Discover Top Posts Tagged with #tin selenide

Van der Waals forces can play unexpected role in thin film properties

Researchers have demonstrated the ability to use van der Waals forces to tune the physical and electronic properties of ferroelectric thin films. The work opens the door to new techniques for engineering materials for use in smaller, more energy efficient electronic devices. "Epitaxy is when you deposit a crystalline layer of material on top of another crystalline layer of material," says Yin Liu, an assistant professor of materials science and engineering at North Carolina State University and co-corresponding author of a paper on the work published in ACS Nano. "When you are doing this with thin films, and the two layers are chemically bonded, the structure of those two layers have to match. However, if the two layers are bonded using van der Waals forces, the layers can have different orientations.

Research team develops new thin film deposition process for tin selenide-based materials

A research team has developed a new thin film deposition process for tin selenide-based materials. This process utilizes the metal-organic chemical vapor deposition (MOCVD) method, enabling thin film deposition on large wafer surfaces at a low temperature of 200°C, achieving exceptional precision and scalability. The research findings were published online in Advanced Materials on April 9, 2024. MOCVD is a cutting-edge technique that employs gaseous precursors to carry out chemical reactions with outstanding precision, making it possible to deposit thin films on wafer-scale materials used in semiconductors. Thanks to this innovative method, the team was able to synthesize tin selenide materials (SnSe2, SnSe) with uniform thicknesses in just a few nanometers on wafer units.

Curious compound: Tin selenide may hold the key for thermoelectric solutions

Researchers at the FAMU-FSU College of Engineering and the National High Magnetic Field Laboratory discovered that atomic-level structural changes occur when the compound tin selenide heats up—changes that help it to conduct electricity but not heat. The study provides information that could lead to new technologies for applications such as refrigeration or waste heat recovery from cars or nuclear power plants. The research was published by Nature Communications. "Tin selenide is a curious compound," said Theo Siegrist, a chemical and biomedical engineering professor at the FAMU-FSU College of Engineering. "It has gotten a lot of interest for its special high-temperature thermoelectric properties. Optimizing those characteristics may lead to viable options for sustainable power generation and other uses in the future." Scientists already knew that tin selenide had a high thermoelectric coefficient at elevated temperatures, meaning it can create a strong electric current from a temperature gradient. The question was why and how.

Controlling heat flow in a solid by switching crystal structure dimensionality

Just as an electrical switch regulates the flow of electric current, thermal switches can control the flow of heat. These switches serve as thermal control devices and are useful for thermal management applications. For example, they can be used in industries to reduce waste heat, resulting in cost and energy savings. These switches require materials whose thermal conductivity (κ) can be modulated to a large extent. This would allow the switch to have an "on" and "off" state depending on the thermal conductivity. However, such materials are rare and challenging to develop, and those that have been developed show only small reversible variations in their κ.

Now, in a study published in Advanced Electronic Materials, researchers from Tokyo Institute of Technology (Tokyo Tech) and the National Institute for Materials Science, Japan, have taken things to the next level with a material that can achieve a large variation in its κ by changing its crystal structure dimensionality. The team achieved this remarkable feat by using a solid solution of lead selenide (PbSe) and tin selenide (SnSe), which can switch between a 3-dimensional (3D) cubic crystal structure and a 2-dimensional (2D) layered crystal structure with changes in temperature.

Physicists Startled To Discover a New Way To Shape a Material’s Atomic Structure With Light

X-ray laser experiments show that intense light distorts the structure of a thermoelectric material in a unique way, opening a new avenue for controlling the properties of materials.

Thermoelectric materials convert heat to electricity and vice versa, and their atomic structures are closely related to how well they perform.

Now researchers have discovered how to change the atomic structure of a highly efficient thermoelectric material, tin selenide, with intense pulses of laser light. This result opens a new way to improve thermoelectrics and a host of other materials by controlling their structure, creating materials with dramatic new properties that may not exist in nature.

“For this class of materials that’s extremely important, because their functional properties are associated with their structure,” said Yijing Huang, a Stanford University graduate student who played an important role in the experiments at the Department of Energy’s SLAC National Accelerator Laboratory. “By changing the nature of the light you put in, you can tailor the nature of the material you create.”

Team achieves 30-fold enhancement of thermoelectric performance in polycrystalline tin selenide

The continued depletion of fossil fuel-based energy resources is leading us towards a growing energy crisis. Consequently, this has set in motion a search for sustainable alternative resources. Thermoelectric energy conversion—a process of generating electricity from waste heat—has gained momentum as the next potential energy harvesting technology. Generators made up of thermoelectric materials are used to harvest thermal energy via the "Seebeck effect." The temperature difference in the thermoelectric material creates a flow of charge carriers, generating electrical energy.

For efficient conversion, a thermoelectric material must have a high conversion efficiency (ZT), which needs a high Seebeck coefficient (S), a high electronic conductivity (σ), and a low thermal conductivity (κ). The material tin selenide (SnSe) is known to exhibit a record high ZT in its single crystal form. However, the performance deteriorates in practical polycrystals because of a low σ and a high κ.

In a recent study published in Advanced Science, a team of researchers from Japan, led by Associate Professor Takayoshi Katase from Tokyo Institute of Technology (Tokyo Tech) managed to enhance the ZT of polycrystalline SnSe by demonstrating a high σ and a low κ simultaneously. The team achieved this remarkable breakthrough by introducing tellurium (Te) ion into the structure of SnSe.

A new way to shape a material's atomic structure with ultrafast laser light

Thermoelectric materials convert heat to electricity and vice versa, and their atomic structures are closely related to how well they perform.

"For this class of materials that's extremely important, because their functional properties are associated with their structure," said Yijing Huang, a Stanford University graduate student who played an important role in the experiments at the Department of Energy's SLAC National Accelerator Laboratory. "By changing the nature of the light you put in, you can tailor the nature of the material you create."

The experiments took place at SLAC's X-ray free-electron laser, the Linac Coherent Light Source (LCLS). The results were reported today in Physical Review X and will be highlighted in a special collection devoted to ultrafast science.

High-efficiency thermoelectric materials: New insights into tin selenide

Tin selenide might considerably exceed the efficiency of current record holding thermoelectric materials made of bismuth telluride. However, it was thought its efficiency became enormous only at temperatures above 500 degrees Celsius. Now measurements at the BESSY II and PETRA IV synchrotron sources show that tin selenide can also be utilised as a thermoelectric material at room temperature -- so long as high pressure is applied.

The thermoelectric effect has been known since 1821: with certain combinations of materials, a temperature difference generates an electric current. If one end of the sample is heated, for example using waste heat from a combustion engine, then part of this otherwise lost energy can be converted into electrical energy. However, the thermoelectric effect in most materials is extremely small. This is because to achieve a large thermoelectric effect, heat conduction must be poor, whereas electrical conductivity must be high. However, heat conduction and electrical conductivity are almost always closely associated.

For this reason, the search for thermoelectric materials concentrates on compounds with special crystalline structures such as bismuth telluride (Bi2Te3). Bismuth telluride is one of the best thermoelectric materials known to date. However, both bismuth and tellurium are rare elements, which limit their large-scale use. So the search continues for suitable thermoelectric materials among more abundant non-toxic elements.

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