Alloys lattice parameter

Alloy Lattice parameter" t/nm Fermi wavelength itp/ nm Amplitude A Phase factor rad... 

Assume that you want to grow a Gai.xIUxAs layer for use as a photodetector. The mole fraction of the film has been chosen to be x = 0.813 such that the detector will have a 1.0 eV energy gap. Assuming a linear relation between lattice constant and alloy composition (Vegard s Law) you estimate the alloy lattice parameter to be 0.572 nm for this alloy. 

Above the solution treatment temperature (ca 1250°C), the alloy is single phase with a bcc crystal stmcture. During cooling to ca 750—850°C, the sohd solution decomposes spinodally into two other bcc phases a and lattice parameter composition. The matrix a-phase is rich in Ni and Al and weakly magnetic as compared with which is rich in Fe and Co. The a -phase tends to be rod-like in the (100) dkection and ca 10 nm in diameter and ca 100 nm long. As the temperature is decreased, segregation of the elements becomes mote pronounced and the difference between the saturation polarizations of the two phases increases. 

We have calculated the Bloch Spectral Functlonii (BSF) at the Fermi energy, AB(k, F), for fee CucPdi.c and CUcPti.c, random alloys for various value of c. Die site potentials used have been obtained ab initio via the relativistic LDA-KKR-CPA method at the lattice parameters corresponding to the total energy minimum. 

Lattice gas Lattice parameter Lattice strain anisotropy Lic[uid alloys... 

Fig. 4. Lattice parameter changes of Ni-Cu alloys and of Ni-Cu hydrides from 100% by weight of Ni to 100% wt. Cu. O, Ni-Cu +, (3-Ni-Cu hydride phases of alloys with different Ni content. After Baranowski and Majchrzak (26, 25a).

As far as the lattice parameters are concerned, the difference between those of a particular host alloy and of its respective hydride decrease as the group lb metal content in the alloy increases. 

The hydrides of copper-nickel alloys have been studied by Baranowski and Majchrzak (25, 25a), who observed their existence up to a ratio Ni/Cu = 1. Figure 4 represents the lattice parameter of the alloys and their /3-phase hydrides as a function of the alloy content in nickel and copper. 

It is worth mentioning that the hydrides of the alloys are formed with much greater ease than those of the respective pure transition metals. This is probably due to the fact that the increase in lattice parameters caused by the incorporation of hydrogen is smaller in the former case—less work is thus required to be done by the system and the process is energetically more favorable. 

Homogeneous alloys of metals with atoms of similar radius are substitutional alloys. For example, in brass, zinc atoms readily replace copper atoms in the crystalline lattice, because they are nearly the same size (Fig. 16.41). However, the presence of the substituted atoms changes the lattice parameters and distorts the local electronic structure. This distortion lowers the electrical and thermal conductivity of the host metal, but it also increases hardness and strength. Coinage alloys are usually substitutional alloys. They are selected for durability—a coin must last for at least 3 years—and electrical resistance so that genuine coins can be identified by vending machines. 

Figure 2. (b) Formation and lattice parameters of perovskite borides M gPdjB. B content from as-cast alloys ", = La. Ce, Pr, Eu, Gd, Dy. 

Figure 10(a) shows a TEM image of a sample containing Co and Ni in the ratio 4-1 (Co4Nil) whereas Figure 10(b) is a TEM image of the ColNil sample (implanted at a total fluence 40 x 10 ions/cm ) the SAED pattern for ColNil sample exhibits a single alloy fc.c. phase with lattice parameter a = 0.3533(12) nm, whereas, when the... 

Bulk Ag-Al alloys, containing up to 12 a/o Al, were electrodeposited from melt containing benzene as a co-solvent. Examination by x-ray diffraction (XRD) indicated that the low-Al deposits were single-phase fee Ag solid solutions whereas those approaching 12 a/o were two-phase, fee Ag and hep i>-Ag2Al. The composition at which ti-Ag2Al first nucleates was not determined. The maximum solubility of aluminum in fee silver is about 20.4 a/o at 450 °C [20] and is reduced to about 7 a/o at room temperature. One would expect the lattice parameter of the fee phase to decrease only slightly when aluminum alloys substitutionally with silver because the... 

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