Phase Behavior and Defect Structure of HoBaCo2O6-δ
, Dmitry S. Tsvetkov *, Ivan L. Ivanov, Dmitry A. Malyshkin, Vladimir V. Sereda and Andrey Yu. Zuev
Round 1
Reviewer 1 Report
The authors studied the phase behavior and defect structure of double perovskite HoBaCo2O6-x via thermogravimetric and flow reactor methods in the intermediate-temperature range of 573-773 K. The results are interesting but several issues should be solved to further improve the quality of the manuscript.
1. In the introduction part, the lanthanide contraction and gadolinium break phenomena for lanthanides are important to modulate the oxygen vacancies in the double perovskites RBaCo2O5.5+x. Besides, due to the tunable oxygen vacancies in this system, double perovskites have also been used in many catalysis fields, such as room-temperature electrochemistry and water treatment (DOI: 10.1016/j.apcatb.2021.120463). The phase transition of double perovskite and single perovskite for RBaCo2O5.5+x is also reported (DOI: 10.1039/C9TA06020K). These points are necessary to describe the feature, development and application of this system. The authors should mention these points combining above references.
2. The goodness of XRD fitting should be given. The obtained structure can be draw in the inset of the XRD fitting for better understanding the double perovskite. Also, the software of XRD refinement should be pointed out.
3. For material-based research, basic characterizations such as SEM and TEM should at least be conducted and analyzed.
4. The statement of “three phase transitions in the temperature range 298-773 K” is not clearly proven and XRD should be also measured in the temperature range 298-773 K.
Minor editing of English language required
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The authors presented a well-organized draft and would recommend to include after the following comments.
1. Is the structural transformation reversible?
2. I would advise the authors to take the DSC reverse swipe (high temperature to low temperature ).
3. Can the authors show the morphological and elemental characterization( SEM, EDS) at different temperatures?
4. I don't see any temperature-dependent XRD to support the structural transition claim
5. The thermal stability (TGA) must be included in the revised article.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The revised version can be accepted.
Reviewer 2 Report
The present version of the manuscript is acceptable and the authors have addressed all the issues.
