• PDF / 1,133,907 Bytes
• 9 Pages / 595.276 x 790.866 pts Page_size
• 4 Downloads / 155 Views

DOWNLOAD

REPORT

---

Oxygen vacancy-dependent multiferroic properties and the valence state of Fe in Bi6-xSmxFe1.4Ni0.6Ti3O18 ceramics prepared by combined combustion method Jianan Lu 1 & Yongjie Yin 1 & Wei Wang 1 & Xiangyu Mao 1 & Xiaobing Chen 1,2 Received: 8 September 2019 / Accepted: 14 May 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020

Abstract Sm-modified Bi6-xSmxFe1.4Ni0.6Ti3O18 (BSFNT- x) ceramics were prepared using the combined conbusiton method to investigate their multiferroic and dielectric properties. It is found that a structural phase evolution from an orthorhombic phase to a tetragonal one and then back to the orthorhombic phase over the doping range. The remanent polarization (2Pr) was increased up to 15.4 μC/cm2 when the Sm content is 0.30, which is attributed to the structural distortion and the oxygen vacancies induced by Sm modification. In the meanwhile, the remanent magnetization (2Mr) was also increased up to 1.9 emu/g in the BSFNT- 0.25 sample. The temperature spectra of the dielectric loss show the characteristics of dielectric relaxation from 120 K to 500 K, which can be ascribed to the electronhopping between Fe3+ and Fe2+ ions. The XPS measurement indicates that a small amount of Sm modification enhances the inhibition of oxygen vacancies. However, the content of Fe2+ ions increases when Sm content is greater than 0.20. Keywords Aurivillius structure . Ceramics . Multiferroic . Oxygen vacancies

1 Introduction Multiferroic materials, which integrate at least two of the orderings among ferroelectric, magnetic and ferroelastic ordering [1–3], can be classified into single phase compounds and composites. Their potential applications in multi-functional multistate RAMs, solid oxide fuel cells, gas sensing, and photo catalysis have high lighted multiferroicity in materials research community [4–8]. Aurivillius phase compoundsare one type of the promising single phase multiferroic materials which have a general chemical formula Am − 1Bi2BmO3m + 3, where A is a large ionic-radius cation such as Na+, Ca2+, Pb2+, and Bi3+, and B is a small ionic-radius cation such as Fe3+, Ti4+, Nb5+, Ta5+ and W6+ [9–13]. In the crystal structure of Aurivillius phase compounds, perovskite blocks (Am − 1BmO3m + 1) of m layers of BO6 octahedra with A-site cations are sandwiched between * Xiangyu Mao [email protected] * Xiaobing Chen [email protected] 1

College of Physics Science and Technology, Yangzhou University, Yangzhou 225002, People’s Republic of China

2

Guangling College, Yangzhou University, Yangzhou 225002, People’s Republic of China

Bi2O2 layers [14, 15]. The Bi2O2 layers are considered to play an important role not only in polarization properties but also in the high durability of memory devices against repeated switching of polarization [16, 17]. In analogy to the formation of multiferroic composites, ferroelectricity is usually induced by the behavior of A-site ions in Aurivillius phase compounds while magnetism is produced by B-site ions with partially filled shells such as Cr3+, Mn3+ and