Thermoelectric Properties of Nickel and Boron Co-Substituted NaCo₂O₄ Prepared by Electrospinning Technique

Abstract

In this study nickel and boron doped sodium cobalt oxide NaCo2-xNixByO4 (0≤x≤0.3, 0≤y≤0.1) nanocrystalline thermoelectric ceramic powders were synthesized using electrospinning techniques and then consolidated into bulk ceramics. The differences in the microstructure and thermoelectric properties of the samples as a result of doping effect have been investigated. The crystalline structures of the powders and nanofibers were characterized using X-ray diffraction and scanning electron microscopy and BET Analysis before and after the calcination process at different temperatures. Nanofibers prepared by the use of electrospinning technique, have a diameter of approximately 300 nm, and the diameter of the grains of calcined powders was observed to range between 150 to 500 nanometers. Thermoelectric properties of the bulk ceramics were measured by physical properties measurement system (Lot-Oriel PPMS) in a temperature range of 15–300 K. The calculated values of dimensionless figure of merit at 300 K are 4.25×10-5, 5.3×10-6, 8.6×10-5 and 9×10-6 for sintered powders from undoped, Ni and B doped powders, respectively.

Enhanced thermoelectric properties of lightly Nb doped SrTiO3 thin films

“…For industrial applications and competitive energy conversion ZT $ 1 is considered to be a desirable benchmark. 21,22 Figures of ZT > 1 have already been reported for p-type oxides; 23,24 however, for n-type oxides, ZT barely exceeds 0.5, 25 and this value has only been measured in ZnO ceramics at very high temperatures (T > 1000 K). 26 For STO-based materials, the highest experimental ZT reported to date is 0.46 at T ¼ 1000 K, which was measured in a Pr (5%):Nb (20%)-doped STO superlattice.…”

Synthesis of boron and rare earth stabilized graphene doped polyvinylidene fluoride (PVDF) nanocomposite piezoelectric materials

“…It has been found that the mechanical stretching in the electro‐spinning process is more effective than applied electrical polarization to induce ferroelectric phases . In addition, the advantage of this method over other methods, is making the material more homogeneous, robust and easily preparable .…”

Na site doping a pathway for enhanced thermoelectric performance in Na1−x CoO2; the case of Gd and Yb dopants

“…Given the phenomenal and promising low κ L in Na 1−x CoO 2 , doping has extensively been used to improve the Seebeck coefficient of Na 1−x CoO 2 further with the ambition of bringing its ZT to values above unity [7,8,21,[23][24][25][26][27][28][29][30][31][32]. Nonetheless, dopants have usually been chosen based on the mere nominal oxidation state, atomic mass considerations and the solubility limits of the applied synthesis method [33].…”