김병효 교수

Uniform and extremely small-sized iron oxide nanoparticles (ESIONs) of < 4 nm were synthesized via the thermal decomposition of iron-oleate complex in the presence of oleyl alcohol. Oleyl alcohol lowered the reaction temperature by reducing iron-oleate complex, resulting in the production of small-sized nanoparticles. XRD pattern of 3 nm-sized nanoparticles revealed maghemite crystal structure. These nanoparticles exhibited very low magnetization derived from the spin-canting effect. The hydroph

Nanomaterials in the size range of 3–50 nm have received increased attention in the last few decades because they exhibit physical properties that are intermediate to those of individual molecules and bulk materials. Similarly, ultrasmall nanoparticles (USNPs), with sizes in the 1–3 nm range, exhibit unique properties distinct from those of free molecules and larger-sized nanoparticles. These properties are greatly sensitive to both the composition and size of the particles, and thus, the abilit

Precise three-dimensional (3D) atomic structure determination of individual nanocrystals is a prerequisite for understanding and predicting their physical properties. Nanocrystals from the same synthesis batch display what are often presumed to be small but possibly important differences in size, lattice distortions, and defects, which can only be understood by structural characterization with high spatial 3D resolution. We solved the structures of individual colloidal platinum nanocrystals by d

Thanks to recent advances in the synthesis of high-quality inorganic nanoparticles, more and more types of nanoparticles are becoming available for medical applications. Especially, metal oxide nanoparticles have drawn much attention due to their unique physicochemical properties and relatively inexpensive production costs. To further promote the development and clinical translation of these nanoparticle-based agents, however, it is highly desirable to reduce unwanted interbatch variations of th

For the past few decades, nanoparticles of various sizes, shapes, and compositions have been synthesized and utilized in many different applications. However, due to a lack of analytical tools that can characterize structural changes at the nanoscale level, many of their growth and transformation processes are not yet well understood. The recently developed technique of liquid-phase transmission electron microscopy (TEM) has gained much attention as a new tool to directly observe chemical reacti

We present a rapid and reliable method for determining the sizes and size distributions of <5 nm-sized iron oxide nanocrystals (NCs) using matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS). MS data were readily converted to size information using a simple equation. The size distribution obtained from the mass spectrum is well-matched with the data from transmission electron microscopy, which requires long and tedious analysis work. The size distributio

Charge carrier mobility in transparent conducting oxide (TCO) films is mainly limited by impurity scattering, grain boundary scattering, and a hopping transport mechanism. We enhanced the mobility in nanocrystal (NC)-based TCO films, exceeding even typical values found in sputtered thin films, by addressing each of these scattering factors. Impurity scattering is diminished by incorporating cerium as a dopant in indium oxide NCs instead of the more typical dopant, tin. Grain boundary scattering

Nanoparticle-based thin films are increasingly being used in various applications. One of the key factors that determines the properties and performances of these films is the type of ligands attached to the nanoparticle surfaces. While long-chain surfactants, such as oleic acid, are commonly employed to stabilize nanoparticles and ensure high monodispersity, these ligands often hinder charge transport due to their insulating nature. Although thermal annealing can remove the long-chain ligands,

The 3D atomic arrangements of materials determine the free energy landscape, thus governing the physical and catalytic properties of those materials. The 3D structures of nanoparticles can deviate from the periodic atomic arrangement of their bulk counterparts due to the dominance of surface dangling bonds, defects, and dislocations. One approach to understand the structure of nanoparticles and their resulting unique properties involves precise probing of the 3D positions of all constituent atom

Nickel and nickel phosphide nanoparticles are highly useful in various fields, owing to their catalytic and magnetic properties. Although several synthetic protocols to produce nickel and nickel phosphide nanoparticles have been previously proposed, controllable synthesis of nanoparticles using these methods is challenging. Herein, we synthesized highly monodisperse nickel and nickel phosphide nanoparticles via thermal decomposition of nickel-oleylamine-phosphine complexes in organic solvents. T