A5 High-temperature, high-pressure properties of chalcogenides and low-valent transition-metal oxides

Project A5 (2019-2023) will investigate the relationship between crystal structure, electronic configuration and lattice dynamical properties using closely interwoven experimental and theoretical methodologies. Two new candidate systems for phase change materials (InxSey and GexSi1-xTe) will be explored using in situ studies at high temperature and/or high pressure to gain insight into the microscopic phenomena. The theoretical bond-projected force constants methodology will be further developed, as it seems to be a promising atomic interaction descriptor to be utilized as a new coordinate in the phase-change material treasure map. The investigations will be expanded towards the study of a Mott system (VxOy), which can be considered as a bridge between PCM and VCM materials. Furthermore, the combined experimental and theoretical investigations aim at the control of volume expansion through multiparametric studies and at the identification of oxygen diffusion pathways in the VxOy.


Chalcogenides: Vibrational properties and the role of temperature and pressure

In the current period of this project, further investigations of the bonding properties and lattice dynamics of chalcogenides and their relation to functional properties are planned based on the methods developed in the first period. Several more compositions will be in the focus of interest, and those compounds will be chosen carefully regarding to chemical relationships and microscopical criteria, where as an additional parameter pressure will be incorporated. The aim of the project is to reach a more general picture of the relation between vibrational, electronic and functional properties.


Chalcogenides: Vibrational properties and the role of temperature

This project is dedicated to a combined theoretical and experimental study of the vibrational and thermal properties of chalcogenide-based phase change materials. Latest investigations of the lattice dynamics of the amorphous and crystalline phases in the Ge-Sb-Te system reveal peculiarities, for the higher energy vibrational modes, that are suspected to be related to the functionality, in particular the large optical contrast between these phases. The combination of a theoretical approach with both a micro- and macroscopic experimental study of the lattice dynamics will yield an advanced model of the specific vibrational properties that characterize the amorphous and crystalline phases in phase change materials, and it will provide insight into the relation between these (functional) properties, such as resistivity and optical contrast.

Principal investigators:

Prof. Dr. rer. nat. R. Dronskowski
Institute für Anorganische Chemie
RWTH Aachen University
Phone: +49 (0)241 80 93642
E-mail: drons@HAL9000.ac.rwth-aachen.de

Dr. rer. nat. habil. K. Friese
Jülich Center for Neutron Science (JCNS-2) and
Peter Grünberg Institut (PGI-4)
Forschungszentrum Jülich GmbH
Phone: +49 (0)2461 61 3826
E-mail: k.friese@fz-juelich.de

Prof. Dr. rer. nat. R. Hermann
Jülich Center for Neutron Science (JCNS-2) and
Peter Grünberg Institut (PGI-4)
Forschungszentrum Jülich GmbH
Phone: +49 (0)2461 61 4786
E-mail: r.hermann@fz-juelich.de