Lead-Free BNT–BT<sub>0.08</sub>/CoFe<sub>2</sub>O<sub>4</sub> Core–Shell Nanostructures with Potential Multifunctional Applications
Marin Cernea,
Roxana Radu,
Harvey Amorín,
Simona Gabriela Greculeasa,
Bogdan Stefan Vasile,
Vasile Adrian Surdu,
Paul Ganea,
Roxana Trusca,
Marwa Hattab,
Carmen Galassi
Affiliations
Marin Cernea
National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
Roxana Radu
National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
Harvey Amorín
Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid, Spain
Simona Gabriela Greculeasa
National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
Bogdan Stefan Vasile
Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 060042 Bucharest, Romania
Vasile Adrian Surdu
Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 060042 Bucharest, Romania
Paul Ganea
National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
Roxana Trusca
Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 060042 Bucharest, Romania
Marwa Hattab
Research Laboratory of Environmental Science and Technologies, Carthage University, BP.1003, Hammam-Lif, Ben Arous 2050, Tunisia
Carmen Galassi
National Research Council of Italy–Institute of Science and Technology for Ceramics (CNR–ISTEC), Via Granarolo 64, I–48018 Faenza, Italy
Herein we report on novel multiferroic core–shell nanostructures of cobalt ferrite (CoFe2O4)–bismuth, sodium titanate doped with barium titanate (BNT–BT0.08), prepared by a two–step wet chemical procedure, using the sol–gel technique. The fraction of CoFe2O4 was varied from 1:0.5 to 1:1.5 = BNT–BT0.08/CoFe2O4 (molar ratio). X–ray diffraction confirmed the presence of both the spinel CoFe2O4 and the perovskite Bi0.5Na0.5TiO3 phases. Scanning electron microscopy analysis indicated that the diameter of the core–shell nanoparticles was between 15 and 40 nm. Transmission electron microscopy data showed two–phase composite nanostructures consisting of a BNT–BT0.08 core surrounded by a CoFe2O4 shell with an average thickness of 4–7 nm. Cole-Cole plots reveal the presence of grains and grain boundary effects in the BNT–BT0.08/CoFe2O4 composite. Moreover, the values of the dc conductivity were found to increase with the amount of CoFe2O4 semiconductive phase. Both X-ray photoelectron spectroscopy (XPS) and Mössbauer measurements have shown no change in the valence of the Fe3+, Co2+, Bi3+ and Ti4+ cations. This study provides a detailed insight into the magnetoelectric coupling of the multiferroic BNT–BT0.08/CoFe2O4 core–shell composite potentially suitable for magnetoelectric applications.
