Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The dance of crystal structures

10.11.2004


The word “crystal” is a technical term; iron and steel, for example, are crystals whereas glass is not. In fact, "crystal" means materials of a crystalline structure.



Just like any other kind of material, crystals can change their structure. For example, if the temperature rises sufficiently, it passes from a solid to a liquid state. But other, not so noticeable, structural changes also take place, such as those that occur in the solid state, itself. These changes are known as solid-to-solid phase transitions and are induced by changes in either temperature or pressure. Moreover, the electrical and magnetic properties of the crystals are affected during these transitions and are, thereby, of great interest for technology.

At the Leioa (Bizkaia) campus of the University of the Basque Country (EHU), a research team has been analysing solid-to-solid transitions of crystals. They selected a group of crystals known as double perovskites for this purpose. Prior to the analysis a certain amount of preparation work is required in the lab: the perovskites have to be synthesised.


Synthesis of crystals in the laboratory

The synthesis of crystals in the laboratory is not a simple process. First, the component powders of the crystal have to be mixed and compacted and then they have to be stabilised in the kiln. For example, to mention one method of synthesis, in order to obtain the Sr2NiWO6 perovskite, SrCO3, NiO and WO3 powders have to be blended. The result of the blend will also be a powder - perovskite powder.

But the resulting perovskite is not always the desired one and this is why it is necessary to characterise the compound obtained once it has been synthesised. That is, in this example, it has to be confirmed that it is, in fact Sr2NiWO6 perovskite and not another one, or, at least the same perovskite but with a few impurities.

Finally, once the desired perovskite has been obtained, various techniques are applied: X-ray diffraction, neutron diffraction, synchrotron radiation, Raman spectroscopy, etc. With all these, information about the crystal structure is obtained - location of the elements, their vibration frequency and a number of other properties. In order to carry this out, moreover, researchers have to travel to France and the United States, given that, in the University of the Basque Country, there is no synchotron; neither can Raman spectroscopy be carried out.

Solid structure is adaptable

So, the solid structure of the crystal is adaptable. But how? For example, when pressure increases, the structure of the crystal compacts so crystal atoms are nearer to each other. This may produce an increase in the vibration frequency of these atoms. At some point, the stability of the structure will break and change the location of components, thus, a solid-to-solid phase transition will have taken place.

Must be remenbered that these transitions are often accompanied by changes in the electrical and magnetic properties of the crystals: for example, the conductivity of the crystal can change when it reaches a certain temperature. The work at Leioa is targeting those values of temperature and pressure accompanied by transitions in the perovskites.

Garazi Andonegi | alfa
Further information:
http://www.elhuyar.com
http://www.basqueresearch.com

More articles from Physics and Astronomy:

nachricht DGIST develops 20 times faster biosensor
24.04.2017 | DGIST (Daegu Gyeongbuk Institute of Science and Technology)

nachricht New quantum liquid crystals may play role in future of computers
21.04.2017 | California Institute of Technology

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

DGIST develops 20 times faster biosensor

24.04.2017 | Physics and Astronomy

Nanoimprinted hyperlens array: Paving the way for practical super-resolution imaging

24.04.2017 | Materials Sciences

Atomic-level motion may drive bacteria's ability to evade immune system defenses

24.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>