As economically viable alternatives to lithium-ion batteries, magnesium-ion-based all-solid-state batteries have been researched to meet the criteria for an ideal energy storage device.

No abstract

Polymer (poly(vinylidene fluoride) (PVDF)) nanocrystal composites based on lanthanum nickelate (percolative oxide) and barium titanate were fabricated to obtain material systems with a high dielectric constant and low loss to be used for high-charge-storage applications. Lanthanum nickelate (LaNiO) nanocrystallites were synthesized from a simple citrate-assisted sol-gel route that yielded agglomerated crystallites of an average size of 120 nm. The defective nature of the lanthanum nickelate nanocrystals was revealed by the transmission electron microscopy studies. Hot-pressing method was executed to fabricate the LaNiO/PVDF nanocrystal composites, and their dielectric characteristics showed a low percolation threshold in the region of f (volume fraction of lanthanum nickelate) = 0.10. The percolative conductive filler-polymer nanocrystal composite at the percolation threshold exhibited a dielectric constant (ε) and loss ( D) of 55 and 0.263, respectively, at 10 kHz; the dielectric constant obtained was more than 5 times that of host matrix PVDF. To further improve upon the obtained dielectric properties from the two-phase composites, a high-dielectric-constant material, barium titanate (BaTiO) nanocrystals, with an average size of 100 nm, was embedded in the polymer matrix as the third phase. The dielectric properties of the three-phase nanocrystal composites were measured as a function of the volume fraction of lanthanum nickelate (which was limited within the percolation threshold), and a dielectric constant as high as 90 and the associated loss of 0.13 at 10 kHz were achieved from f = 0.09 and f = 0.20. The obtained dielectric constant from this system is 9 times more than that of PVDF and 3 times that of a two-phase barium titanate/PVDF composite, which proves to be a promising material for charge-storage applications.

Five isomorphous AMVO vanadates of niobium and tantalum, namely, BaNbVO, BaTaVO, SrNbVO, SrTaVO, and PbTaVO, were prepared by solid-state reactions and structurally characterized by single-crystal and powder X-ray diffraction techniques. Barium and strontium compounds, respectively, have centrosymmetric and noncentrosymmetric types of layered structure, wherein [MVO] anionic layers are interleaved with A cations. Both types of layered structure are found for lead compound. The strontium and lead compounds are type I phase-matching materials with second-harmonic-generating efficiencies of 33-50% of LiNbO, and their dielectric properties were evaluated. A three-dimensional structural variant was also identified for strontium compounds, which crystallize in noncentrosymmetric orthorhombic space group C222.

Polycrystalline BiFeO 3 and Bi 0.9 Gd 0.1 Fe 1−x Ti x O 3 (x = 0, 0.01, 0.05 and 0.1) samples were synthesized by solid-state reaction route. Structural, magnetic and ferroelectric properties of these samples were investigated. X-ray powder diffraction (XRD) results confirmed the presence of a significant amount of Bi 2 Fe 4 O 9 impurity phase in the undoped BiFeO 3 sample. Mössbauer spectroscopy studies corroborated the XRD studies to confirm the presence of impurity phase. We have observed that gadolinium (Gd 3+) and titanium (Ti 4+) doping, respectively, on Bi 3+ and Fe 3+ sites facilitated a significant reduction in the impurity phase formation in BiFeO 3. Interestingly, Gd 3+doping significantly reduced the impurity phase formation as compared to the undoped BiFeO 3 sample. This impurity phase formation was further overcome by doping higher (x ≥ 0.05) amounts of Ti in BiFeO 3. The crystallographic site occupancies of Gd and Ti were confirmed by Rietveld refinement of XRD data, Mössbauer spectroscopy and magnetization measurements. An enhancement in ferromagnetic properties along with moderate ferroelectric properties have been observed after co-doping. There was an increasing trend in remnant polarization (P r) with the increase in Ti concentration besides an improvement in the characteristic saturation magnetization. Our results demonstrate that Gd 3+ and Ti 4+ doping could be used to enhance multifunctional properties of BiFeO 3 ceramics to enable them as potential material for various devices.