Publication detail

Cobalt-induced structural modulation in multiferroic Aurivillius-phase oxides

Koval, V. Shi, Y. Skorvanek, I. Viola, G. Bures, R. Saksl, K. Roupcova, P. Zhang, M. Jia, C. Yan, H.

Original Title

Cobalt-induced structural modulation in multiferroic Aurivillius-phase oxides

Type

journal article in Web of Science

Language

English

Original Abstract

Attaining robust magnetic long-range order in ferroelectric Aurivillius-phase oxides at room temperature has recently attracted considerable attention of materials scientists and engineers for the development of magnetoelectric-active materials in microelectronics and spintronics. Here, we report the structural evolution and its relation to the macroscopic magnetization of a series of samples of Aurivillius (Bi4.3Gd0.7)(Fe1-xCox)(1+y)Ti3-2yNbyO15(x= 0, 0.3, 0.5 andy= 0, 0.3) compounds prepared by a solid state reaction, aiming at shedding light on the Co substitution-induced ferromagnetism at room temperature and above. The Co-free composition showed a single-phase four-layered Aurivillius structure (space groupA2(1)am), while the Co substitution was found to give rise to a mixed-layer structure composed of four- and three-layered phases. Rietveld analysis of the synchrotron X-ray diffraction data showed that the reduction in the number of layers across the Aurivillius morphotropic transition boundary is accompanied by a structural phase transformation fromA2(1)amtoB2cb. The disordered intergrowth of these phases was evidenced by high-resolution transmission electron microscopy and found to originate from a nanoscale structural modulation occurring at the interface between the two phases. A sextet suggesting long-range magnetic ordering in the doped samples was deduced from Mossbauer spectra. Magnetic-property measurements, indeed, confirmed a ferromagnetic state of these samples at elevated temperatures. The highest values of the remanent and saturation magnetization at room temperature were obtained for the compositions withx= 0.3, in which the occurrence and enhancement of the magnetization can be attributed to the ferromagnetic clustering of the FeO(6)and CoO(6)octahedra and, partly, also to spin canting effects and/or a double-exchange magnetic interaction between the mixed valence cobalt through oxygen. The cooperative freezing of randomly distributed Fe-O-Co clusters is suggested to be responsible for the spin glass-like behaviour observed at low temperatures. The occurrence and enhancement of the magnetization in the ferroelectric Co-doped Aurivillius ceramics are attributed, respectively, to the structural modulation and the population of the ferromagnetic clusters near the interface of the four- and three-layered phases.

Keywords

ROOM-TEMPERATURE; X-RAY; MAGNETOELECTRIC MEASUREMENTS; MAGNETIC-PROPERTIES; FERROMAGNETISM; BI5FETI3O15; TITANATE; BEHAVIOR

Authors

Koval, V.; Shi, Y.; Skorvanek, I.; Viola, G.; Bures, R.; Saksl, K.; Roupcova, P.; Zhang, M.; Jia, C.; Yan, H.

Released

7. 7. 2020

Publisher

ROYAL SOC CHEMISTRY

Location

CAMBRIDGE

ISBN

2050-7534

Periodical

Journal of Materials Chemistry C

Year of study

8

Number

25

State

United Kingdom of Great Britain and Northern Ireland

Pages from

8466

Pages to

8483

Pages count

18

URL

https://pubs.rsc.org/en/content/articlelanding/2020/TC/D0TC01443E#!divAbstract

BibTex

@article{BUT170355,
  author="Koval, V. and Shi, Y. and Skorvanek, I. and Viola, G. and Bures, R. and Saksl, K. and Roupcova, P. and Zhang, M. and Jia, C. and Yan, H.",
  title="Cobalt-induced structural modulation in multiferroic Aurivillius-phase oxides",
  journal="Journal of Materials Chemistry C",
  year="2020",
  volume="8",
  number="25",
  pages="8466--8483",
  doi="10.1039/d0tc01443e",
  issn="2050-7534",
  url="https://pubs.rsc.org/en/content/articlelanding/2020/TC/D0TC01443E#!divAbstract"
}