Lead-Free BNT–BT0.08/CoFe2O4 Core–Shell Nanostructures with Potential Multifunctional Applications

Abstract

Herein we report on novel multiferroic core–shell nanostructures of cobalt ferrite (CoFe2O4)–bismuth, sodium titanate doped with barium titanate (BNT–BT0.08), prepared by a two–step wet chemical procedure, using the sol–gel technique. The fraction of CoFe2O4 was varied from 1:0.5 to 1:1.5 = BNT–BT0.08/CoFe2O4 (molar ratio). X–ray diffraction confirmed the presence of both the spinel CoFe2O4 and the perovskite Bi0.5Na0.5TiO3 phases. Scanning electron microscopy analysis indicated that the diameter of the core–shell nanoparticles was between 15 and 40 nm. Transmission electron microscopy data showed two–phase composite nanostructures consisting of a BNT–BT0.08 core surrounded by a CoFe2O4 shell with an average thickness of 4–7 nm. Cole-Cole plots reveal the presence of grains and grain boundary effects in the BNT–BT0.08/CoFe2O4 composite. Moreover, the values of the dc conductivity were found to increase with the amount of CoFe2O4 semiconductive phase. Both X-ray photoelectron spectroscopy (XPS) and Mössbauer measurements have shown no change in the valence of the Fe3+, Co2+, Bi3+ and Ti4+ cations. This study provides a detailed insight into the magnetoelectric coupling of the multiferroic BNT–BT0.08/CoFe2O4 core–shell composite potentially suitable for magnetoelectric applications.

Synergistic magnetoelectric enhancement in 0–3 particulate multiferroic composites: unveiling the exceptional interplay of Ba0.85Sm0.15TiO3 and Co0.85Sm0.15Fe2O4 phases for superior energy conversion

“…The peaks at 457.9 and 463.71 eV, which correspond to Ti 4+ , are attributed to Ti 2p 3/2 and Ti 2p 1/2 , respectively. 37 The Ba 3d level consists of two peaks, Ba 3d 3/2 and Ba 3d 5/2 , with binding energies of 794.81 and 779.45 eV, respectively, and a peak difference of 15.36 eV, indicating that both barium atoms are in the Ba 2+ state. 38 It has been observed that the oxygen-deficient area is associated to the peak for O 1s spectra between 529.38 and 532.24 eV.…”

Variable Dielectric and Ferroelectric Properties in Size-Controlled Cobalt Ferrite

“…Nanomaterial is the heart of nanotechnology which can offer benefits of remarkable relative surface area and ultra-small size. These features assist in attaining excellent electrical, mechanical, optical, magnetic properties, and chemical reactivity [1][2][3][4][5]. Among nanoparticles, synthesis of spinel-type ferrite structures has gain immense attention in recent years in the field of ceramics.…”

“…These nano-spinel ferrites are attractive because of remarkable electrical as well magnetic characteristics, which are relatively less in their bulk counter parts. Consequently, they are exciting because of characteristics as well as potential ability in the areas of semiconductor technology, biotechnology, and medical facilities [1][2][3][4].…”

“…CoFe 2 O 4 nanoparticles (CFNPs) exhibit electric nature because of manifestation of dipoles via transferring of charges among multivalent Fe ions. These CFNPs parade robust structure stability and is vital for device applications [1,[7][8][9].…”

“…The synthesis of CFNP with essential physical characteristics and constituent reactivity play key role in devices. Over the last two decades, different methods like co-precipitation, sol-gel, and auto-combustion have evolved for preparation of CFNPs [1,[7][8][9]. In all these methods, by controlling the mixing extent, homogenoussized particles can be prepared.…”