The present investigation was supported by the Grant Agency of the Ministry of Education, Science, Research and Sport of the Slovak Republic (project 2/0112/22).&#160;The present investigation was also supported by ERA-MIN3 POTASSIAL 27 project.

1. Preparation of CuS mixture with the stoichiometry 1.6:1
<ol>
	<li>Tare the weighing paper.</li>
	<li>Weigh 7.6024 g of elemental copper and 2.3974 g of elemental sulfur powder to achieve the stoichiometry ratio of Cu and S at 1.6:1, with a total mass of 10 g.</li>
	<li>Before milling, mix the Cu and S powder. After weighing, introduce both Cu and S powders into a plastic weighing dish and mix intensively with a spatula, until a powder of homogeneous color free from large lumps of sulfur is obtained. 
	NOTE: The purpose of the mixing is to homogenize the powder and ensure a uniform distribution of powders before the milling experiment.</li>
</ol>
2. Preparation of SnSe mixture with the stoichiometry 1:1
<ol>
	<li>Tare the weighing paper.</li>
	<li>Weigh 6.0055 g of Sn and 3.9945 g of Se to make the stoichiometry ratio 1:1, with a total mass of 10 g.</li>
	<li>Before milling, mix the Sn and Se powder by using a spatula to ensure homogeneity (the rules from 1.3 also apply here).</li>
</ol>
3. Sensor setup
<ol>
	<li>Place the sensor board on the top of the jar lid and insert the sensor transistor into the small hole that passes through the lid.</li>
	<li>Switch on the sensor device and connect it to the software on the laptop via Bluetooth.</li>
</ol>
4. Performing milling with in situ temperature monitoring
NOTE: The necessary equipment, including the scheme of the temperature monitoring device, is shown in Figure 1.
<ol>
	<li>Insert tungsten carbide balls, as specified in Table 1, into the milling jar using the tweezers or just &#34;pour&#34; them inside using gravitational force.</li>
	<li>Transfer the prepared sample either from section 1 or section 2 to the tungsten carbide milling jar for the synthesis of Cu1.8S or SnSe.</li>
	<li>Close the milling jar with the lid that has been set up with the sensor from section 3.</li>
	<li>Load the jar into the mill by placing the jar and the counterweight into the P7 planetary mill and setting the parameters on the display as specified in Table 1.</li>
	<li>Type the name of the sample on the active software.</li>
	<li>Press the Start button on the milling display.</li>
	<li>After hearing the milling start, click Start in the active software for the sensor to begin recording the temperature during milling.</li>
	<li>When the MSR occurs, indicated by the sudden increase in temperature, stop the milling and the temperature measurement immediately. 
	NOTE: Repeat the experiment with the same system once again for reproducibility</li>
</ol>
5. Collecting samples
<ol>
	<li>Open the jar over a paper sheet in the fume hood, separate the milling balls by sieving the powder through the strainer. The balls remain on the strainer while the fine powder drops on the paper. In the case of large agglomerates, these are removed from ther strainer using tweezers.&#160;Collect the sample from the paper.</li>
</ol>
6. Transferring the powders
<ol>
	<li>Transfer the powders from the paper to the glass vials using the gravitational force and&#160;spatula, label them, and store them in the desiccator before the measurement.</li>
</ol>
7. Labeling the glass vials
<ol>
	<li>Label the glass vials based on the sample name.</li>
</ol>
8. Cleaning the jar and sensor
<ol>
	<li>Clean the sensor transistor by wiping it with the tissue soaked in etaben.</li>
	<li>In the case of the jar, pour 75 mL of the etaben solution into the milling jars and perform milling at 300 rpm for 5 min.</li>
	<li>Use a steel strainer to collect the balls from the jars, and dispose of the toxic aqueous waste into the container.</li>
	<li>Repeat steps 8.2 and 8.3 until the jar and the balls are free from the solid powder.</li>
</ol>
9. Processing data from in situ temperature monitoring
<ol>
	<li>After finishing the monitoring, the software saves the data automatically as .xlsx files in the download folder on the computer.</li>
	<li>Process the data in the data treatment software to plot the graph temperature vs time. The raw data obtained from the measurement are directly stored as a .csv file and are already segregated into columns.</li>
</ol>
10. Powder X-ray diffraction (XRD) measurement
<ol>
	<li>Crush the obtained samples by using a mortar and pestle. The samples&#39; appearance is depicted in Figure 2.</li>
	<li>Transfer each sample with a spatula to the sample holders and label each sample holder.</li>
	<li>Gently compress the powder with a glass slide, carefully sliding or rotating it to flatten the surface evenly.</li>
	<li>Transfer the sample holder to the XRD diffractometer.</li>
	<li>Set up the XRD measurement in the computer using the XRD commander program programming the given measurement conditions. 
	NOTE: The instrument used in this study is an X-ray diffractometer using CuK&#945; (40 kV, 40 mA) radiation. The parameter for the powder X-ray diffraction (PXRD) experiment: 2-theta range: 10&#176;-80&#176;, step time: 1 s, step size 0.05 s.</li>
	<li>Start the PXRD measurement. The XRD data is saved as a &#34;.raw file &#34;on the computer disk.</li>
	<li>After finishing the measurement, collect the powder back from the sample holder into the glass vial using paper.</li>
	<li>Convert the .raw file into another file type that is suitable for processing in data treatment software (e.g., Origin) 
	NOTE: The PowDLL converter will allow one to convert the file extensions to the desired extension, for example, to .xy format, which is required for Rietveld refinement.</li>
</ol>
11. Rietveld refinement
<ol>
	<li>Do the proper semi-quantitative phase analysis using the XRD software to identify the phases that will be included in the refinement.</li>
	<li>Download corresponding .CIF files from the internet, e.g., from Crystallography Open Database. Download the one for CuS, rhombohedral Cu1.8S, cubic Cu1.8S, SnSe, and SnSe2.</li>
	<li>Run JEdit and powder diffraction data analysis software. 
	NOTE: The powder diffraction data analysis software used here is Topas Academic software. JEdit was formerly modified to be capable of working with the powder diffraction data analysis software.</li>
	<li>Create an input file in JEdit. Ensure that the file contains information about the diffractometer and structural parameters of the phases that are included in the refinement.</li>
	<li>Decide which parameters will be refined.</li>
	<li>Run the refinement in powder diffraction data analysis software. The software saves the result in the .out file, which automatically becomes the new input &#34;.inp&#34; file if another refinement is run.</li>
	<li>Modify the input parameters to get the best refinement possible (determined by the Rwp factor) and run the refinement again.</li>
	<li>Once it is not possible to further improve the refinement, modify the input file in such a way as to save also the results as a .xyd file, which can be read by Origin software.</li>
	<li>Run the refinement for one last time and export the .xyd file.</li>
	<li>Find the information about crystallite size and phase composition in the refinement result (there is an option to run the refinement to provide this information) and note it down.</li>
	<li>Process the data in data analysis software and make the final figures. 
	NOTE: This study used Origin software.</li>
</ol>

Synthesis of High-ZT Thermoelectric Materials via Mechanochemical Methods

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The authors have no competing financial interests

Mechanically induced self-propagating reactions (MSR) are an immediate transformation of precursors into products via an exothermic combustion-like process activated by mechanical action (similar to self-heat sustaining reactions where similar processes are activated by heat). The occurrence of MSR can often be identified by changes in the physical appearance of the product, a distinct smell at the moment of the reaction, or a scratching sound from the milling&#160;jar. However, empirical evidence suggests that these sen...

Statistically, more than 60% of energy in the world is lost, mostly as waste heat.&#160;Utilizing&#160;the waste heat for thermoelectricity (TE) applications has a great potential. TE offers a suitable method to convert waste heat into electrical energy. Special applications, like electrical energy sources in radioactive thermoelectric generators for space research and/or replacing the old Hg-Zn batteries in cardiac pacemakers, can be mentioned1.
Among various TE materials, chalcogenides belong among the favorites, especially if they are composed of abundant and non-toxic elements. Chalcogenides with tellurium, lead, and germanium content were reported as perspective TE materials in the past, with Bi2Te3 and (Bi,Sb)2Te3 being among the most prominent examples. However, both Bi and Te are rare and/or toxic, making the mass production of TE materials with this composition challenging2. Looking forward to selection among chalcogenides, the new alternatives that bear in mind non-toxicity, earth-abundancy, and TE efficiency are considered. Two systems that fulfill these criteria are copper sulfides Cu2-xS and tin selenide SnSe.
Copper sulfides are present frequently in nature as minerals in several compositions, with chalcocite Cu2S and covellite CuS as border members. In between, several&#160;non-stoichiometric&#160;compounds exist3. Among them, Cu1.97S and Cu1.98S, with interesting properties, were already synthesized by directly melting the elements Cu and S4,5.&#160;&#160;Also, digenite Cu1.8S is particularly interesting for thermoelectrics.
Tin selenide SnSe represents a high TE figure among chalcogenides. The synthesis at&#160;1223 K for over 9.5 h led to its ultralow thermal conductivity and subsequent high thermoelectric efficiency6. Accompanying phenomena were not studied.
Synthesis routes of copper sulfides and tin selenides encompass mostly high-temperature treatment of reaction precursors4,7,8,9,10. However, there are also alternative, more environmentally sound synthesis routes such as mechanochemical synthesis3,11,12,13. The&#160;mechanochemical synthesis of chalcogenides&#160;from elements can, under some circumstances, occur as a mechanically induced self-propagating reaction (MSR), which is a combustion-like process instantly yielding the products in a very short timeframe14,15,16. For both systems reported in this study, the MSR was reported- for Cu1.8S, it was done instantly, albeit the Cu:S ratio 1.6 needed to be used due to the volatility of sulfur16,17, and for SnSe, it occurred in about 15 s16.
The ignition of an MSR is accompanied by a sudden increase in temperature and pressure. Upon monitoring these characteristics via specifically engineered milling jars, it is possible to determine the MSR onset. However, the commercially available devices for planetary ball milling monitoring offer only the data collection every 2 s, and due to the location of the sensors, MSR can be detected only via pressure monitoring, neither by temperature one16,18. Moreover, the mentioned system is not transferrable and can only be both purchased and used together with the specifically engineered milling jar, which is both limiting and costly. We have recently developed a transferrable device capable of collecting temperature data every 80 ms19. This advanced measuring system developed for in situ temperature monitoring during mechanochemical synthesis significantly enhances the capabilities over existing commercial solutions. This system employs an NRBG104F3435B2F NTC thermistor, featuring a resistance tolerance of &#177;1% at 25 &#176;C and a beta value tolerance of &#177;1%, ensuring high-precision temperature measurements. With a data capture frequency of every 80 milliseconds, the system provides a high-resolution monitoring crucial for detecting the initiation of MSRs. The thermistor&#39;s high sensitivity to temperature changes, indicated by a steep resistance-temperature relationship, ensures accurate detection of rapid temperature spikes. The temperature sensor is strategically placed within an existing screw mechanism used for pressure release and gas addition, located in the hole of a massive cap. This placement protects the sensor from mechanical collisions and signal noise caused by the milling balls, ensuring stable and reliable temperature readings.&#160;The limitation is that the ball diameter needs to be larger than the hole diameter. With 10 mm balls, there is no problem. The system&#39;s wireless communication capability and robust sealing mechanism prevent material or heat leakage, thereby enhancing the reliability and accuracy of the temperature data collected during the milling process. Designed to be cost-effective and portable, this system represents a significant advancement in the real-time&#160;temperature monitoring of chemical reactions during planetary ball milling, offering critical insights for the optimization of materials synthesis.
This study aims to demonstrate the performance of this newly developed device by monitoring temperature during the mechanochemical synthesis of two selected metal chalcogenides that are interesting for TE applications. Another objective is to show the sustainable, simple, and time-saving character of the mechanochemical synthesis, which is boosted when the reaction occurs as an MSR.

<table><tbody><tr><td>Copper</td><td>Pometon, Germany</td><td>7440-50-8</td><td>Red powder</td></tr><tr><td>D8 Advance diffractometer&amp;nbsp;</td><td>Bruker, Germany</td><td>M88-E03036</td><td>X-ray instrument</td></tr><tr><td>DiffracPlus Evaluation package release</td><td>Bruker, Germany</td><td>DOC-M85-EXX002</td><td>Diffraction analysis software</td></tr><tr><td>Etaben</td><td>Mikrochem, Slovakia</td><td>64-17-5</td><td>solution</td></tr><tr><td>Jedit</td><td>Open Source software</td><td></td><td>Programmer&#039;s text editor</td></tr><tr><td>Project SAV 1.0</td><td></td><td></td><td>Software developed to record data from in situ temeprature monitoring</td></tr><tr><td>Pulverisette P7 planetary mill</td><td>Fritsch, Germany</td><td>07.5000.00</td><td>The milling device, utilized in the synthesis of Cu&lt;sub&gt;1.8&lt;/sub&gt;S and SnSe</td></tr><tr><td>Selenium</td><td>Acros Organic, Germany</td><td>7782-49-2</td><td>Gray powder</td></tr><tr><td>Sulfur</td><td>Sigma Aldrich, Germany</td><td>7704-34-9</td><td>Yellow powder</td></tr><tr><td>Tin</td><td>Merck, Germany</td><td>7440-31-5</td><td>Gray powder</td></tr><tr><td>Topas Academic</td><td>Coelho Software</td><td></td><td>General non-linear least squares software driven by a scripting language. Its main focus is in crystallography, solid state chemistry and optimization.</td></tr></tbody></table>

demonstrating the simplicity and in situ temperature monitoring of the mechanochemical synthesis of metal chalcogenides suitable for thermoelectrics

Mechanochemical synthesis is an extremely useful strategy to reach thermoelectric materials due to its solvent-free one-step character, as the targeted thermoelectricity (TE) materials in a nanocrystalline format can be prepared by mere high-energy milling of elemental precursors. Nevertheless, the subsequent densification method (e.g., spark plasma sintering or hot pressing) is required afterward, similarly to other synthetic methodologies. In this study, the simplicity of mechanochemical synthesis is&#160;presented for two selected metal chalcogenides, namely copper sulfide (Cu1.8S, digenite) and tin selenide (SnSe, svetlanaite), which are known for high ZT values. These compounds can be prepared via a mechanically induced self-propagating reaction (MSR), which is a combustion-like process instantly yielding the products in a very short timeframe (within 1 min). The occurrence of MSR can be well-tracked by in situ temperature monitoring since an abrupt temperature increase occurs at the moment of MSR. We have developed a device which is capable of monitoring the temperature inside the milling jar every 80 ms during planetary ball milling, and it is therefore possible to very precisely track the moment of MSR ignition. The developed device presents an improvement in the monitoring capabilities in comparison with commercially available analogs. This contribution aims to provide a visual insight into all steps, with simple high-energy ball milling of elements to reach TE materials and in situ temperature monitoring being the central points.

The temperature during milling was recorded using Project SAV 1.0 software and plotted accordingly. Figure 3 demonstrates the changes in temperature with milling time. For the Cu1.8S samples (Figure 3A), the ignition times fall within the range of 0-0.6 s. In the sample Cu1.8S-1, the MSR occurred before temperature data collection began. Therefore, when performing the two next experiments (Cu1.8S-2 and 4), data collection was sta...

Demonstrating the Simplicity and In Situ Temperature Monitoring of the Mechanochemical Synthesis of Metal Chalcogenides Suitable for Thermoelectrics

Here, we present a protocol to synthesize two metal chalcogenides (Cu1.8S and SnSe) suitable for thermoelectrics via an ultrafast (second-range), solvent-free, and one-step mechanochemical synthesis using elemental precursors. Simultaneously, we demonstrate the monitoring of the temperature in the jar during planetary ball milling in situ by the newly developed device.

Mechanochemical synthesis is an extremely useful strategy to reach thermoelectric materials due to its solvent-free one-step character, as the targeted ...

demonstrating-simplicity-situ-temperature-monitoring-mechanochemical

Research

JoVE Journal

Chemistry

303 Views.  Slovak Academy of Sciences. Het doel van ons onderzoek is de ontwikkeling van een overdraagbaar apparaat dat in staat is om de temperatuur in de maalpot op een hoogfrequente manier te bewaken en tegelijkertijd de eenvoud van de mechanochemische synthese aan te tonen op twee voorbeelden van metaalchalcogeniden die geschikt zijn voor thermo-elektrische toepassingen. Momenteel worden metaalchalcogeniden meestal gesynthetiseerd met behulp van meerstaps, milieubelastende methodologieën, vaa...

Video: Demonstratie van de eenvoud en in situ temperatuurbewaking van de mechanochemische synthese van metalen chalcogeniden die geschikt zijn voor thermo-elektriciteit

Thermal Measurement Techniques in Analytical Microfluidic Devices

Thermal measurement techniques have been used for many applications such as thermal characterization of materials and chemical reaction detection. Micromachining techniques allow reduction of the thermal mass of fabricated structures and introduce the possibility to perform high sensitivity thermal measurements in the micro-scale and nano-scale devices. Combining thermal measurement techniques with microfluidic devices allows performing different analytical measurements with low sample consumption and reduced measurement time by integrating the miniaturized system on a single chip. The procedures of thermal measurement techniques for particle detection, material characterization, and chemical detection are introduced in this paper.

Here, we present three protocols for thermal measurements in microfluidic devices.

Thermal measurement techniques have been used for many applications such as thermal characterization of materials and chemical reaction detection. ...

Engineering

Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film synthesis) for the purpose of exploratory materials research. Certain materials pose a challenge wherein the traditional bulk Hall bar device fabrication method is insufficient to produce a measureable device for sample transport measurement, principally because the single crystal size is too small to attach wire leads to the sample in a Hall bar configuration. This can be, for example, because the first batch of a new material synthesized yields very small single crystals or because flakes of samples of one to very few monolayers are desired. In order to enable rapid characterization of materials that may be carried out in parallel with improvements to their growth methodology, a method of device fabrication for very small samples has been devised to permit the characterization of novel materials as soon as a preliminary batch has been produced. A slight variation of this methodology is applicable to producing devices using exfoliated samples of two-dimensional materials such as graphene, hexagonal boron nitride (hBN), and transition metal dichalcogenides (TMDs), as well as multilayer heterostructures of such materials. Here we present detailed protocols for the experimental device fabrication of fragments and flakes of novel materials with micron-sized dimensions onto substrate and subsequent measurement in a commercial superconducting magnet, dry helium close-cycle cryostat magnetotransport system at temperatures down to 0.300 K and magnetic fields up to 12 T.

We describe the methodology of mechanical exfoliation and deposition of flakes of novel materials with micron-sized dimensions onto substrate, fabrication of experimental device structures for transport experimentation, and the magnetotransport measurement in a dry helium close-cycle cryostat at temperatures down to 0.300 K and magnetic fields up to 12 T.

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film ...

High-resolution Thermal Micro-imaging Using Europium Chelate Luminescent Coatings

Micro-electronic devices often undergo significant self-heating when biased to their typical operating conditions. This paper describes a convenient optical micro-imaging technique which can be used to map and quantify such behavior. Europium thenoyltrifluoroacetonate (EuTFC) has a 612 nm luminescence line whose activation efficiency drops strongly with increasing temperature, due to T-dependent interactions between the Eu3+ ion and the organic chelating compound. This material may be readily coated on to a sample surface by thermal sublimation in vacuum. When the coating is excited with ultraviolet light (337 nm) an optical micro-image of the 612 nm luminescent response can be converted directly into a map of the sample surface temperature. This technique offers spatial resolution limited only by the microscope optics (about 1 micron) and time resolution limited by the speed of the camera employed. It offers the additional advantages of only requiring comparatively simple and non-specialized equipment, and giving a quantitative probe of sample temperature.

Europium thenoyltrifluoroacetonate (EuTFC) has an optical luminescence line at 612 nm, whose activation efficiency decreases strongly with temperature. If a sample coated with a thin film of this material is micro-imaged, the 612 nm luminescent response intensity may be converted into a direct map of sample surface temperature.

Micro-electronic devices often undergo significant self-heating when biased to their typical operating conditions. This paper describes a convenient ...

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and forging. Adoption of this technique is proceeding despite disagreement concerning the underlying mechanism responsible for EAD. The experimental procedure described herein enables a more explicit study compared to previous EAD research by removing thermal effects, which are responsible for disagreement in interpreting previous EAD results. Furthermore, as the procedure described here enables EAD observation in situ and in real time in a transmission electron microscope (TEM), it is superior to existing post-mortem methods that observe EAD effects post-test. Test samples consist of a single crystal copper (SCC) foil having a free-standing tensile test section of nanoscale thickness, fabricated using a combination of laser and ion beam milling. The SCC is mounted to an etched silicon base that provides mechanical support and electrical isolation while serving as a heat sink. Using this geometry, even at high current density (~3,500 A/mm2), the test section experiences a negligible temperature increase (&#60;0.02 &#176;C), thus eliminating Joule heating effects. Monitoring material deformation and identifying the corresponding changes to microstructures, e.g. dislocations, are accomplished by acquiring and analyzing a series of TEM images. Our sample preparation and in situ experiment procedures are robust and versatile as they can be readily utilized to test materials with different microstructures, e.g., single and polycrystalline copper.

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Isolating electrical and thermal effects on electrically assisted deformation (EAD) is very difficult using macroscopic samples. Metallic sample micro- and nanostructures together with a custom test procedure have been developed to evaluate the impact of applied current on the formation without joule heating and evolution of dislocations on these samples.

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and ...

In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for Cu(In,Ga)Se2 Solar Cells

The levelized cost of electricity (LCOE) of photovoltaic (PV) systems is determined by, among other factors, the PV module reliability. Better prediction of degradation mechanisms and prevention of module field failure can consequently decrease investment risks as well as increase the electricity yield. An improved knowledge level can for these reasons significantly decrease the total costs of PV electricity. 
In order to better understand and minimize the degradation of PV modules, the occurring degradation mechanisms and conditions should be identified. This should preferably happen under combined stresses, since modules in the field are also simultaneously exposed to multiple stress factors. Therefore, two 'Combined Stress test with in situ measurement' setups have been designed and constructed. These setups allow the simultaneous use of humidity, temperature, illumination, and electrical biases as independently controlled stress factors on solar cells and minimodules. The setups also allow real-time monitoring of the electrical properties of these samples. This protocol presents these setups and describes the experimental possibilities. Moreover, results obtained with these setups are also presented: various examples about the influence of both deposition and degradation conditions on the stability of thin film Cu(In,Ga)Se2 (CIGS) as well as Cu2ZnSnSe4 (CZTS) solar cells are described. Results on the temperature dependency of CIGS solar cells are also presented.

In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for CuIn,GaSe2 Solar Cells

Two &#39;Combined Stress test with in situ measurement&#39; setups, which allow real-time monitoring of accelerated degradation of solar cells and modules, were designed and constructed. These setups allow the simultaneous use of humidity, temperature, electrical biases, and illumination as independently controlled stress factors. The setups and various experiments executed are presented.

The levelized cost of electricity (LCOE) of photovoltaic (PV) systems is determined by, among other factors, the PV module reliability. Better prediction ...

Asymmetric Thermoelectrochemical Cell for Harvesting Low-grade Heat under Isothermal Operation

Low-grade heat is abundantly available in the environment as waste heat. The efficient conversion of low-grade heat into electricity is very difficult. We developed an asymmetric thermoelectrochemical cell (aTEC) for heat-to-electricity conversion under isothermal operation in the charging and discharging processes without exploiting the thermal gradient or the thermal cycle. The aTEC is composed of a graphene oxide (GO) cathode, a polyaniline (PANI) anode, and 1M KCl as the electrolyte. The cell generates a voltage due to the pseudocapacitive reaction of GO when heating from room temperature (RT) to a high temperature (TH, ~40-90 &#176;C), and then current is successively produced by oxidizing PANI when an external electrical load is connected. The aTEC demonstrates a remarkable temperature coefficient of 4.1 mV/K and a high heat-to-electricity conversion efficiency of 3.32%, working at a TH = 70 &#176;C with a Carnot efficiency of 25.3%, unveiling a new promising thermoelectrochemical technology for low-grade heat recovery.

Low-grade heat is abundant, but its efficient recovery is still a great challenge. We report an asymmetric thermoelectrochemical cell using graphene oxide as a cathode and polyaniline as an anode with KCl as the electrolyte. This cell works under isothermal heating, exhibiting a high heat-to-electricity conversion efficiency in low-temperature regions.

Low-grade heat is abundantly available in the environment as waste heat. The efficient conversion of low-grade heat into electricity is very difficult. We ...

In Situ Surface Temperature Measurement in a Conveyor Belt Furnace via Inline Infrared Thermography

Measuring the surface temperature of objects that are processed in conveyor belt furnaces is an important tool in process control and quality assurance. Currently, the surface temperature of objects processed in conveyor belt furnaces is typically measured via thermocouples. However, infrared (IR) thermography presents multiple advantages compared to thermocouple measurements, as it is a contactless, real-time, and spatially resolved method. Here, as a representative proof-of-concept example, an inline thermography system is successfully installed into an IR lamp powered solar firing furnace, which is used for the contact firing process of industrial Si solar cells. This protocol describes how to install an IR camera into a conveyor belt furnace, conduct a customer correction of a factory calibrated IR camera, and perform the evaluation of spatial surface temperature distribution on a target object.

This protocol describes how to install an infrared camera into a conveyor belt furnace, conduct a customer correction of a factory calibrated IR camera, and evaluate the spatial surface temperature distribution of an object of interest. The example objects are industrial silicon solar cells.

Measuring the surface temperature of objects that are processed in conveyor belt furnaces is an important tool in process control and quality assurance. ...

Performing In Situ Closed-Cell Gas Reactions in the Transmission Electron Microscope

Gas reactions studied by in situ electron microscopy can be used to capture the real-time morphological and microchemical transformations of materials at length scales down to the atomic level. In situ closed-cell gas reaction (CCGR) studies performed using (scanning) transmission electron microscopy (STEM) can separate and identify localized dynamic reactions, which are extremely challenging to capture using other characterization techniques. For these experiments, we used a CCGR holder that utilizes microelectromechanical systems (MEMS)-based heating microchips (hereafter referred to as &#34;E-chips&#34;). The experimental protocol described here details the method for performing in situ gas reactions in dry and wet gases in an aberration-corrected STEM. This method finds relevance in many different materials systems, such as catalysis and high-temperature oxidation of structural materials at atmospheric pressure and in the presence of various gases with or without water vapor. Here, several sample preparation methods are described for various material form factors. During the reaction, mass spectra obtained with a residual gas analyzer (RGA) system with and without water vapor further validates gas exposure conditions during reactions. Integrating an RGA with an in situ CCGR-STEM system can, therefore, provide critical insight to correlate gas composition with the dynamic surface evolution of materials during reactions. In situ/operando studies using this approach allow&#160;for detailed investigation of the fundamental reaction mechanisms and kinetics that occur at specific environmental conditions (time, temperature, gas, pressure), in real-time, and at high spatial resolution.

Performing In Situ Closed-Cell Gas Reactions in the Transmission Electron Microscope

Here, we present a protocol for performing in situ TEM closed-cell gas reaction experiments while detailing several commonly used sample preparation methods.

Gas reactions studied by in situ electron microscopy can be used to capture the real-time morphological and microchemical transformations of materials at ...

Magnetometric Characterization of Redox-Active MOFs Solid-State Electrochemistry

Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks

Electrochemical energy storage has been a widely discussed application of redox-active metal-organic frameworks (MOFs) in the past 5 years. Although MOFs show outstanding performance in terms of gravimetric or areal capacitance and cyclic stability, unfortunately their electrochemical mechanisms are not well understood in most cases. Traditional spectroscopic techniques, such as X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS), have only provided vague and qualitative information about valence changes of certain elements, and the mechanisms proposed based on such information are often highly disputable. In this article, we report a series of standardized methods, including the fabrication of solid-state electrochemical cells, electrochemistry measurements, the disassembly of cells, the collection of MOF electrochemical intermediates, and physical measurements of the intermediates under the protection of inert gases. By using these methods for quantitatively clarifying the electronic and spin state evolution within a single electrochemical step of redox-active MOFs, one can provide clear insight into the nature of electrochemical energy storage mechanisms not only for MOFs, but also for all other materials with strongly correlated electronic structures.

Author Spotlight: Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks  

Ex situ magnetic surveys can directly provide bulk and local information on a magnetic electrode to reveal its charge storage mechanism step by step. Herein, electron spin resonance (ESR) and magnetic susceptibility are demonstrated to monitor the evaluation of paramagnetic species and their concentration in a redox-active metal-organic framework (MOF).

Electrochemical energy storage has been a widely discussed application of redox-active metal-organic frameworks (MOFs) in the past 5 years. Although MOFs ...

Deposition of Bi2Te3 and Sb2Te3 Thin Films on Glass Substrates via RF Sputtering

Fabrication of Bi2Te3 and Sb2Te3 Thermoelectric Thin Films using Radio Frequency Magnetron Sputtering Technique

Through various studies on thermoelectric (TE) materials, thin film configuration gives superior advantages over conventional bulk TEs, including adaptability to curved and flexible substrates. Several different thin film deposition methods have been explored, yet magnetron sputtering is still favorable due to its high deposition efficiency and scalability. Therefore, this study aims to fabricate a bismuth telluride (Bi2Te3) and antimony telluride (Sb2Te3) thin film via the radio frequency (RF) magnetron sputtering method. The thin films were deposited on soda lime glass substrates at ambient temperature. The substrates were first washed using water and soap, ultrasonically cleaned with methanol, acetone, ethanol, and deionized water for 10 min, dried with nitrogen gas and hot plate, and finally treated under UV ozone for 10 min to remove residues before the coating process. A sputter target of Bi2Te3 and Sb2Te3 with Argon gas was used, and pre-sputtering was done to clean the target&#39;s surface. Then, a few clean substrates were loaded into the sputtering chamber, and the chamber was vacuumed until the pressure reached 2 x 10-5 Torr. The thin films were deposited for 60 min with Argon flow of 4 sccm and RF power at 75 W and 30 W for Bi2Te3 and Sb2Te3, respectively. This method resulted in highly uniform n-type Bi2Te3 and p-type Sb2Te3 thin films.

Author Spotlight: Advancements in High-Performance Thermoelectric Thin Films Through Radio Frequency Magnetron Sputtering

The manuscript describes a protocol for radio frequency magnetron sputtering of Bi2Te3 and Sb2Te3 thermoelectric thin films on glass substrates, which represents a reliable deposition method that provides a wide range of applications with the potential for further development.

Demonstrating the Simplicity and In Situ Temperature Monitoring of the Mechanochemical Synthesis of Metal Chalcogenides Suitable for Thermoelectrics

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