| 1. |
- Sillassen, M, et al.
(författare)
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Concentration-dependent ionic conductivity and thermal stability of magnetron-sputtered nanocrystalline scandia-stabilized zirconia
- 2010
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Ingår i: SOLID STATE IONICS. - : Elsevier Science B.V., Amsterdam.. - 0167-2738. ; 181:23-24, s. 1140-1145
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Tidskriftsartikel (refereegranskat)abstract
- Nanocrystalline (nc) scandia-stabilized zirconia (SSZ) electrolytes with scandia contents of 5.9 to 15.9 mol% ere synthesized by reactive magnetron sputtering. For scandia content andgt;= 9.1 mol%, the as-deposited films were pure cubic phase with andlt; 111 andgt; texture, while traces of tetragonal phase was found for lower Sc content. Single-line profile analysis of the 111 X-ray diffraction peak yielded an out-of-plane grain size of similar to 10 nm and a microstrain of 2.0-2.2%, regardless of scandia content, for films deposited at 400 degrees C and a bias of -70 V. Films deposited at higher bias voltages showed a reduced grain size, yielding a grain size of similar to 6 nm and a microstrain of similar to 2.5% at -200 V and -250 V with additional incorporation of argon. Temperature-dependent impedance spectroscopy of the SSZ films showed that the in-plane ionic conductivity had a maximum close to 10.7 mol% and decreased almost an order of magnitude as the scandia - content was increased to 15.9 mol%. The activation energy for oxygen ion migration was determined to be between 130-1.43 eV. In addition, no dependence on grain size was observed. The above observations suggest a bulk mechanism for ionic conduction.
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| 2. |
- Sillassen, M., et al.
(författare)
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Ionic conductivity and thermal stability of magnetron-sputtered nanocrystalline yttria-stabilized zirconia
- 2009
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 105:10, s. 104907-
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Tidskriftsartikel (refereegranskat)abstract
- Thermally stable, stoichiometric, cubic yttria-stabilized zirconia (YSZ) thin-film electrolytes have been synthesized by reactive pulsed dc magnetron sputtering from a Zr-Y (80/20 at. %) alloy target. Films deposited at floating potential had a ‹111› texture. Single-line profile analysis of the 111 x-ray diffraction peak yielded a grain size of ~20 nm and a microstrain of ~2% regardless of deposition temperature. Films deposited at 400 °C and selected bias voltages in the range from -70 to -200 V showed a reduced grain size for higher bias voltages, yielding a grain size of ~6 nm and a microstrain of ~2.5% at bias voltages of -175 and -200 V with additional incorporation of argon. The films were thermally stable; very limited grain coarsening was observed up to an annealing temperature of 800 °C. Temperature-dependent impedance spectroscopy analysis of the YSZ films with Ag electrodes showed that the in-plane ionic conductivity was within one order of magnitude higher in films deposited with substrate bias corresponding to a decrease in grain size compared to films deposited at floating potential. This suggests that there is a significant contribution to the ionic conductivity from grain boundaries. The activation energy for oxygen ion migration was determined to be between 1.14 and 1.30 eV.
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| 3. |
- Eurenius, Karinh, 1980, et al.
(författare)
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Intermediate temperature ionic conductivity of Sm1.92Ca0.08Ti2O7–δ pyrochlore
- 2011
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Ingår i: J Solid State Electrochem. - : Springer Science and Business Media LLC. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- The results of concentration cell electromotive force methods (EMF) and electrochemical impedance spectroscopy measurements on the pyrochlore system Sm1.92Ca0.08Ti2O7–δ are presented. The data have been used to estimate total and partial conductivities and determine transport numbers for protons and oxide ions under various conditions. The EMF techniques employed include corrections for electrode polarisation resistance. The measurements were performed using wet and dry atmospheres in a wide pO2 range using mixtures of H2, N2, O2, and H2O in the temperature region where proton conductivity was expected (500–300 °C). The impedance measurements revealed the conductivity to be mainly ionic under all conditions, with the highest total conductivity measured being 0.045 S/m under wet oxygen at 500 °C. Both bulk and grain boundary conductivity was predominantly ionic, but electronic conductivity appeared to play a slightly larger part in the grain boundaries. EMF data confirmed the conductivity to be mainly ionic, with oxide ions being the major conducting species at 500 °C and protons becoming increasingly important below this temperature.
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| 4. |
- Lunca Popa, Petru, et al.
(författare)
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Highly oriented δ-Bi2O3 thin films stable at room temperature synthesized by reactive magnetron sputtering
- 2013
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Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 113:4
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Tidskriftsartikel (refereegranskat)abstract
- We report the synthesis by reactive magnetron sputtering and structural characterization of highly (111)-oriented thin films of δ–Bi2O3. This phase is obtained at a substrate temperature of 150–200 °C in a narrow window of O2/Ar ratio in the sputtering gas (18%–20%). Transmission electron microscopy and x-ray diffraction reveal a polycrystalline columnar structure with (111) texture. The films are stable from room temperature up to 250 °C in vacuum and 350 °C in ambient air.
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