Electrical properties
The carrier types (n or p) of dilute magnetic semiconducting oxide nanoparticles are determined by the hot point probe method using a setup whose schematic is pictured here. The carrier type is dependent on the defects present, and correlates to the structural and magnetic properties.
Thin Films
Thin films of Co doped SnO2 show varying thickness with different amounts of Co, as well as changes in the magnetic properties. Shown also are films deposited on silicon and alumina substrates for studying gas sensing and solar cell applications.
Magnetic gas sensing
Nanoparticles of Fe2O3 and Fe doped SnO2 have been used to detect hydrogen gas by measuring the changes in their magnetic properties. A schematic is shown of a possible magnetic gas sensing device using a thin film of these materials.
Magnetic properties
Magnetic susceptibility is measured as a function of applied magnetic field to determine the type of magnetism a sample displays, and how that magnetism varies with composition, temperature and other properties. Ni doped CeO2 and Co doped TiO2 data are shown here.
Toxicology studies
The toxicity of nanoparticles is determined for various bacterial organisms, cancer cells and healthy cells. ZnO nanoparticles show selective toxicity to the cancer cells. The TEM image shows ZnO nanoparticles showing affinity towards attaching onto a bacteria cell. Nanoparticles of other oxides are under investigation to study these effects.
Forced hydrolysis
ZnO and Fe doped ZnO nanoscale materials are prepared by the forced hydrolysis route. The structure, band gap and size of the nanoparticles are affected by the concentration of Fe. This method can yield large quantities of nanoscale materials in a single step.
Charge state and composition
The chemical composition and states of ions and atoms within a material are detected via x-ray photoelectron spectroscopy. Shown here are Ni doped CeO2 and Co doped SnO2.
Electron paramagnetic resonance
Electron paramagnetic resonance is used to identify the local environment of magnetic species in transition metal doped metal oxides. Shown here are the simulations and experimental data for Ni doped CeO2 and Fe doped SnO2.
Nanoscale sizes
The size of ZnO nanoparticles is controlled by tuning the synthesis procedure. The change in size is visible in HRTEM images and confirmed by x-ray diffraction and spectrophotometry. Note how the surface to volume ratio changes drastically in the nanoscale region.
