Selective formation of cubic or tetragonal zirconia thin films of transparent, with no use of metal ion stabilizer by heating molecular precursor films under mild conditions

Abstract

Cubic or tetragonal zirconia thin films of transparent and 100 nm thickness were selectively formed on a quartz glass substrate by heat-treating the molecular precursor films involving Zr(IV) complexes of nitrilotriacetic acid, at 500[Formula: see text]C in air for 1 h. A precursor solution was prepared by a reaction of the ligand and zirconium tetrabutoxide in alcohol under the presence of butylamine. By the addition of H2O2 or H2O into the solution, the spin-coated precursor films were converted to cubic zirconia thin films by the abovementioned procedure. Further, the identical phase was produced also in the case of the electro-sprayed precursor film which was formed by an addition of H2O2 into the solution. On the other hand, the tetragonal zirconia thin film was obtained from a precursor film formed by using a solution dissolving the original Zr(IV) complex of the ligand, without H2O2 nor H2O. The crystal structure of all thin films was determined by using both the X-ray diffraction (XRD) patterns and Raman spectra. Thus, the zirconia thin films of both crystals could be facilely and selectively obtained with no use of hetero-metal ion stabilizers. The XPS spectra of the thin films show that the O/Zr ratio of the cubic phase is 1.37 and slightly larger than tetragonal one (1.29), and also demonstrate that the nitrogen atoms, which may contribute to stabilize these metastable phases at room temperature, of about 5−7 atomic% was remained in the resultant thin films. The adhesion strengths of cubic zirconia thin film onto the quartz glass substrate was 68 MPa and larger than that of tetragonal one, when the precursor films were formed via a spin coating process. The optical and surface properties of the thin films were also examined in relation to the crystal systems.

An overview of the socio-economic impacts of the green hydrogen value chain in Southern Africa

“…We have recently fabricated several functional thin films that could be suitable as components for the fuel cell. For example, a recent paper (Shafudah, Nagai and Sato, 2021) reports on manufacturing a cubic zirconia thin film that could be suitable for a solid electrolyte in solid oxide fuel cells. An advantage of this is that most of the basic materials for the fuel cell can be sourced locally in SADC (e.g., South Africa is known for its abundance of platinum, which is a critical anodic and cathodic material).…”