Influence of Synthetic Conditions on the Crystal Structure, Optical and Magnetic Properties of o-EuFeO₃ Nanoparticles

Round 1

Reviewer 1 Report

The manuscript titled “Influence of synthetic conditions on the crystal structure, optical and magnetic properties of o-EuFeO₃ nanoparticles” by Tien et al. explores the crystal structure and related physical properties of EuFeO₃ nanoparticles synthesized using the co-precipitation method with various precipitating agents. The authors have conducted thorough characterization and made notable discoveries regarding the sample's magnetism. However, the manuscript lacks a central idea to captivate readers' interest. Therefore, I recommend that the authors consider revising the writing style or rearranging the content of the article to enhance its appeal before publication.

Please consider the following specific comments for revision:

1. The optimal annealing temperature has been determined as 850 ℃, rendering much of the content in Figures 1-3 suitable for the supporting file. Focusing on the differences in structure and temperature stability between S1 and S2 samples at 850 ℃, as depicted in Figures 4-7, would be sufficient.

2. The synthesized sample demonstrates relatively high magnetic Ms values compared to similar systems, as indicated in Figure 7. The entire paper should be organized around this central finding. The authors should reference recently published work on significantly enhancing the ferromagnetism of EuFeO3 (Nano Letters, 2023, 23, 1273−1279) for relevant ideas.

3. The sentence "The results show that sample S.1 has slightly better magnetic properties than sample S.1" on page 8 is written incorrectly and should be revised accordingly.

Please consider the improments to the writting and double-check for grammar errors.

Author Response

Dear Reviewer 1,

I would like to send you our responses based on your comments.

Thank you for your time and your consideration.

Best Regards 

Author Response File: Author Response.docx

Reviewer 2 Report

This paper concern with synthesis, characterization of EuFeO₃ nanoparticle by co precipitation method using two different participation agents. The samples were annealed at different temperature 750-950 C and characterized using XRD, UV, TEM…etc. The paper is well arranged deals, however the the observed result and its relation with sample microstructure should be further explained. The paper can be published after mending the following comments. 

Comments:

1-     Please indicate what do you mean by stable in the abstract line 22. As I can see from table S1 the lattice parameters have been changed with increase of annealing temperature. What is the microstrain of the samples from Rietveld analysis?

2-     Please indicate how the optical absorption was taken?

3-     What is the space group of used reference ICDD in the XRD analysis to match O-EuFeO3?

4-     Please rewrite sentence line 148-153 as the statement looks wrong and don't follow the result in figure2b

5-     Please explain more about the optical properties of the materials? why S1 has smaller E_g than sample 2? What is the relation between E_g and sample microstructure such as microstrain?  

The authors may refer to latest publication (Results Phys. 36 (2022) 105446. doi.org/10.1016/j.rinp.2022.105446 & J. Phys. Condens. Matter. 32 (2019) 35810. https://doi.org/10.1088/1361-648x/ab4845.)

6-     Could the author add more discussion in section 3.2 and compare their results with other literature.

Author Response

Dear Reviewer 2,

I would like to send you our responses based on your comments.

Thank you for your time and your consideration.

Best Regards 

Author Response File: Author Response.docx

Reviewer 3 Report

In this manuscript entitled "Influence of synthetic conditions on the crystal structure, optical and magnetic properties of o-EuFeO3 nanoparticles",  the magnetic, optical, and physicochemical characteristics of o-EuFeO3 nanoparticles have been investigated by means of EDXS, PXRD, TG/DSC, FTIR, TEM, UV-Vis DRS, and VSM.

The authors have found that the o-EuFeO3 nanoparticles reveal a homogeneous distribution of the main elements.The synthesized powders are low-bandgap materials with Eg of 2.31 - 2.39 eV and these nanoparticles show the soft magnetism and superparamagnetic behavior. 

Generally, the present work shows some important results, but some issues need to be addressed before acceptance.

1. Two very recently updated articles  [such as Yan Wang et al., J. Appl. Phys. 132, 183907 (2022); Bojun Zhao et al., Materials 2023, 16, 75] related to the magnetic properties of magnetic oxides should be cited in the introduction or discussion part. These references have detailed structural measurements (e.g. XRD, SEM and EDS, etc) and magnetic characterizations (e.g. MT curves and MH loops, MCE effects, etc).

2. “...where 0.94 is the Scherrer constant for spherical particles...”. 0.94? please re-check it.

3. The results of EDXS are suggested to be provided in this paper.

4. “...the synthesized o-EuFeO3 powders possess soft magnetism and appear to behave as a superparamagnetic material [19,26,36]...”. From Figure 7, it may be superparamagnetic and cannot be determined to be superparamagnetic (as this phenomenon can also occur in paramagnetic materials). Further clarification is needed.

5. There are references [35-36] in the article, but only [1-34] appears in the references part.

Minor editing of English language required

Author Response

Dear Reviewer 3,

I would like to send you our responses based on your comments.

Thank you for your time and your consideration.

Best Regards 

Author Response File: Author Response.docx

Reviewer 4 Report

I have the following comments for the authors:

1: In abstract: Please refrain from using such statements as “To contribute to the discovery of new properties...........”. Please rewrite the abstract in such a way that it tells about the main results reported in the manuscript, not about what characterization has been done in the manuscript.

2. Page-04, line-144: why the fitted word has been used here! Since no Rietveld fitting has been shown here, so I think the fitted word must not be used.

3: Page-05, line-193: How did authors calculate the average particle size, as it is not possible to clearly see them in TEM images? I would recommend removing the particle size histogram, Fig-4 C, & d, from the manuscript as these particles are agglomerated.

4: In the magnetic part:  from the MH curve it is evident that these nanoparticles are showing a paramagnetic character, therefore mentioning their HC, Mr, and Ms values is not correct. Consequently, the discussion about the magnetic properties needs to be re-write.

5: also, there are mistakes in referencing, they have cited ref. No. 35 and 36 (page-08, lines 244, & 249) in the manuscript but they are not there in the manuscripts reference section!

NA

Author Response

Dear Reviewer, 

We are carefully revised our manuscript.

We hope that the revised manuscript will be suitable for your journal.

Many thanks.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors have appropriately addressed my concerns. Based on the revisions made, I would recommend the publication of this paper in the Coatings journal.

Author Response

Dear Reviewer 1,

We would like to send you our response.

Thank you for your time and your consideration.

Author Response File: Author Response.docx

Reviewer 3 Report

The paper has been improved and can be accepted.

Author Response

Dear Reviewer 3,

We would like to send you our response.

Thank you for your time and your consideration.

Author Response File: Author Response.docx

Reviewer 4 Report

I have this comment for the author:

 In the magnetic part: from the M-H curve it is evident that these nanoparticles are showing a paramagnetic character, therefore mentioning their H_c, M_r, and M_s values is not correct.

In the present case, it is not appropriate to mention the saturation magnetization, as there is no saturation (obvious for the MH curve), therefore their H_c, M_r, and M_s values MUST BE omitted from the discussion, along with the table containing these values. also, the authors keep on mentioning the super-para-magnetism, if so would have been the case, the MH curve should have shown a well-known S-shape.

Please cite & refer to this paper or any other reference from the literature for how superparamagnetic particles MH curve should look like.

[https://doi.org/10.1021/acs.jpcc.1c01606,     J. Phys. Chem. C 2021, 125, 10693−10707]

Thanks.

NA

Author Response

Dear Reviewer 4,

We would like to send you our response.

Thank you for your time and your consideration.

Author Response File: Author Response.docx