Dresden 2014 – wissenschaftliches Programm

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MI: Fachverband Mikrosonden

MI 11: Crystallography in Materials Science (KR jointly with DF, MI)

MI 11.3: Vortrag

Donnerstag, 3. April 2014, 15:45–16:00, CHE 184

Theoretical investigation of the high pressure structure of CaTe — •Oliver Potzel and Gerhard Taubmann — Institute of Theoretical Chemistry, University of Ulm, D-89069 Ulm, Germany

The majority of the alkaline halides and the alkaline earth chalcogenides undergoes a structural phase transition from the B1 (rock-salt) structure to the B2 (CsCl) structure at elevated pressures [1].

The x-ray diffraction data of CaTe at high pressures (320 - 400 kbar) fit to a simple cubic indexing (B2) except for two reflections near the (110) peak [2]. This indicates the possible existence of an intermediate structure within the transition from the B1 to the B2 structure.

We are currently using the evolutionary algorithms of the USPEX code [3] with the periodic DFT code VASP [4] in order to predict the structure of CaTe at a pressure of 350 kbar.

Preliminary DFT studies without genetic algorithms pointed to an AgO structure. In these calculations, all known (binary) AB structures were taken into account.

The results are to be verified by the comparison of the calculated data to the experimental diffraction data.

[1] O. Potzel, G. Taubmann, J. Solid State Chem. 184, 1079 (2011)

[2] H.G. Zimmer, H. Winzen, K. Syassen, PRB 32, 4066 (1985)

[3] A.R. Oganov , C.W. Glass, J. Chem. Phys. 124, 244704 (2006)

[4] G. Kresse, J. Furthmüller, PRB 54, 11169 (1996)