Shock wave synthesis of aluminium nitride with rocksalt structure

Abstract

The high pressure phase of aluminium nitride with rocksalt structure (rs) is a ceramic with high potential and a challenging material to investigate. The rs-AlN was synthesised and recovered by shock wave experiments using the flyer-plate method with multiple reflections at peak pressures between 15 and 43 GPa. Successful syntheses were carried out using AlN nanopowder with ambient pressure wurtzite structure (w-AlN) as starting material. The high pressure modification could, however, not be obtained when starting from submicron w-AlN. The recovery of rs-AlN is sensitive to the synthesis conditions as these influence the reconversion of rs-AlN to w-AlN.

Keywords:

• aluminium nitride
• shock wave synthesis
• rocksalt structure
• high pressure

Acknowledgements

This work was performed within the Cluster of Excellence ‘Structure Design of Novel High-Performance Materials via Atomic Design and Defect Engineering (ADDE)’ that is financially supported by the European Union (European regional development fund) and by the Ministry of Science and Art of Saxony (SMWK). This work is part of the research of the FHP, financially supported by the ‘Dr.-Erich-Krüger-Foundation’ and the Priority Programme SPP1236 ‘Synthesis, “in situ” characterisation and quantum mechanical modelling of Earth Materials, oxides, carbides and nitrides at extremely high pressures and temperatures’ of the German Research Foundation (DFG). The authors would also like to thank Dr H. Krebs and his group from the Federal Institute for Materials Research and Testing (BAM), division explosives, for the calculation of the active plane wave generator and the determination of the Gurney constants.