Investigating and tuning negative thermal expansion in Zn2GeO4 via light ion doping: A XAS study

This proposal aims to investigate the anomalous behavior of the negative thermal expansion (NTE) in Zn2GeO4 compound and how it can be tuned by appropriated doping with light ions (Li or Mg). Materials which exhibit NTE are of great interest because of the possibility to create compounds with a tunable coefficient of thermal expansion in specific temperature ranges. However, a full understanding and controlling of NTE mechanisms are still a scientific challenging since this behavior can be driven by different mechanisms, such as low-wavenumber phonons, spontaneous polarization, or charge transfer phenomena. Therefore, this study envisages the use of the high-brilliance XAS beamline BM23 station to shed light on the NTE at local level of Zn2GeO4 nanocrystals. We expected to better understand the mechanisms of NTE in Zn2GeO4, which may enable a full control of their intrinsic thermal expansion