Size-Dependent Phase Transformations in Bismuth Oxide Nanoparticles. I. Synthesis and Evaporation

At the nanoscale material properties can be tuned by altering the size and shape of the specimen. Such effects are quite well investigated for metallic materials. On the other hand inorganic compounds have received relatively little interest due to the more demanding experimental procedures. While the size effects are similar for any kind of inorganic material, the degree of size-dependent changes depends on the bond strength and bond nature of the material at the surface: the higher the surface energy, the stronger the size dependence. These thoughts are demonstrated in this contribution by investigating the size-dependent thermodynamic properties of monodisperse, size-selected bismuth oxide (Bi₂O₃) nanoparticles in the range between 6 and 50 nm. This first part is mainly concerned with evaporation, while the second part (<i>J. Phys. Chem. C</i> <b>2014</b>, 10.1021/jp509841s) covers size-dependent melting. Heating experiments up to the evaporation of the particles were performed with a new, custom method based on loss of matter caused by evaporation. The results in this part show the validity of the Kelvin equation and a size-dependent evaporation behavior of this oxide

Feasibility study of nanoparticle synthesis from powders of compounds with incongruent sublimation behavior by the evaporation/condensation method

In this paper we investigate the feasibility of a fabrication route to produce nanocrystals of compound material with incongruent sublimation behavior via the simple evaporation of the powder of the compound. The generation of stoichiometric particles would only be possible if the particle formation occurs at temperatures below the incongruent sublimation point. Our experiments, done on three different III-V compounds, show that the simple evaporation of the powder of those materials to obtain stoichiometric particles is not possible. Particle formation does not start at temperatures below the incongruent sublimation point. Particles synthesized consisted not of the compound but almost entirely of the more volatile group-Velement, leading to a change in the composition of the source material and thus to irreproducible behavior

Size-Dependent Phase Transformations in Bismuth Oxide Nanoparticles. I. Synthesis and Evaporation

At the nanoscale material properties can be tuned by altering the size and shape of the specimen. Such effects are quite well investigated for metallic materials. On the other hand inorganic compounds have received relatively little interest due to the more demanding experimental procedures. While the size effects are similar for any kind of inorganic material, the degree of size-dependent changes depends on the bond strength and bond nature of the material at the surface: the higher the surface energy, the stronger the size dependence