Formation of High‐Quality, Epitaxial La ₂ Zr ₂ O ₇ Layers on Biaxially Textured Substrates by Slot‐Die Coating of Chemical Solution Precursors

Abstract

Crystallization studies were performed of epitaxial La 2 Zr 2 O 7 (LZO) films on biaxially textured Ni–3at.%W substrates having thin Y 2 O 3 (10 nm) seed layers. LZO films were deposited under controlled humid atmosphere using reel‐to‐reel slot‐die coating of chemical solution precursors. Controlled crystallization under various processing conditions has revealed a broad phase space for obtaining high‐quality, epitaxial LZO films without microcracks, with no degradation of crystallographic texture and with high surface crystallinity. Crack‐free and strong c ‐axis aligned LZO films with no random orientation were obtained even at relatively low annealing temperatures of 850°–950°C in flowing one atmosphere gas mixtures of Ar–4% H 2 with an effective oxygen partial pressure of P(O 2 )∼10 −22 atm. Texture and reflection high‐energy electron diffraction analyses reveal that low‐temperature‐annealed samples have strong cube‐on‐cube epitaxy and high surface crystallinity, comparable to those of LZO film annealed at high temperature of 1100°C. In addition, these samples have a smoother surface morphology than films annealed at higher temperatures. Ni diffusion rate into the LZO buffer film is also expected to be significantly reduced at the lower annealing temperatures.