Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Certain Doped-Oxide Ceramics Resist Ohm's Law

22.09.2010
For months, Anthony West could hardly believe what he and his colleagues were seeing in the lab -- or the only explanation for the unexpected phenomena that seemed to make sense.

Several of the slightly doped high-purity barium titanate (BT) ceramics his research group was investigating were not following the venerable Ohm's Law, which relates electrical voltage to current and resistance. Applying or removing a voltage caused a gradual change in the materials' electrical resistance. The new effect was seen consistently regardless of the temperature or whether the experiments were conducted in vacuum, air, or in an oxygen atmosphere. The time to stabilize and the final, steady-state resistance were, however, both temperature-dependent.

"I was not immediately convinced myself about the non-Ohm's Law behavior," said West, Professor of Electroceramics and Solid State Chemistry at the University of Sheffield in England. "Interfacial effects are well known for their non-Ohmic behavior. We needed to be really convinced that our results were not influenced in some way by interfacial effects."

West's proposed mechanism for the non-Ohm behavior is also unconventional: the ionization of only one of the two extra electrons from oxygen atoms that are attached to dopant atoms. This process leaves behind a positively charged "hole" that can move fairly readily in what is called a hole current. West and his colleagues at Sheffield and the Universidat Jaume 1 in Castellon, Spain, described their latest experiments with calcium-doped BT in the journal Applied Physics Letters, which is published by the American Institute of Physics. Similar results with zinc and magnesium dopants were published earlier this year in other technical journals. Calcium, zinc and magnesium are known as "acceptor" dopants, which can promote hole currents.

Undoped BT and "donor"-doped materials did not exhibit this unusual behavior. West believes that these results may ultimately lead to a better understanding of how ceramics used in electrical circuits degrade and may possibly even stimulate new insights into high-temperature superconductivity mechanisms in oxide ceramics.

The article, "Field enhanced bulk conductivity of acceptor-doped BaTi1-xCaxO3-x ceramics" by Nahum Maso, Marta Prades, Hector Beltran, Eloisa Cordoncillo, Derek C. Sinclair, and Anthony R. West appears in the journal Applied Physics Letters. See: http://link.aip.org/link/applab/v97/i6/p062907/s1

Journalists may request a free PDF of this article by contacting jbardi@aip.org

ABOUT APPLIED PHYSICS LETTERS
Applied Physics Letters, published by the American Institute of Physics, features concise, up-to-date reports on significant new findings in applied physics. Emphasizing rapid dissemination of key data and new physical insights, Applied Physics Letters offers prompt publication of new experimental and theoretical papers bearing on applications of physics phenomena to all branches of science, engineering, and modern technology. Content is published online daily, collected into weekly online and printed issues (52 issues per year). See: http://apl.aip.org/
ABOUT AIP
The American Institute of Physics is a federation of 10 physical science societies representing more than 135,000 scientists, engineers, and educators and is one of the world's largest publishers of scientific information in the physical sciences. Offering partnership solutions for scientific societies and for similar organizations in science and engineering, AIP is a leader in the field of electronic publishing of scholarly journals. AIP publishes 12 journals (some of which are the most highly cited in their respective fields), two magazines, including its flagship publication Physics Today; and the AIP Conference Proceedings series. Its online publishing platform Scitation hosts nearly two million articles from more than 185 scholarly journals and other publications of 28 learned society publishers.

Jason Socrates Bardi | Newswise Science News
Further information:
http://www.aip.org

More articles from Physics and Astronomy:

nachricht Igniting a solar flare in the corona with lower-atmosphere kindling
29.03.2017 | New Jersey Institute of Technology

nachricht NASA spacecraft investigate clues in radiation belts
28.03.2017 | 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: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

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...

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

Researchers shoot for success with simulations of laser pulse-material interactions

29.03.2017 | Materials Sciences

Igniting a solar flare in the corona with lower-atmosphere kindling

29.03.2017 | Physics and Astronomy

As sea level rises, much of Honolulu and Waikiki vulnerable to groundwater inundation

29.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>