Zirconium oxide ionic conductivity

Zr02+ 15 mole%CaO calcia-stabilized zirconium oxide 17.3.7 defect structure and mechanism of ionic conduction 17.3.7.3 oxygen ion resistivity of polycrystalline material 17.3.7... 

Calcia-stabilized zirconium oxide 18, 17.3.7 Defect structure and mechanism of ionic conduction 18,17.3.7.3 Oxygen ion resistivity of polycrystalline material 18, 17.3.7 OiZr... 

The unique property of solid solutions on the basis of zirconium oxide is oxygen-ionic conductivity and it is due to their crystal structure type. The solid solution of stabilized zirconium oxide has a cubic structure of fluorite type with anionic vacancies that leads to electrical conductivity abrupt increase at temperature increase of > 600° C. 

YSZ exhibits purely oxygen ionic conduction (with no electronic conduction). The crystalline array of Zr02 has two oxide ions to every zirconium ion. But in Y2O3 there are only 1.5 oxide ions to every yttrium ion. The result is vacancies in the crystal structure where oxide ions are missing. So, oxide ions from the cathode leap from hole to hole until they reach the anode [1]. 

The corrosion resistance of some metals ultimately depends on the presence of a thin oxide film formed by the reaction of the metal with the environment. This is the case of titanium, tantalum, zirconium, molybdenum, aluminium, cobalt, chromium, etc. Table 9.23 gives the physicochemical properties of the oxides formed on some metals. A low oxide solubility is important to guarantee a low rate of corrosion, since any loss in oxide thickness, due to chemical dissolution, will tend to be balanced by oxidation of the metallic substrate. The oxides should also possess low ionic conductivity. 

M. J. Verkerk, B. J. Middlehuis, and A. J. Burggraaf [1982] Effect of Grain Boundaries on the Conductivity of High-Purity Zirconium Oxide-Yttrium Oxide Ceramics, Solid State Ionics 6, 159-170. 

Solid-state electrolyte Ionic conductivity Zirconium oxide... 

Redox electrodes consisting of ciystalline zirconium dioxide, doped with calcium or yttrium oxides to render it ionically conducting, are used to monitor oxygen in combustion gases and molten metallurgical samples. The redox... 

The sol-gel chemistry of Zr02 is similar to other tetravalent metal compounds such as Si02 and Ti02 Precursors such as zirconium halides and alkoxides are largely available, and they all hydrolyze rapidly in the presence of water. Zirconium oxide (and especially yttrium-stabilized Zr02 (YSZ)) is widely used as a thermal barrier but also as an ionic conductor (electroceramic). Even if it is not widely used for gas detection, its ionic conductivity makes it attractive as a sensor to control the oxygen level and thus the air/luel ratio in internal combustion engines. 

Polydimethylsiloxane (PDMS)/zirconia/HPW hybrid membranes 80 and 500 pm thick were cast by modified sol-gel technique [160], where HPW (1.6-14 wt.%) was incorporated with Zr/PDMS hybrid matrix by Coulomb force and/or ionic bonding. Flexible, homogeneous, and transparent hybrid membranes were formed in the molar ratio of zirconium to PDMS from 2 to 8, while at higher zirconium concentration, the membrane became brittle and soft, and the hybrid membranes synthesized with HPW were heterogeneous. IR studies confirmed the formation of bond between Zirconium oxide moiety and PDMS via Zr-O-Si bonds. Zr/PDMS hybrid membranes, therefore, possess a good thermal stability at least up to 300°C and shows small proton conductivity of the order of 10 S/cm, and with increase in temperature, the conductivity increased from 4 x 10 S/cm at 30°C to 5 X 10 S/cm at 150°C. The conductivity of the membrane was improved on the... 

The development of the ideas mentioned above has taken place over more than a century, in 1890, it was not yet clear what electrical conduction was. The electron had not quite been defined. Metals were known to conduct electricity in accord with Ohm s law, and aqueous ionic solutions were known to conduct larger entities called ions. Nernst then made the breakthrough of observing various types of conduction in stabilised zirconia, that is zirconium oxide doped with several mole per cent of calcla, magnesia, yttria, etc. Nernst found that stabilised zirconia was an insulator at room temperature, conducted ions in red hot conditions, from 600 to 1000°C and then became an electronic and ionic conductor at white heat, around 1500°C, He patented an incandescent electric light made from a zirconia filament and sold this invention which he had been using to illuminate his home [1-3], He praised the simultaneous invention of the telephone because it enabled him to call his wife to switch on the light device while he travelled back from the university. The heat-up time was a problem even then [4],... 

Croce et al. developed a series of composited membranes based on poly(ethylene oxide) (PEO) and lithium salts with the dispersion of functionalized Zr02 ceramic filler." The composite polyelectrolyte containing 5 wt% zirconium displayed improved ionic conductivity than the unmodified membranes by one order of... 

Nemst [1,2] studied the behavior of solid ionic conductors— high temperamre ceramics—for use as filaments in light bulbs. Nernst made a breakthrough discovery based on the observation of different types of conductivity in stabilized zirconia, or zirconium oxide doped by a few mole per cent of calcia, magnesia, yttria, etc. At that time, the use of other materials for this purpose was problematic due to their unfavorable resistance characteristics—a rise in temperature caused an increase in resistance, and thus the metal wires were not able to obtain a... 

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