Influence of processing conditions on the ionic conductivity of holmium zirconate (Ho2Zr2O7)

Abstract

This is a repository copy of Influence of processing conditions on the ionic conductivity of holmium zirconate (Ho2Zr2O7).

Environmentally sustainable facile synthesis of nanocrystalline holmium hafnate (Ho2Hf2O7): Promising new oxide-ion conducting solid electrolyte

“…The values of the activation energies were 1.24 (± 0.01) eV for bulk conductivity and 1.55 (± 0.01) eV for grain boundary conductivity. Details on the ionic conductivity of similar material Ho 2 Zr 2 O 7 synthesised employing LAP has been recently reported by Sardar et al [45] which further supports that Ho 2 Hf 2 O 7 is a promising material for SOFC electrolyte.…”

Microstructure and impedance spectroscopy of high density holmium hafnate (Ho2Hf2O7) from nanoparticulate compacts

“…12 compares the total, bulk and grain boundary conductivity of pellets sintered using SSS and TSS processes. Above comparison suggests that although the SSS processed Ho2Hf2O7 sample exhibits slightly better results than that of TSS processed sample, the difference in the results are insignificant compared to that observed in the case of Ho2Zr2O7 [29] samples synthesised and processed employing similar techniques. This suggests that since the physical properties such as density, grain size and sintering temperatures of samples sintered using TSS process are consistently better than SSS processed samples in most ceramic materials it is better to employ TSS process for processing nanopowders of ion-conducting ceramics for electrochemical applications.…”

“…The complex impedance plots for SSS and TSS processed Ho2Hf2O7 nanopowders exhibit consistent results for both heating and cooling cycles indicating that Ho2Hf2O7 responds reversibly throughout the temperature range of measurements. The values of bulk (1.00⨯10 -4 S.cm -1 ) and grain boundary (4.66⨯10 -5 S.cm -1 ) conductivities of Ho2Hf2O7 pellets prepared using the SSS and TSS process are not distinctly different unlike in the case of Ho2Zr2O7 [29] and therefore the main advantage of TSS process over SSS process for processing the nanopowders of Ho2Hf2O7 is for yielding better physical properties such as lower sintering temperature, smaller grain size and higher density. The magnitude of oxide ion conductivity and the activation energy for various processes (bulk, grain boundary and total)…”

“…We have recently synthesised for the holmium hafnate (Ho2Hf2O7) nanoparticles, with cubic defect-fluorite structure, below 600°C through LAP and reported its structural and morphological properties [27]. We have also reported on the synthesis and characterisation of holmium zirconate (Ho2Zr2O7) [28] and on the influence of processing conditions on ionic conductivity [29]. Holmium zirconate has been shown to be a reasonably good oxide ion conducting solid electrolyte with an activation energy for conduction slightly better than the conventional solid electrolytes such as yttria stabilized zirconia (YSZ) and gadolinium doped ceria (GDC) [30].…”

Dense ceramics with complex shape fabricated by 3D printing: A review

“…Generally speaking, electrolytes are not suitable for SOFC due to void formation, unless the porosity in the electrolyte layers is desirable. This is because the dense electrolyte can not only provide the necessary mechanical support but also promote high ionic conductivity [115]. 3D printing of dense electrolyte can simplify the manufacturing process, avoiding the manual assembly of multiple joints and seals from single cells to SOFC components, and the electrochemical performances of cells with the electrolyte by 3D printing are comparable to those by traditional method.…”