Chun Chuen Yang

National Central University | NCU · Department of Physics

We describe the transport characteristics and the observation of a type of magnetoresistive behavior in nonmagnetic nanocompacts, consisting of mixtures of Ag and PbO nanoparticles packed into compact units at various mass compositions and compacting densities. Semiconductorlike, intermediate, and metallic transports may all be revealed by tuning t...

Nanocomposite materials, consisting of ensembles of Ag and Co nanoparticles, have been successfully fabricated, with various compositions and packing densities. The transport and magnetic characteristics of the compounds were studied. In particular, a crossover from a positive magnetoresistance (MR) at low applied magnetic fields to a negative magn...

The magnetic properties of fully oxygenated hexagonal Lu1−xScxMnO3 (x = 0, 0.5, and 1) have been investigated by means of neutron diffraction and ac magnetization measurements. All three compounds crystallized into a hexagonal symmetry of space-group P63cm. No structural changes were observed between 10 and 300 K. Anomaly of antiferromagnetic chara...

A lightly Co-doped spinel Li(Mn0.976Co0.024)2O4 was prepared which crystallizes into a cubic Fd3̄m structure at 300K. No structural changes were found as the temperature was reduced to 7K. Magnetic susceptibility and magnetic neutron diffraction measurements reveal developments of magnetic correlations below 150K. The magnetic correlations were sti...

The superconducting parameters of fine Pb powders, having mean particle diameters much smaller than the London penetration depth and the coherence length of bulk Pb, were measured using conventional means. The crystalline structures of the nanoparticles remain in fcc symmetry. The quantum size effects become significant for particles smaller than ∼...

Pb nanoparticles in a powder form has been successfully fabricated by employing the gas condensation method. Analyses based on the x-ray diffraction profiles and the AFM images showing a mean particle size of 6 nm, with a relatively narrow size distribution of half-width 1.5 nm, for the powder. It is known that bulk Pb has a superconducting transit...

We report on the successful fabrication of a fine Au powder with a mean particle size of 4 nm. A crossover from a positive thermal expansion at low temperatures to a negative thermal expansion at high temperatures was observed in the fcc cell parameter at around 125 K. Using a discrete electronic energy level scheme for nanoparticles, we introduce...

Neutron diffraction, ac magnetic susceptibility and magnetization measurements have been performed to study the magnetic properties of Ce-doped La0.7Ce0.15Ca0.15MnO3. A slightly distorted monoclinic P 21 /c symmetry for the crystal structure was found to describe the high-resolution powder diffraction pattern, taken at room temperature, better than...

A fine Au powder, with a mean particle diameter of 4 nm, has been successfully fabricated. The crystalline structure of the 4 nm Au nanoparticles remains in fcc symmetry. No structural changes were found between 15 and 450 K. A crossover from a positive thermal expansion at low temperatures to a negative thermal expansion at high temperatures was o...