Evolutions of the Microstructure and Properties of the (CrMoNbTaZr)NX Films Prepared by Reactive Magnetron Sputtering: Effects of Stoichiometry and Crystallinity
Round 1
Reviewer 1 Report
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What is “bonding structure of the elements in the films”?
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English should be improved. The are many misprints, misspelling (e.g., lines 13, 56-58, 63, 73-75,... 120, 140-149, 156-158, 178, 202-207 and many others including Table 2).
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The aime of this work is unclear (lines 76-80). After all, what is the novelty compared to similar investigations? Wasn't the influence of nitrogen content on the properties of such films studied earlier?
- The data presented in Table 2 are very strange. Stoichiometric compound should be in connection with oxidation state of corresponding element. The problem is that the are many different oxidation states for each metals used and thus some different nitrides.
- Incorrect or unclear expressions, incorrect figure captures (e.g., 150-151, 165, 173-175 etc.)
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Used elements form a lot of nitrides of different composition depending on oxidation states. The data presented in Table 2 are very strange. Stoichiometric compound should be in connection with oxidation state of corresponding element. The problem is that the are many different oxidation states for each metals used and thus some different nitrides.
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Table 3 is not informative enough. The data may be included in text.
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Preparation of the samples should be described better to explain the origin of oxygen (especially different O content) in the films.
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What does mean stoichiometric composition (e.g., compare fig. 3)? For which stoichiometric nitrides exactly are presented the plots in Fig. 1? In other words, which nitrides are considered stoichiometric for these elements taking into account the variety of them?
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The dependence of Ra on RN should be explained using the well-known results from the literature cited by dear authors.
Quality of English is insufficient
Author Response
Point 1: What is “bonding structure of the elements in the films”?
Response: It may be better to use the expression “film chemistry” here.
Point 2: English should be improved. The are many misprints, misspelling (e.g., lines 13, 56-58, 63, 73-75,... 120, 140-149, 156-158, 178, 202-207 and many others including Table 2).
Response: We recorrected them accordingly: Some of them are shown in the following table. Please find more in red in the revision.
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line |
former |
new |
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13 |
scaNing |
scanning (It is a misspelling for all “nn”. We have checked the whole manuscript) |
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56-58 |
More attentions are focused on amorphous thin films, because of the reduced surface roughness |
Amorphous thin films have received attentions due to reduced surface roughness |
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63 |
Chang and Chen reported the preparation of (AlCrTaTiZr)N/(AlCrTaTiZr)N0.7 bilayer structure of high resistance at 900 °C |
Chang and Chen reported the preparation of an (AlCrTaTiZr)N/(AlCrTaTiZr)N0.7 bilayer structured film, which was thermally stable at 900 °C |
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73-75 |
Various crystallographic structure for the under-stoichiometric HEAN were reported, from amorphous to fine sized BCC or FCC, as a result of multi-phase combination |
Various crystallographic structure for the under-stoichiometric HEAN were reported, from amorphous to fine sized crystallites, because of the combined phases of HEA and HEAN. |
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120 |
A wide scan was first performed with a passing energy of 80 eV for 10 min to determine the elemental chemical states. |
To characterize the chemical states of the elements, a wide scan was performed with a passing energy of 80 eV for 10 min. |
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140-149 |
Further increasing RN from 0.4 to 0.6 results in slow increase of N from 48.2 to 51.1 at.%, respectively. |
As RN furtherly increases from 0.4 to 0.6, the nitrogen concentration increases from 48.2 to 51.1 at.%. |
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156-158 |
Assuming that the chemically stoichiometric HEAN possesses homogeneous solid solution in NaCl-type, the N concentration in a stoichiometric HEAN can be theoretically estimated. |
Suppose that the stoichiometric HEAN is a homogeneous solid solution in NaCl-type, then the N concentration can be theoretically estimated. |
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178 |
In view of high O concentration and low deposition rate for them, it is deduced that the target became poisoning when RN increases to 0.5 and 0.6. |
In view of high O concentration and low deposition rate, the film was prepared by a poisoned target when RN increases to 0.5. |
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202-207 |
Figure 3 (b) also reveals the binding state of Cr2O3 in pure HEA. As shown in figure 3 (c)-(f), Mo, Nb and Ta show metallic state in pure HEA, while Zr reveals composite binding of metal and oxide. |
In pure HEA, Mo, Nb and Ta show simple metal states, while elements Cr and Zr also show the states of oxide. |
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Table 2 |
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Removed |
Point 3: The aime of this work is unclear (lines 76-80). After all, what is the novelty compared to similar investigations? Wasn't the influence of nitrogen content on the properties of such films studied earlier?
Response: Thank you for your kind comment. We optimized this section (Lines 71-81).
Point 4: The data presented in Table 2 are very strange. Stoichiometric compound should be in connection with oxidation state of corresponding element. The problem is that the are many different oxidation states for each metals used and thus some different nitrides.
Response: Table 2 was removed.
Point 5: Incorrect or unclear expressions, incorrect figure captures (e.g., 150-151, 165, 173-175 etc.)
Response: We have corrected the expressions.
Point 6: Table 3 is not informative enough. The data may be included in text.
Response: Table 3 comes from some mathematical procedures given by the cited references. Sorry but we wonder if the dear reviewer is advising to fill the processes of calculation. It might be too long to show them. If it is necessary, we suggest attaching the processes as a supplement.
Point 7: Preparation of the samples should be described better to explain the origin of oxygen (especially different O content) in the films.
Response: Thank you for your opinion. We have stated that the base pressure for each film is 8×10–4 Pa. We suggest that the oxygen in the films results from 1) during deposition, residual O (both from chamber- adsorption and leaking) incorporates into the films; 2) O adsorption onto the films by exposure. The XPS study reveals much larger O concentration than the EDS, which indicates that O is highly prone to incorporate because of the composition.
Point 8: What does mean stoichiometric composition (e.g., compare fig. 3)? For which stoichiometric nitrides exactly are presented the plots in Fig. 1? In other words, which nitrides are considered stoichiometric for these elements taking into account the variety of them?
Response: We consider stoichiometric HEAN as the nitride of all metals in FCC unit cell. Then the stoichiometric composition of nitrogen is calculated by the compositions of metals.
Point 9: The dependence of Ra on RN should be explained using the well-known results from the literature cited by dear authors.
Response: We have changed the expression. Please find them in Line 237-238.
Point 10: Comments on the Quality of English Language. Quality of English is insufficient.
Response: We have recorrected the expression of English.
Dear reviewer, the attached file is the same with the shown content.
Reviewer 2 Report
Authors claims that the increase in the oxygen fraction was attributed to the film thickness. I not convince by this statement because films were quite thick or at least much thicker than the penetration depth of XPS. I think it more related with a compromise between microstructure and stoichiometric of the film (diffusion/reaction properties after expose the film to air)
There is a change in the ratio of Cr/M (M = Mo, Ta, Nb, Zr) with RN do you have an explanation for this?. (at first glance its seems that stoichiometric of Cr is 0.5 more than 1)
Did you estimate the composition using the XPS survey? the EDS penetration depth is about 40 micros at ca. 40keV (for your films is almost bulk). For XPS is few nms, thus, a comparison between bulk to surface could give you more useful information.
The table 2 contains a lots of speculations, I recommend to not be included in the manuscript. In order to do good x-ray crystallographic study of this kind of films an area detector should be used.
Authors showed a well defined structure at RN = 0.3 but a mix of structures above. Thus, could be discussed as solid state solution vs composite in function of RN (instead of multiphase HEANx)? There are several properties that could be explained with a single or several solid compounds conforming the film.
The label of the figure 11 is incomplete.
when crystallographic structures are mentioned, they have to be in the correct way. For example FCC unit cell structure instead of FCC structure. Because it is refereed to the translation symmetry of the crystal.
Dear Authors,
From my point of view the manuscript is quite complete however, the English must be polish. There are also worlds with one funny n than two: eg. scaning instead of scanning (I think is a problem with a auto-corrector from Asian language).
Also an incorrect use of few words
eg. in the label of the Figure 3 is written "typical films". Since this are new films, they are not typical. The sentence has no sense. (although I know what the authors want to express with this phrase, you should modify it)
Author Response
Response to Reviewer 2 Comments
Point 1: Authors claims that the increase in the oxygen fraction was attributed to the film thickness. I not convince by this statement because films were quite thick or at least much thicker than the penetration depth of XPS. I think it more related with a compromise between microstructure and stoichiometric of the film (diffusion/reaction properties after expose the film to air)
Response: Thank you for your kind opinion. We suggest that O comes from 1) incorporating of residual O (both from chamber- adsorption and leaking) during deposition. O is highly prone to incorporate. At high deposition rate, the O concentration in the films is around 5 at.%. However, for the films with lower deposition rate, O incorporates into the films at a larger volume fraction. 2) adsorption of O by exposure in air (as evidenced by larger O concentration by XPS). We agree with you that the microstructure and stoichiometry influence the O adsorption. We revised the manuscript (Line 199).
Point 2: There is a change in the ratio of Cr/M (M = Mo, Ta, Nb, Zr) with RN do you have an explanation for this?. (at first glance its seems that stoichiometric of Cr is 0.5 more than 1)
Response: We suggest that the varying Cr/M composition ratios are caused by the randomness of the detection, though each one of the EDS results is an average of 5 detect areas. However, the XPS of pure HEA didn’t show a special Cr/M ratio comparing with other films.
Point 3: Did you estimate the composition using the XPS survey? the EDS penetration depth is about 40 micros at ca. 40keV (for your films is almost bulk). For XPS is few nms, thus, a comparison between bulk to surface could give you more useful information.
Response: We also received the composition by XPS. The XPS showed much larger concentration of O than EDS, which agrees with reviewer’s opinion of strong O adsorption after expose the film to air. However, the compositions (such as Cr/Me ratio and N/Me) by EDS and XPS couldn’t coincide well partly because both of them are semi-quantitively. And the different depth-scale extended the randomness. Therefore, the XPS composition was not shown.
Point 4: The table 2 contains a lots of speculations, I recommend to not be included in the manuscript. In order to do good x-ray crystallographic study of this kind of films an area detector should be used.
Response: Table 2 was removed.
Point 5: Authors showed a well defined structure at RN = 0.3 but a mix of structures above. Thus, could be discussed as solid state solution vs composite in function of RN (instead of multiphase HEANx)? There are several properties that could be explained with a single or several solid compounds conforming the film.
Response: The authors agree with reviewer’s opinion that the properties are relevant with the microstructure. We tried to illustrate how the varying microstructure determines the properties, please find them in the “discussion” section.
Point 6: The label of the figure 11 is incomplete.
Response: Labels of figure 11 (b) and (c) are filled in the revision.
Point 7: when crystallographic structures are mentioned, they have to be in the correct way. For example FCC unit cell structure instead of FCC structure. Because it is refereed to the translation symmetry of the crystal.
Response: Thanks! FCC unit cell structure is very exact. We recorrected them (FCC and BCC) all through the revised manuscript.
Point 8: From my point of view the manuscript is quite complete however, the English must be polish. There are also worlds with one funny n than two: eg. scaning instead of scanning (I think is a problem with a auto-corrector from Asian language)…Also an incorrect use of few words..eg. in the label of the Figure 3 is written "typical films". Since this are new films, they are not typical. The sentence has no sense. (although I know what the authors want to express with this phrase, you should modify it)
Response: Thank you very much. We have asked for English improvement in the revised manuscript.
Dear reviewer, the attached file is the same with the shown content.
Reviewer 3 Report
Overview and general recommendation:
HEAs have taken the field of materials science, or, more precisely, metallurgy, by storm; indeed, they are likely to be central to the field of structural, and perhaps functional, materials for another decade or longer. Because of this, the current study, “Evolutions of the microstructure and properties of the (CrMoNbTaZr)NX films prepared by reactive magnetron sputtering: Effects of stoichiometry and crystallinity” is on a topic of relevance and general interest to the readers of the journal. In general, I believe that more attention should be placed on potential innovative applications for HEAs. Most efforts in the field are focused on mechanical properties but unexpected features of HEAs that might be interesting for other applications. Particularly, HEAs with multi-functional properties might lead to new processes or products. Thus, it will be worth exploring where specific properties may be expected that are better than those of established material classes.
On the one hand, I felt confident that the authors performed a careful and thorough study. On the other hand, I found some of the description of some very important points were inadequate or completely missing. Therefore, I recommend that a minor revision is warranted. I explain my concerns in more detail below.
Comments:
In the Introduction section, could you kindly elaborate on the specific factors or considerations that led you to choose the reactive magnetron sputtering for your research?
In the Materials and Methods section, it really should be mentioned the distance target-substrate, and accelerating voltages that were used in morphological characterizations and EDX measurements of the samples. The EDX data were obtained from how many different locations on each surface (…x magnification/location), and mediated? Provide sufficient details to allow the work to be reproduced by an independent researcher.
The EDX spectrum analysis is somewhat unreliable due to line overlap, particularly for elements like C, N, O, etc., where the spectral lines are beyond the instrumental resolution range. To validate the compositional consistency, you conducted an EDS analysis. Could you please specify the approximate depth of the EDS analysis in micrometers? Although the standardless EDS technique you employed is semi-quantitative, considering your aim to observe a trend in N concentration, it is recommended to acquire another EDX spectrum with low energy (max 2kV) to focus on quantification using the K shell of N (energy 0.392).
The authors did not clearly describe what the XPS analysis gives (data on the chemical composition at a certain depth from the surface) and what the EDS analysis gives (the integral amount of deposited material).
Your research presents a valuable contribution to the field, and the findings are intriguing. However, in order to enhance the impact of your study, I kindly request you to provide a more precise and specific conclusion. While the current conclusions touch upon important aspects, they appear somewhat generalized. Adding more concrete and explicit statements, supported by data, will further strengthen the significance of your research. This would allow readers to grasp the specific implications and applications of your work more effectively.
Minor editing of English language required.
Author Response
Response to Reviewer 3 Comments
Point 1: In the Introduction section, could you kindly elaborate on the specific factors or considerations that led you to choose the reactive magnetron sputtering for your research?
Response: Thank you for your kind opinion. We have added the reason for studying thin films by reactive magnetron sputtering, please find them in red (Lines 70-72) in the introduction.
Point 2: In the Materials and Methods section, it really should be mentioned the distance target-substrate, and accelerating voltages that were used in morphological characterizations and EDX measurements of the samples. The EDX data were obtained from how many different locations on each surface (…x magnification/location), and mediated? Provide sufficient details to allow the work to be reproduced by an independent researcher.
Response: We have revised the manuscript by adding the parameters of deposition (target-substrate distance, Line 97) and characterization (accelerating voltages, Line 116-117; data collection, Line 123-125).
Point 3: The EDX spectrum analysis is somewhat unreliable due to line overlap, particularly for elements like C, N, O, etc., where the spectral lines are beyond the instrumental resolution range. To validate the compositional consistency, you conducted an EDS analysis. Could you please specify the approximate depth of the EDS analysis in micrometers? Although the standardless EDS technique you employed is semi-quantitative, considering your aim to observe a trend in N concentration, it is recommended to acquire another EDX spectrum with low energy (max 2kV) to focus on quantification using the K shell of N (energy 0.392).
Response: Thank you for your kind Point. Because of the metal compositions in the present study, the EDX was operated at 10 kV, which results in a depth of detection of about 15 μm. Low energy helps to receive more accurate atomic O/N ratio. Currently, our EDX received insufficient counts at low energy. We will carefully optimize the data.
Point 4: The authors did not clearly describe what the XPS analysis gives (data on the chemical composition at a certain depth from the surface) and what the EDS analysis gives (the integral amount of deposited material).
Response: Thank you for your comment. We have recorrected them in Line 195-197.
Point 5: Your research presents a valuable contribution to the field, and the findings are intriguing. However, in order to enhance the impact of your study, I kindly request you to provide a more precise and specific conclusion. While the current conclusions touch upon important aspects, they appear somewhat generalized. Adding more concrete and explicit statements, supported by data, will further strengthen the significance of your research. This would allow readers to grasp the specific implications and applications of your work more effectively.
Response: We have revised the description of conclusion, thank you for your kind comment.
Dear reviewer, you can also find the response through the attached file.
