Thursday, 2 June 2022: 15:20
West Meeting Room 208 (Vancouver Convention Center)
Chemical synthesis of ceramic-based MgHf4P6O24 oxide electrolyte was achieved using the sol-gel method [1-3], and this resulted in a considerably low activation energy (Ea = 0.74 ± 0.04 eV) and a promising ionic conductivity in the order of 10-4 Scm-1 at 747 oC. Some dried sample powders of MgHf4P6O24 oxide electrolyte were calcined at a relatively low temperature of 900 oC, the calcined nanopowders were pressed into pellets of 13 mm diameter (Ø) and 3.8 mm thickness with a uniaxial steel die at 5 kN compressive pressure and then sintered at temperature range, 1000 ≤ T(oC) ≤ 1300. In this study, 1300 oC was however adopted as the sintering temperature having achieved optimum density and stable composition. X-ray diffraction reveals a good crystallinity of MgHf4P6O24 phase with an average crystallite size of 20±2 nm at the 800 oC calcination temperature, and this data has been found to be consistent with the TGA-DSC (as presented in Figure 1) and HT-XRD thermal analysis profiles and peaks, respectively. Crystallographic phase analysis of MgHf4P6O24 solid-state electrolyte using rietveld refinement was reported for the first time in this study. Furthermore, the electrical and thermodynamic properties of the MgHf4P6O24 solid-state electrolyte were also measured and reported in this study. Consequently, the average transference number and ionic conductivity data for this chemically stable and highly mobile Mg2+-cations in MgHf4P6O24 solid-state electrolyte measured using the thermo-electrochemical method (EMF approach) is 0.84 ± 0.03 at 700 ± 5 oC and 4.52 x 10-4 Scm-1 at 747 oC, respectively.
References
[1] M. Adamu, and G.M. Kale, The Journal of Physical Chemistry C, 120, 17909-17915 (2016).
[2] G.M. Kale, L. Wang, and Y. Hong, International Journal of Applied Ceramic Technology, 1(2), 180-187 (2004).
[3] M. Adamu, K.T. Jacob, and G.M. Kale, Journal of The Electrochemical Society, 167(2), 027532 (2020).
[4] M. Adamu and G.M. Kale, ECS Transactions, 98(12), 17-38 (2020).
Figure 1. DSC-TGA curves of MgHf4P6O24 dried xerogel powders with a scan rate of 10 oC min-1 in the air [4].