Effects of the Bi3+ substitution on the structural, vibrational, and magnetic properties of bismuth layer-structured ferroelectrics

Magnetic and Magnetoelectric Properties of AurivilliusThree- and Four-Layered Intergrowth Ceramics

“…It is difficult to explain each phonon mode and its overlapping with weak intensity. The detailed phonon modes indicated in Figure 4 are almost well-matched with the literature [29][30][31]. The modes observed at 260 cm −1 (ν3) are attributed to the internal angles torsional bending of (Ti/Fe/Co)O6 bonding.…”

“…They found that the Co-ion substitution in the phase of Fe (for B-site) has shown higher ferromagnetic and magnetoelectric properties [8]. In view of this, many researchers [21][22][23][24][25][26][27][28][29][30][31] are preparing Co/Fe-modified (at B-site) compounds, and therefore intergrowth route is considered to be an effective way to improve ferroic properties, especially in Aurivillius materials.…”

Lead-Free Aurivillius Phase Bi2LaNb1.5Mn0.5O9: Structure, Ferroelectric, Magnetic, and Magnetodielectric Effects

“…Initially, it should be noted that the Bi 3+ and Pb 2+ cations in pristine PbBi 2 Nb 2 O occupy identical positions in the perovskite layer A (1)-site and the Bi 2 O 2 layer A (2)-site due to the stereochemically active 6s 2 lone pair possessed by both cations, which moreover have similar ionic radii. , As deduced above from the Raman spectroscopy analysis, substituting La 3+ for Pb 2+ results in the presence of Bi 3+ only in the Bi 2 O 2 layer, whereas the La 3+ cations are partially found only on the perovskite layer A (1)-site . This preference was also reported in previous studies, where it was argued that the substitution of Ln 3+ cations in the Bi 2 O 2 layer is unfavorable due to the absence of a 6s 2 lone pair. , Therefore, the initial structural model used for Rietveld refinement contained all the Bi 3+ cations on the A (2)-site and all the La 3+ cations on the A (1)-site. The Mn 3+ and Nb 5+ cations were assumed to occupy the perovskite layer B (1)-site with fractions of 25 and 75%.…”

“…16 absence of a 6s 2 lone pair. 26,41 Therefore, the initial structural model used for Rietveld refinement contained all the Bi 3+ cations on the A(2)-site and all the La 3+ cations on the A(1)site. The Mn 3+ and Nb 5+ cations were assumed to occupy the perovskite layer B(1)-site with fractions of 25 and 75%.…”

“…Furthermore, the existence of unpaired d -electrons often leads to significant electrical conductivity, degrading the ferroelectric properties. − Therefore, new routes are necessary to retain the ferroelectricity, possibly achieved by substituting different A - and B -site cations. Previous reports have demonstrated that substituting lanthanide ions (Ln 3+ ) on the A -site improves the ferroelectric polarization of Aurivillius compounds because oxygen vacancies are minimized and leakage currents are reduced. , The substitution of Ln 3+ ions with smaller ionic radii was also found to reduce the distance between the exchange-coupled magnetic ions via deviation of the B –O– B bond angles from 180°, thus improving the ferromagnetic properties. − Therefore, simultaneously substituting La 3+ for Pb 2+ on the A -site and Mn 3+ for Nb 5+ on the B -site in PbBi 2 Nb 2 O 9 is one potential way to design a new multiferroic Aurivillius phase.…”