Magnetic Diagram of the High-Pressure Stabilized Multiferroic Perovskites of the BiFe1-yScyO3 Series

Abstract

Magnetic properties of the high-pressure stabilized perovskite BiFe1-yScyO3 phases (0.1 ≤ y ≤ 0.9) have been studied by means of magnetization measurements and neutron diffraction. The metastable perovskites of this series undergo irreversible polymorphic transformations upon annealing, the phenomenon referred to as conversion polymorphism. It has been found that the solid solutions with y ≥ 0.70 exhibit no long-range magnetic ordering regardless of their polymorph modification, while those with y ≤ 0.60 are all antiferromagnets. Depending on the scandium content, temperature and structural distortions, three types of the antiferromagnetic orderings, involving collinear, canted and cycloidal spin arrangements, have been revealed in the phases obtained via conversion polymorphism and the corresponding magnetic phase diagram has been suggested.

Spontaneous and Induced Ferroelectricity in the BiFe1−xScxO3 Perovskite Ceramics

“…Obtained results together with data of earlier magnetic studies [ 15–17 ] confirm the true multiferroic character of the BiFe 1− x Sc x O 3 solid solutions. The BFSc30 composition is of particular interest.…”

“…Annealing was conducted at 870 K for 4 h. The phase content and structural parameters of the samples were controlled by XRD and neutron diffraction, as described in other studies. [14][15][16][17][18] Before the PFM measurements, one side of the plate-shaped sample was polished. The opposite side was electroded with silver paste.…”

“…For the BiFe 1Àx Sc x O 3 system, a systematical study of the structure and magnetic properties was conducted for the entire concentration range. [14][15][16][17][18] The compositions with 0 ≤ x ≤ 0.25 as High-pressure synthesis method allows obtaining single-phase perovskite BiFe 1Àx Sc x O 3 ceramics in the entire concentration range. As-prepared compositions with x from 0.30 to 0.55 have the antipolar orthorhombic Pnma structure but can be irreversible converted into the polar rhombohedral R3c or the polar orthorhombic Ima2 phase via annealing at ambient pressure.…”

Suppression of the Cycloidal Spin Arrangement in BiFeO3 Caused by the Mechanically Induced Structural Distortion and Its Effect on Magnetism

“…The latter sample does not show the hysteresis behavior (see our previous work (Da Silva et al, 2011)), whereas the asprepared material exhibits extraordinarily high values of coercive field (H c ∼ 0.71 T at 5 K, H c ∼ 1.1 T at 300 K) and remanent magnetization (M r ∼ 0.15 emu/g at 5 K, M r ∼ 0.13 emu/g at 300 K) (see Table 3 and Figure 7). Note that values of these quantities for the as-prepared ferrite are significantly larger than those observed for the doped BiFeO 3 with the consequently "chemically" induced structural distortion (Mao et al, 2016;Sharma et al, 2019;Fertman et al, 2020).…”

“…It is known that the particle size reduction of BiFeO 3 below the typical period length of ∼62 nm can lead to the suppression of its spiral spin structure, resulting in the ferromagnetic behavior of the nanomaterial (Mazumder et al, 2007;Park et al, 2007;Zhong et al, 2010;Castillo et al, 2013;Huang et al, 2013;Landers et al, 2014;Li et al, 2019). Additionally, the destruction of the cycloidal spin arrangement in BiFeO 3 can be induced by the crystal lattice distortion provoked by atom doping (Widatallah et al, 2014;Mao et al, 2016;Ting et al, 2017;Godara et al, 2018;Sharma et al, 2019;Xian et al, 2019;Dubey et al, 2020;Fertman et al, 2020;Sánchez-De Jesús et al, 2020). The present work gives evidence of the fact that the suppression of the cycloidal spin configuration in BiFeO 3 with the average particle size exceeding λ can also by caused by the mechanically induced crystal lattice distortion.…”