Formation dynamics of mesocrystals composed of organically modified CeO2 nanoparticles: analogy to a particle formation model

Mesocrystals, non-classical crystalline nanostructured materials composed of aligned nanoparticles, present considerable potential for use in various engineering fields. Nevertheless, their formation mechanism and methods for size and morphology control remain unclear. For this study, the mesocrysta...

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Published inCrystEngComm Vol. 21; no. 25; pp. 3836 - 3843
Main Authors Andrzej-Alexander Litwinowicz, Takami, Seiichi, Asahina, Shunsuke, Hao, Xiaodong, Yoko, Akira, Gimyeong Seong, Tomai, Takaaki, Adschiri, Tadafumi
Format Journal Article
LanguageEnglish
Published Cambridge Royal Society of Chemistry 2019
Subjects
Agglomerates
Agglomeration
Cerium oxides
Crystal growth
Crystallization
Monomers
Morphology
Nanoparticles
Nanostructured materials
Polycrystals
Reaction time
Stability
Superstructures
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Summary:Mesocrystals, non-classical crystalline nanostructured materials composed of aligned nanoparticles, present considerable potential for use in various engineering fields. Nevertheless, their formation mechanism and methods for size and morphology control remain unclear. For this study, the mesocrystal formation process under hydrothermal conditions was first observed for l-glutamic-acid-modified cerium oxide nanoparticle clusters using a flow reactor system which was able to control the reaction time to within 1 s. At reaction times of less than 1 s at 548 K, spherical agglomerates composed of truncated octahedral nanoparticles with random orientations were observed. Such spherical agglomerates altered their shape to cubic assemblies with an ordered superstructure as the reaction time proceeded to 8.0 s. Observations made using HRTEM and cross-section SEM with EBSD confirmed the evolution from spherical polycrystals to cubic mesocrystals. The mesocrystal formation process was analogous to conventional crystal formation and growth, where primary nanoparticles act as monomers to form an ordered structure via non-ordered agglomeration. Based on the idea that organically modified nanoparticles behave similarly to monomers in conventional crystallization, mesocrystal size control was achieved by varying the primary nanoparticle concentration and the affinity of the solvent towards the nanoparticles.
ISSN:1466-8033
DOI:10.1039/c9ce00473d