A Novel Class of Multiferroic Material, Bi₄Ti₃O₁₂·nBiFeO₃ with Localized Magnetic Ordering Evaluated from Their Single Crystals

Abstract

Novel multiferroic materials have attracted increasing attention in recent years. Aurivillius bismuth‐layer structured Bi4Ti3O12·nBiFeO3 (BTFO: n = 1–3, 5) compounds with potential multiferroic properties are such a compound. However, the data on these BTFOs are ambigious, inconsistent, and incomplete. Therefore BTFOs were grown into single crystals for a systematic evaluation. Their crystal structures and microstructures show that intergrowth of layer structure occurs easily in this class of material. Their ferroelectric measurements show strong anisotropy and dielectric peaks at high temperature, accompanied by an abnormal loss that corresponds to their polar phase transition. At room temperature, ferroelectric hysteresis loops were successfully measured; the loops show a strong dependence in their polarization and coercive field on different values of n and anisotropy. Magnetic measurement shows that all the single crystals display magnetic transitions at high temperatures and weak ferromagnetism at room temperature. Electron spin resonance (ESR) results show the coexistence of ferromagnetic and paramagnetic signal components in all the compounds. Scanning probe microscope measurements show magnetic domains switched together with electric domains by use of an electric field. Therefore we conclude that overall spin disorder with localized order is the character of this class of material, with observed magnetoelectric (ME) coupling. This work could also point the way to novel multiferroic materials in locally magnetic ordered systems.

Evaluating the Band Gaps of Semiconductors by Cataluminescence

“…The XRD patterns of the as-prepared film BFTO- n ( n = 1, 2, 3) indicated that the materials show a single Aurivillius phase. With the increase of n , the peaks at ∼30.3 and ∼32.8° shifted to the opposite direction, which is consistent with the results reported in the previous literature . Besides, the EDS patterns of Bi 4+ n Fe n Ti 3 O 12+3 n ( n = 1–4) are shown in Figure B in order to analyze the elemental content and distribution, and corresponding elemental analysis results are shown in Table S1 and Figure C, which proved that the atomic ratio of Bi, Ti, Fe, and O is almost identified with that added in the synthesis process.…”

“…With the increase of n, the peaks at ∼30.3 and ∼32.8°shifted to the opposite direction, which is consistent with the results reported in the previous literature. 41 Besides, the EDS patterns of Bi 4+n Fe n Ti 3 O 12+3n (n = 1−4) are shown in Figure 1B in order to analyze the elemental content and distribution, and corresponding elemental analysis results are shown in Table S1 and Figure 1C, which proved that the atomic ratio of Bi, Ti, Fe, and O is almost identified with that added in the synthesis process. Further, elemental mapping patterns for BFTO-1 are presented in Figure 1D−H, which shows the uniform distribution of the elements Bi, Fe, Ti, and O.…”

Progress and Perspectives on Aurivillius-Type Layered Ferroelectric Oxides in Binary Bi4Ti3O12-BiFeO3 System for Multifunctional Applications

“…More importantly, this individual single-crystalline nanoplate can verify intrinsic FM and FE properties of Aurivillius-type BFTO-n compounds [59]. Apart from the nano-crystals, single crystals of the BFTO-n were grown by using modified micro-pulling down method [60]. The growth system uses mirror halogen lamps and a Pt tube, and the type of heater lamp, tube diameter, heating power, molten zone properties, and rotation speed are key factors and should be adjusted for different crystal types.…”

“…In the last decade, numerous pieces of research focused on the BFTO-n with integer n, for example, Bi 5 FeTi 3 O 15 , Bi 6 Fe 2 Ti 3 O 18 , and Bi 7 Fe 3 Ti 3 O 21 . The reported studies have mainly embodied two aspects: (i) doping ions into A-sites [19][20][21][22][23][24][25][26][27][28][29] and/or substituting magnetic transition ions into B-sites [30][31][32][33][34][35][36][37][38][39][40][41][42][43] inside the layered perovskite structure to realize a significant enhancement in the multiferroic performances, and (ii) controllable synthesis of materials in ceramics [44][45][46], thin films [47][48][49][50][51][52], nano-crystallines [53][54][55][56][57][58] and single crystals [59][60][61] to observe the growth process [62][63][64]…”

Synthesis, optical, and magnetic properties of six‐layered Aurivillius bismuth ferrititanate

“…The Aurivillius layers (Bi 2 O 2 ) 2+ and distorted perovskite slabs produce great polarization in the structure . The most well‐known Aurivillius oxides are BiFeO 3 and Bi 4 Ti 3 O 12 . The combination between BiFeO 3 and Bi 4 Ti 3 O 12 results in different Aurivillius phases, which is denoted by Bi n+1 Fe n−3 Ti 3 O 3n+3 (n ≥ 4) .…”