| Autor: |
Khannanov A; Laboratory for Advanced Carbon Nanomaterials , Kazan Federal University , Kazan 420008 , Russian Federation., Kiiamov A; Laboratory for Advanced Carbon Nanomaterials , Kazan Federal University , Kazan 420008 , Russian Federation.; Institute of Physics , Kazan Federal University , Kremlyovskaya str. 18 , Kazan 420008 , Russian Federation., Valimukhametova A; Laboratory for Advanced Carbon Nanomaterials , Kazan Federal University , Kazan 420008 , Russian Federation., Tayurskii DA; Laboratory for Advanced Carbon Nanomaterials , Kazan Federal University , Kazan 420008 , Russian Federation.; Institute of Physics , Kazan Federal University , Kremlyovskaya str. 18 , Kazan 420008 , Russian Federation., Börrnert F; Materialwissenschaftliche Elektronenmikroskopie , Universität Ulm , Albert-Einstein-Allee 11 , 89081 Ulm , Germany., Kaiser U; Materialwissenschaftliche Elektronenmikroskopie , Universität Ulm , Albert-Einstein-Allee 11 , 89081 Ulm , Germany., Eigler S; Institute of Chemistry and Biochemistry , Freie Universität Berlin , Takustraße 3 , 14195 Berlin , Germany., Vagizov FG; Institute of Physics , Kazan Federal University , Kremlyovskaya str. 18 , Kazan 420008 , Russian Federation., Dimiev AM; Laboratory for Advanced Carbon Nanomaterials , Kazan Federal University , Kazan 420008 , Russian Federation. |
| Abstrakt: |
Stabilizing nanoparticles on surfaces, such as graphene, is a growing field of research. Thereby, iron particle stabilization on carbon materials is attractive and finds applications in charge-storage devices, catalysis, and others. In this work, we describe the discovery of iron nanoparticles with the face-centered cubic structure that was postulated not to exist at ambient conditions. In bulk, the γ-iron phase is formed only above 917 °C, and transforms back to the thermodynamically favored α-phase upon cooling. Here, with X-ray diffraction and Mössbauer spectroscopy we unambiguously demonstrate the unexpected room-temperature stability of the γ-phase of iron in the form of the austenitic nanoparticles with low carbon content from 0.60% through 0.93%. The nanoparticles have controllable diameter range from 30 nm through 200 nm. They are stabilized by a layer of Fe/C solid solution on the surface, serving as the buffer controlling carbon content in the core, and by a few-layer graphene as an outermost shell. |
