Synthesis, Characterization, and Electromagnetic Wave Absorbing Properties of M12+–M24+ Substituted M-Type Sr-Hexaferrites
Round 1
Reviewer 1 Report
Title of the reviewed article: Synthesis, characterization, and electromagnetic wave absorbing properties of M12+-M24+ substituted M-type Sr-hexaferrites
The present article is very interesting and summarizes information on several important analyses of tested materials that are promising in the field of EM absorbers. The analyses of material parameters are suitably complemented by SEM images and the article may be useful for the researchers in this field to direct further research. There are only a few weaknesses in the manuscript that need to be corrected before publication. However, these are mostly just formalities requiring only minimal changes in the actual version of the article. All my comments are summarized in the following points.
• "Electromagnetic wave (EM)" on line 13 (in the abstract) and "electromagnetic (EM) wave" on line 34 (in the introduction) - in the following context, the correct placement of the abbreviation is in the second case.
• The text "...related to the magnetic anisotropy field (Ha)" - specifies Ha as the magnetic field, whereas Ha is the magnetic field intensity.
• It would be useful to better define the samples for permeability/permittivity measurements.
• Within the Materials and Methods chapter, the preparation of the tested materials is only very briefly described. It would be useful to provide more specific information on the differences in the mix of raw materials when preparing different representatives of M-type Sr-hexaferrites.
• The text "...closely related to the imaginary part of the permeability (μ"). The magnetic loss (μ") of hexaferrites increases" two parameters with the same symbol are mentioned. The meaning is the same, but the labeling needs to be better specified. On line 125 it is not necessary to redefine the parameter μ' and only the full name or symbol can be used.
• On lines 64 to 66 it would be possible to consolidate the information on the supplier of the compounds in a shorter text (chemical compounds are supplied by only two manufacturers and always in the same purity).
• The text break between lines 90 and 100 is longer than one page and the reader slightly loses continuity - it would be useful to finish the sentence before the long text break. The same problem occurs on lines 152 and 163.
• The detail of the XRD patterns in Figure 1c is difficult to read (large difference between the font size in the base image and in the crop). I would enlarge the image (overlapping the frame of figure 1c) or present it separately with a description of the peak shift.
• Instead of "% changes" I prefer the verbal description "percentage change".
• The authors list "f > 1 GHz" on line 133 and "f (≤ 18 GHz)" on line 136 - I would unify the use of parentheses.
• In Figure 3f it is not clearly visible that μ" is plotted on the y-axis and I would increase the readability of the values on the x-axis.
• On lines 166 and below, reference is made to Fig. 4 and the label Fig. 3 is used.
• In the caption of Table 2, "...real (ε') and imaginary (ε") parts of permittivities at 1 GHz (ε'), ..." is probably used in addition to "(ε')" after 1 GHz.
• In the case of the description of the trend of the imaginary component of the complex permittivity, it is not appropriate to state that it is close to zero, but that it is, e.g., in the tenths, hundredths or lower orders (line 213).
• In the caption of Figure 8, "SrFe12-2xZnxZrxO19 (x = 0.6, 0.7, 0.8, 0.9, 1.0, 1.1)" is shown, while no curve is given for x = 0.6.
Comments for author File: 
Comments.pdf
Author Response
Thanks for the professional reviews. Please refer to the attached file.
Author Response File: Author Response.pdf
Reviewer 2 Report
The manuscript of Kim and Kang describes a very systematic and carefully performed study of a series of Mn-Ti, Zn-Ti, and Zn-Zr substituted M-type Sr-hexaferrites, which included synthesis, crystal structure and high-frequency properties determination and analysis. In general, this investigation was done very comprehensively and in a very systematic way. Conclusions are well-supported by experimental results. Even if from my perspective there is no breakthrough in this study, it deserves to be published in Appl.Sci.
Author Response
Thank you for your deep understanding and positive review of our research. Typos were corrected through the manuscript.
Reviewer 3 Report
In the paper "Synthesis, characterization, and electromagnetic wave absorbing properties of M12+-M24+ substituted M-type Sr-hexaferrites" the authors propose 3 substitution for M-type Sr-hexaferrites. The obtained materials were characterized and parameters like: permittivity, permeability, reflection loss, EM absorption were reported.
Comparing the 3 hexaferrites synthetized they showed that Zn-Zr substitution was the most effectively in decreasing the intrinsic property of the magnetocrystalline anisotropy.
The results are well reported and considering that the Zn-Zr substitution was the first time reported, one can say that the findings are promising for future development in the field. The paper can be considered for publication
Author Response
Thank you for your deep understanding and positive review of our research.
Reviewer 4 Report
The manuscript deals with measurements of EM-absorption properties of Mn-Ti, Zn-Ti, Zn-Zr "doubly-substituted" M-type Sr-hexaferrites. The authors perform standard measuremens of the permeability and permittivity, determining numerically values of the reflection loss (a characteristic of the absorption efficiency) within a well established program. They obtain the absorption characteristics in a wide range of frequencies (X band and Ku band).
In my opinion, because of the presence of a large number of data on the hexaferrite absorbers available in the literature, the paper suffers from lack of a systematic comparison of the obtained absorption properties to the relative materials, M-type hexaferrites and W-type hexaferrites, and most importantly, to the Co-substituted Sr-hexaferrites mentioned in the Introduction, whose replacement has motivated the work. It makes the assessment of the achievable characteristics, thus, the usability of the studied materials difficult for the reader. I suggest elaborating the result or/and the conclusions sections in order to convince the reader about the importance of the reported achievement. Such a comparison is needed, even, if the only advantage of the research is a reduction of the cost of the material.
Remark:
the name of the second author is incomplete.
Author Response
Thank you for your deep understanding and positive review of our research. I understand your suggestion. However, we'd like to ask your kind understanding that we cannot respond to your suggestion due to the limitations of our current time and capabilities.
Reviewer 5 Report
Detailed comments and advices are listed below:
(1)
It is suggested that the author make an in-depth analysis of this background and elicit scientific questions. The point is to clarify the importance and value of the text. Related literature, ADV. FUNCT. MATER., 2021, 31, 2100470; MATER. SCI. ENG. R-REPORTS, 2021,145, 100627.
(2)
Please further explain the meaning of the XRD diagram, emphasizing important results or rules.
(3)
If the new method is not used in the preparation of the material, please provide references. (4) Please explain the role of the two heating processes in the material.
(5)
The author said: "This μ' spectral transition (f <1 GHz) is associated with magnetic domain wall motion.", please provide relevant references.
(6)
The author did not give the reflection loss and SEM images other than the Zn-Zr substitution sample, which makes the title inconsistent with the content, please give reasons.
(7)
Whether Table 1 is important for material characterization or microwave absorbing performance, please give its meaning.
(8)
In Fig. 3 and Fig. 6, please give a linear horizontal axis to clearly see how the curve changes in the X-band and Ku-band.
(9)
Please provide more mechanism explanations for the absorbing performance of the material, and please give a graph of the change of the absorbing performance of the material with the value of "x" under the same thickness.
(10)
Please check the reference format, for example: the period is missing at the end of reference number one. References are old, please cite more new ones.
(11)
The author should check and correct some description errors in the manuscript, such as: "(g-h)" in the caption of Fig. 4 should be replaced with "(f-h)"; the author said: "SEM-BSE (back scattered electron) images of the x = 1.0, 1.5, and 2.0 samples are shown in Figs. 3(f)–3(h)”, but in fact the SEM-BSE images is shown in Fig. 4.
(12)
Wave attenuation and energy conversion need to be detailed, related literature, CARBON, 2010, 48, 788-796; ADV. MATER., 2014, 26, 3484-3489; SMALL, 2018, 14, 1800987.
Author Response
Thank you very much for your positive review on our paper and meticulous and accurate comments. It was a great help.
Please refer to the attached file.
Author Response File: Author Response.pdf
