Solid state transitions of Bi2O3 nanoparticles

• Published in: Journal of materials research Vol. 29; no. 12; pp. 1383 - 1392
• Main Authors: Guenther, Gerrit, Guillon, Olivier
• Format: Journal Article
• Language: English
• Published: New York, USA Cambridge University Press 28-06-2014; Springer International Publishing; Springer Nature B.V
• Subjects: Applied and Technical Physics; Biomaterials; Cooling; Glass substrates; Grain size; Inorganic Chemistry; Materials Engineering; Materials research; Materials Science; Nanoparticles; Nanostructured materials; Nanotechnology; Solid state physics; Studies; Temperature; Thin films; nanoparticles; structural characterization; oxide; metastable; size-stabilized; polymorphism; size-selected; phase transition; size-dependent
• ISSN: 0884-2914; 2044-5326
• DOI: 10.1557/jmr.2014.124

The solid-state phase transitions of bismuth(III) oxide (Bi2O3) nanoparticles were investigated by complementary methods such as differential scanning calorimetry, differential thermal analysis with combined thermogravimetry and mass spectrometry, and high-temperature x-ray diffraction as compacted nanopowder. At room temperature the particles resided in the β-phase, which is usually a metastable high-temperature phase of bulk Bi2O3. The complementary experimental methods were linked and a nanophase (tetragonal β-phase) → bulk-phase (monoclinic α-phase) transition was identified which was preceded by crystal growth and evaporation of O and C containing species. It was also shown that the atmosphere (more precisely its absolute pressure) has an influence on the transition behavior. An interpretation was proposed that successfully explains all observations from this work and from literature: A sudden destabilization takes place around 735 K due to the loss of the stabilizing, carbonized surface. This leads to the observed transformation to the bulk-phase. But if the particles are smaller than a certain, critical size in the nanorange and are not allowed to grow, they remain in the nanophase until they melt.