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Probing the bulk ionic conductivity by thin film hetero-epitaxial engineering

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ABSTRACT

Highly textured thin films with small grain boundary regions can be used as model systems to directly measure the bulk conductivity of oxygen ion conducting oxides. Ionic conducting thin films and epitaxial heterostructures are also widely used to probe the effect of strain on the oxygen ion migration in oxide materials. For the purpose of these investigations a good lattice matching between the film and the substrate is required to promote the ordered film growth. Moreover, the substrate should be a good electrical insulator at high temperature to allow a reliable electrical characterization of the deposited film. Here we report the fabrication of an epitaxial heterostructure made with a double buffer layer of BaZrO3 and SrTiO3 grown on MgO substrates that fulfills both requirements. Based on such template platform, highly ordered (001) epitaxially oriented thin films of 15% Sm-doped CeO2 and 8 mol% Y2O3 stabilized ZrO2 are grown. Bulk conductivities as well as activation energies are measured for both materials, confirming the success of the approach. The reported insulating template platform promises potential application also for the electrical characterization of other novel electrolyte materials that still need a thorough understanding of their ionic conductivity.

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MgO + BZO + (STO + BZO) × 20 superlattice. (a) The XRD analysis shows the epitaxial orientation and the satellite peaks of the superlattice. (b) The RHEED patterns (from bottom to top MgO → BZO → STO) reveal an almost ideal layer-by-layer growth of the whole heterostructure. (c) The HR-STEM analysis shows a highly ordered growth of the complete structure with a very small degree of out-of-plane misalignment, as revealed by the SAED pattern shown in the inset. Spots from the MgO substrate are marked in bold while weak spots marked with arrowheads stem from the BZO/STO heterostructure.
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Figure 3: MgO + BZO + (STO + BZO) × 20 superlattice. (a) The XRD analysis shows the epitaxial orientation and the satellite peaks of the superlattice. (b) The RHEED patterns (from bottom to top MgO → BZO → STO) reveal an almost ideal layer-by-layer growth of the whole heterostructure. (c) The HR-STEM analysis shows a highly ordered growth of the complete structure with a very small degree of out-of-plane misalignment, as revealed by the SAED pattern shown in the inset. Spots from the MgO substrate are marked in bold while weak spots marked with arrowheads stem from the BZO/STO heterostructure.

Mentions: The growth and the electrical properties of the MgO + BZO + STO template platform were studied using a multi-layered heterostructure of the two materials. Twenty STO/BZO bilayers were grown on BZO-buffered MgO according to the scheme: MgO + BZO + (STO + BZO) × 20. The thickness of each layer of BZO and STO was about 2 nm. Figure 3 shows the XRD, RHEED and HR-TEM analysis of this sample.


Probing the bulk ionic conductivity by thin film hetero-epitaxial engineering
MgO + BZO + (STO + BZO) × 20 superlattice. (a) The XRD analysis shows the epitaxial orientation and the satellite peaks of the superlattice. (b) The RHEED patterns (from bottom to top MgO → BZO → STO) reveal an almost ideal layer-by-layer growth of the whole heterostructure. (c) The HR-STEM analysis shows a highly ordered growth of the complete structure with a very small degree of out-of-plane misalignment, as revealed by the SAED pattern shown in the inset. Spots from the MgO substrate are marked in bold while weak spots marked with arrowheads stem from the BZO/STO heterostructure.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036489&req=5

Figure 3: MgO + BZO + (STO + BZO) × 20 superlattice. (a) The XRD analysis shows the epitaxial orientation and the satellite peaks of the superlattice. (b) The RHEED patterns (from bottom to top MgO → BZO → STO) reveal an almost ideal layer-by-layer growth of the whole heterostructure. (c) The HR-STEM analysis shows a highly ordered growth of the complete structure with a very small degree of out-of-plane misalignment, as revealed by the SAED pattern shown in the inset. Spots from the MgO substrate are marked in bold while weak spots marked with arrowheads stem from the BZO/STO heterostructure.
Mentions: The growth and the electrical properties of the MgO + BZO + STO template platform were studied using a multi-layered heterostructure of the two materials. Twenty STO/BZO bilayers were grown on BZO-buffered MgO according to the scheme: MgO + BZO + (STO + BZO) × 20. The thickness of each layer of BZO and STO was about 2 nm. Figure 3 shows the XRD, RHEED and HR-TEM analysis of this sample.

View Article: PubMed Central - PubMed

ABSTRACT

Highly textured thin films with small grain boundary regions can be used as model systems to directly measure the bulk conductivity of oxygen ion conducting oxides. Ionic conducting thin films and epitaxial heterostructures are also widely used to probe the effect of strain on the oxygen ion migration in oxide materials. For the purpose of these investigations a good lattice matching between the film and the substrate is required to promote the ordered film growth. Moreover, the substrate should be a good electrical insulator at high temperature to allow a reliable electrical characterization of the deposited film. Here we report the fabrication of an epitaxial heterostructure made with a double buffer layer of BaZrO3 and SrTiO3 grown on MgO substrates that fulfills both requirements. Based on such template platform, highly ordered (001) epitaxially oriented thin films of 15% Sm-doped CeO2 and 8 mol% Y2O3 stabilized ZrO2 are grown. Bulk conductivities as well as activation energies are measured for both materials, confirming the success of the approach. The reported insulating template platform promises potential application also for the electrical characterization of other novel electrolyte materials that still need a thorough understanding of their ionic conductivity.

No MeSH data available.


Related in: MedlinePlus