Alloys In Concentration Range Research Articles

Expermimental Determination of the Enthalpies of Formation of the Copper-Zirconium Amorphous Alloys

The enthalpies of formation from pure crystalline elements at 298K were measured in the Cu-Zr amorphous alloys in concentration range 0.3-0.7 mole fraction of zirconium by means of a solution calorimeter based on liquid aluminium. The enthalpy of formation in the intermetallic compounds CuZr,CuZr 2 was defined on the basis of published before and obtained in this study data. The comparison of the enthalpies of formation of liquid, amorphous and crystalline alloys in the Cu-Zr system was made. The conclusions about the reasons of easy amorphisation in this system was made on the basis of this data.

The compositional dependence of the optical and electrical properties of hydrogenated amorphous Si-Ge films prepared by co-sputtering

Hydrogenated amorphous Si-Ge alloy films were prepared by co-sputtering from two half-disc targets. The films are about 1 μm thick and 12.5 cm long. The composition along the length of the film varies continuously from 70 to 5 at.% Si. The optical absorption and photoconductivity as a function of wavelength were measured. The energy gap as evaluated form these measurements decreases linearly from 1.65 eV for 70 at.% Si to 1.1 eV for 7 at.% Si. The photoconductance response ημτ varies markedly with composition, where η is the quantum efficiency for photocarrier generation, μ the mobility and τ the lifetime of the photocarriers. At the silicon-rich end ημτ = 2 × 10 -6 cm 2 V -1, decreases to 2 × 10 -9 cm 2 V -1 at around 40 at.% Si and increases again by one order of magnitude at the germanium-rich end. On the whole the characteristics of our sputtered films are comparable with those reported for similar alloys prepared by glow discharge. An important advantage of the sputtered films, however, is that it is possible to prepare a whole range of alloy concentrations in one run.