Synthesis and characterization of the semiconducting metastable phase Al6Ge5

• Published in: Materials letters 2015-01, Vol.138, p.222-224
• Main Authors: Esmilaire, R., Beaudhuin, M., Hermet, P., Fréty, Nicole, Ravot, D., Viennois, R.
• Format: Article
• Language: English
• Subjects: Acoustics; Chemical Sciences; Cristallography; Crystal structure; Density functional theory; Intermetallic alloys and compounds; Material chemistry; Mathematical analysis; Mechanical alloying; Metallurgy; Purity; Raman; Semiconductors; Simulation and Modeling; Synthesis; Thermoelectricity
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2014.10.001

Metastable Al6Ge5 phase has been synthesized by mechanical alloying. Influence of milling time and stoichiometric ratio on the amount of Al6Ge5 were studied. In the better synthesis conditions, one finds purity of 58wt% from Rietveld refinement, the highest purity reported so far. For the first time, the crystal structure of Al6Ge5 has been fully solved by Rietveld refinement and confirmed by density functional theory (DFT) based calculation. We reported the experimental unpolarized Raman spectrum and the assignment of the main lines is performed using our DFT calculations. The existence of low energy optical modes able to scatter acoustical phonons and its semiconducting nature makes this compound promising for thermoelectric applications. •The highest purity reported for Al6Ge5 has been obtained by mechanical alloying.•Full structure of Al6Ge5 has been solved.•Full assignments of the Raman active modes have been performed.•Al6Ge5 can be a promising material for thermoelectric applications.