Hydrogen Assisted Magnesiothermic Reduction of Y-Doped, Nanocrystalline TiO2
Round 1
Reviewer 1 Report
In this article, the authors report the results of a study on the effect of the addition of yttrium to the preparation of titanium dioxide, carried out through the solvo-thermolysis of titanium tetrabutoxide, and the affect on the subsequent hydrogen-assisted magnetothermic reduction to low-oxygen titanium metal oxide. The reduction was carried out with a flow of 5% of hydrogen in argon to reach a partial reduction. The materials are characterized by XRD and SEM.
In my opinion the topic of the article is interesting and of interest to Metals readers, however the object of the research seems to be in a preliminary phase and some aspects are not explored, leaving many doubts.
I suggest some changes:
1. The abstract should be improved in the final part, specifying why the doped TiO2 powders have been identified as a potential alternative for HAMR experiments. Furthermore, the sentece: "The formation of the byproduct MgO phase is also discussed" is not complete, some conclusions should be added.
2. Figures need to be improved, scales need to be the same in all graphs, and the font size needs to be larger. Figure 8 is fundamental, however it is difficult to read, perhaps it would be better to divide it into two figures, and in any case the size of the lines, the color and the font size need to be improved.
3. Characterizations (par. 3.1) should show comparison between doped and non-doped TiO2. Evidence of alloy formation is missing.
4. What is the purpose of particle distribution? The findings should be discussed and placed in the context of the research.
5. The crystallite size was calculated on peak 101 (without commas, line 129). Based on the diffractogram of Figure 3? Was a manipulation done? Was the baseline corrected with some software? I have some bugs about fitting. It is requested to deepen this aspect.
6. Page 4 line 135 "The Anatase phase peaks were observed to increase in intensity but not reduce in width. Simultaneously, an amorphous 'hump' was observed to decrease following calcination, suggesting the nucleation of new, nanocrystalline TiO2 grains from amorphous phase TiO2 present in the powders ". Comparisons using diffractograms, in intensity and width should be done with caution. Has any software been used? Was the baseline done? How was the comparison made? Quantitative or qualitative?
7. EDS must be shown.
8. Yttrium is not present in the EDS, how can this be justified? How can we be sure that yttrium doped titanium dioxide?
9. In paragraph 3.2, there are problems similar to those encountered in the previous paragraph, such as lack of EDS, interpretation of diffractograms. In any case
10. Conclusions are schematic, therefore easy to understand, however a brief introduction to the conclusions should be added.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
- The study of the effects of Y doping on the HAMR is the novelty of this paper.
- The nanocrystalline TiO2 formed caused the morphology change is also a new finding of this paper.
The following are a few comments/suggestions on this paper:
- Page 3, line 96. What is the total amount of powers used in the reduction experiments?
- Page 6, what is the black power shown in Figure 7 after the reduction?
- Page 9, it is suggested to label the locations where the EDS analysis was done. Do you have the overall conversion rate of the TiO2 (oxygen removal pct) to support your argument that the reduction rate of the doped particles is faster than the undoped?
- In figure 9 c&d, why there is such a significant change in the morphology of the MgO product?
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 3 Report
The paper focus on the use of the Y-doped and undoped TiO2 powders to To investigate the influence of rare-earth dopant species on the HAMR process. Several catalyst characterizations were done in order to highlight some trends about HAMR phases. In general, the results mostly support the authors' conclusions. Moreover, the originality, mechanism, and scientific reliability of the work are clear. In my opinion, there are some minor points that the authors should address before it is accepted for publication.
1°) Figure 2 please make “2” in subscript for “TiO2” and please delete the double title in the picture of figure
2°) figure 7 can be deleted. No scientific behavior can be seen
3°) at any moment the authors discussed the results of TEM ?
4°) It will be interesting, if authors detailed more this sentence (line 263) based on figure 9 “ The absence of titanium-hydride phases from the present analysis was sensible. Scientific explanation are needed here
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors adequately addressed the issues proposed in the suggestions of the first round, improving the writing of the manuscript. Some doubts about the results and interpretations of the characterizations have been clarified.
