Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists explain unusual and effective features in perovskite

28.06.2016

An international team of scientists have described how charge-carrying particles move in perovskite

Perovskite is a material with an almost ideal structure. The majority of high-temperature superconductors are perovskite-based due to their non-ideal structure. The material can also be used to produce flexible solar batteries without rare-earth metals, which would help to reduce costs and enable large-scale manufacture.


Praseodymium atoms are shown in green, oxygen atoms in orange, and titanium atoms in purple.

Credit: MIPT

One of the authors notes the manganite-like properties of perovskites. "This material exhibits many interesting and intriguing properties, most notably giant magnetoresistance. Many manganite properties are unknown, despite the fact that manganites have been studied for decades. We tried to work out what the conduction mechanism is of one of the most common compounds - Pr1-xCaxMnO3," he says. All these features have been experimentally discovered, but the processes to explain these unique properties are unknown.

Semiconductors were discovered more than 150 years ago. Electricity was a new development at the time. It was obvious that there were isolators like rubber and glass, conductors like copper and gold, and some uncertain materials, semiconductors, which did not fit into any category. The mechanisms of semiconductors remained unknown for about a century. It was not until the 1930s that the problem was solved and the first transistor was made. Nowadays it is difficult to imagine any electronic device without transistors.

Unfortunately, it is not possible to see charge movement in a material under a microscope. This is why researchers at Terahertz Spectroscopy Laboratory decided to use indirect detection methods. To test which particles are conductive, they applied different frequency voltages and measured the relationship between frequency and induced current.

The scientists measured the frequency and temperature dependence of conductivity and permittivity in a broad frequency range (5-3000 cm-1) to cover all the bases. Wide temperature ranges - from 10 to 300 K (-263 to 27 °C) - of the samples were obtained to distinguish similar dependences of samples with different conduction mechanisms. But even this was insufficient to clarify the nature of charge carries. For this reason, researchers compared perovskites with different ratios of calcium (Ca) and praseodymium (Pr).

The group of scientists headed by Boris Gorshunov, Terahertz Spectroscopy Laboratory supervisor, (Lenar Kadyrov PhD, and laboratory scientists Elena Zhukova and Vladimir Anzin are also authors of this article) thus discovered that the charge carriers in Pr1-xCaxMnO3 perovskites are polarons. A polaron is an electron moving through the constituent atoms of a material, causing the neighboring positive charges to shift toward it and the neighboring negative charges to shift away.

The properties of perovskites are ideal for electron-phonon (phonons are vibrations in a crystal lattice) coupling, determined by the interplay between symmetry breaking interactions. The researchers established that polarons move coherently (as one unit). That is to say charge carriers behave more like uncoupled particles. The idea of coherence is used in lasers, superconductors, highly accurate distance measurements, quantum calculations etc.

Establishing how conduction occurs could help perovskite research projects and large-scale applications to progress. For example, there is already a high-efficiency perovskite-based device for separating water into oxygen and hydrogen. Perovskites can also be used as LEDs, however they are currently only able to function at the temperature of liquid nitrogen.

Media Contact

Matvey Kireev
matthew@phystech.edu
7-916-065-1016

 @phystech

https://mipt.ru/english/ 

Matvey Kireev | EurekAlert!

Further reports about: Terahertz polarons semiconductors temperature

More articles from Physics and Astronomy:

nachricht Only an atom thick: Physicists succeed in measuring mechanical properties of 2D monolayer materials
17.01.2018 | Universität des Saarlandes

nachricht Black hole spin cranks-up radio volume
15.01.2018 | National Institutes of Natural Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Polymers Based on Boron?

18.01.2018 | Life Sciences

Bioengineered soft microfibers improve T-cell production

18.01.2018 | Life Sciences

World’s oldest known oxygen oasis discovered

18.01.2018 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>