Nanostructural control in solution-derived epitaxial Ce_1−xGd_xO_2−yfilms

Abstract

A novel mechanism based on aliovalent doping, allowing fine tuning of the nanostructure and surface topography of solution-derived ceria films, is reported. While under reducing atmospheric conditions, non-doped ceria films are inherently polycrystalline due to an interstitial amorphous Ce(2)C(3) phase that inhibits grain growth, a high quality epitaxial film can be achieved simply by doping with Gd(3+) cations. Gd(3+) [Formula: see text] Ce(4+) substitutions within the lattice are accompanied by charge-compensating oxygen vacancies throughout the volume of the crystallites acting as an efficient vehicle to reduce the barrier for grain boundary motion caused by interstitial Ce(2)C(3). In this way, the original nanostructure is self-purified by pushing the amorphous Ce(2)C(3) phase towards the free surface of the film. Once a full epitaxial cube-on-cube oriented ceria film is obtained, its surface morphology is dictated by the interplay between faceting on low energy {110} and/or {111} pyramidal planes and truncation of those pyramids by (001) ones. The development of the latter requires the suppression of their polar character which is thought to be achieved by charge compensation between the dopand and oxygen along [Formula: see text] directions.

Self‐Organization of Heteroepitaxial CeO2 Nanodots Grown from Chemical Solutions

“…Growth of nanostructures was performed under controlled atmosphere (Ar-10 % H 2 or static air) at a maximum temperature of 1000°C during variable times [12,15]. Under these heating conditions it was verified by XPS measurements of films that no C was retained in the films [33]. Atomic Force Microscopy (AFM Molecular Imaging PicoSPM) was used in the tapping mode at room temperature to investigate the different evolution stages of the nanostructures.…”

Influence of Morphology and Texture of CeO2 on YBa2Cu3O7 (YBCO) Growth and BaCeO3 Formation in Solution‐Derived Synthesis

“…These local variations, which are caused by a deteriorating texture, will result in displacements at the surface and in the formation of a higher surface roughness. [27] The optimization of the complete synthesis process results in the following proposed thermal process: an IR-assisted drying stage at 210°C, a calcination ramp of 2°C min -1 , a calcination level of 900°C, a calcination dwell time of 60 min, a sintering ramp of 10°C min -1 , a sintering level of 1050°C and a sintering dwell time of 30 min. The applied Ar/(5%) H 2 flow was kept constant at 80 mL min -1 , which resulted in an appropriate oxygen partial pressure in our tube furnace setup.…”

“…This mismatch can be influenced by use of metal substitution. [27,28] CSD methods allow for easy control of this metal substitution on an atomic scale. A further optimization of the surface morphology, on the other hand, will prove to be significantly harder, as the thermal synthesis process has already been fine-tuned.…”

Surface engineering of biaxial Gd2Zr2O7 thin films deposited on Ni–5at%W substrates by a chemical solution method

“…20,29,30 XPS surface analysis reveals the amount of carbon residue in the homogeneous zone of films quenched from different stages during crystallization, as shown in Fig.3a. Although CO 2 adsorption has influence on the absolute intensity of the C1s peak, it can still be clearly concluded that the evolution of the amount of aliphatic carbon residue is processing dependent, i.e., the amount of carbon decreases with the crystallization proceeding.…”