TY - JOUR

T1 - A rapid one-step mechanosynthesis and characterization of nanocrystalline CaFe2O4 with orthorhombic structure

AU - Berchmans, L. J.

AU - Myndyk, M.

AU - Da Silva, K. L.

AU - Feldhoff, Armin

AU - Šubrt, J.

AU - Heitjans, Paul

AU - Becker, K. D.

AU - Šepelák, V.

N1 - Funding Information: The present work was supported by the German Research Foundation (DFG) in the framework of the Priority Programme “Crystalline Non-equilibrium Phases” (SPP 1415). The authors (L.J.B., K.D.B., V.Š.) thank the German Academic Exchange Service (DAAD) and the Department of Science and Technology (DST), Government of India, for supporting their mutual research stays at the Braunschweig University of Technology, the Karlsruhe Institute of Technology, and the Central Electrochemical Research Institute, Karaikudi, within a German-Indian (DAAD-DST) Joint Research Collaboration Programme. Partial support by the APVV (0728-07), the VEGA (2/0065/08), and the Academy of Sciences of the Czech Republic is gratefully acknowledged.

PY - 2010/6/18

Y1 - 2010/6/18

N2 - CaFe2O4 nanopowders were prepared via single-step mechanochemical processing of two various mixtures of precursors: simple oxides (CaO and α-Fe2O3) and elemental metal and oxide powders (Ca and α-Fe2O3). The mechanically induced evolution of the CaO/α-Fe2O3 and Ca/α-Fe2O3 mixtures was followed by 57Fe Mössbauer spectroscopy, XRD, and HR-TEM. The mechanosynthesis of CaFe2O4 proceeds very rapidly if starting from the metal/oxide system; after only 1 h of the mechanochemical treatment performed at room temperature, the synthesis of the complex oxide is almost completed. This is in a strong contrast to the conventional solid-state synthesis of CaFe2O4, which requires prolonged exposure (∼20 h) at considerably elevated temperatures (∼1400 K). It was revealed that mechanosynthesised CaFe2O4 nanoparticles with an average size of about 15 nm possess the core-shell structure consisting of an ordered inner core surrounded by a disordered surface shell with the thickness of about 1.9 nm. The main structural features of the surface shell of nanoparticles are distorted oxygen octahedra.

AB - CaFe2O4 nanopowders were prepared via single-step mechanochemical processing of two various mixtures of precursors: simple oxides (CaO and α-Fe2O3) and elemental metal and oxide powders (Ca and α-Fe2O3). The mechanically induced evolution of the CaO/α-Fe2O3 and Ca/α-Fe2O3 mixtures was followed by 57Fe Mössbauer spectroscopy, XRD, and HR-TEM. The mechanosynthesis of CaFe2O4 proceeds very rapidly if starting from the metal/oxide system; after only 1 h of the mechanochemical treatment performed at room temperature, the synthesis of the complex oxide is almost completed. This is in a strong contrast to the conventional solid-state synthesis of CaFe2O4, which requires prolonged exposure (∼20 h) at considerably elevated temperatures (∼1400 K). It was revealed that mechanosynthesised CaFe2O4 nanoparticles with an average size of about 15 nm possess the core-shell structure consisting of an ordered inner core surrounded by a disordered surface shell with the thickness of about 1.9 nm. The main structural features of the surface shell of nanoparticles are distorted oxygen octahedra.

KW - Core-shell morphology

KW - Mechanochemical processing

KW - Microstructure

KW - Mössbauer spectroscopy

KW - Nanostructured materials

KW - Transmission electron microscopy

UR - http://www.scopus.com/inward/record.url?scp=77953131649&partnerID=8YFLogxK

U2 - 10.1016/j.jallcom.2010.03.199

DO - 10.1016/j.jallcom.2010.03.199

M3 - Article

AN - SCOPUS:77953131649

VL - 500

SP - 68

EP - 73

JO - Journal of Alloys and Compounds

JF - Journal of Alloys and Compounds

SN - 0925-8388

IS - 1

ER -