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Description
Chemical modifications in the iron site of BiFeO$_3$ represent the direct approach to tune the magnetic behaviour of this material. However, using the conventional synthesis routes, it is possible to achieve the substitution rates of a few atomic percent only. Most of the reported single-phase BiFe$_{1−y}$B$^{3+}_{y}$O$_3$ perovskite compositions with $y > 0.1$ were prepared via high-pressure synthesis.
In high-pressure stabilized perovskite solid solutions of the BiFe$_{1−y}$Sc$_y$O$_3$ system, a series of structural transitions with increasing $y$ was found. Moreover, it was revealed that annealing of the as-prepared perovskite phases results in irreversible transformations into new structural phases with interesting combinations of ferroic orders [1]. In the $0.1 \leq y < 0.3$ range, some peculiarities of the temperature-dependent magnetic moment below $T_N$ were observed and associated with possible transitions between different antiferromagnetic structures corresponding to collinear, canted, and cycloidal spin arrangements [2]. Similar temperature anomalies of the magnetic behaviour below $T_N$ were then revealed in the Fe-rich compositional range of the BiFe$_{1−y}$[Zn$_{0.5}$Ti$_{0.5}$]$_y$O$_3$ perovskites [3].
We present the temperature and compositional behaviours of the crystal structure and the magnetic properties of the BiFe$_{1−y}$B$^{3+}_{y}$O$_3$ perovskites (where B$^{3+}$ = Ga, Co, Mn, Cr, [Zn$_{0.5}$Ti$_{0.5}$] and Sc) in the vicinity of parent bismuth ferrite. Among these, Cr$^{3+}$, Mn$^{3+}$, and Co$^{3+}$ are magnetic cations of transition metals from the same 3d series to which iron belongs, while Ga$^{3+}$, Sc$^{3+}$ and [Zn$_{0.5}$Ti$_{0.5}$]$^{3+}$ are non-magnetic. Besides, as compared with iron, gallium is smaller, scandium is considerably bigger, and [Zn$_{0.5}$Ti$_{0.5}$]$^{3+}$ is slightly bigger than Fe$^{3+}$ in octahedral coordination. The crystal structure sequences, phase diagrams and the $T_N(y)$ dependences are compared and discussed.
References
[1] D. D. Khalyavin et al., “The phenomenon of conversion polymorphism in Bi-containing metastable perovskites,” Chemical Communications, vol. 55, no. 32. Royal Society of Chemistry (RSC), pp. 4683–4686, 2019. https://doi.org/10.1039/c9cc00472f
[2] E. L. Fertman et al., “Magnetic Diagram of the High-Pressure Stabilized Multiferroic Perovskites of the BiFe1-yScyO3 Series,” Crystals, vol. 10, no. 10. MDPI AG, p. 950, Oct. 17, 2020. https://doi.org/10.3390/cryst10100950
[3] A. N. Salak et al., “Magnetic Behaviour of Perovskite Compositions Derived from BiFeO3,” Magnetochemistry, vol. 7, no. 11. MDPI AG, p. 151, Nov. 16, 2021. https://doi.org/10.3390/magnetochemistry7110151
