Accessible Thermoelectric Characterization: Development and Validation of Two Modular Room Temperature Measurement Instruments

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In my opinion, the method and the results are acceptable, but the way it is communicated it not what researchers expect. The overall paper needs a restructuring and a polishing before it can be published. Let me give a few examples:

• The equations 3 and 4 contain subindexes that are never explained.
• The way that the currents are written in those equations seems to indicate that you measure 8 currents, which is false.
• The figures are not really professional, look for example at the labels in figure 1 d), they are impossible to read.
• For clarity, the setup should be described in a separate section before the results and discussion section.
• A table with the samples used, the values that you expect, the values that you measured and the deviations would help a lot.
• Also the English is grammatically correct, but the general feeling is more like a report made by undergraduates.

I believe that the article has good content, but it is not really well explained.

Author Response

Comment 1:

The equations 3 and 4 contain subindexes that are never explained.

Response 1:

Figure 2 was extended with measurement positions which are related to the equations 3, 4, 6, 7 with references in the text as well to improve clarity.

Comment 2:

The way that the currents are written in those equations seems to indicate that you measure 8 currents, which is false.

Response 2:

Equations were modified to improve clarity and hopefully prevent confusion. However, 8 currents were indeed "measured". Newly prepared supplementary materials include more details about the measurements.

Comment 3:

The figures are not really professional, look for example at the labels in figure 1 d), they are impossible to read.

Response 3:

The relevant Figure was changed to to improve readability. Subpart d) was moved to the Supplementary Materials to get a bigger size picture and to allow for more detailed description of all the elements shown. Together with detailed description of output files for both instruments.  

Comment 4:

For clarity, the setup should be described in a separate section before the results and discussion section.

Response 4:

This was our initial intended ordering as well. Based on your comment I requested and was granted an approval from Inorganics editorial office to swap Materials and Methods and Results and Discussion sections to improve readability. 

Comment 5:

A table with the samples used, the values that you expect, the values that you measured and the deviations would help a lot.

Response 5:

We did not want to add such a table to the manuscript itself. We created a section in the new Supplementary Materials for this manuscript where this section is included. Together with other sections requested by other reviewers.

Comment 6:

Also the English is grammatically correct, but the general feeling is more like a report made by undergraduates.

Response 6:

Minor adjustments were made throughout the manuscript. The overall "feeling" was not changed to keep the intended simplicity. This is meant to allow other groups to easily replicate/modify/evolve described devices or procedures to allow more groups access to low-cost rapid thermoelectrics testing.  

Reviewer 2 Report

Comments and Suggestions for Authors

In this study, the authors have designed two instruments (THEMA and RelaMag) for cost-effective and fast thermoelectric characterization at room temperature. The work is appealing and will be of interest to a broader audience. I have few minor comments. The manuscript can be accepted for publication after minor revision.

1. The authors have referred to α²σ as ‘thermopower’ whereas the correct term is ‘power factor.’ The term ‘thermopower’ is generally used for the Seebeck coefficient.

2. Why did the authors choose SnSe for testing the system instead of a more widely studied and stable material such as Bi2Te3?

3. Could the authors provide reproducibility data for the Seebeck and electrical conductivity measurements over multiple runs? And include the uncertainty?

4. Can you please include the measurement error in the measurements compare to commercial setups.

Author Response

Comment 1:

The authors have referred to α²σ as ‘thermopower’ whereas the correct term is ‘power factor.’ The term ‘thermopower’ is generally used for the Seebeck coefficient.

Response 1:

Upon further study of the literature, we have corrected the term thermopower to power factor. This was caused mainly by few older sources that referred to α²σ as thermopower and to α as Seebeck coefficient only.

Comment 2:

Why did the authors choose SnSe for testing the system instead of a more widely studied and stable material such as Bi2Te3?

Response 2:

SnSe was chosen mainly as it is material we are (and were) studying. Because of that we had results for these materials from many instruments. These results were then used as a baseline during development and were also shown as a comparison. For THEMA device we also did calibration/testing with select pure elements prepared in different ways.

We did not synthesize Bi2Te3 because one of our goals was to eliminate the use of expensive Te and we believed this material to be studied enough in other works.

Our preliminary results are showing that SnSe is also a very stable thermoelectric material. Samples show little to no change in electrical properties after 2 years in storage and multiple thermal cycles. These results are not finalized yet and will be included in the future paper.

Comment 3:

Could the authors provide reproducibility data for the Seebeck and electrical conductivity measurements over multiple runs? And include the uncertainty?

Response 3:

As stated in the manuscript data can be provided upon request. However, based on your comment and of one other reviewer we decided to create Supplementary materials document for this manuscript where more data is provided. Relevant Figures were also updated accordingly. RelaMag instrument currently has a limitation in the software. User specifies how many times a single configuration is measured and how many times all the measurements are repeated and calculates an average of all these results. All results from each cycle are stored but from a single point only average is stored. Full output from RelaMag is also included in the file. We are currently working on the new version of the software which will include an option to store all the results and therefore allow more detailed calculation of uncertainty.

Comment 4:

Can you please include the measurement error in the measurements compare to commercial setups.

Response 4:

Relevant Figure was updated. More details were also added to the Supplementary Materials.

Reviewer 3 Report

Comments and Suggestions for Authors

This is a very interesting piece of work on thermoelectric measurements. Two instruments are developed, i.e., THEMA and RelaMag. These two instruments are inexpensive, easily reproducible, ease of reproduction and modification. It is believed that they are broadly applicable to a wide range of thermoelectric systems for rapid screening of novel materials as thermoelectric. Following queries are for the authors.

Line 4 on page 3, “od” could be “of”;

Line 13 from bottom on page 6, “(Figure 2c)” could be “(Figure 3c)”;

Line 2-3 at section 3.1 on page 9, “Figure 5a” could be “Figure 1a”;

Please confirm above issues.

 

There are no discussions on Figure 3a on page 7. Few sentences on it will be very helpful. For instance, explain the meaning of “mBi” in this diagram, and so on.

Author Response

Comment 1:

Line 4 on page 3, “od” could be “of”;

Line 13 from bottom on page 6, “(Figure 2c)” could be “(Figure 3c)”;

Line 2-3 at section 3.1 on page 9, “Figure 5a” could be “Figure 1a”;

Response1:

All of these have been addressed and corrected. Thank you for pointing them out.

 

Comment 2:

There are no discussions on Figure 3a on page 7. Few sentences on it will be very helpful. For instance, explain the meaning of “mBi” in this diagram, and so on.

Response 2:

Additional references were added to the 2.3 section. All of these point to specific parts of the relevant Figure, hopefully explaining what is shown more clearly. mBi meaning was clarified in the Figure caption.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I agree with the improvements and I consider it acceptable for publication.

Reviewer 2 Report

Comments and Suggestions for Authors

I think it would be a good idea to accept the manuscript in the current form.

Reviewer 3 Report

Comments and Suggestions for Authors

After revision, the paper is well-presented and can be published.