Characterisation of microstructure and hardness of perovskite-structured Ba0.5Sr0.5Co0.8Fe0.2O3− under different sintering conditions

Abstract

Microstructural evolution of Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF) has been investigated using commercial powders sintered at different conditions. All the samples, characterised by the porosity P and grain size D, are determined to be a single cubic phase. The grain growth kinetics is evaluated using D n =tK 0 exp(-Q/RT). Grain boundary diffusion is the dominant controlling mechanism of densification and the Ba/Sr diffusion is the rate-controlling species. Additionally, the Vickers hardness (H V ) of BSCF is measured at ambient condition. The H V is successfully described by an exponential function of porosity, H V = H 0 exp (-bP). The porosity is the dominant factor determining the hardness when it is over 0.06. Otherwise, the Vickers hardness shows a dependence on pore size. Compared with the strong dependence of hardness 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 2 / 21 on porosity, no correlation between hardness and grain size or grain orientation has been found. *Manuscript Click here to view linked References

First-principles calculations to investigate elastic, electronic and thermophysical properties of the Dy2Bi2Fe4O12 ferromagnetic semiconductor

“…This value is 93% in accordance with the value of 7.85 GPa reported for the Ba 2 Sr 2 Co 3.2 Fe 0.8 O 12 perovskite-type material, measured experimentally and extrapolated for the zeroporosity case, as expected for the theoretical calculations performed in the present investigation [48]. The evidently hard character of the material occurs because the existence of mutually perpendicular screw axes together with the symmetry of specular planes favours atomic packing in the crystalline cell.…”

A case study of the effect of Ni substitution on the sintering behaviours of Ba0.5Sr0.5Co0.8Fe0.2O3−δ oxygen transport membranes

“…When the pores are dragged along the grain boundary, it lowers the driving force for grain boundary mobility thereby slowing grain growth [38]. A grain growth exponent greater than two can be related to pores and the impurity contained in materials [26,27]. Therefore, it can be observed in Figure 5 that pores can be the dominant factor for the higher grain growth exponent of BSCF.…”

“…The phase compositions of the BSCF and BSCF–Ni samples were determined by X-ray powder diffraction (XRD; PW1830, Philip, Eindhoven, the Netherlands) with Cu K α radiation (λ = 0.154 nm) coupled with the Rietveld refinement using the Topas software (Bruker). The detail of the Rietveld refinement can be found elsewhere [27]. The densities of the samples were determined from the Archimedes method in distilled water.…”

Exploring the performance of dual-phase oxygen transport membranes for carbon capture purposes

“…Phase structure of the material was determined using X-ray diffraction (XRD) while morphologies were observed using a scanning electron microscope (SEM). Relative density was calculated using Archimedes' method in distilled water (L. Wang et al, 2016;da Conceição et al, 2011).…”