Max Planck Institute for Solid State Research: Chemistry

Abteilung Jansen
Abteilung Maier
Abteilung Simon
Emeritus

Abteilung Jansen

	Prof. Dr. Martin Jansen
	Phone:	+49 (0)711 6 89 - 15 00
	Fax:	+49 (0)711 6 89 - 15 02
	E-Mail:	M.Jansen@fkf.mpg.de

Jansen's department puts its main emphasis on basic research in the field of preparative solid state chemistry with the goal of developing modern materials. Classes of materials currently under investigation include oxides and nitrides of metals and nonmetals as well as fullerenes, e.g., new binary and ternary oxides synthesized under high oxygen pressure, ionic conductors, structural oxide ceramics and pigments, amorphous inorganic nitridic covalent networks, or endohedral fullerenes and fullerides. Besides employing traditional solid state synthesis methods, a large number of alternative techniques is used, e.g., the sol-gel process, synthesis under high pressure, via an rf-furnace, at low temperatures in liquid ammonia, by electrochemical methods, or by low-temperature atomic beam deposition. Optimizing the syntheses of these materials is only a first, though crucial step, however. In addition, their chemical and physical properties, in particular optical, electrical and magnetic behavior, are analyzed both at high and low temperatures, with particular emphasis on X-ray diffraction and spectroscopic methods. This provides the basis for placing the results in the proper context regarding structure-property relationships and modern concepts of bond theory. A long-term goal of the department is to increase the predictability of solid state chemistry, i.e., to predict the existence of not-yet synthesized compounds, calculate their properties, and finally provide prescriptions for their synthesis. This work involves both theoretical and synthetic aspects. On the theoretical side, structure candidates are determined by studying the energy landscapes of chemical systems using global exploration techniques, while on the preparative side kinetically controlled types of reactions that allow low-temperature synthesis of (possibly metastable) compounds are being developed.

Abteilung Maier

	Prof. Dr. Joachim Maier
	Phone:	+49 (0)711 6 89 - 17 20
	Fax:	+49 (0)711 6 89 - 17 22
	E-Mail:	S.Weiglein@fkf.mpg.de

Maier's department is concerned with physical chemistry of the solid state, more specifically with chemical thermodynamics and transport properties. Emphasis is laid on ion conductors (such as inorganic or organic proton, metal ion and oxygen ion conductors) and mixed conductors (typically perovskites). As local chemical excitations (point defects) are responsible for ion transport and simultaneously represent the decisive acid-base active centers, a major theme of the department is the understanding of mass and charge transport, chemical reactivities and catalytic activities in relation to defect chemistry. This includes experiments (in particular electrochemical studies) as well as theory (in particular phenomenological modelling), and comprises investigations of elementary processes but also of overall system properties. In this context, interfaces and nanosystems are to the fore. Since electrochemical investigation immediately affects the coupling of chemical and electrical phenomena, the research is directed towards both basic solid state problems and the technology of energy and information conversion or storage (fuel cells, lithium-batteries, chemical sensors). Conceptually speaking, we want to address the following questions: Can we -- given the materials, the control parameters and the driving force -- understand or even predict concentrations, mobilities and reactivities of ionic charge carriers? How do these properties change at interfaces and in confined systems? What are the basic mechanisms of ion transport and ion transfer? How can we use this fundamental knowledge to develop at will materials for given (or novel) applications?

Abteilung Simon

	Prof. Dr. Arndt Simon
	Phone:	+49 (0)711 6 89 - 16 40
	Fax:	+49 (0)711 6 89 - 16 42
	E-Mail:	A.Simon@fkf.mpg.de

Simon's department emphasizes the investigation of metal-metal bonding with main group, d- and f-metals. The purpose of the work is on one side the development of structural concepts (e.g. condensed cluster concept) and on the other side the search for new materials, their phase relationships and connections between structure, chemical bonding and properties. Targets are metal-rich compounds of transition metals, particularly oxides and halides, reduced rare earth metal halides, hydride, carbide, boride, boride carbide, aluminide and silicide halides of the rare earth metals, alkali and alkaline earth metal suboxides and subnitrides. Electron microscopy is used to characterize microcrystalline phases up to full structure refinement as well as analysis of real structure. Superconductivity is of special interest following a chemical view of the phenomenon in terms of a tendency towards pairwise localization of conduction electrons in a flat band-steep band scenario. New colossal magnetoresistance materials result from an interplay of d- and f-electrons. Other fields of interest are structures of molecular crystals, in particular, in situ grown crystals of gases and liquids. Experimental techniques like diffractometry with X-rays and neutrons, high-resolution transmission electron microscopy (HRTEM), electron crystallography and measurements of magnetic susceptibility as well as electrical transport properties are used.

Emeritus

	Prof. Dr. Hans Georg von Schnering
	Phone:	+49 (0)711 6 89 - 15 60
	Fax:	+49 (0)711 6 89 - 10 10

Von Schnering's former department investigated cluster compounds with polyanions (elements of group 13, 14, 15) and polycations (transition elements), as well as metal complexes and special molecules. The synthesis of new compounds, crystal growth, structure determination, and determination of chemical and physical properties were central activities and served for a better understanding of structure and properties. The relationships of equilibrium conditions and kinetical processes were investigated by means of phase analysis, decomposition reactions and chemical reactions of solid state materials towards new molecular and polymeric cluster compounds. The determination of superstructures and disordered structures, investigations of valence electronic densities and dynamics of molecules in crystals as well as lattice energy considerations were important additional tools. Evaluation of Periodic Nodal Surfaces (PNS) for crystallographic symmetry groups was done with respect to a generalization of the topological pattern of crystalline matter. Physical phenomena and chemical problems concerning valence electron distributions, ionic conductivity, diffusion effects and phase transitions were also investigated in this context. The experimental work was complemented by quantum mechanical calculations (e.g. Electron Localization Function, ELF). Related software was developed applying new computer architectures. The visualization of experimental and theoretical data by 3D computer graphics was helpful to correlate and to understand even complex phenomena.

₂