Epitaxial growth of BaZrO3 films on single crystal oxide substrates using sol-gel alkoxide precursors

Epitaxial BaZrO3 (barium zirconium oxide) films were grown on single crystal substrates. A BaZrO3 precursor solution was prepared by sol-gel synthesis using an all-alkoxide route. The barium precursors were prepared by reacting barium metal with 2-methoxyethanol, and zirconium precursors were prepared by exchanging ligands between zirconium n-propoxide and 2-methoxyethanol. The resulting BaZrO3 precursor solution was partially hydrolyzed and spin-coated on sapphire (100), SrTiO3 (strontium titanium oxide) (100), and LaAlO3 (lanthanum aluminum oxide) (100) substrates. The films were post-annealed in oxygen at 800 °C for 2 min in a rapid thermal annealer. The coating and the annealing procedures were repeated three times to obtain the desired thickness, 300 nm. X-ray diffraction studies showed the presence of a single (100) cube texture for BaZrO3 films on SrTiO3 and LaAlO3 substrates. The BaZrO3 films grown on sapphire had a random texture. The BaZrO3 films grown on SrTiO3 substrates had a sharp texture compared to that on LaAlO3 substrates. This may be due to the relatively smaller lattice mismatch between SrTiO3 and BaZrO3.