Thermal Conductivity and Oxygen Tracer Diffusion of Yttria Stabilized Zirconia by Molecular Dynamics

One of the most technologically beneficial engineering ceramics is yttria stabilized zirconia (YSZ). As a result, research interest about YSZ has been intensive for many years. In this study, the lattice thermal conductivity and oxygen diffusion coefficient of YSZ are investigated at different temperatures (from 700 K to 1300 K) and zero pressure with the Green-Kubo formalism. We find that the lattice thermal conductivity decreases as the temperature increases, particularly at low temperatures and it shows a slightly temperature independence at high temperatures. The results demonstrate that the YSZ has quite a low thermal conductivity compared with pure zirconia. We also show that the oxygen tracer diffusion coefficient, as calculated from the mean square displacements, has an activation energy of 0.85eV.

Oxygen diffusion in amorphous and partially crystalline gallium oxide

We established a TTT diagram of crystallisation of gallium oxide. Determination of oxygen tracer diffusion coefficients by IEDP/ToF-SIMS allowed us to access the activation energy for amorphous GaO1.5 at low temperatures.

The blocking effect of surface dislocations on oxygen tracer diffusion in SrTiO3

Polishing-induced damaged zone in single-crystal SrTiO3 exploited in diffusion studies to investigate the interaction between oxygen vacancies and dislocations.

Oxygen transport in epitaxial SrTiO₃/SrTi_{1 − <i>x</i>}Fe_<i>x</i>O₃ multilayer stacks

Nano-ionic materials made of strontium titanate (SrTiO3, STO) and solid solutions of strontium ferrite in STO (SrTi1 − xFexO3, STF) are grown on single crystalline STO substrates and characterized. Since STF exhibits an oxygen deficiency and, simultaneously, enables oxygen interstitial defects, a space charge area close to the STO | STF interface is present. Oxygen tracer diffusion experiments and impedance spectroscopy at temperatures from 500 to 700 °C and at oxygen partial pressure ranging from 10−3 to 10−23 bar confirm fast oxygen transport caused by enhanced ionic conductivity at the interface. There, an oxygen diffusion coefficient of 3. 4 × 10−10 m2 s−1 at 600 °C and a p type conductivity of about 360 S m−1 at 700 °C are calculated. Such structures open new options in design of nano-ionic materials for oxygen sensors and energy conversion at temperatures lower than those of conventional materials such as yttrium-doped zirconia.

Limits to the rate of oxygen transport in mixed-conducting oxides

Chemically reasonable limits to the rates of oxygen tracer diffusion and oxygen surface exchange in acceptor-doped oxides are examined.

Oxygen nonstoichiometry, defect structure and oxygen diffusion in the double perovskite GdBaCo2O6−δ

The values of the oxygen self-diffusion coefficient measured by the dc-polarization technique completely coincide with those of the oxygen tracer diffusion coefficient.

Oxygen Tracer Diffusion in A-Axis Oriented ZnO Thin Films Grown on (01-12) Sapphire by Pulsed Laser Deposition

The a-axis oriented ZnO thin films deposited on sapphire substrates by pulsed laser deposition were studied to investigate the effects of pre-annealing on oxygen diffusion. The effect was as follows: the oxygen diffusion coefficient decreased, and the oxygen concentration in the tailing regions of the profiles reduced. Ion images of an oxygen tracer revealed the high-diffusivity paths for oxygen tracer diffusion. The temperature dependence of oxygen tracer diffusion coefficients (Db) in as-deposited and pre-annealed thin films were determined to be Db [cm2/ = 9.2x102 exp (- 405 [kJ/mo / RT) and Db [cm2/ = 1.8x103 exp (- 418 [kJ/mo / RT), respectively. On basis of these results, the crystal orientation on Db and the mechanism for oxygen diffusion were discussed.

Oxygen Tracer Diffusion in BaTiO3 Ceramics - Effect of Zr Impurity from Planetary Ball Milling

We investigated the effect of Zr impurities on the oxygen diffusion pathway in BaTiO3 ceramics by using an ion-imaging technique. Zr impurities were introduced into BaTiO3 ceramics by a planetary ball milling process. The oxygen tracer diffused quickly from the surface up to the grain boundary and then appeared as discontinuous steps at the grain boundary. The results indicate that the grain boundary acted as a blocking layer against oxygen diffusion. The blocking for oxygen diffusion at the grain boundary is thought to originate during the formation and distribution of complex defects between the charged oxygen vacancies and the Ba vacancies near the grain boundary.