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 Hope to discover sure signs of life on Mars? New research says look for the element vanadium
22.09.2017 | University of Kansas

nachricht Calculating quietness
22.09.2017 | Forschungszentrum MATHEON ECMath

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: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>