Synthesis and characterization of hollow nanoparticles of crystalline Gd2O3

Although Gd2O3 (gadolinia) nanoparticle is the subject of intense research interest due to its magnetic property as well as controllable emission wavelengths by doping of various lanthanide ions, it is known to be difficult to prepare monodisperse crystalline gadolinia nanoparticles because it requires high temperature thermal annealing process to enhance the crystallinity. In this article, we demonstrate the synthesis of hollow nanoparticles of crystalline Gd2O3 by employing poly(N-vinylpyrrolidone) (PVP) to stabilize the surface of Gd(OH)CO3·H2O nanoparticles and to successively form SiO2 shell as a protecting layer to prevent aggregation during calcinations processes. Silica shells could be selectively removed after calcinations by a treatment with basic solution to give hollow nanoparticles of crystalline Gd2O3. The formation mechanism of hollow nanoparticles could be suggested based on several characterization results of the size and shape, and crystallinity of Gd2O3 nanoparticles by TEM, SEM, and XRD.