Electrolyte gating with ionic liquids is a powerful tool for inducing novel conducting phases in correlated insulators. An archetypal correlated material is vanadium dioxide (VO(2)), which is insulating only at temperatures below a characteristic phase transition temperature. We show that electrolyte gating of epitaxial thin films of VO(2) suppresses the metal-to-insulator transition and stabilizes the metallic phase to temperatures below 5 kelvin, even after the ionic liquid is completely removed. We found that electrolyte gating of VO(2) leads not to electrostatically induced carriers but instead to the electric field-induced creation of oxygen vacancies, with consequent migration of oxygen from the oxide film into the ionic liquid. This mechanism should be taken into account in the interpretation of ionic liquid gating experiments.

The synthesis of multifunctional magnetic nanoparticles (NPs) is a highly active area of current research located at the interface between materials science, biotechnology and medicine. By virtue of their unique physical properties magnetic nanoparticles are emerging as a new class of diagnostic probes for multimodal tracking and as contrast agents for MRI. Furthermore, they show great potential as carriers for targeted drug and gene delivery, since reactive agents, such as drug molecules or large biomolecules (including genes and antibodies), can easily be attached to their surface. On the other hand, the fate of the nanoparticles inside the body is mainly determined by the interactions with its local environment. These interactions strongly depend upon the size of the magnetic NPs but also on the individual surface characteristics, like charge, morphology and surface chemistry. This review not only summarizes the most common synthetic approaches for the generation of magnetic NPs, it also focuses on different surface modification strategies that are used today to enhance the biocompatibility of these NPs. Finally, key considerations for the application of magnetic NPs in biomedicine, as well as various examples for the utilization in multimodal imaging and targeted gene delivery are presented.

Magnetic nanoparticles of the 3d transition metal oxides have gained enormous interest for applications in various fields such as data storage devices, catalysis, drug-delivery, and biomedical imaging. One major requirement for these applications is a narrow size distribution of the particles. We have studied the nucleation and growth mechanism for the formation of MnO nanoparticles synthesized by decomposition of a manganese oleate complex in high boiling nonpolar solvents using TEM, FT-IR, and AAS analysis. The exceptionally narrow size distribution indicates that nucleation and growth are clearly separated. This leads to a uniform growth with a very narrow size distribution on the existing nuclei. The particle size can be controlled by adjusting the reaction time, reaction temperature, solvent, and heating rate. The particle size increases with temperature, reaction time, and the chain length (boiling point) of the solvent. FT-IR and NMR spectra revealed that the oleate capping agent binds to the surface in a bidentate manner. In addition, XPS measurements indicate that MnO nanocrystals are air-stable. No significant oxidation of Mn2+ to Mn3+ occurred even after several days.

Dielectrics are an important class of materials that are ubiquitous in modern electronic applications. Even though their properties are important for the performance of devices, the number of compounds with known dielectric constant is on the order of a few hundred. Here, we use Density Functional Perturbation Theory as a way to screen for the dielectric constant and refractive index of materials in a fast and computationally efficient way. Our results constitute the largest dielectric tensors database to date, containing 1,056 compounds. Details regarding the computational methodology and technical validation are presented along with the format of our publicly available data. In addition, we integrate our dataset with the Materials Project allowing users easy access to material properties. Finally, we explain how our dataset and calculation methodology can be used in the search for novel dielectric compounds.

Metastable YFeO 3 with the hexagonal YAlO 3 structure was obtained by a sol-gel process at 700 °C, using metal nitrate precursors with pH control and the appropriate citric acid to nitrate ratio. Under similar conditions, YFe 1-x Pd x O 3-δ (0 < x e 0.1) compositions were also prepared. The substitution of Fe by Pd stabilizes the YAlO 3 structure at higher temperatures. The crystal structures of YFe 1-x Pd x O 3-δ (0 e x e 0.1) were refined by Rietveld analysis of X-ray and neutron powder diffraction data. The parent hexagonal YFeO 3 (x ) 0) crystallizes in the space group P6 3 /mmc with a ) 3.5099(3) Å and c ) 11.759(2) Å. The redox-driven mobility of Pd to integrate into the oxide host as ions and to dissociate from it as fcc-Pd nanoparticles was monitored by a combination of X-ray diffraction and X-ray photoelectron spectroscopy. Pd nanoparticles in the reduced samples were detected by scanning backscattered electron microscopy and transmission electron microscopy. The Pd 2+ -containing materials showed significant low-temperature (near 100 °C) catalytic activity for CO oxidation, comparable to that of highly dispersed PdO/Al 2 O 3 , despite their relatively low surface areas.