Nitrides under High Pressure

Pressure-induced cristallization and metastabel high pressure phases

Transition metal nitrides have found increasing popularity in various industrial and academic fields, mainly due to their hardness and magnetic properties. Investigations into the influence of high pressure on nitride synthesis, as well as on nitrides themselves, often leads to unexpected and exotic structures and properties. Our high-pressure experiments are conducted in collaboration with PD Dr. U. Schwarz, at the Max Planck Institute for Chemical Physics of Solids in Dresden, and over the years, has produced numerous exciting results.

Some of our key findings include:

  • The first growth of ε-Fe3Nx single crystals, by using high temperature and pressure to induce a reconstructive phase transition from γ’-Fe4N / ζ-Fe2N to ε-Fe3Nx. [13]

  • Substitution experiments involving ε-Fe3Nx and Co, Ni or Ir, under high temperature and pressure, to form the phases Fe2MNx (M = Co, Ni or Ir). [4, 5]

  • At the ESRF in Grenoble, we produced the unpredicted NiAs-type FeN, under high temperature and pressure, which showed surprising magnetic properties. [6]
Left: ζ-Iron nitride transforms under high-pressure high-temperature conditions without change of composition into ε-type iron nitride (crystal structures). In case of application of purely pressure the zeta-type order is retained (diffraction pattern). Right: Mößbauer spectra of iron in nitrogen after laser heating at different pressure conditions indicate the formation of the high-pressure phase of FeN via different magnetic behavior.

[1] R. Niewa, D. Rau, A. Wosylus, K. Meier, M. Hanfland, M. Wessel, R. Dronskowski, D. A. Dzivenko, R. Riedel and U. Schwarz, Chem. Mater., 2009, 21, 392.

[2] K. Guo, D. Rau, J. von Appen, Y. Prots, W. Schnelle, R. Dronskowski, R. Niewa and U. Schwarz, J. Alloys Compd. 2013, 33, 684.

[3] U. Schwarz, A. Wosylus, M. Wessel, R. Dronskowski, M. Hanfland, D. Rau and R. Niewa, Eur. J. Inorg. Chem. 2009, 2009, 1634.

[4] K. Guo, D. Rau, L. Toffoletti, C. Müller, U. Burkhardt, W. Schnelle, R. Niewa and U. Schwarz, Chem. Mater. 2012, 24, 4600.

[5] K. Guo, D. Rau, W. Schnelle, U. Burkhardt, R. Niewa and U. Schwarz, Z. Anorg. Allg. Chem. 2014, 640, 814.

[6] W. P. Clark, S. Steinberg, R. Dronskowski, C. McCammon, I. Kupenko, M. Bykov, L. Dubrovinsky, L. G. Akselrud, U. Schwarz and R. Niewa, Angew. Chem. Int. Ed. 2017, 56, 7302.

Dieses Bild zeigt Niewa
Prof. Dr. rer. nat.

Rainer Niewa