Nitrate-based metalorganic deposition of CeO 2 on yttria-stabilized zirconia
- PDF / 102,414 Bytes
- 4 Pages / 612 x 792 pts (letter) Page_size
- 95 Downloads / 165 Views
Nitrate-based metalorganic deposition of CeO2 on yttria-stabilized zirconia D.E. Wesolowski and M.J. Cimaa) Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (Received 25 August 2005; accepted 21 October 2005)
An aqueous nitrate metalorganic deposition (MOD) process was used to form a 30-nm-thick c-axis-textured ceria (CeO2) layer on a yttria-stabilized zirconia (YSZ) single-crystal substrate. X-ray diffraction showed the CeO2 layer was an (001) oriented film with a -scan full width at half-maximum of 1.47°. The average roughness of the ceria films, measured by atomic force microscopy, was about 5 nm. Critical current densities of up to 3.6 × 106 A/cm2 were measured on a 0.35-m Ba2YCu3O7−x (YBCO) layer deposited over this cap layer using a trifluoroacetate (TFA)-based MOD ex situ process. The physical vapor deposition-derived ceria cap layer used in the most common coated conductor buffer layer stacks may be replaced by such a MOD processed film. Metalorganic deposition (MOD) has been used with great success in the production of Ba 2 YCu 3 O 7–x (YBCO); however, the production of quality buffer layers has proved more difficult. MOD processes require that enough metal cations dissolve in the solvent to produce an oxide layer of adequate thickness after conversion.1 Heat treatments following the coating step must be optimized to yield films with the performance necessary for an application. YBCO-coated conductor buffer layers must be dense enough to form an effective diffusion barrier, grow epitaxially with the substrate, and provide an adequate lattice match to YBCO.2–4 Also, processing conditions cannot oxidize the bare metal substrate before the deposition of a protective oxide layer.5 Several researchers have performed studies attempting to produce buffer layers using MOD that meet the requirements for YBCO. Twenty-nanometer textured CeO2 seed and cap layers have been successfully grown on a textured Ni–W substrate using an acetylacetonate (acac) solution.2 An all-solution based Ni–W coated conductor, using La2Zr2O7 as a buffer layer and CeO2 as a cap layer, recently carried 1.75 MA/cm2.6 It was found that this MOD-derived CeO2 cap layer reacted more extensively with YBCO than sputtered cap CeO2 layers.6 Many other solution techniques for the production of YBCO buffer layers exist, using many metalorganic compounds to produce a wide variety of oxide layers.2–11 a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2006.0022 J. Mater. Res., Vol. 21, No. 1, Jan 2006
http://journals.cambridge.org
Downloaded: 22 Mar 2015
A nitrate-based solution was used to grow CeO2 on yttria-stabilized zirconia (YSZ) substrates in this study. Nitrate-based solutions have proved to be successful in growing oxide thin films.11 Little research has been done on producing films from nitrate solutions because of several problems, including the hydroscopic nature of the reagents, the necessity of decomposing nitrates from the film during heat treatment, and difficulty in getting t
Data Loading...
