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In situ total scattering experiments of nucleation and crystallisation of tantalum-based oxides: from highly dilute solutions via cluster formation to nanoparticles

DOI: 10.1039/D0NR07871A DOI Help

Authors: Ezgi Onur Sahin (Max-Planck-Institut für Kohlenforschung) , Harun Tueysuez (Max-Planck-Institut für Kohlenforschung) , Candace K. Chan (Arizona State University; Max-Planck-Institut für Kohlenforschung) , Gun-hee Moon (Max-Planck-Institut für Kohlenforschung) , Yitao Dai (Max-Planck-Institut für Kohlenforschung) , Wolfgang Schmidt (Max-Planck-Institut für Kohlenforschung) , Joohun Lim (Max-Planck-Institut für Eisenforschung) , Christina Scheu (Max-Planck-Institut für Eisenforschung) , Claudia Weidenthaler (Max-Planck-Institut für Kohlenforschung)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nanoscale

State: Published (Approved)
Published: November 2020
Diamond Proposal Number(s): 16372

Open Access Open Access

Abstract: The exact formation mechanism of tantalum oxides (and in general, metal/mixed metal oxides) from alkoxide precursors is still not fully understood, particularly when forming cluster-like or amorphous materials. The structural evolution of Ta-based oxides was studied in detail using X-ray total scattering experiments along with subsequent pair distribution function (PDF) analyses. Starting from a tantalum alkoxide precursor (Ta2(OEt)10), the formation of hydrolysed TaxOyHz clusters in highly diluted aqueous solution was analysed. From the PDF data, the connectivity and arrangement of TaxOy octahedra in the cluster could be deduced as well as the approximate size of the clusters (<1 nm). Construction of cluster models allowed for identification of common structural motifs in the TaxOyHz clusters, ruling out the formation of chain- or ring-like clusters. More likely, bulky clusters with a high number of corner-sharing octahedra are formed. After separation of the amorphous solid from the liquid, temperature-induced crystallisation processes were monitored via in situ total scattering experiments. Between room temperature and 600 °C, only small rearrangements of the amorphous structure are observed. At about 610 °C, amorphous TaxOyHz transforms directly into crystalline orthorhombic L-Ta2O5 without formation of any crystalline intermediate structures.

Subject Areas: Materials, Chemistry

Instruments: I15-1-X-ray Pair Distribution Function (XPDF)

Other Facilities: ID11 at ESRF; Petra III, P02.1 at DESY