High-Pressure Synthesis of the Iodide Carbonate Na₅(CO₃)₂I

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors report on the synthesis of Na5(CO3)2I under high pressure.

The paper is clearly written, and considering that very few groups in the world conduct research under extreme conditions such as high pressure, publication of the submitted article in Solids is definitely recommended. Before doing so, however, the authors should clarify a few points in detail.

1) How was the pressure deviation determined, e.g. 18(1) GPa, 4(3) GPa, etc.?

2) The authors solved the structures at 18(1) GPa and 25.1(5) GPa from single crystals, and the structures were deposited in the CCDC crystallographic database. The authors also claim that Na5(CO3)2I is still preserved after decompression, as can be seen in Figure 3.

In this regard, the authors should perform the Rietveld refinement of the 4(3) GPa data using the structure solved at 18 GPa, i.e., the .cif of Na5(CO3)2I at 18(1) GPa. If the structure is preserved at 4.1 GPa, this would be conclusive evidence.

3) The authors also claim that the structure is preserved at 4(3) GPa. However, reflection 105, which is present in 18(1) GPa powder pattern, is absent in the 4(3) GPa powder pattern. Why?

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Authors synthesized a new sodium carbonate iodide using method of HT synthesis under pressure. Material was structurally characterized and some DFT calculations have been performed. I believe this work can be accepted for publications. There are some remarks:

1 - Did you try to synthesize this material at normal pressure? Can you comment on a possibility to do so?  

2 – Did you calculate a dependence of dG vs Pressure? What is the thermodynamic stability range for this phase?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf