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

In this work, we have prepared intergrowth of multiferroic compounds namely Bi4RTi3Fe0.7Co0.3O15-Bi3RTi2Fe0.7Co0.3O12-delta (BRTFCO15-BRTFCO12) (rare earth (R) = Dy, Sm, La) by solid-state reaction method. From the X-ray diffraction Rietveld refinement, the structure of the intergrowths was found to be orthorhombic in which satisfactory fittings establish the existence of three-layered (space group: b 2 c b) and four-layered compounds (space group: A2(1)am). Analysis of magnetic measurements confirmed a larger magnetization for theSm-modified intergrowth compound (BSTFCO15-BSTFCO12) compared to Dy- and La-doped ones. The emergence of higher magnetic properties can be due to distortion in the unit cell when some Bi3+ ions are replaced with the Sm3+, bonding of Fe3+-O-Co3+ as well as a possible mixture of FexCoy-type nanoparticles that are formed generally in the synthesis of intergrowths. The changes in the magnetic state of the Aurivillius intergrowths have been reflected in the magnetoelectric (ME) coupling: higher ME coefficient (similar to 30 mV/Cm-Oe) at lower magnetic fields and is constant up to 3 kOe. The results were corroborated by Raman spectroscopy and variation of temperature with magnetization data. The results revealed that the RE-modified intergrowth route is an effective preparative method for higher-layer Aurivillius multiferroic ceramics.

Automated summary

In this study, intergrowth of multiferroic compounds Bi4RTi3Fe0.7Co0.3O15-Bi3RTi2Fe0.7Co0.3O12-delta (BRTFCO15-BRTFCO12) (rare earth (R) = Dy, Sm, La) were prepared using solid-state reaction method. The X-ray diffraction Rietveld refinement revealed orthorhombic structure with three-layered and four-layered compounds. Magnetic measurements showed that the Sm-modified intergrowth compound had a larger magnetization compared to Dy- and La-doped ones. The higher magnetization can be attributed to distortion in the unit cell, bonding of Fe3+-O-Co3+, and possible mixture of FexCoy-type nanoparticles formed during synthesis of intergrowths. The results demonstrate that the RE-modified intergrowth method is an effective approach for preparing higher-layer Aurivillius multiferroic ceramics.