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

Ezgi Onur Şahin, Harun Tüysüz, Candace K. Chan, Gun Hee Moon, Yitao Dai, Wolfgang Schmidt, Joohyun Lim, Christina Scheu, Claudia Weidenthaler

Research output: Contribution to journalArticlepeer-review

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.

Original languageEnglish (US)
Pages (from-to)150-162
Number of pages13
JournalNanoscale
Volume13
Issue number1
DOIs
StatePublished - Jan 7 2021

ASJC Scopus subject areas

  • Materials Science(all)

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