Search

The lead-free 0.94(Bi0.5Na0.5)TiO3-0.06BaTiO3 (BNT-6BT) at the morphotropic phase boundary (MPB) exhibits exceptional dielectric constant, polarization, and energy storage properties due to its unique arrangement of structural phases and instabilities. In this work, ferromagnetism is introduced into the ferroelectric BNT-6BT matrix by making 0–3 composites with Co0.65Zn0.35Fe2O4 (CZF), i.e., (1-x) BNT-6BT/x CZF, (x = 0.0, 0.25, 0.50, and 0.75). The structural dielectric, energy storage, and magnetic properties of these composites are studied under an Air and Nitrogen (N2) annealing atmosphere. The structural investigation indicates that the pristine BNT-6BT exhibits the coexistence of tetragonal ( P 4 b m ) and rhombohedral ( R 3 c ) phases. In contrast, all the BNT-6BT/CZF composite samples reveal the presence of cubic ( F d 3 ¯ m) phase alongside the tetragonal ( P 4 b m ), and rhombohedral ( R 3 c ) phases. In contrast to the Air-annealed BNT-6BT sample, N2-annealed samples were found to yield a ferroelectric-relaxor crossover followed by a higher dielectric constant (~ 2045), lower tangent loss (~ 0.07), higher polarization maximum (~ 12.31 µC/cm2), higher recoverable energy density (~ 201 mJ/cm3), and higher storage efficiency (~ 99%). Interestingly, N2 annealing induces exotic room-temperature ferromagnetism in non-magnetic BNT-6BT samples. Furthermore, the increase in the CZF doping not only eliminates the depolarization effect but also leads to an increase in dielectric constant (as high as 3919) and saturation magnetization (~ 58 emu/gm). Nonetheless, all the N2 annealing results in enhancement in dielectric constant, lowering of dielectric loss, and increase in Wrec, η, and saturation magnetization as compared to the Air-annealed counterparts. The superior physical properties of N2-annealed samples are ascribed to a substantial increase in the grain and grain boundary barrier properties under N2 annealing. [ABSTRACT FROM AUTHOR]

This work reports the tailoring of optical and magnetic properties in Sb-doped SnO2 nanoparticles (NPs), i.e., Sn1-xSbxO2(x = 0.0, 0.03, 0.06, 0.09) synthesized by gel-combustion technique. The structural properties of these nanoparticles are investigated by the X-ray diffraction (XRD) technique. Detailed structural analysis shows the crystallization of all these NPs in tetragonal rutile structure, as observed in pristine SnO2 without any trace of the secondary phase. Nevertheless, the incorporation of Sb dopant was found to increase the lattice constant systematically. Investigation of surface morphology by scanning electron microscopy and particle size by transmission electron microscopy also indicates a systematic increase in the grain size and particle size with Sb doping. Intriguingly, bandgap and room-temperature ferromagnetism (RTFM) are found to be sensitive to particle size and oxygen vacancies. UV–visible absorption, Fourier transform infrared, photoluminescence, and X-ray photoelectron spectroscopic measurements are carried out to explore the underlying physical mechanisms. Besides, the increase in RTFM and decrease in the bandgap witnessed in Sb-doped SnO2 NPs can be exploited for magneto-optic and spintronic devices. [ABSTRACT FROM AUTHOR]