Controlling grain boundary segregation to tune the conductivity of ceramic proton conductors
Comments
Thank you very much for sharing your research. I have several comments regarding it: 1. You stated that ‘while the bulk conductivity remains relatively constant’, but Fig. 1e shows that the bulk conductivity also varies, by ~5 – 7 times. Perhaps it would be better to give possible reasons for these variations. 2. The mean grain size as a function of sintering temperature or annealing time would be welcome. 3. “size after the highest thermal treatment (+1600 °C) is still at 320 ± 172nm” what is an accuracy of the deviation presented? 320± 170 nm can be a better choice. 4. Fig. 3 g is amazing 5. We have been dealing with Y-doped Ba(Zr,Ce)O3 for a long time (http://dx.doi.org/10.1016/j.jpowsour.2014.09.116, http://dx.doi.org/10.1016/j.jpowsour.2014.12.024, http://dx.doi.org/10.1134/S1063783415020250, https://doi.org/10.1016/j.scriptamat.2015.07.012, https://doi.org/10.1016/j.jpowsour.2017.09.021). Under inappropriate sintering regimes for these materials, Y2O3 as a micro-scale phase was very often formed in triple junctions. However, when we completely replaced Y3+ with Yb3+, no Yb2O3 was observed in any of the experiments. This might indicate that Y and Yb have different segregation energies. Could you please give more details on this aspect (segregation energy differences of Y and Yb)? 6. If Y2O3 was formed in some experiments, this phase can be easily detected via EBSD. Have you tried to find it?