Control of the 2D/3D transition of the growth mechanism in the YBCO/Ce1−xLaxO2−x/2/SrTiO3 system

Chambonnet, D.; Keller, D.; Belouet, C.

doi:10.1016/s0921-4534(98)00203-2

Cited by 15 publications

(9 citation statements)

References 18 publications

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“…XRD experiments by Bae et al 8 show that the CeO 2 fluorite structure is maintained for La concentrations up to x = 0.40 (for La 2 Ce 2 O 7 x = 0.50), and only at higher La concentrations the pyrochloric ordering of the cations (La III and Ce IV ) appears. These authors also observe that the lattice parameter does not expand in a linear fashion as was reported earlier by Chambonnet et al 19 , and assume this reduced expansion is due to the clustering of O-vacancies. Other authors find multiple non-linear regions in the expansion of the lattice parameter.…”

supporting

confidence: 70%

DFT study of La$_2$Ce$_2$O$_7$: disordered fluorite vs pyrochlore structure

Vanpoucke,

Bultinck,

Cottenier

et al. 2013

Preprint

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The crystal structure of Lanthanum Cerium Oxide (La2Ce2O7) is investigated using ab initio density functional theory (DFT) calculations. The relative stability of fluorite-and pyrochlore-like structures is studied through comparison of their formation energies. These formation energies show the pyrochlore structure to be favored over the fluorite structure, apparently contradicting the conclusions based on experimental neutron and X-ray diffraction (XRD). By calculating and comparing XRD spectra for a set of differently ordered and random structures, we show that the pyrochlore structure is consistent with diffraction experiments. For these reasons, we suggest the pyrochlore structure as the ground state crystal structure for La2Ce2O7.

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supporting

confidence: 70%

DFT study of La$_2$Ce$_2$O$_7$: disordered fluorite vs pyrochlore structure

Vanpoucke,

Bultinck,

Cottenier

et al. 2013

Preprint

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“…[5][6][7][8][9][10][11][12] and Ni/double Gd 2 Zr 2 O 7 /CeO 2 . 13,14 To suppress the production cost for long length coated conductors, one is looking to replace the current three or two buffer layers by one single buffer layer applicable on textured Ni-(W) tape [15][16][17][18] and other substrates including magnesium oxide (MgO), 19 strontium titanate (STO) 20 and lanthanum aluminate (LAO). 21 In these publications, possible lattice matched buffer layers that have been reported for this purpose include YBiO 3 , Gd 3+ doped CeO 2 , La 3+ doped CeO 2 or Eu 3+ doped Yb 2 O 3 .…”

Section: Introductionmentioning

confidence: 99%

“…21 In these publications, possible lattice matched buffer layers that have been reported for this purpose include YBiO 3 , Gd 3+ doped CeO 2 , La 3+ doped CeO 2 or Eu 3+ doped Yb 2 O 3 . [15][16][17][18][19][20][21] All these works report a possibility of growing single buffer layer on the given substrate with optimized properties. These single buffer layers showed good superconducting properties.…”

Section: Introductionmentioning

confidence: 99%

Aqueous CSD approach for the growth of novel, lattice-tuned LaxCe1−xOδ epitaxial layers

et al. 2012

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Lanthanum-cerium oxide (LCO) films were deposited on Ni-5%W substrates by chemical solution deposition (CSD) from water-based precursors. LCO films containing different ratios of lanthanum and cerium ions (from CeO 2 to La 2 Ce 2 O 7 ) were prepared. The composition of the layers was optimized towards the formation of LCO buffer layers, lattice-matched with the superconducting YBa 2 Cu 3 O y layer, useful for the development of coated conductors. Single, crack-free LCO layers with a thickness of up to 140 nm could be obtained in a single deposition step. The crystallinity and microstructure of these lattice-matched LCO layers were studied by X-ray diffraction techniques, RHEED and SEM. We find that only layers with thickness below 100 nm show a crystalline top surface although both thick and thin layers show good biaxial texture in XRD. On the most promising layers, AFM and (S)TEM were performed to further evaluate their morphology. The overall surface roughness varies between 3.9 and 7.5 nm, while the layers appear much more dense than the frequently used La 2 Zr 2 O 7 (LZO) systems, showing much smaller nanovoids (1-2 nm) than the latter system. Their effective buffer layer action was studied using XPS. The thin LCO layers supported the growth of superconducting YBCO deposited using PLD methods.

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“…It is well understood that the existence of some small a/b grains would improve the critical current of the YBCO film, but if the a/b-axis grain increases or becomes large, the superconductor characterisation of the thin film will deteriorate. Other groups reported that increase of the crystal mismatch between the substrate and the thin film, increases the size and the number of the off axis grains [10]. Hence, we expect more a/b-axis domains of the YBCO film on the bare LAO crystal than those for YBCO crystals on the CeO 2 buffer layer because of the larger mismatch between YBCO film and bare LAO crystal in comparison with the one with CeO 2 buffer as is visible in the SEM pictures.…”

mentioning

confidence: 99%

MOD growth of epitaxial cerium oxide buffer layer on LAO substrates for fabrication of c-axis oriented YBCO

Hosseini

Abari

Vesaghi

et al. 2012

Micro &Amp; Nano Letters

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Epitaxial cerium oxide (CeO 2) buffer layer has been grown on lanthanum aluminate (LAO) single crystal substrates for fabrication of c-axis oriented YBa 2 Cu 3 O 72x (YBCO). Precursor solution of cerium acetylacetonates with viscosity of 0.6 centipoises was spin coated on the 1 × 1 cm area LAO substrates. The calcination was carried out by very slow ramp (18C per minute) until the final temperature of 5008C in oxygen flow to remove most of the organic compounds. The final heat treatment has been done at 7808C by a ramp of 208 per minute in gas flow of mixed argon-oxygen with 5 Pa partial pressure of oxygen. The thickness of the deposited CeO 2 buffer layer was 20 nm. Then, 100 nm thick YBCO film was deposited by sputtering on the CeO 2 buffered LAO substrate. Another film with same deposition conditions was also fabricated on the bare LAO crystal for comparison. The scanning electron microscopy (SEM) and X-ray diffraction characterisations show a/b axis YBCO decreases significantly when using the CeO 2 buffered LAO instead of the bare LAO. R-T and J c measurements of the samples are also reported. Superconducting transition width of the fabricated film on the substrate with CeO 2 buffer layer is less than 0.4 K and the J c of the fabricated film is above 3.5 MA/cm 2 .

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Control of the 2D/3D transition of the growth mechanism in the YBCO/Ce1−xLaxO2−x/2/SrTiO3 system

Cited by 15 publications

References 18 publications

DFT study of La$_2$Ce$_2$O$_7$: disordered fluorite vs pyrochlore structure

DFT study of La$_2$Ce$_2$O$_7$: disordered fluorite vs pyrochlore structure

Aqueous CSD approach for the growth of novel, lattice-tuned LaxCe1−xOδ epitaxial layers

MOD growth of epitaxial cerium oxide buffer layer on LAO substrates for fabrication of c-axis oriented YBCO

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