Transition metal oxide films

Abstract

The sol‐gel method can be used to produce multicomponent oxide materials which have a homogeneous composition even at the atomic level. Thin transition metal oxide films are shown to exhibit different properties from those of the bulk materials and both the crystal structure and the valence state of the materials can be sensitively controlled by doping. Recent progress in the field is reviewed, including the production of highly oriented films, valence‐controlled oxides, the control of instable phase formation and atmosphere‐sensitive structural transformations.

Sol-flame synthesis of cobalt-doped TiO2 nanowires with enhanced electrocatalytic activity for oxygen evolution reaction

“…Existing doping methods for nanostructured materials can be broadly categorized into in situ and ex situ methods. In situ doping methods incorporate dopants during the material growth by methods such as solid-state mixing, 15,16 sol-gel, [17][18][19] hydrothermal, [20][21][22] sputtering [23][24][25] and solution-combustion. 26,27 The in situ doping methods have the following advantages: (1) flexible choice of dopant materials, (2) easy control of dopant precursor concentrations, and (3) simplicity in that no additional doping steps are required.…”

Formation of Highly Crystallized β‐PbO Thin Films by Cathodic Electrodeposition of Pb and Its Rapid Oxidation in Air

“…The fabrication of such thin-film materials presently relies on vacuum technologies, for example, physical and chemical vapor deposition. Recently, increasing attention has been paid to solution-phase processing such as sol±gel, [1] electrodeposition (ED), and chemical bath deposition (CBD), [2] since these methods are environmentally benign and cost effective. Although it is often supposed that the solution-phase processes yield thin films with poorly controlled structures, recent examples of heteroepitaxial thin-film growth, such as CBD of CdS on InP(111), [3] ED of Cu 2 O on Au(100), [4] and ED of ZnO on GaN(002), [5] have proven the high quality of materials that can be achieved by these methods.…”

Dopant Reduction in p-Type Oxide Films upon Oxygen Absorption

“…The doping of foreign atoms having a different valence controls the nonstoichiometry to create the mixed valence state which indicates a dramatic change in the electrical and optical properties. − However, the doping mechanism in the transition metal oxide is not fully understood due to inhomogeneous distribution of dopants in the solid. The sol−gel method provides a considerably homogeneous mixed valence oxide. − In the preceding paper, the homogeneous mixed valence state of Fe 2+ and Fe 3+ in an n-type iron oxide with Ti-doping was realized with the sol−gel technique. , …”