Short-range Order Clusters Research Articles

Spatial ordering and interference scattering of electrons by a system of mixed-valence iron ions in HgSe: Fe crystals

The spatial ordering of charges in mixed-valence systems is considered. The dependence of the correlation sphere radius on the iron impurity content is obtained from the balance equation for the d holes and neutral centers in the short-range order cluster of a Fe3+ ion. The penetrating hard sphere model is proposed for the rigorous description of the spatial ordering in mixed-valence systems and the calculation of correlation functions.

Carrier recombination in clusters of NiO

We studied the dependence of carrier recombination pathways in nanoparticles of NiO on surface conditions. Two types of 0.6 nm short-range order clusters of NiO were prepared in reverse micelles of dodecyl benzene sulfonate. The steady-state absorption and time-resolved fluorescence measurements were done in order to investigate the photo-physical properties of d–d in-gap transitions. The NiO nanoclusters and bulk steady-state optical absorption and emission properties are comparatively discussed from the prospective of Laporte's rules relaxation. The results of the time-resolved emission studies allowed us to develop the phenomenological model of the in-gap carrier recombination in NiO clusters.

Short-Range Order and Nanocrystallization in Amorphous Zr-Ti-Cu-Ni-Al

AbstractWe have examined the effect of Ti content on the crystallization kinetics of Zr-based amorphous alloys. In Zr59Ti3Cu20Ni8Al10, annealing above the glass transition temperature produces 50-100 nm crystalline precipitates, as seen in transmission electron microscope images. In contrast, TEM images and diffraction patterns from annealed Zr54.5Ti7.5Cu20Ni8Al10 show no evidence of crystalline phase formation. Structural changes upon annealing do occur in this alloy, however, as revealed by field ion microscopy. The effect of Ti is to favor the formation of clusters of short-range order; this tendency for clustering is apparently the cause of difference in crystallization behavior between the two alloys.

Structural Investigation of Amorphous Ni2B by EXAFS and XRD

The structure and thermostability of hyperfine amorphous Ni 2 B catalysts (HA-Ni 2 B) have been studied by EXAFS, XPD and DSC. The samples prepared by chemical reduction have been proved to be amorphous. The grain size is between 5 nm and 20 nm. A short-range order cluster is formed. The distances of Ni-B or Ni-Ni did not alter due to the change of the conditions but the coordination number of Ni is changed. The HA-Ni 2 B is only stable up to 140°C. Over 140°C, the crystal Ni and an intermediate formed. Finally the intermediate disappears but some B 2 O 3 can be detected.

On the high temperature electrical resistivity behaviour of Cu 55-Ni 45 alloy

Resistivity measurements supplemented with electron microscopy investigation in a Cu 55-Ni 45 alloy are reported, in the temperature range 273–700 K. An anomalous high temperature resistivity minimum is observed at 673 K whereas at the same temperature diffuse intensity maxima appear. It is suggested that the resistivity minimum could be attributed to the effect of short range order cluster formation.