization of directed depositions of bulk crystals and nano-layers of the solid solution phases with a defined composition within the homogeneity range. In order to avoid expensive trial-and-error methods, methods of modeling the synthesis parameters (CalPhaD) are combined with experimental methods of synthesis and characterization. Finally, parameter optimization aims at setting suitable conditions for the deposition of crystals down to the monolayer limit of the investigated 2D materials. The crystals obtained can be identified and characterized physico-chemically with a broad spectrum of methods of the project partners. With the investigation of pseudo-binary systems M1−xM´xX3 and M(X1−yYy)3, mid-term prerequisites are to be created for investigations of quaternary systems M1−xM´x(X1−yYy)3 with a rational approach.

• DFG Programme: Research Grants