Formation mechanisms of ZnO spherulites and derivatives
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ZnO microparticles have been solvothermally synthesized from zinc acetate and formic acid. The resulting microspherulites consist of radially arranged nanorods which undergo a range of re-crystallisation pathways to produce particles with different terminal morphologies. Crystallisation on the particle surface results in hex-agonal microdisc decorated hierarchical microspheres. These particles expose only the (0001) crystallographic plane of ZnO and further develop into a sea-urchin like morphology, when the microdiscs grow up along the  direction into hexagonal microrods. Alternatively, crystallisation of the particle core into a ZnO plate, facilitates asymmetric assembly of nanocrystallites, forming a hexagonal cone on one side of the plate. The particle has a mushroom-like terminal morphology. When simultaneous surface and core re-crystallisation takes place, wood gyro-shaped particles are observed, in which all the surface discs face a single direction. The microstructures of the particles were investigated using XRD, electron microscopy and surface colouring with adsorbed charged dyes. Structural studies of the early growth stages and subsequent morphology evolution support a dipole field driven formation mechanism. This work offers an improved understanding of the for-mation of other spherulites, in particular, naturally occurring mineral calcium carbonate spherulites.
Connolly , B , Greer , H F & Zhou , W 2019 , ' Formation mechanisms of ZnO spherulites and derivatives ' , Crystal Growth & Design , vol. 19 , no. 1 , pp. 249-257 . https://doi.org/10.1021/acs.cgd.8b01332
Crystal Growth & Design
Copyright © 2018 American Chemical Society. This work has been made available online in accordance with the publisher’s policies. This is the author created accepted version manuscript following peer review and as such may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1021/acs.cgd.8b01332
DescriptionThe authors thank EPSRC for a platform grant (EP/K015540/1) and a Capital Equipment Grant EP/L017008/1.
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