C,N-codoped MoSi2 ceramic with excellent heat resistance for microwaves absorption application

Microwave absorption (MA) materials with high heat resistance have a wide range of applications in many fields. In this work, a C,N-codoped MoSi2 ceramic was prepared via a facile solid-phase reaction method and its MA properties was investigated. On the one hand, the results indicate that this ceramic possesses excellent heat resistance and the weight of the MoSi2 is almost constant when the temperature is lower than 800°C. On the other hand, this ceramic shows good MA performance when the filler loading ratio increases to 30 vol%, the value of reflection loss (RL) could reach to −17.70 dB at 7.44 GHz with the thickness of 2.0 mm and the effective electromagnetic absorption bandwidth (RL below −10 dB) could reach to 1.88 GHz (9.28–11.16 GHz) with the thickness of 1.5 mm. Multi-polarization resonance loss is considered as the predominant attention mechanism on the MA performance of this MoSi2 ceramic. This research provides a new idea for understanding resonance mechanism and greatly expands the application scope of MoSi2 ceramic in MA area.


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Recommendation?
Major revision is needed (please make suggestions in comments)

Comments to the Author(s)
In this paper, the preparation and properties of C,N-Codoped MoSi2 Ceramic have been studied in detail, and the MA and dielectric properties of MoSi2 Ceramics have been explored.This work is well structured and easy to read, the research objectives and methods are sound, in line with the journal scope of RSOS. The following minor comments might help to improve the quality of the manuscript: 1) 3.2 Synthesis of C,N-codoped MoSi2 Ceramic:"the mixture was heated for 8h at temperature of 80℃","the material was sintered at heating rate of 10℃•min-1 from room temperature to 1400℃" .Please explain the reasons for choosing 80℃、1400℃ and the heating rate. Why not use sectional heating? 2) 4.2 Elemental Composition and Thermal Stability of MoSi2: Compared with pure MoSi2, which element in C,N-Codoped MoSi2 has the greatest influence on its thermal stability? Why doping with C and N? What are the advantages of C and N? 3) 4.3 Dielectric and MA Properties:Temperature has a particularly important effect on the dielectric properties. Therefore, the authors are encouraged to add a short discussion about the relation of dielectric properties of sample and temperature. There are some recent publications recommended to add in the reference section: i. Omran M , Li K , Chen J , et al. Dielectric properties

Decision letter (RSOS-200740.R0)
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Comments to the Author: (There are no comments.) ********************************************** Reviewers' Comments to Author: Reviewer: 1 Comments to the Author(s) This manuscript (ID=RSOS-200740) started a study about C,N-codoped-MoSi2 ceramic was prepared via a facile solid phase reaction method, and its MA properties was investigated. The material can resist high temperature and have proper reflection loss to electromagnetic wave. Comparatively speaking, the composites have potential to be a stable material to weaken the microwave strength. Overall, the manuscript has quite clear layout and is well written. In consequence, I recommend this manuscript for publication in Royal Society Open Science after some minor revisions. 1. The formula of reflection loss should contain magnetic parameter μ, so for non-magnetic samples, it is also necessary to state that μ=1. 2. There are some grammar mistakes and mis-spellings, please check the whole manuscript. 3. On introduction section, the authors should summarize similar reports about materials of microwave absorption to stress their novelty. 4. Theoretically, the value of ε should not be negative, for most occasions it might be the error of vector network analyzer. However, it is mentioned in the manuscript that 25 vol% sample has a potential to be a metamaterial. Why you get this conclusion, as other samples do not have this characteristic? Please give the mechanism explanation.

Reviewer: 2
Comments to the Author(s) In this paper, the preparation and properties of C,N-Codoped MoSi2 Ceramic have been studied in detail, and the MA and dielectric properties of MoSi2 Ceramics have been explored.This work is well structured and easy to read, the research objectives and methods are sound, in line with the journal scope of RSOS. The following minor comments might help to improve the quality of the manuscript: 1) 3.2 Synthesis of C,N-codoped MoSi2 Ceramic:"the mixture was heated for 8h at temperature of 80℃","the material was sintered at heating rate of 10℃•min-1 from room temperature to 1400℃" .Please explain the reasons for choosing 80℃、1400℃ and the heating rate. Why not use sectional heating? 2) 4.2 Elemental Composition and Thermal Stability of MoSi2: Compared with pure MoSi2, which element in C,N-Codoped MoSi2 has the greatest influence on its thermal stability? Why doping with C and N? What are the advantages of C and N?

Decision letter (RSOS-200740.R1)
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Response to editor and reviewers
Dear Editors and Reviewers: Thank you for your letter and for the reviewers' comments concerning our manuscript entitled "C,N-Codoped MoSi2 Ceramic with Excellent Heat Resistance for Microwaves Absorption Application" (ID: RSOS-200740). These comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval.
Reviewer: 1 1. The formula of reflection loss should contain magnetic parameter μ, so for nonmagnetic samples, it is also necessary to state that μ=1.
Response: Thank you for the helpful suggestion. We have supplemented the information of μ in the formula. The changes are marked with " " in the revised manuscript and supporting information.

2.
There are some grammar mistakes and mis-spellings, please check the whole manuscript.
Response: Thank you for reminding. We have tried our best to check the whole paper carefully and correct the grammar mistakes.

3.
On introduction section, the authors should summarize similar reports about materials of microwave absorption to stress their novelty.
Response: Thank you for reminding. More similar reports about materials of microwave absorption was added. The changes are marked with " " in the revised manuscript.

4.
Theoretically, the value of ε should not be negative, for most occasions it might be the error of vector network analyzer. However, it is mentioned in the manuscript that