Introduction because of its good hightemperature electrical conductivity, thermal stability, and chemical. The importance of the e ect of vacancyvacancy interaction to conductivity was also proposed in a kmc model for praseodymium doped. Ionic conductivity of ceriayttria stabilized zirconia electrolyte materials. The sintering behaviour of a number of commercially produced 8 mol% yttriastabilized zirconia powders has been studied.
Effect of the ionic conductivity of the electrolyte in. Yttria stabilized zirconia ysz is among the most important ion conducting solids and acts as a kind of model material representing fast oxide ion. Mar 01, 2004 the effective oxygen conductivities in the zirconia networks of porous lsm ysz and lsmsysz composites i. Revisiting the temperature dependent ionic conductivity of yttria. However, it was found that the intergrain resistance changed little despite a remarkable change of the deposition temperature. We design and create a unique cell geometry of templated micrometerthick epitaxial nanocomposite films which contain. Ionic conductivity of nanocrystalline yttriastabilized. Interface effects on the ionic conductivity of dopedceria. Introduction ionic conductivity is the ability of a material to conduct electric current. This paper describes the effect of yttria stabilized zirconia ysz additions. Guo, in a comment on the original report, concluded that the measured conductivity of the zro 2. The porous specimens 3 mol% ysz were prepared using the fugitive polymer method, where different amounts of. The chemical homogeneity, particle size and the morphology of the asreceived.
The temperature dependent conductivity of yttria stabilized zirconia ysz exhibits a bending in arrhenius plots which is frequently discussedintermsoffreeandassociatedoxygenvacancies. Electrical conductivity of yttria stabilized zirconia. Effect of nanograin size on the ionic conductivity of spark plasma sintered 8ysz electrolyte. Yttriastabilized zirconia ysz is a ceramic in which the cubic crystal structure of zirconium dioxide is made stable at room temperature by an addition of yttrium oxide. Here, we choose 8 mol% yttriastabilized zirconia ysz as an electrolyte material because it is a one of the most popular pure oxygen ion conductors. However, they are prone to electronic conduction at low partial pressures of oxygen. Seeing oxygen disorder in yszsrtio3 colossal ionic conductor. High ionic conductivity in confined bismuth oxidebased. Ionic conductivity and activation energy for oxygen ion. For hydrated zro 2 samples, nevertheless, a protonbased conductivity on the surface has also been inferred. Ysz single crystals were systematically deformed by compression tests at 0 c, and their electrical conductivity was measured by an ac impedance method.
Ionic conductivity in yttriastabilized zirconia thin. Enhancing ionic conductivity of bulk singlecrystal yttria. Pdf improved ionic conductivity in strained yttria. Ionic conductivity increased by two orders of magnitude in. The ionic conductivity of the yszstoysz ysz 62 nm film was 0. Ionic conductivity and thermal stability of magnetron. Strain effects on oxygen ionic conductivity of yttria.
Pdf ionic conductivity in nanoscale ceo2ysz heterolayers. Ionic conductivity in nanoscale ceo2 ysz heterolayers. Therefore, we hoped that the addition of bi 2 o 3 might also have a influence like that and be beneficial to the improment of the conductivity of ysz. Ionic conduction ionic conduction is caused by the movement of some negatively or positively charged ions which hop from lattice site to lattice site under the influence of an electric field. Ionic conductivity of nanocrystalline yttriastabilized zirconia csic. Role of lattice strain and defect chemistry on the oxygen. Ionic conductivity ysz electrolyte material for solid oxide fuel cell applications.
On the contrary, the ysz conductivity remains unperturbed and shows the same values of about 0. I argue that the claimed ionic conductivity lacks experimental support and that the observed conductivity enhancement is. A relative ionic conduction variation map around the dislocation was then estimated based on the wellestablished strainconductivity and chemistryconductivity relationships in ysz. Studies on ionic conductivity of stabilized zirconia ceramics 8ysz densified through conventional and nonconventional sintering methodologies.
The dense specimens were either single crystal 8 mol% ysz or sintered polycrystalline 3 mol% and 8 mol% ysz. Bi2o3 enhances the conductivity of zirconia, improving its capability as a solid electrolyte for intermediate or even lower temperatures. Ionic conductivity ysz electrolyte material for solid. We propose that a faster ionic conductivity path can be formed around the dislocation core due to the coupling of the tensile strain field and dopant. Influence of yttriastabilized zirconia on microstructure and. Here, we studied similar multilayer samples and compare the oxygen diffusion data with the ionic conductivity data. Ionic conductivity in nanoscale ceo2ysz heterolayers. Oxygen ion diffusivity in strained yttria stabilized zirconia.
The ionic conductivity of these nanocolumns is enhanced by over 2 orders of magnitude compared to plain ysz films. Prinz, and wei cai department of mechanical engineering, stanford university, stanford, california 94305, usa received 29 december 2010. In a h fuel cell, o and h are supplied separately to an anode and cathode that are separated by an electrically insulating electrolyte ionic conductor. The crystal structure and ionic conductivity of layered composite of sdcyszsdc p.
Colossal ionic conductivity at interfaces of epitaxial. The crystal structure and ionic conductivity of layered. Thermal conductivity of dense and porous yttriastabilized. Abinitio kinetic monte carlo model of ionic conduction in. The microstructure of ysz ni cermet shows a welldefined porous network, which is necessary for the enhancement of electrochemical performance of the anode. Oxygen ion diffusivity in strained yttria stabilized. Ionic conductivity of nanocrystalline yttriastabilized zirconia. Abinitio kmc model of ionic conduction in bulk ysz 3 well as on the position of y ions.
Sinterability of commercial 8 mol% yttriastabilized zirconia. The thermal conductivity of dense and porous yttriastabilized zirconia ysz ceramics has been measured as a function of temperature in the range 25 to c. Using impedance spectroscopy, the total electrical conductivity was measured between 200 and 500 c under ambient atmosphere as well as in dry atmosphere for oxygen partial pressures ranging from 1 to 10 4 bar. It was confirmed that a great number of dislocations were introduced. Ionic conductivity in yttriastabilized zirconia thin universiteit. The ionic conductivity in the stabilized zirconia system is due to the mobility of oxygen vacancies created by doping with an element of lower. Pdf effect of nanograin size on the ionic conductivity.
Densityfunctional theory dft within the localdensity approximation with gradient correction was used to calculate a set of energy barriers that oxygen ions encounter during migration in. Seeing oxygen disorder in yszsrtio3 colossal ionic. Improvement on the ionic conductivity was observed by addition of 9 mol% yttria stabilized zirconia to la0. Enhancement of mixed conductivity in nibased ysz cermet for. Using impedance spectroscopy, the total electrical conductivity was measured between 200 and 500 c under ambient atmosphere as well as in dry atmosphere for oxygen partial pressures ranging from 1 to 104 bar. However,theveryhighdopingconcentrationinyszleadstosuchastrong defect interaction that the concept of free vacancies becomes highly questionable. The effective oxygen conductivities in the zirconia networks of porous lsmysz and lsmsysz composites i. For all samples examined, a single cubicphase was observed, stable between room temperature and 800 c. The results of the interpolation database turn out to be similar to the 8. Structural and electrical properties of the yszstoysz. Fleig,z institute of chemical technologies and analytics, tu wien, 1060 vienna, austria. Ionic conductivity in yttriastabilized zirconia thin films grown by pulsed laser deposition 5 1 theory yttriastabilized zirconia is often used in gas sensing techniques as electrolyte.
Revisiting the temperature dependent ionic conductivity of. Sinterability of commercial 8 mol% yttriastabilized. Yttriastabilized zirconia ysz with a typical composition of 8 mol. Ionic conductivity of mesostructured yttriastabilized. The ionic conductivity of yttriastabilized zirconia ysz single crystals 10 mol % y 2 o 3 zro 2 was enhanced by introducing high density of dislocations. Colossal ionic conductivity at interfaces of epitaxial zro2.
Zakharovb received 4th february 2008, accepted 2nd may 2008 first published as an advance article on the web 20th june 2008 doi. Y 2 o 3 srtio 3 heterostructure is due to electron holes in srtio 3 and not oxygen vacancies in ysz. Ionic conductivity in yttriastabilized zirconia thin films grown by pulsed laser deposition 1 summary in this report the ionic conductivity of yttriastabilized zirconia ysz is researched. Improved ionic conductivity in strained yttriastabilized zirconia thin films appl. Improved lithium ionic conductivity in article composite. Pdf yttriastabilized zirconia ysz thin films with thickness ranging from 6 nm to 100 nm were prepared by rf sputtering on 0001 al2o3 substrates. This paper describes the effect of yttria stabilized zirconia ysz additions on ceo 2 0. Improved ionic conductivity in strained yttriastabilized. Mixed ionicelectronic conductivity in yttriastabilized. Thus, in this study, ysz, which constitutes the electrolytes of solid oxide fuel cell sofc, thermal barrier coating. Ysz transports oxygen through its lattice and can, for example, be used for the detection of oxygen. These oxides are commonly called zirconia zr o 2 and yttria y 2 o 3, hence the name. In order to attain reliable results in probing the effect of strain on ionic transport in ysz, it is important to consider a realistic.
The oxygen conductivities of porous ysz and sysz alone followed a koh. The rst sofc generation has been prepared by the tape casting and the sintering method. Atomic scale origin of enhanced ionic conductivity at crystal. As a main result we obtained reliable information on possible. Similar to bulk ysz, a constant ionic conductivity is observed over the whole oxygen partial pressure range investigated. In particular, simulated amorphisation and recrystallisation was used to generate an atomistic model for a ceo 2 ysz yttrium stabilised zirconia heterolayered system and, using this model, the ionic diffusivity, conductivity and associated activation energy barriers were calculated. In this study, yttria stabilized zirconia ysz electrolytes were deposited using 8 mol% and 4. Enhancing ionic conductivity of bulk singlecrystal yttriastabilized zirconia by tailoring dopant distribution eunseok lee, friedrich b. This involves the movement of an ion from one site to another through defects in the crystal lattice of a solid or aqueous solution ionic conduction is one mechanism of current. It transports oxygen through its lattice and is chosen for its high ionic conductivity and chemical stability in oxidizing, high temperature environments. Pdf ionic conductivity of nanocrystalline yttriastabilized. In this report the ionic conductivity of yttriastabilized zirconia ysz is researched. Ionic conductivity and its temperature dependence of.
A number of reports have suggested that nanometric thin films of yttriastabilized zirconia ysz deposited on mgo can support high ionic conductivity, but the results remain controversial and. Pdf ionic conductivity of nanocrystalline yttriastabilized zirconia. The occurrence of spacecharge effects in ysz, and the possibility of enhancing its oxygen ion conductivity in nanometer sized ysz grains or thin. We consider two factors contributing to the increase in ionic conductivity at or near the interface. The biggest relative conductivity enhancement was found in the lower temperature region. I argue that the claimed ionic conductivity lacks experimental support and that the observed conductivity enhancement is most probably due to the ptype. Another migration energy database for 615 mol % ysz was then established by linearly inter polating between the 8. Because of its good hightemperature electrical conductivity, thermal stability, and chemical stability, 8 mol% yttriastabilized zirconia 8ysz ceramic material has been used as an oxygen ion conductor in oxygen sensors 1,2,3,4 and solid oxide fuel cells 5,6,7. Ionic conductivity in yttriastabilized zirconia thin films. The porous specimens 3 mol% ysz were prepared using the fugitive polymer method. Apr 10, 20 yttriastabilized zirconia ysz thin films with thickness ranging from 6 nm to 100 nm were prepared by rf sputtering on 0001 al2o3 substrates and exhibited epitaxial growth along 111110 ysz. Ionic conductivity in uniaxial micro strainstress fields. Predicting ionic conductivity of solid oxide fuel cell. Design principles of coplanar interdigitated micro.
Ionic conductivity in uniaxial micro strainstress fields of. The ionic conductivity shows a sizeable increase relative to sdc and ysz bulk values. Ionic conductivity of yszczo multilayers with variable. The ionic conductivity of ysz deposits at the direction perpendicular to the deposit surface was significantly increased through the microstructure development on increasing the deposition temperature. Hydrogen surface reactions and adsorption studied on y2o3. This involves the movement of an ion from one site to another through defects in the crystal lattice of a solid or aqueous solution. Effect of bismuth oxide on the microstructure and electrical. At room temperature, the conductivity increases by 11 orders of magnitude with the addition of swcnt to the ysz. Dislocationenhanced ionic conductivity of yttriastabilized. There is much debate surrounding the emergence of colossal ionic conductivity in highly strained films of yszsto heterostructures. Thermally stable, ordered mesoporous thin films of. The enhancement of the conductivity is observed, along with a ysz layer thickness independent conductance, showing that it is an interface process.
Influence of microstructure on the ionic conductivity of. Heterostructured multilayers have been controversially reported to alter the oxygen ion conductivity of solid electrolytes by inducing interfacial mechanical strain. Ionic conductivity of ceriayttria stabilized zirconia. Here, we fabricated thin film multilayers composed of 9 mol% y2o3 doped zro2 ysz and ce1. The effect of different sintering regimes on the density and microstructure of the sintered ceramic was determined using density measurements, scanning electron microscopy sem and dilatometry. Thermal conductivity, phase stability, and oxidation. Ionic conductivity of stabilized zirconia networks in. Densityfunctional theory dft within the localdensity approximation with gradient correction was used to calculate a set of energy barriers that oxygen ions encounter during migration in ysz by a vacancy mechanism. Pdf studies on ionic conductivity of stabilized zirconia. This study investigates the influence of bi 2 o 3 on the polymorphic phasing and ionic conductivity of ysz via xray diffraction xrd, electron diffraction, electron microscopy, dielectric. Ionic conductivity of mesostructured yttriastabilized zirconia thin. Such an enhancement is attributed to the epitaxial strain, an effect that is mostly confined in the ysz layers. At high temperatures 300 c, the ionic conduction of the ysz becomes relevant and a mixed ionicelectronic transport is observed. Therefore, the temperature dependent conductivity of ysz is reconsidered.
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