Preparation and Properties of Co-Doped Magnesium Lanthanum Hexaluminat Blue Ceramics

Round 1

Reviewer 1 Report

“In this paper, the authors described the preparation process of Co-doped  LaMgAl11-xCoxO19 ceramics and have been studied their properties. Traditional methods such as XRD, SEM, optical spectrophotometry were used for experimental investigations. The work provides interesting information, relevant to the scope of the Ceramics journal.

However, in the current form, this paper is not suitable for publication. It certainly needs a major revision by the following reasons:

1. First of all, I would like to say that English is quite poor and needs careful corrections from a native speaker, including numerous misprints.
2. Please describe in detail how were the color coordinate L*, a*, b* were calculated.
3. The readability is poor. Please represent your results more logically.
4. The caption of Fig. 2 should be represented. It looks like powders of Co-doped LaMgAl11O19, not the ceramics. What about the density of the sintered ceramics, grain sizes, and other mechanical properties?
5. The authors should add the PDF card for XRD peaks interpretation of LaMgAl11-xCoxO19
6. In Fig. 4. the authors should change the caption of Fig. In Fig.4 the authors present reflectance spectra of sintered ceramics. I recommend changing the Fig. 4, the authors demonstrate the dependence between bandgap and Co concentration. Fig. 3 looks like the same for Fig. 4. In addition, the authors should represent the x-axis in eV units for correct representation.
7. Please use ceramics in plural form instead of a single one in the text of the manuscript. 
8. The dependence is shown In Fig. 5 for b* points does not connect with text e.g. “…and the -b* values representing blue are greater than 20, and they increase first and then decrease. When x = 1.0, the maximum value of 35.36 is reached…” Please pay attention to it.
9. Page 6. I cannot read the text of the manuscript due to Fig. with SEM images. They hide the text.

It will be better if the authors represent the photo of the sintered ceramics  

10. Part 3.3. The influence of other factors on the optimal doping amount should be change on the effect of temperature on…..etc.
11. The Figure with XRD results and reflection spectra should be combined for clear analysis. You should change the Caption of the Figure. The unit measurements of R is % not a.u.
12. Fig. 7 please put the full description on x-axis not y, but year.
13. The references part should be reorganized based on journal rules. Please pay attention to it.

Finally, if the authors speak about the potential as jewelry and decorative applications they should demonstrate color photos for the more interesting representation of obtained results.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

This paper is about the doping of the cobalt ion in the LaMgAl11-xCoxO19 synthesized by the traditional method: solid state reaction. The work data is very interesting to reveal that the calcination temperature above 1450 ° C does not affect the color of the material. In addition, it is interesting to analyze the color at room temperature for months to check for changes.

• Why is the sample with x = 1 an optimal amount of doping?
• Are the values L *, a * and b * statistically different for example from figure 6? It would be interesting to do tukey analysis on the data. Most current references: Synthesis and characterization of pigments based on copper-zinc aluminate (CuxZn1-xAl2O4) by combustion Doi: 10.1016/j.ceramint.2019.09.224 ; Synthesis and characterization of colourful aluminates based on nickel and zinc Doi: 10.1016/j.jallcom.2019.152477.
• It would be interesting to put the photo of the synthesized powders.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

After reconsideration, the authors have improved the manuscript.

However, the major revisions are needed by the following reasons:

First of all, I would like to make comments of authors responses to my first remarks:

1. First turn on the spectrophotometer (CM-3600A, Konica Minolta) and the computer. Then use black and white standard samples to calibrate the equipment, and then place the prepared sample on the stage for measurement. The computer screen will display the L * a * b * value.

It is not a suitable answer to my question about the color coordinate L*, a*, b*. Please add information about the calculation of the coordinate.

Point 3. In Fig. 4. the authors should change the caption of Fig. In Fig.4 the authors present reflectance spectra of sintered ceramics. I recommend changing the Fig. 4, the authors demonstrate the dependence between bandgap and Co concentration. Fig. 3 looks like the same for Fig. 4. Also, the authors should represent the x-axis in eV units for correct representation.

I strongly recommended changing Fig. 4. The authors should present the dependencies between Band gaps [eV] and Co content [wt.%]. If the authors speak about bandgap values more reasonably use eV to represent in Fig.
Please pay attention to it! I think will be better to combine Fig.3 and Fig.4 with the above recommendation.

Point 4: The authors should add the PDF card for the XRD peaks interpretation of LaMgAl11-xCoxO19.

If the author used the Jade software to analyze the measured XRD data you should put the description into the Experimental part.
Also what about the particle size of the initial powders?

Point 2: Please represent your results more logically. Please use ceramics in plural form instead of a single one in the text of the manuscript. Part 3.3. The influence of other factors on the optimal doping amount should be change on the effect of temperature on…..etc.

I hope the authors will use my recommendation. Because I did not see changes in the text.

The English language should be reconsidered. In text also there are some inaccuracies e.g.

3.1. phase analysis please use capital letter P.

2.3 Optical performance. .... in the visible light range, please change on the visible spectral range from ... to... etc.

The authors used white and black samples for reflection measurement.
What does it mean? What the optical characteristics of these samples?

The nature of reflection bands practically did not define. It will be better to put relevant information where represent similar effects.

Fig. 7 should be reconsidered, especially the authors should change the Caption of the Figure, please add the full description of the Fig. The unit measurements of R is %, not a.u.. But now the authors combine together % and arb.u. It is not correct.

Also, the authors should pay attention to all Figures in the manuscript. especially for the x, and y-axis.

In Fig. 6 authors show the samples. However what the difference between them. Please make notes in Fig. Please pay attention to it.

The references part still can not be reorganized based on journal rules.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 3

Reviewer 1 Report

After reconsideration, the authors have improved the manuscript.

However, the minor revisions are needed by the following reasons:

Some obvious grammatical and spelling mistakes appear in the manuscript.

The authors must improve their English writing and correct the manuscript,

ideally with the help of a native speaker.

1. line 6 (LaMgAl11-xCoxO19) were prepared by doping Co with high

temperature solid phase reaction
please change it on (LaMgAl11-xCoxO19) doped with Co were prepared by high

temperature solid-phase reaction.....

2. line 64 the measured xrd data please change it on measured XRD data

3. line 130 3.2. The diffuse reflflectance.... please change it on reflectance

There are a lot of other lexical and grammatical mistakes. Please change it.

4. Fig. 4 Represented not curve, but dependence between forbidden band and Co content please change it.

5. The References part has not changed since my first comments.

Author Response

According to your suggestion, we have modified the sentences that need to be replaced, and revised the reference format of the paper.