Nav: Home

High-efficiency thermoelectric materials: New insights into tin selenide

April 24, 2019

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.

Six years ago, a research team from the USA discovered that tin selenide above 500 degrees Celsius can convert about 20 per cent of heat into electrical energy. This is an enormous efficiency and considerably exceeds the value for bismuth telluride. In addition, tin and selenium are abundant.

This extremely large thermoelectric effect is related to a phase transition or re-arrangement of the crystal structure of tin selenide. The crystal structure of tin selenide consists of many layers, similar to filo or puff pastry. At 500 degrees Celsius, the layers start to self-organise and the heat conduction decreases, while charge carriers remain mobile. The efficiency of the thermoelectric effect in this crystallographic orientation of tin selenide has not been exceeded by any other material to date.

High pressure works

An international team led by Dr. Ulrich Schade at the HZB has now comprehensively examined samples of tin selenide with the aid of infrared spectroscopy at BESSY II and hard X-rays at PETRA IV. The measurements show that the desired crystal structure is produced by either high temperature at normal pressure or high pressure (above 10 GPa) at room temperature. The electronic properties also change from semiconducting to semi-metallic in the high-temperature structure. This fits the predictions from theoretical calculations of the model and also from band-structure calculations.

"We are able to explain with our data and our calculations why tin selenide is such an outstanding thermoelectric material over a wide temperature and pressure range", says Schade. Further development work will be necessary to guarantee long-term stability, for example, before thermoelectrical devices based on tin selenide really come onto the market, though. Then tin selenide might become an economical and readily available alternative to bismuth telluride.
-end-


Helmholtz-Zentrum Berlin für Materialien und Energie

Related Crystal Structure Articles:

4D imaging with liquid crystal microlenses
Most images captured by a camera lens are flat and two dimensional.
Solution of the high-resolution crystal structure of stress proteins from Staphylococcus
One of the main factors favoring a microorganism's survival in extreme conditions is preserving ribosomes -- a macromolecular complex comprising RNA and proteins
A laser, a crystal and molecular structures
Researchers have built a new tool to study molecules using a laser, a crystal and light detectors.
A new method for quantifying crystal semiconductor efficiency
Japanese scientists have found a new way to successfully detect the efficiency of crystal semiconductors.
Crystal clear: Understanding magnetism changes caused by crystal lattice expansion
An international team including researchers from Osaka University demonstrated helimagnetic behavior in a cubic perovskite material by expanding the lattice through barium doping.
Capturing the surprising flexibility of crystal surfaces
Images taken using an atomic force microscope have allowed researchers to observe, for the first time, the flexible and dynamic changes that occur on the surfaces of 'porous coordination polymer' crystals when guest molecules are introduced.
How a crystal is solvated in water
How a molecule from a solid crystal structure is solvated in a liquid solvent has been observed at a molecular level for the first time by chemists at Ruhr-Universität Bochum.
Nature-inspired crystal structure predictor
Scientists from Russia found a way of improving the crystal structure prediction algorithms, making the discovery of new compounds multiple times faster.
Modeling crystal behavior: Towards answers in self-organization
The University of Tokyo Institute of Industrial Science researchers have created a model to explore the transition behavior of crystal lattices.
Crystal structure reveals how curcumin impairs cancer
Through x-ray crystallography and kinase-inhibitor specificity profiling, University of California San Diego School of Medicine researchers, in collaboration with researchers at Peking University and Zhejiang University, reveal that curcumin, a natural occurring chemical compound found in the spice turmeric, binds to the kinase enzyme dual-specificity tyrosine-regulated kinase 2 (DYRK2) at the atomic level.
More Crystal Structure News and Crystal Structure Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

In & Out Of Love
We think of love as a mysterious, unknowable force. Something that happens to us. But what if we could control it? This hour, TED speakers on whether we can decide to fall in — and out of — love. Guests include writer Mandy Len Catron, biological anthropologist Helen Fisher, musician Dessa, One Love CEO Katie Hood, and psychologist Guy Winch.
Now Playing: Science for the People

#543 Give a Nerd a Gift
Yup, you guessed it... it's Science for the People's annual holiday episode that helps you figure out what sciency books and gifts to get that special nerd on your list. Or maybe you're looking to build up your reading list for the holiday break and a geeky Christmas sweater to wear to an upcoming party. Returning are pop-science power-readers John Dupuis and Joanne Manaster to dish on the best science books they read this past year. And Rachelle Saunders and Bethany Brookshire squee in delight over some truly delightful science-themed non-book objects for those whose bookshelves are already full. Since...
Now Playing: Radiolab

An Announcement from Radiolab