Microwave-Assisted Hydrothermal Synthesis of Hydroxyapatite Flakes as Substrates for Titanium Dioxide Film Deposition
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis manuscript presents the synthesis of hydroxyapatite (HAp) flakes via a microwave-assisted hydrothermal method. These flakes were then used to make a substrate for depositing titanium dioxide (TiO2) films using chemical vapor deposition with metal–organic precursors (MOCVD).
Although the goal of this research is well oriented, the experimental and discussion parts lack some serious factors. Please address the following issues. Once these issues are rectified, the manuscript is acceptable for publication.
1. The following sentence is not clear. What is meant by “when leaving the MW oven? Please rephrase the sentence.
Hydroxyapatite flakes are obtained depending on the amount of glutamic acid used in the synthesis process and the filtering of the sample when leaving the microwave oven.
2. The experimental part needs some additional information.
Authors wrote:
“The next step was to deposit the TiO2 thin films on the HAp flakes using the metal–organic chemical vapor deposition technique (MOCVD) [12].”
Although reference [12] is given, please briefly mention what steps were taken after the deposition of TiO2. Was the HAp/TiO2 film subjected to annealing after the deposition?
3. In the abstract authors wrote: “These flakes are intended for use as substrates. Please explain how hydroxyapatite (HAp) substrates was prepared. Bare flakes alone cannot provide a good support as a substrate.
4. HAp/TiO2 film must have been deposited on some other substrate. Table 1 shows the Substrate Temperature as 500 oC. More information is needed here.
5. Authors wrote:
“(HAp/Ti) composite material. Specifically, we aim to investigate crystalline hydroxyap- 62 atite flakes as an efficient substrate for titanium dioxide coatings. Furthermore, we suggest 63 innovative uses for the HAp/Ti composite material, thereby contributing to the develop- 6”
In some places authors wrote HAp/TiO2 and in some places HAp/Ti. Why this inconsistency?
6. I noticed crystallite size of HAp and TiO2 are not given. By looking at the fatty peaks of XRD in figure 2(b), it is possible to calculate the size of TiO2 nanocrystals at least.
7. The following sentence is bit confusing.
“To obtain the elemental composition of HAp/TiO2 powders, an Electronic….”.
In this case TiO2 films is deposited on HAp. Therefore writing “HAp/TiO2 powders” is confusing. Please rephrase the sentence.
8. The following article provides a minute details on the mechanism of microwave-assisted hydrothermal/solvothermal processes. Incorporating it as a reference is very helpful to the readers.
https://doi.org/10.1002/advs.202106052
Author Response
We sincerely appreciate that you have taken the time to review our work Microwave-Assisted Hydrothermal Synthesis of Hydroxyapatite Flakes as Substrates for Titanium Dioxide Film Deposition. We welcome your comments which are all valuable and helpful in improving the quality of our article.
The observations have been carefully studied, and, in the same way, the proper corrections have been made, hoping that they will meet your expectations and thus have your approval. The following pages of this document respond to the indications of each reviewer.
The text highlighted in green corresponds to each of the observations made by the reviewers, while the text highlighted in yellow shows the correction made by the authors. The authors welcome any further observations or future comments.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsIn this Communication, the author reported the synthesis of TiO2 coated HAp, which will applied for photocatalysis.
(1) What is the purpose of this work? What problem will solved by this study?
(2) Figure 4 and 5, “This aluminum presence is likely attributed to contamination from impurities in the gases utilized during the MOCVD synthesis process”, how can aluminum exists in the gases? The aluminum impurities most probably came from the raw materials.
(3) Figure 4 and 5, why dose there exits carbon element in TiO2 and HAp? Which demonstrated that this method is not perfect, or the operation of the experiment is not standard.
(4) As the EDS analysis was conducted, where is the elements content of weight percentages or atomic percentages?
(5) There are only XRD, SEM, and EDS, which is not sufficient for a scientific paper, even if it is a Communication. Some other quantitative characterization should provided, such as the thickness of TiO2 coating, etc.
(6) What does application of the obtained TiO2/HAp materials?
Comments on the Quality of English LanguageModerate editing of English language required
Author Response
We sincerely appreciate that you have taken the time to review our work Microwave-Assisted Hydrothermal Synthesis of Hydroxyapatite Flakes as Substrates for Titanium Dioxide Film Deposition. We welcome your comments which are all valuable and helpful in improving the quality of our article.
The observations have been carefully studied, and, in the same way, the proper corrections have been made, hoping that they will meet your expectations and thus have your approval. The following pages of this document respond to the indications of each reviewer.
The text highlighted in green corresponds to each of the observations made by the reviewers, while the text highlighted in yellow shows the correction made by the authors. The authors welcome any further observations or future comments.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsReview of Ceramics-2926508 for the Authors: The study presents a synthesis of hydroxyapatite flakes synthesized by the microwave method as substrates for titanium dioxide thin film deposition. The scientific idea is valid, however the discussion and conclusions are somewhat questionable.
Tittle : Appropriate
Abstract: Some more important results should be highlighted.
Introduction: Sufficient text.
Experimental: Change everything into readable units. 10 ° per min is not appropriate. At least change it to 10° min-1. Also, 10 °/min? Are you sure? That’s 8 minutes for the whole pattern.
Results and discussion: XRD–As much as preferred orientation sounds exciting for scientific work, it is highly unlikely that the anomalies in the patterns stem from it, especially when you consider the synthesis pathway. Also, checking your references on this matter in the discussion left me even more confused. Cobalt oxide thin film growth and hydroxyapatite flake growth have what in common exactly? If you are convinced of your results, please acquire some TEM micrographs which show the preferred orientation of the (100) plane and do a Rietveld refinement analysis and determine the composition. Moreover, you may then comment on why the (300) plane is higher in intensity than the (211) plane. Otherwise, try not to state your vague assumptions as facts without proper references or scientific claim and support. In my opinion, you probably have contribution from other phases which appeared during microwave synthesis so you should just remove that sentence. Also, please comment on the amorphous hump in your Hap pattern. Is that the organic residual?
SEM – It is not common practice to address images by their magnification especially because the final size scale is not solely dependent on the objective magnification alone. Also, I suggest you remove the black bar in the images and set your own scale in the pure images.
Conclusions- “This underscores the successful integration of hydroxyapatite flakes in TiO2 thin films.” Didn’t you synthesize the flakes first and then deposit the titania films later?
I propose publishing after (thorough) major revision.
Comments on the Quality of English LanguageLanguage is acceptable.
Author Response
We sincerely appreciate that you have taken the time to review our work Microwave-Assisted Hydrothermal Synthesis of Hydroxyapatite Flakes as Substrates for Titanium Dioxide Film Deposition. We welcome your comments which are all valuable and helpful in improving the quality of our article.
The observations have been carefully studied, and, in the same way, the proper corrections have been made, hoping that they will meet your expectations and thus have your approval. The following pages of this document respond to the indications of each reviewer.
The text highlighted in green corresponds to each of the observations made by the reviewers, while the text highlighted in yellow shows the correction made by the authors. The authors welcome any further observations or future comments.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThe reviewed work concerns the production of hydroxyapatite flakes covered with a layer of titanium dioxide. The authors of the work received interesting material that can have a wide range of applications. Nevertheless, there is no such information in the introduction part of the article. Such information should be included in this part of the work with reference to current literature reports. Moreover, the work should be supplemented with some additional information:
1. Taking into account the obtained results of structural and morphological investigations, it can be seen that the thickness of the TiO2 layer on HAp is significant. Did the authors of the paper try to determine the thickness of the TiO2 coating on HAp? Is it possible to control the thickness of the TiO2 coating in the MOCVD process?
2. The SEM images in Figure 3c and 2d are the same. In this case, it may be worth showing some other area of the sample in one of the Figures.
3. The authors of the work emphasized that the microscopic analysis of the sample surfaces was performed at a voltage of 20 kV. In fact, Figures 2 and 3 show other voltage values that are more suitable for the analysis/observation of these types of materials. The description should be unified.
4. Did the authors of the publication try to determine other physicochemical properties of the manufactured materials, such as surface wettability or chemical composition (XPS, FTIR), which are important from the point of view of biomedical applications?
Author Response
We sincerely appreciate that you have taken the time to review our work Microwave-Assisted Hydrothermal Synthesis of Hydroxyapatite Flakes as Substrates for Titanium Dioxide Film Deposition. We welcome your comments which are all valuable and helpful in improving the quality of our article.
The observations have been carefully studied, and, in the same way, the proper corrections have been made, hoping that they will meet your expectations and thus have your approval. The following pages of this document respond to the indications of each reviewer.
The text highlighted in green corresponds to each of the observations made by the reviewers, while the text highlighted in yellow shows the correction made by the authors. The authors welcome any further observations or future comments.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe amended changes are acceptable. Therefore, I recommend publishing the manuscript.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe author addressed all the issues raised in the previous round of revision
Comments on the Quality of English LanguageModerate editing of English language required
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors have cleared out the confusing parts of the scientific work and confined the discussion within the limitations of their instrumental methods. I would still advise the authors to remove the black bar at the bottom of every image, but this does not influence the quality of the work. In my opinion, the manuscript is now ready to be published.
Comments on the Quality of English LanguageLanguage is acceptable.
Reviewer 4 Report
Comments and Suggestions for AuthorsTaking into account the responses received to the reviewer's suggestions, I believe that the work may be published in the Ceramics journal as a short communication. .
