| Autor: |
Kast MG; Department of Chemistry and Biochemistry and the Materials Science Institute, University of Oregon , Eugene, Oregon 97403, United States., Cochran EA; Department of Chemistry and Biochemistry and the Materials Science Institute, University of Oregon , Eugene, Oregon 97403, United States., Enman LJ; Department of Chemistry and Biochemistry and the Materials Science Institute, University of Oregon , Eugene, Oregon 97403, United States., Mitchson G; Department of Chemistry and Biochemistry and the Materials Science Institute, University of Oregon , Eugene, Oregon 97403, United States., Ditto J; Department of Chemistry and Biochemistry and the Materials Science Institute, University of Oregon , Eugene, Oregon 97403, United States., Siefe C; Department of Chemistry and Biochemistry and the Materials Science Institute, University of Oregon , Eugene, Oregon 97403, United States., Plassmeyer PN; Department of Chemistry and Biochemistry and the Materials Science Institute, University of Oregon , Eugene, Oregon 97403, United States., Greenaway AL; Department of Chemistry and Biochemistry and the Materials Science Institute, University of Oregon , Eugene, Oregon 97403, United States., Johnson DC; Department of Chemistry and Biochemistry and the Materials Science Institute, University of Oregon , Eugene, Oregon 97403, United States., Page CJ; Department of Chemistry and Biochemistry and the Materials Science Institute, University of Oregon , Eugene, Oregon 97403, United States., Boettcher SW; Department of Chemistry and Biochemistry and the Materials Science Institute, University of Oregon , Eugene, Oregon 97403, United States. |
| Abstrakt: |
Thin films with tunable and homogeneous composition are required for many applications. We report the synthesis and characterization of a new class of compositionally homogeneous thin films that are amorphous solid solutions of Al 2 O 3 and transition metal oxides (TMO x ) including VO x , CrO x , MnO x , Fe 2 O 3 , CoO x , NiO, CuO x , and ZnO. The synthesis is enabled by the rapid decomposition of molecular transition-metal nitrates TM(NO 3 ) x at low temperature along with precondensed oligomeric Al(OH) x (NO 3 ) 3-x cluster species, both of which can be processed from aq solution. The films are dense, ultrasmooth (R rms < 1 nm, near 0.1 nm in many cases), and atomically mixed amorphous metal-oxide alloys over a large composition range. We assess the chemical principles that favor the formation of amorphous homogeneous films over rougher phase-segregated nanocrystalline films. The synthesis is easily extended to other compositions of transition and main-group metal oxides. To demonstrate versatility, we synthesized amorphous V 0.1 Cr 0.1 Mn 0.1 Fe 0.1 Zn 0.1 Al 0.5 O x and V 0.2 Cr 0.2 Fe 0.2 Al 0.4 O x with R rms ≈ 0.1 nm and uniform composition. The combination of ideal physical properties (dense, smooth, uniform) and broad composition tunability provides a platform for film synthesis that can be used to study fundamental phenomena when the effects of transition metal cation identity, solid-state concentration of d-electrons or d-states, and/or crystallinity need to be controlled. The new platform has broad potential use in controlling interfacial phenomena such as electron transfer in solar-cell contacts or surface reactivity in heterogeneous catalysis. |
