The optical band gap is a basic property of optical materials. The measured band gap depends not only on the material but also on its characteristics such as crystallinity and stoichiometry. The optical band gap of chromium aluminum oxide films was measured and calculated by three different methods. Firstly, we used the conventional experimental-graphical method, which is commonly used. However...

the synthesis of nano- structured cobalt through a controlled chemical process followed by heat treating at various temperatures is studied. the product is characterized by icp, xrd, fesem , and tem, indicating that the as- synthesized particles have an amorphous structure with 1.76 for co/b ratio, an average size of 50 nm. the transformation of intermediate phases into single phase nano- cryst...

Organic substances can adopt an amorphous solid or semisolid state, influencing the rate of heterogeneous reactions and multiphase processes in atmospheric aerosols. Here we demonstrate how molecular diffusion in the condensed phase affects the gas uptake and chemical transformation of semisolid organic particles. Flow tube experiments show that the ozone uptake and oxidative aging of amorphous...

Phase change or Ovonic memory technology has gained much interest in the past decade as a viable solution for the rapid increase in the demand for memory storage. This unique technology, first proposed by S. Ovshinsky in 1968, is based on storing information on the crystalline and amorphous phases of a material. The most common phase-change materials (PCMs) use chalcogenide alloys such as the G...

Tungsten-containing amorphous carbon films were produced by dual magnetron sputter deposition. The formation of carbide phases after heat treatment in inert gas at temperatures up to 2800 K was investigated by X-ray diffraction for tungsten concentrations below 25 at%. After deposition, each film consists of an amorphous carbon matrix with atomically dispersed W inclusions. Annealing up to 2800...

Solute clustering and partitioning behavior in the early crystallization stage of an Fe73.5Si13.5B9Nb3Cu1 amorphous alloy have been studied by employing a three dimensional atom probe (3DAP) and a high resolution electron microscope (HREM). 3DAP results have clearly shown that Cu atom clusters are present in the amorphous state after annealing below the crystallization temperature. The density ...

The density of the amorphous phase of metals is generally thought to be related to glass formation, but this correlation has not been demonstrated experimentally to date. In this work, systematic deflection measurements using microcantilevers and a combinatorial deposition method show a correlation between glass-forming ability and the density change upon crystallization over a broad compositio...

The high-pressure behavior of H(2)O ice at temperatures below 100 K has been investigated to 20 GPa by Raman spectroscopy. Between 10 and 80 K, high density amorphous (hda) ice formed from ice I(h) undergoes a phase transition near 5 GPa to ice VII' and a transition at 14 GPa to a different phase. At 14 GPa, a new low-frequency band appears at ~150 cm(-1) that steeply increases in frequency wit...

The transient reflectivity response of phase-change Ge2Sb2Te5 films to intense femtosecond laser pulses is studied by ultrafast coherent phonon spectroscopy. The three different phases amorphous, fcc-, and hcp-crystalline , as well as laser-crystallized films, are investigated, featuring different photoexcited carrier and coherent optical phonon dynamics. At least two main phonon frequencies ar...