| 1. |
- Eklund, Per, 1977-, et al.
(författare)
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Thermal Stability and Phase Transformations of γ-/Amorphous-Al2O3 Thin Films
- 2009
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Ingår i: Plasma processes and polymers. - : Wiley. - 1612-8850. ; 6:1, s. 907-911
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Tidskriftsartikel (refereegranskat)abstract
- Magnetron-sputtered Al2O3 thin films were annealed in ambient air. The phase compositions of the as-deposited Al2O3 films were (i) fully amorphous, (ii) nanocrystalline γ-Al2O3 in an amorphous Al2O3 matrix, and (iii) fully crystalline γ. For all samples, annealing to 1 100-1 150 °C resulted in a transformation to α-alumina. The transformation paths depend on the phase fraction of γ in the as-deposited films. For amorphous films and films with low initial γ fraction, the intermediate phase θ-Al2O3 appeared in the range of 1 000-1 100 °C. For predominantly crystalline γ-Al2O3 as-deposited films no intermediate Al2O3 phases were observed, indicating a direct γ-to-α phase transformation at ≈1 100 °C.
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| 2. |
- Sillassen, Michael, et al.
(författare)
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Low-Temperature Superionic Conductivity in Strained Yttria-Stabilized Zirconia
- 2010
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Ingår i: ADVANCED FUNCTIONAL MATERIALS. - : John Wiley and Sons, Ltd. - 1616-301X .- 1616-3028. ; 20:13, s. 2071-2076
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Tidskriftsartikel (refereegranskat)abstract
- Very high lateral ionic conductivities in epitaxial cubic yttria-stabilized zirconia (YSZ) synthesized on single-crystal SrTiO3and MgO substrates by reactive direct current magnetron sputtering are reported. Superionic conductivities (i.e., ionic conductivities of the order similar to 1 Omega(-1)cm(-1)) are observed at 500 degrees C for 58-nm-thick films on MgO. The results indicate a superposition of two parallel contributions - one due to bulk conductivity and one attributable to conduction along the film substrate interface. Interfacial effects dominate the conductivity at low temperatures (andlt;350 degrees C), showing more than three orders of magnitude enhancement compared to bulk YSZ. At higher temperatures, a more bulk-like conductivity is observed. The films have a negligible grain-boundary network, thus ruling out grain boundaries as a pathway for ionic conduction. The observed enhancement in lateral ionic conductivity is caused by a combination of misfit dislocation density and elastic strain in the interface. These very high ionic conductivities in the temperature range 150-500 degrees C are of great fundamental importance but may also be technologically relevant for low-temperature applications.
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