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:

Machine learning technique speeds up crystal structure determination
A computer-based method could make it less labor-intensive to determine the crystal structures of various materials and molecules, including alloys, proteins and pharmaceuticals.
An improved method for protein crystal structure visualization
During crystallization atoms are arranged in a 3D lattice structured in a specific way.
Gazing into crystal balls to advance understanding of crystal formation
Researchers at The University of Tokyo Institute of Industrial Science conducted simulations considering and neglecting hydrodynamic interactions to determine whether or not these interactions cause the large discrepancy observed between experimental and calculated nucleation rates for hard-sphere colloidal systems, which are used to model crystallization.
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.
More Crystal Structure News and Crystal Structure Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Teaching For Better Humans 2.0
More than test scores or good grades–what do kids need for the future? This hour, TED speakers explore how to help children grow into better humans, both during and after this time of crisis. Guests include educators Richard Culatta and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#556 The Power of Friendship
It's 2020 and times are tough. Maybe some of us are learning about social distancing the hard way. Maybe we just are all a little anxious. No matter what, we could probably use a friend. But what is a friend, exactly? And why do we need them so much? This week host Bethany Brookshire speaks with Lydia Denworth, author of the new book "Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond". This episode is hosted by Bethany Brookshire, science writer from Science News.
Now Playing: Radiolab

Space
One of the most consistent questions we get at the show is from parents who want to know which episodes are kid-friendly and which aren't. So today, we're releasing a separate feed, Radiolab for Kids. To kick it off, we're rerunning an all-time favorite episode: Space. In the 60's, space exploration was an American obsession. This hour, we chart the path from romance to increasing cynicism. We begin with Ann Druyan, widow of Carl Sagan, with a story about the Voyager expedition, true love, and a golden record that travels through space. And astrophysicist Neil de Grasse Tyson explains the Coepernican Principle, and just how insignificant we are. Support Radiolab today at Radiolab.org/donate.