Gas-phase crystallization of titanium dioxide nanoparticles

Petri Ahonen, Anna Moisala, Unto Tapper, Jorma Jokiniemi, Esko Kauppinen (Corresponding Author)

    Research output: Contribution to journalArticleScientificpeer-review

    21 Citations (Scopus)


    We have investigated the development of crystal morphology and phase in ultrafine titanium dioxide particles. The particles were produced by a droplet-to-particle method starting from propanolic titanium tetraisopropoxide solution, and calcined in a vertical aerosol reactor in air. Mobility size classified 40 nm diameter particles were conveyed to the aerosol reactor to investigate particle size changes at 20-1200°C with 5-1 s residence time. In addition, polydisperse particles were used to study morphology and phase formation by electron microscopy. According to differential mobility analysis, the particle diameter was reduced to 21-23 nm at 600°C and above. Precursor decomposition occurred between 20°C and 500°C. The increased mobility particle size at 700°C and above was observed to coincide with irregular particles at 700°C and 800°C and faceted particles between 900°C and 1200°C, according to transmission electron microscopy. The faceted anatase particles were observed to approach a minimized surface energy by forming {101} and {001} crystallographic surfaces. Anatase phase was observed at 500-1200°C and above 600°C the particles were single crystals. Indications of minor rutile formation were observed at 1200°C. The relatively stable anatase phase vs. temperature is attributed to the defect free structure of the observed particles and a lack of crystal-crystal attachment points.
    Original languageEnglish
    Pages (from-to)43-52
    JournalJournal of Nanoparticle Research
    Issue number1-2
    Publication statusPublished - 2002
    MoE publication typeA1 Journal article-refereed


    • aerosol decomposition
    • titanium dioxide
    • nanoparticles
    • anatase
    • crystallization
    • crystal morphology


    Dive into the research topics of 'Gas-phase crystallization of titanium dioxide nanoparticles'. Together they form a unique fingerprint.

    Cite this