Understanding the electronic structure of a given material is the key to explain its chemical and physical characteristics and, furthermore, to design materials with task-specific properties. Although certain concepts, e.g., those of Zintl and Klemm, allow recognizing the interdependence between the crystal structures and electronic structures in several intermetallics, certain intermetallics, particularly, polar intermetallics [1], lack of valence-electron-rules. For instance, an application [2] of the Zintl-Klemm concept to LaCuxTe2 with x = 0.28 (see below) results in the assignment of a −1.28 charge per tellurium atom within the linear, undistorted tellurium chains. Furthermore, the existence of such linear, undistorted tellurium chains [3] is remarkable, as such low-dimensional building units typically distort due to electronic instabilities.

In the lack of full knowledge about the electronic structures and the occurence of electronic instabilties for such tellurides, there is a need to address the following 

Zintl-phases or polar intermetallics?


Identifying the actual electronic structures
and trends for such tellurides

 

Methodological Approach

  • Syntheses of tellurides, whose electronic structures cannot be described by applying the Zintl-Klemm concept 
  • Characterizations of the crystal structures and physical properties
  • Determinations of the electronic structures by means of quantum-chemical techniques (bonding analyses)   


Is it possible to predict the occurence of electronic instabilities?

 

Notably, the formations of charge-density-waves
 or a superconducting state are related
to the presence of such instabilities!

 

Methodological Approach

  • Finding of a plausible descriptor, which relates the experimentally determined properties to the computed parameters
  • Compilation of a library of test data and evaluation as well as optimization of the descriptor
  • Application to a data repository by means of a high-throughput, quantum-chemical process

 

Available Instrumentation

To prepare samples under a dry argon atmosphere with strict exclusion of air and moisture, we use a glove-box, which is also equipped with a digital microscope. The samples are flame-sealed under a dynamic vacuum that is generated using a vacuum- and inert-gas-line equipped with a high-vacuum-pump-unit. Box as well as tube furnaces (Tmax: 1200 °C) are utilized to heat our samples. To determine the crystal structures, yields, and physical properties of the obtained products, access to diverse instrumentation including single-crystal and powder X-ray diffractometers is provided. For the explorations of the electronic band structures by means of quantum-chemical techniques, access to two different computer clusters is provided.

 

 

 

 

 

 

 

 

 

References

  1. a) J. D. Corbett, Inorg. Chem. 2010, 49, 13−28; b) F. C. Gladisch, S. Steinberg, Crystals 2018, 8, 80. 
  2. G. A. Papoian, R. Hoffmann, Angew. Chem. Int. Ed. 2000, 39, 2408−2448.
  3. a) N.-H. Dung, M.-P. Pardo, P. Boy, Acta Crystallogr., Sect. C 1983, 39, 668-670; b) F. Q. Huang, P. Brazis, C. R. Kannewurf, J. A. Ibers, J. Am. Chem. Soc. 2000, 122, 80−86.

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