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 Astronomers find unexpected, dust-obscured star formation in distant galaxy
24.03.2017 | University of Massachusetts at Amherst

nachricht Gravitational wave kicks monster black hole out of galactic core
24.03.2017 | NASA/Goddard Space Flight Center

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: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>