Development of a metal-organic deposition process for growth of lanthanum manganate buffer layers for coated conductors

Abstract

One embodiment of YBa2Cu3O7-x (YBCO)-coated conductors consists of YBCO film grown using a metal-organic deposition (MOD) process on a buffer layer stack deposited on a Ni-W substrate. A possible alternative is to replace the multilayer buffer stack with a single layer of LaMnO3 (LMO) grown by MOD. A suitable temperature (T) – oxygen partial pressure (PO2) process-window to grow LMO films via MOD on Ni substrates has been identified. Untextured LMO was grown on pure Ni. However, we have not been able to grow phase-pure LMO films on either bare or Y2O3-coated, biaxially textured Ni-5W (at.%) due to the incongruent, overlapping requirements of having the PO2 low enough to not oxidize the Ni-5W substrate but high enough to convert the metal-organic precursors to LMO and the relatively high temperatures needed to form an epitaxial film in an MOD process. The main problem is that tungsten from the substrate reacts with cations in the overlying film forming tungstates when the films are processed in the T-PO2 window.