Chattopadhyay, Shreyasi and Bysakh, Sandip and Saha, Jony and De, Goutam (2018) Electrospun ZrO2 nanofibers: precursor controlled mesopore ordering and evolution of garland-like nanocrystal arrays. Dalton Transactions, 47 (16). pp. 5789-5800. ISSN 1477-9226

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We observed that the hydrolysis-condensation reaction of precursors makes a significant difference in constructing ordered mesopores in electrospun ZrO2 nanofibers. Transmission-SAXS studies confirm the generation of uniform clusters of size similar to 1.44 nm in the ZrOCl2 center dot 8H(2)O (inorganic salt) derived sol due to its relatively slow hydrolysis-condensation process. These initial -Zr-O-Zr- clusters acted as building blocks to form uniform 3D ordered cubic (Pm (3) over barm) mesopores in the presence of Pluronic F127 surfactant. In contrast, the commonly used Zr-alkoxide (zirconium n-propoxide) precursor, which is highly hydrolysable even after the use of a controlling agent, generates larger clusters with broad size distributions due to the uncontrolled hydrolysis-condensation of alkoxy groups. Accordingly, in the presence of F127, the alkoxide derived sol yielded disordered mesopores in the resultant fibers. XRD under dynamic heating conditions (up to 900 degrees C) and the corresponding TEM studies of the ZrOCl2 center dot 8H(2)O derived nanofibers confirmed the retention of mesopores even in the extremely thin nanofibers (diameter similar to 15-25 nm) after the amorphous to crystal phase transformation (cubic/tetragonal). An interesting morphological transformation has been observed in the nanofibers at 900 degrees C where the fibers have been uniformly segmented by distinct single nanocrystals (width similar to 15-65 nm) with mesopores. Further heat-treatment at 1100 degrees C made these segmented nanofibers nonporous, and a garland-like appearance with monoclinic nanocrystal arrays was formed.

Item Type: Article
Subjects: Engineering Materials
Divisions: Nano-Structured Materials
Depositing User: Bidhan Chaudhuri
Date Deposited: 03 Sep 2018 12:07
Last Modified: 03 Sep 2018 12:07

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