Properties of Composite Powder Based on Boron Nitride Prepared under Concentrated Light

Round 1

Reviewer 1 Report

The authors report their synthesis and measurements of BN-based composites, with an emphasis on the synthesis conditions, structures, and phases. The sizes of the obtained particles are in a wide range, but the nanostructures can have a thickness as small as 10 nm, and some nanoparticles are found to have a size of 50 nm. The authors also observed the dependence of the bandgap on the distance from the reaction zone. This work is interesting as the BN-based nanoparticles they obtained could be potentially used for a number of applications. I would recommend an acceptance if the authors can address the following points in a revised manuscript:

1. I would suggest that the unit of “nm” is used for the size of nanoparticles/nanostructures. The authors use the unit of micrometer for all cases in the present manuscript. This is an optional suggestion.

2. The authors provide a useful review of the chemical bonding of 2D hexagonal boron nitride in Introduction (Paragraphs 3 and 4). Additional reference(s) regarding the bonding and electronic structures should be added. In a paper published in APL [Dang, et al., APL 104, 093104(2014)], the properties of electronic structures and chemical bonding of both 2D hexagonal and cubic boron nitride (c-BN and h-BN) based on first-principles calculations are reported. The paper is of relevance and should be cited.

3. Lines 100-113: It is unclear why a dash or a hyphen is placed in front of the size of the particles.

4. Captions of Figures 1-3, 5, 6: 0,05 should be 0.05 and 0,20 should be 0.20. I guess this is a typo.

Author Response

Dear Reviewer,

Thank you very much for your valuable comments and feedback regarding our research paper. We've made changes according to each of your suggestions.

(1) Unfortunately, using the unit of “nm” for the size of nanoparticles/nanostructures will result on the numerous errors.  We would like to leave the unite of micrometer for this manuscript.

(2) Reference on the paper of [Dang, et al., APL 104, 093104(2014)] was inserted in the manuscript.

(3) - (4) corrected

Reviewer 2 Report

In this paper the authors present synthesis under concentrated light and characterization of  of composite powder based on boron nitride. Sizes and architecture highly dependent of the synthesis conditions. An amorphous powder with the largest band gap of 5.2 eV with a minimum particle size of 0.05 μm and a minimum amount of oxide phases precipitates. Introduction is well structured and present the state of the art in this field. Experimental part is clear and well written. Analysis methods are modern and correct used for characterization of the obtained materials. Results and discussion are illustrative and clear. Conclusions are short and have to be extended.

Author Response

Dear Reviewer,

Thank you very much for your valuable comment and feedback regarding our research paper. We've extended our conclusions. The changes are highlighted in yellow.

Reviewer 3 Report

The authors reported the synthesis and characterizations of composite powder-based boron nitride through concentrated light heating. I found that synthesis method is novel and could be interested to the readership of Condensed Matter. Some minor suggestions are as follows:

1. Some important information is missing in the schematic of Figure 4, such as the position of the heating lamp and the radiation direction. Moreover, it will be helpful if the authors label the corresponding components in the experimental furnace.

2. What's the estimated growth temperature of BN and what's the estimated temperature can be achieved by using concentrated lamp heating?

3. The authors studied the properties of obtained BN versus the distance to the reaction zone. It will be more meaningful if this correlation can be translated into with estimated temperature range.

Author Response

Dear Reviewer,

Thank you very much for your valuable comments and feedback regarding our research paper. We've made possible corrections and comments according to each of your suggestions.

1. Some important information is missing in the schematic of Figure 4, such as the position of the heating lamp and the radiation direction. Moreover, it will be helpful if the authors label the corresponding components in the experimental furnace.

We have inserted a reference [15] to help understand the missing important information, such as the position of the heating lamp and the radiation direction in the schematic of Figure 4. Unfortunately, the name of the author's labels of the relevant components in the experimental furnace will be too long. Picture will be too saturated with information and it will be difficult to understand.

2. What's the estimated growth temperature of BN and what's the estimated temperature can be achieved by using concentrated lamp heating?

We have made some corrections The changes are highlighted in yellow.

This is a problematic aspect of this work. We cannot control the temperature properly, because the operation of high-voltage xenon lamps is very unstable and therefore this paper presents only qualitative estimates of the processes occurring during heating. Pyrometer measurements showed that the temperature on the side surface of the sample can reach 1450 ^oC. However, the temperature in the reaction zone is much higher and can reach above 2000 ^oC, because the combustion of boron in nitrogen. This temperature is difficult to measure accurately due to the instability of the xenon lamp and the influence of the wall of the quartz chamber, which is covered with precipitated powder during heating, which means even more difficult to control.

3. The authors studied the properties of obtained BN versus the distance to the reaction zone. It will be more meaningful if this correlation can be translated into with estimated temperature range.

This would be good, but not realistic for our experimental conditions, as any temperature data will be incorrect at the next moment of the experiment.

We found some correlations without the estimated temperature range and decided to provide only qualitative data that have fairly clear regularities and explanations.