Synthesis of Submicron, Nanostructured Spherical Powders of Y3Al5O12-Phases by the Method by Ultrasonic Spray Pyrolysis and Investigation of Their Structure and Properties
, Leonid V. Vinogradov 2, Maxim D. Larionov 2 and Yuliya E. Mukhina 2Round 1
Reviewer 1 Report
I do not have additional questions.
Author Response
Thanks for the review
Reviewer 2 Report
The manuscript has been well revised. The manuscript is in accepetable format.
Author Response
Thanks for the review
Reviewer 3 Report
A proofreading is required.
For example, line 82 "which requires" is marked twice
Some missing results :
Why you did not analyzed the first powder (Figure 4) after the same thermal treatment as with the urea treated powder and compared the XRD patterns
Why the density values after sintering are not presented?
Author Response
- A proofreading is required. For example, line 82 "which requires" is marked twice (строка 82 «для чего требуется» отмечена дважды).
Answer: The error has been fixed.
- Some missing results: Why you did not analyzed the first powder (Figure 4) after the same thermal treatment as with the urea treated powder and compared the XRD patterns.
Answer:
From the text of the article it clearly follows that the powders synthesized at a temperature of 1100°C do not meet the requirements for them. The process of phase formation in them did not take place to the full extent. The synthesized powders still retain a significant amount of the amorphous component (Fig. 4). Many granules turned out to be fragile, loose and partially split into separate fragments. This indirectly indicated that the nominal furnace temperature of 1100°C was insufficient for the complete completion of YAG phase formation in the reactor of the laboratory setup. Therefore, the authors of the work had to resort to an extraordinary method of increasing the pyrolysis temperature, using urea added to the working solution as the initiator of the exothermic reaction.
Figure 3 in the text of the article is presented mainly for a visual demonstration of the internal composition of aerosol granules, consisting of a large number of nanosized particles, from which a branched nanosized polycrystalline substructure is formed inside the granule in a certain range of higher temperatures. It is this substructure that imparts increased activity to aerosol powders at the stage when the main role in the mass transfer mechanism begins to be played by the boundaries of grains formed during the sintering of powder particles.
- Why the density values after sintering are not presented.
Answer: Note taken into account. An addition has been made in the text of the article (pages 7-8, red font)
Reviewer 4 Report
- Density must be measured of the samples.
- This reviewer disagrees that Figure 7 proves that the samples do not contain residual pores. Figure 7b looks to have pores. It is better to section and polish samples for SEM analysis.
- It is confusing that Figure 3 shows a Vertical furnace, but Figure 2 shows a Horizontal furnace. Please change Figure 2 so that it better matches the experimental apparatus.
- The first paragraph of the introduction is way too long. It needs to be broken up in to multiple paragraphs
- The introduction section on FSP is very confusing. It needs to be rewritten. What is the “first case” and the “second case”? It is not clear. What are the authors describing?
- There is obviously a range for the particle sizes for the powder shown in Figure 5. Please provide that range in the paper. And change the abstract to include this information.
- The abstract appears to claim that pure YAG powder was made, but Figure 6 shows YAP. Please change the abstract to say this.
- There are a lot of unmarked XRD peaks in Figure 8. Please label these peaks. Are there additional phases in the sintered materials?
- This reviewer disagrees that the authors have shown that the “best” results are obtained when sintered at 1700C for 6 hrs. Only two sintering conditions are presented. That is not enough data to claim it is “best”.
- The motivation for this work is to create ceramics for high-power solid-state lasers. Strength and optical properties are critical for these types of ceramics, but no data is presented. Can the authors perform hardness measurements or optical properties measurements? Or maybe you can just show a picture of the samples to show the optical nature of the ceramics.
Author Response
- Density must be measured of the samples.
Answer: Note taken into account. An addition has been made in the text of the article (pages 7-8, red font)
- This reviewer disagrees that Figure 7 proves that the samples do not contain residual pores. Figure 7b looks to have pores. It is better to section and polish samples for SEM analysis.
Answer: Ideally transparent material must have a density of at least 99.985% of the theoretical density. However, visual analysis of the SEM image of the surface of a sample sintered at a higher temperature and longer sintering time does not reveal the presence of noticeable pores. More detailed studies of the structure of this material will be presented in subsequent publications, since their implementation will require significant time and material costs.
- It is confusing that Figure 3 shows a Vertical furnace, but Figure 2 shows a Horizontal furnace. Please change Figure 2 so that it better matches the experimental apparatus.
Answer:
Note taken into account. Figure 1 orientation aligned with Figure 2.
- The first paragraph of the introduction is way too long. It needs to be broken up in to multiple paragraphs.
Answer: The remark was taken into account - the text of the introduction was divided into several paragraphs.
- The introduction section on FSP is very confusing. It needs to be rewritten. What is the “first case” and the “second case”? It is not clear. What are the authors describing?
Answer: Note taken into account. For a better perception of the text, changes have been made to the corresponding paragraph (red font).
- There is obviously a range for the particle sizes for the powder shown in Figure 5. Please provide that range in the paper. And change the abstract to include this information..
Answer: Note taken into account. Changes have been made to the text of the article (page 1 and page 6, red font)
- The abstract appears to claim that pure YAG powder was made, but Figure 6 shows YAP. Please change the abstract to say this.
Answer: Note taken into account. Necessary changes have been made to the text of the annotation (red font).
- There are a lot of unmarked XRD peaks in Figure 8. Please label these peaks. Are there additional phases in the sintered materials?
Answer: When preparing the working solution, chemical reagents with the qualification “chemically pure” were used, therefore, in the structure of the sintered material there is a small amount of impurities, traces of which appear on the XRD pattern. In this regard, the identification of side peaks was not carried out.
- This reviewer disagrees that the authors have shown that the “best” results are obtained when sintered at 1700C for 6 hrs. Only two sintering conditions are presented. That is not enough data to claim it is “best”.
Answer: The article does not claim that the second sintering mode is optimal. In this case, it is shown that with an increase in the sintering temperature and an increase in the duration of the process, the quality of the material improves markedly. Optimization of sintering modes, as well as optimization of the process of obtaining the aerosol powders themselves, is the task of the following research.
- The motivation for this work is to create ceramics for high-power solid-state lasers. Strength and optical properties are critical for these types of ceramics, but no data is presented. Can the authors perform hardness measurements or optical properties measurements? Or maybe you can just show a picture of the samples to show the optical nature of the ceramics.
Answer: The task of the work was to study the possibility of obtaining YAG powders - phases with special properties. The new powders should not agglomerate and, at the same time, have a sintering activity close to that of nanopowders. According to research by A. Ikesue, the main requirement for powders intended for the manufacture of transparent polycrystalline ceramics is their low tendency to form agglomerates (they must be weakly agglomerating). The study successfully demonstrated the possibility of synthesizing such powders by ultrasonic spray pyrolysis, proving the promise of using this method to obtain powder raw materials suitable for the manufacture of laser polycrystalline ceramics. Improvement of the method for the synthesis of aerosol powders, as well as a detailed study of the properties of transparent polycrystalline ceramics obtained from them, is a task for further research.
Round 2
Reviewer 3 Report
No more comments
Author Response
Tried to fix the spelling
Reviewer 4 Report
The motivation for this work is to create ceramics for high-power solid-state lasers. The purity of the material is critical for laser ceramics. Please identify the extra peaks present in Figure 8. It is not sufficient to call them "trace impurities." For diffraction peaks to be present, the diffracted volume must contain a few weight percent of that material, which is not a "trace" amount.
The text additions to page 7 need to be proof read. A few sentences are duplicated.
Author Response
1) The motivation for this work is to create ceramics for high-power solid-state lasers. The purity of the material is critical for laser ceramics. Please identify the extra peaks present in Figure 8. It is not sufficient to call them "trace impurities." For diffraction peaks to be present, the diffracted volume must contain a few weight percent of that material, which is not a "trace" amount.
Reply to remark: Taking into account the importance of this remark, we have thoroughly analyzed all the results of the X-ray diffraction analysis of aerosol powders and sintered ceramics available to us and determined the affiliation of all peaks present in Figure 8. In the graphic images in Fig. 8a and 8b have added clarifying data.
2) The text additions to page 7 need to be proof read. A few sentences are duplicated.
Reply to remark: The corresponding paragraph has been checked and corrected by us. Thank you kindly for detecting this error.
3) Moderate English changes required
Reply to remark: Tried to make adjustments.
