Marcela L. Redígolo

Magnetization reversal in europium sulfide nanocrystals

The authors report the observation of the reversal in the magnetization hysteresis curve of europium sulfide nanocrystals. This phenomenon was investigated through the temperature-dependent magnetization of two classes of nanomaterials, nanocrystalline (2.0nm⩽dNCs⩽100nm) and quantum confined (dNCs⩽2.0nm), where dNCs is the diameter of the nanomaterial. The effect of the size of the nanomaterial on the magnetization is attributed to the competition between the magnetic properties of strained surface atoms and unstrained core atoms. Superconducting quantum interference device probed the magnetic response. Electron microscopy and X-ray diffraction spectroscopy revealed the crystallinity and monodispersivity of the nanomaterials.

Stepwise assembly of europium sesquioxide nanocrystals and nanoneedles

The stepwise self-assembly of europium sesquioxide nanocrystals into larger, anisotropic europium hydroxychloride nanostructures is observed. This involves the thermally assisted growth of 4.0 nm nanocrystals into elongated structures, called nanoneedles, and the subsequent assembly of those nanoneedles into larger, oriented bundles, called nanospindles. High-resolution transmission electron microscopy provides the size distribution, shape and atomic spacing of the nanostructures, whereas selective area electron diffraction and x-ray diffraction measurements identify their crystallinity. The optical properties, attributed to the environment of the host lattice for the europium ions, are investigated through photoluminescence measurements.

Stepwise Assembly of Eu2O3 Nanocrystals and Nanoneedles

We report the stepwise assembly of europium oxide (Eu2O3) nanocrystals into one dimensional europium hydroxychloride (Eu(OH)2Cl) nanostructures. Synthesized via a simple colloidal chemistry procedure, the Eu2O3 nanocrystals organized into anisotropic nanoneedles and nanospindles via solution‐phase heat treatment. Transmission electron microscopy (TEM) revealed the shape and crystalline arrangement of the nanostructures.