Equations of State of Simple Solids (Including Pb, NaCl and LiF) Compressed in Helium or Neon in the Mbar Range
Round 1
Reviewer 1 Report
Review Minnerals-628760
“Equations of state of simple solids (including Pb, NaCl and LiF) compressed in helium or neon in the Mbar range” by Dewaele.
This paper reports P-V data of Pb, NaCl, and LiF at room temperature up to megabar pressures using a previously updated ruby and W gauges (W is calibrated by ruby). The author also obtained the fitted parameters () for the Rydberg-Vinet equation of state (EOS). However, the author failed to show motivation and verify the qualities of his data. Extensive studies have been conducted to measure the P-V data of pressure gauges at both room and elevated temperatures (e.g. Dorogokupets, 2002; Dorogokupets and Dewaele, 2007; Fei et al., 2007; Ye et al., 2017; Murakami and Takata, 2019; and references in this manuscript). Firstly, the author does not cite the papers mentioned in this review. In particular, the Dorogokupets and Dewaele (2007) is his own paper and includes the P-V data of B1-NaCl and B2-NaCl, which are not presented as a comparison. Secondly, the motivation for this study is not well organized. The progress and status of EOS of commonly used materials (Au, Pt, KCl, NaCl, MgO, W, Pb, et al.) are not presented. The reason why the author chose NaCl, Pb, and LiF is not given. Thirdly, usually when performing PVT EOS fitting, one would fix the V0 if the phase is quenchable because the measurements at ambient condition is the most precise and reliable. Lastly, the author doesn’t compare all available P-V data published previously. In conclusion, I am hesitated to recommend accepting this paper in the current form, and major revision (at least) is required.
There are also some minor mistakes as follows:
(1) line 115: “The author declare no conflict of interest”. Declare should be declares
(2) line 134, the title of the reference is missing
Author Response
This paper reports P-V data of Pb, NaCl, and LiF at room temperature up to megabar pressures using a previously updated ruby and W gauges (W is calibrated by ruby). The author also obtained the fitted parameters () for the Rydberg-Vinet equation of state (EOS). However, the author failed to show motivation and verify the qualities of his data. Extensive studies have been conducted to measure the P-V data of pressure gauges at both room and elevated temperatures (e.g. Dorogokupets, 2002; Dorogokupets and Dewaele, 2007; Fei et al., 2007; Ye et al., 2017; Murakami and Takata, 2019; and references in this manuscript). Firstly, the author does not cite the papers mentioned in this review. In particular, the Dorogokupets and Dewaele (2007) is his own paper and includes the P-V data of B1-NaCl and B2-NaCl, which are not presented as a comparison.
I thank the referee for the information on a new paper on NaCl-B2 behavior under high pressure. In Murakami and Takata article, the volume of NaCl-B2 is measured up to 120 GPa but the pressure is not measured using ruby or any gauge calibrated against ruby, it is therefore impossible to compare it with the current measurements. I have not found any article by Ye published in 2007 which provides original EoS data for the compounds mentioned in the current paper. The papers by Dorogokupets et al. do not report new P-V data, but make a review of published data. Fei et al. 2007 measurement of NaCl EoS is now included in the section on NaCl-B2 EoS: “The P-V data collected using platinum as an X-ray pressure gauge up to 110 GPa also agree with the current one (the Birch-Murnaghan parameters from Table 1 in ref 8 have been considered, because there is a likely typographic error in Vinet parameters). The calibration of platinum gauge used by Fei et al. diverges by less than 0.2% with Ref. 4 in that range. ” Figure 3 has been modified to include this data set.
Secondly, the motivation for this study is not well organized. The progress and status of EOS of commonly used materials (Au, Pt, KCl, NaCl, MgO, W, Pb, et al.) are not presented.
The aim of the paper is not to make an extensive review of the high-pressure EoS of these materials. The aim is to provide corrections to published EoS parameters (when ruby was used as a gauge) subsequent to the improvement of ruby pressure metrology. The data in question have been published before ~2012, when researchers decided to use alternative metrologies to ruby luminescence, or ruby with an updated calibration. This is now more clearly stated in the introduction of the manuscript. The interest of Pb, NaCl and LiF behavior under compression is also shortly introduced: “I present here EoS parameters for several simple solids (metals - alkali halides - diamond) measured with similar techniques in the Mbar range, between 2003 and 2012, which originally considered various calibrations of the ruby luminescence gauge. Here, an unified ruby pressure metrology (based on Ref. 4) is used. Corrections to published EoS, subsequent to the update of the ruby scale, are listed in Table 1. In addition, P-V data are provided for some additional compounds: hcp-Pb, NaCl and LiF. NaCl and LiF are standards for static and dynamic compression measurements, and Pb behavior under high compression is typical of post-transition metals, and also used as a standard. These measurements are presented in the third section and compared with literature data. ”
Thirdly, usually when performing PVT EOS fitting, one would fix the V0 if the phase is quenchable because the measurements at ambient condition is the most precise and reliable.
The measurement of V0 under ambient conditions made with the same equipment has the same uncertainty than all other measurements, plus a possible error due to a remaining pressure. Fitted V0 has a decreased uncertainty due to the statistics. The fit was therefore made with free V0. As noted now: “The fitted V0 is within experimental error bars of measured volume under ambient conditions, when available”.
Lastly, the author doesn’t compare all available P-V data published previously.
In the case of Pb, NaCl and LiF, the data are compared with published the P-V data that I am aware of. For other materials, a comparison with all published data is beyond the scope of this article (see above).
There are also some minor mistakes as follows:(1) line 115: “The author declare no conflict of interest”. Declare should be declares (2) line 134, the title of the reference is missing
The mistakes have been corrected.
Reviewer 2 Report
Please see my comments that I am sending in a separate email. for some unknown reason, I am unable to copy my comments into this space.
Comments for author File: 
Comments.pdf
Author Response
This short manuscript represents a review of a significant amount of careful work together with work done by the author to determine the equations of state (EOS) at ambient temperature of more than twenty elements. The author presents data for volumes, bulk moduli, and derivatives of bulk moduli for these elements. Comparisons are made with what were previously taken as the benchmark sets of data from other workers. A definite feature of this manuscript is the application of a unified pressure metrology for the available data. The description of the methods used and the analysis of the data is clear and definitely describes what is considered to be the state-of-the-art for high-pressure EOS data. The tables and figures are clear and well described. The differences or disagreements among studies is clearly described and presented fairly. The reference list is suitably comprehensive. In summary, this clearly written and careful analysis of EOS data of many elements should be a welcomed addition to the literature regarding selected basic properties of these elements.
I thank the referee for this positive feedback. I note that the referee considers that the reference list is comprehensive, which contradicts referee #1 opinion. This divergence likely arises from a misunderstanding of the purpose of the manuscript by referee #1 (see above).
I have only a very minor comment for the author. On page 7, the sentence that contain the phrase - the domain which contraints the most the value of -the domain that places the most constraints on the value of
Mistake corrected.
Reviewer 3 Report
The manuscript gives a brief summary of the method used in the measurements of room temperature equations of state of 18 simple solids by the author and her colleagues. In addition, new data of Pb, NaCl, and LiF are included in this manuscript, making the total number of 21 solids. These samples were in helium or neon pressure medium, and the x-ray diffraction measurements were performed using the small and bright synchrotron beam. The experimental approach is the state-of-the-art. Such high quality experimental data are not only essential for understanding the equations of state of materials, but also provide a critical check for the pressure gauge of ruby fluorescence. I recommend publication of this manuscript in Minerals. Meanwhile, a few minor comments are included below.
Include uncertainties in tabulated numbers in Tables 1-4 Line 13, change "atomic volume" to "unit cell volume" Line3 38-39: The description of "no pressure drift" is an overstatement. When using helium or neon as pressure medium, it is common to observe pressure drift with time. It will be helpful for the author to include more detail information on the pressure drift, such as data collection time, wait time between two pressure points, and the pressure drift observed (even if it is negligible). A related matter is the pressure gradient across the sample chamber. Including the information of pressure variations (assuming that there were several ruby balls across the chamber) will be also helpful.
Author Response
The manuscript gives a brief summary of the method used in the measurements of room temperature equations of state of 18 simple solids by the author and her colleagues. In addition, new data of Pb, NaCl, and LiF are included in this manuscript, making the total number of 21 solids. These samples were in helium or neon pressure medium, and the x-ray diffraction measurements were performed using the small and bright synchrotron beam. The experimental approach is the state-of-the-art. Such high quality experimental data are not only essential for understanding the equations of state of materials, but also provide a critical check for the pressure gauge of ruby fluorescence. I recommend publication of this manuscript in Minerals. Meanwhile, a few minor comments are included below.
I thank the referee for this advice.
Include uncertainties in tabulated numbers in Tables 1-4
Line 13, change "atomic volume" to "unit cell volume" done
Line3 38-39: The description of "no pressure drift" is an overstatement. When using helium or neon as pressure medium, it is common to observe pressure drift with time. It will be helpful for the author to include more detail information on the pressure drift, such as data collection time, wait time between two pressure points, and the pressure drift observed (even if it is negligible).
This point is now discussed more accurately: “The pressure is increased with steps of 1 GPa to 4 GPa, with sufficient stabilization time to collect the data with negligible pressure drift (less than 0.5 GPa, estimated by measuring the pressure before and after X-ray exposure). This requires wait time of up to 30 minutes for low pressure (below 20 GPa) points, and of less than 10 minutes for highest pressure points. The data collection time is typically 5 minutes, one minute for ruby pressure measurement and another 2 minutes for the X-ray diffraction exposure (including beam search), and two minutes to check the pressure after exposure. ”
A related matter is the pressure gradient across the sample chamber. Including the information of pressure variations (assuming that there were several ruby balls across the chamber) will be also helpful.
There was only one pressure gauge in our experiments. It is now described: “In order to diminish the measurement bias due to pressure gradients (which can reach 0.4 GPa at 50 GPa [9]), the gauge was located less than 4 microns away from the sample”.
Round 2
Reviewer 1 Report
The author has addressed my concerns. I recommend accepting the manuscript for publication.
