Title: Multiferroic nanocrystalline BiFeO₃ and BiCrO₃ thin films prepared by ion beam sputtering

Authors: P. Couture; G.V.M. Williams; J. Kennedy; J. Leveneur; P.P. Murmu; S.V. Chong; S. Rubanov

Addresses: National Isotope Centre, GNS Science, 30 Gracefield Road, P.O. Box 31312, Lower Hutt 5010, New Zealand; School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand; The MacDiarmid Institute for Advanced Materials and Nanotechnology, SCPS, P.O. Box 600, Wellington 6140, New Zealand ' School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand; The MacDiarmid Institute for Advanced Materials and Nanotechnology, SCPS, P.O. Box 600, Wellington 6140, New Zealand ' National Isotope Centre, GNS Science, 30 Gracefield Road, P.O. Box 31312, Lower Hutt 5010, New Zealand; The MacDiarmid Institute for Advanced Materials and Nanotechnology, SCPS, P.O. Box 600, Wellington 6140, New Zealand ' National Isotope Centre, GNS Science, 30 Gracefield Road, P.O. Box 31312, Lower Hutt 5010, New Zealand ' National Isotope Centre, GNS Science, 30 Gracefield Road, P.O. Box 31312, Lower Hutt 5010, New Zealand ' The MacDiarmid Institute for Advanced Materials and Nanotechnology, SCPS, P.O. Box 600, Wellington 6140, New Zealand; Robinson Research Institute, Victoria University of Wellington, P.O. Box 33436, Lower Hutt 5046, New Zealand ' University of Melbourne, Bio 21 Institute, Melbourne, Victoria 3010, Australia

Abstract: BiFeO₃ and BiCrO₃ films were made by room temperature sputtering followed by thermal annealing in a partial oxygen atmosphere. The annealed films were found to be nanocrystalline, with an average particle size of 11 nm for BiFeO₃ and 8 nm for BiCrO₃. The saturation moment per formula unit is 0.39 μ_B for BiFeO₃ which is significantly greater than that found in bulk BiFeO₃ (0.02 μ_B). A similar enhancement was also found in previous studies of BiFeO₃ nanoparticles where the nanoparticle size was small. However, no large enhancement of the saturation moment per formula unit was identified for the annealed BiCrO₃ films. The annealed BiFeO₃ films displayed superparamagnetic behaviour and the particle size estimated from the blocking temperature is comparable to that estimated from the X-ray diffraction data. Our results show that sputtering and oxygen annealing is a method that can be used to make nanocrystalline BiFeO₃ and BiCrO₃ films.

Keywords: multiferroic thin films; ion beam sputtering; superparamagnetic behaviour; particle size; magnetisation; BiFeO3 nanoparticles; bismuth ferrite; nanocrystalline thin films; BiCrO3; thermal annealing; nanotechnology.

DOI: 10.1504/IJNT.2017.082445

International Journal of Nanotechnology, 2017 Vol.14 No.1/2/3/4/5/6, pp.56 - 65

Published online: 24 Feb 2017 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article