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

    18 Citations (Scopus)

    Abstract

    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
    Volume4
    Issue number1-2
    DOIs
    Publication statusPublished - 2002
    MoE publication typeA1 Journal article-refereed

    Fingerprint

    Titanium Dioxide
    Crystallization
    titanium oxides
    Titanium dioxide
    Nanoparticles
    Gases
    crystallization
    vapor phases
    nanoparticles
    Crystals
    Aerosols
    Particle size
    Interfacial energy
    Crystal
    Electron microscopy
    Particles (particulate matter)
    anatase
    Aerosol
    Particle Size
    Titanium

    Keywords

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

    Cite this

    Ahonen, Petri ; Moisala, Anna ; Tapper, Unto ; Jokiniemi, Jorma ; Kauppinen, Esko. / Gas-phase crystallization of titanium dioxide nanoparticles. In: Journal of Nanoparticle Research. 2002 ; Vol. 4, No. 1-2. pp. 43-52.
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    abstract = "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.",
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    author = "Petri Ahonen and Anna Moisala and Unto Tapper and Jorma Jokiniemi and Esko Kauppinen",
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    Gas-phase crystallization of titanium dioxide nanoparticles. / Ahonen, Petri; Moisala, Anna; Tapper, Unto; Jokiniemi, Jorma; Kauppinen, Esko (Corresponding Author).

    In: Journal of Nanoparticle Research, Vol. 4, No. 1-2, 2002, p. 43-52.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - Gas-phase crystallization of titanium dioxide nanoparticles

    AU - Ahonen, Petri

    AU - Moisala, Anna

    AU - Tapper, Unto

    AU - Jokiniemi, Jorma

    AU - Kauppinen, Esko

    PY - 2002

    Y1 - 2002

    N2 - 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.

    AB - 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.

    KW - aerosol decomposition

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    KW - nanoparticles

    KW - anatase

    KW - crystallization

    KW - crystal morphology

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