High-conductivity material demonstrates role of oxygen ions in enhancing their capabilities

Feb 27, 2013

Yttria stabilized zirconia, also known as YSZ, is a material of great interest because of its relatively high oxygen-ion based conductivity. In particular, it finds applications in electrochemical devices, such as solid oxide fuel cells and oxygen sensors. In a study published in European Physical Journal B, Kia Ngai, from the University of Pisa in Italy, and colleagues from the Complutense University in Madrid, Spain, devised a model of the oxygen-ion dynamics that contribute to the conductivity of YSZ.

The problem is that fuel cells currently operate above 700 ºC, which strongly limits their use. Understanding oxygen-ion diffusion is key to helping lower operating temperature down to room temperature. Previous attempts to do so were done with the so-called coupling model (CM), describing simple physical concepts related to ion-ion interaction. This helped uncover the importance of ion-ion correlation in limiting long-range ion mobility, and thus conductivity.

The trouble is that experiments show that ionic conductivity in YSZ requires an activation energy that is much higher than that supplied by describing independent ion hopping. Relying on the CM model, the authors first established a quantitative description of the ion dynamics in YSZ. Then they compared the predictions of the CM with experimental results and with simulations, particularly those of nanometric-scale thin films, published in the last ten years.

Thus, in their model, they established the connection between the level of the energy barrier for independent ion-hopping simulations and the level of activation energy measured experimentally for long-range movement of . In addition, they attributed an increase of the conductivity in nanometers-thick YSZ films to a decrease in the ion-ion correlations. This model could also be used to study the conductivity relaxation of so-called molten, glassy and crystalline ionic conductors and ambient temperature .

Explore further: After 13 years, progress in pitch-drop experiment (w/ video)

More information: Ngai K.L., Santamaria J. and Leon C. (2013), Dynamics of interacting oxygen ions in yttria stabilized zirconia: bulk material and nanometer thin films, European Physical Journal B, DOI: 10.1140/epjb/e2012-30737-2

add to favorites email to friend print save as pdf

Related Stories

Tunable plastic thermometers

Dec 15, 2010

(PhysOrg.com) -- Researchers at the Universities of Queensland and New South Wales in Australia have discovered that the ability of a plastic to conduct electricity can be tuned by exposure to an ion beam. ...

Recommended for you

Novel technique opens door to better solar cells

Apr 14, 2014

A team of scientists, led by Assistant Professor Andrivo Rusydi from the Department of Physics at the National University of Singapore's (NUS) Faculty of Science, has successfully developed a technique to ...

Probing metal solidification nondestructively

Apr 14, 2014

(Phys.org) —Los Alamos researchers and collaborators have used nondestructive imaging techniques to study the solidification of metal alloy samples. The team used complementary methods of proton radiography ...

Glasses strong as steel: A fast way to find the best

Apr 13, 2014

Scientists at Yale University have devised a dramatically faster way of identifying and characterizing complex alloys known as bulk metallic glasses (BMGs), a versatile type of pliable glass that's stronger than steel.

User comments : 0

More news stories

Robotics goes micro-scale

(Phys.org) —The development of light-driven 'micro-robots' that can autonomously investigate and manipulate the nano-scale environment in a microscope comes a step closer, thanks to new research from the ...

Biologists help solve fungi mysteries

(Phys.org) —A new genetic analysis revealing the previously unknown biodiversity and distribution of thousands of fungi in North America might also reveal a previously underappreciated contributor to climate ...