Nanoparticles formed on oxide surfaces are of key importance in many fields such as catalysis and renewable energy. Here, we control B-site exsolution via lattice strain to achieve a high degree of exsolution of nanoparticles in perovskite thin films: more than 1100 particles μm
−2
with a particle size as small as ~5 nm can be achieved via strain control. Compressive-strained films show a larger number of exsolved particles as compared with tensile-strained films. Moreover, the strain-enhanced in situ growth of nanoparticles offers high thermal stability and coking resistance, a low reduction temperature (550 °C), rapid release of particles, and wide tunability. The mechanism of lattice strain-enhanced exsolution is illuminated by thermodynamic and kinetic aspects, emphasizing the unique role of the misfit-strain relaxation energy. This study provides critical insights not only into the design of new forms of nanostructures but also to applications ranging from catalysis, energy conversion/storage, nano-composites, nano-magnetism, to nano-optics.
High-density ZnO nanorods can be grown on pregrown one-dimensional nanostructures via thermal chemical vapor deposition of Zn at a low temperature of 500 °C, producing various heterostructures. We demonstrate it using carbon nanotubes, GaN nanowires, GaP nanowires, SiC nanowires, and SiC core-C shell coaxial nanocables. The diameter of ZnO nanorods is in the range of 80-150 nm, and the maximum length is about 3 µm. The ZnO nanorods align vertically on the walls of 1D nanostructures, with a uniform growth direction of [001]. We suggest a vapor-liquid-solid growth mechanism that Zn vapor deposits on the 1D nanostructures and produces the outer layers encapsulating the 1D nanostructures; the ZnO nanorods are grown out from the outer layers of the nanocable structure. The length and density of ZnO nanorods are controllable by the deposition time. All of these heterostructures exhibit intense UV photoluminescence and cathodoluminescence. The green emission intensity is correlated with the density of the ZnO nanorods.
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