Pseudobinary alloys

Along with the lattice constant the congment sublimation temperature is a useful guide as to which pseudobinary alloys, ( 0) (BC) or... 

During the growth of solid solutions (e. g., pseudobinary alloys and doped compounds), the melt composition at the interface can be a function of time, a situation that results in a natural composition gradient in the growth direction. Heteroepitaxy, the growth of an epitaxial film with a composition different from that of the substrate, is more difficult compared with other... 

Pseudobinary alloys of (CeRu2—GdRu2) (4), (YOs2-GdOs2) (29), (GdRu ThRu ) (6), (GdOs2-LaOs2) (5), and perhaps some others... 

Bernard, J. E., and A. Zunger (1987). Electronic structure of ZnS, ZnSe, ZnTe and their pseudobinary alloys. Phys. Rev. B36, 3199-228. 

One topic has not been included in this article. Many authors have made a thorough study of dilute pseudobinary alloys containing low concentrations of magnetic rare earth atoms. We feel that these investigations, many of which are related to the Kondo effect, belong properly to the field of dilute magnetic alloys and they are therefore reported there. An excellent review of this topic has been... 

A number of multi-impurity experiments on Kondo systems were reported in the literature. Most of the early work is cited in the review by S.E. Barnes (1981a). A tutorial discussion on the Kondo effect has been given by Taylor (1975). Of these multi-impurity experiments, here we discuss Gd-ESR experiments obtained in LaA doped with Kondo impurities. Gd-ESR has been utilized to study the effects of a Kondo impurity in the pseudobinary alloy Lai jcCexAl2 Gd (Davidov et al. 1972). Similar experiments were performed by Weissenberger (1981) in the intermetallic compound (La,Y,Ce)Al2 Gd. In this alloy Ce behaves like a Kondo impurity and the Kondo temperature can be varied from 0.4 to 100 K. The most important result of this investigation was the dependence of the residual linewidth A/7o on the state of the Ce impurity, e.g. on the single-ion Kondo temperature. 

I. Electronic and lattice properties. In this section the electronic properties of magnetically ordering divalent EuSe arc altered by introducing TmSe, provoking possible intermediate valence. In this pseudobinaiy alloy system the substitution of Eu by Tm decreases the lattice constant, but since divalent Tm has a smaller ionic radius than divalent Eu there is no lattice pressure exerted on Tm as long as the compounds are semiconductors (see fig. 106). Thus Tm as well as Eu remain divalent. Kaldis et al. (1982) have shown that in the pseudobinary alloy system a number of miscibility gaps exist, but at x = 0.2 a compositionally induced SMT is found, i.e., for x <0.2 the compounds... 

The pseudobinary alloys under study crystallize in the cubic CujAu-structure for y smaller than 0.9, and in the hexagonal TiNi 3-structure when y is greater than 0.93. Calculations (Eriksson et al. 1988d) were done at the measured molecular volume, but for the CujAu structure. 

Ordering behaviors and age-hardening in experimental AnCn-Zn pseudobinary alloys for dental applications, S. H. Seol, T. Shiraishi, Y. Tanaka, E. Mima, K. Hisatsnne, and H. I. Kim, Biomaterials, 2002, 23(24), 4873-9. 

The AuAl2-AuGa2-AuIn2 problem Knight shifts and relaxation times in their pseudobinary alloys, G. C. Carter, I.D. Weisman, L. H. Bennett, and R. E. Watson, Phys. Rev. B, 1972,5(9), 3621. 

Cho] Cho, W.K., Han, K.H., Phase Constitution and Lattice Parameter Relationships in Rapidly Sohdilied (Feo,65Mno,35)o.83Alo,i7-xC and Fe3Ali xC Pseudobinary Alloys , Metall. Trans. A, 16A, 5-10 (1985) (Crys. Stracture, Experimental,, 14)... 

Figure 4.10 The ternary phase diagram for Al-Ga-As. Each light line represents alloys of eonstant eomposition as labeled for eaeh line. The dark horizontal line represents the pseudobinary alloy Al Gai. As. This is a eontinuously-soluble alloy as shown in the inset. Figure inset based on data from Referenee 1.

Individual lines on these diagrams represent the energy gap dependence in individual pseudobinary alloys. Regions contained by four curves are for quartemary alloys, and define the region of phase space that should, if the alloy were completely miscible, be accessible with a given quaternary alloy. 

Substituting Equations 6.11 and 6.12 into 6.1 and the result into 6.10, a set of alloy stability curves in x and y are obtained for quaternary alloys. These curves are similar to points on the curve in Figure 4.18c at a given temperature and define a region of composition space in which the alloy is unstable and may decompose. In addition to direct calculation from known values, the bond energies in Equation 6.11 may be obtained by fitting observed spinodal decomposition data for pseudobinary alloys in a given quaternary system. 

Band gap bowing occurs in ternary and quaternary alloys as it does in binary and pseudobinary alloys. The behavior of quaternary alloys and can be treated in the same way. For a typical quaternary of the form Ai xBxCyDi y, Equation 6.13 for the energy of a specific part of the band stractrrre (for example, the direct gap) can be generalized to [2] ... 

Here Eabcd is the energy of a given band in the quaternary and Eabd, Eabc, Eacd> and Ebcd are the energies of the same band that would have been detErmined from Equation 6.13 for each individual pseudobinary alloy. Thus, Equation 6.17 is a linear interpolation of the pseudobinary alloy values. This approach produces a reasonable estimate of the gap values. [2] There are other methods for estimating the alloy energy gap that increase the effective bowing but the performances of these methods are not particularly improved. 

Binary and pseudobinary alloys allow tailoring of the energy gap or lattice parameter. Ternary and higher alloys may permit independent control of these. Properties of semiconductors determined by relatively large volumes of the material (hrmdreds of atoms) generally change linearly with alloy composition. Examples include mechanical properties and lattice constant. 

Solubility of semiconductor alloys is determined primarily by first- and second-nearest neighbor bonds. In pseudobinary alloys the alloyed elements are second-nearest neighbors. Regular solution theory using energies of tetrahedral clusters of atoms is effective in modeling solubility and may be applied to binary, pseudobinary, and higher-order alloys. 

Consider the two pseudobinary alloys (Gai xlnx)As and (Ali.xlnx)As where we will assume that the latter is restricted to the direct-gap portion of the composition range. Which of these would you expect (without looking at the tables)... 

ALD reactions involving more than two elements can also be designed. For the case of deposition of an alloy (for example a pseudobinary alloy), one must rely on a well-characterized competition for surface reaction sites. Thus, to deposit an AlxGai xAs alloy one would need to know how an A1 precursor would compete with a Ga precursor for a favored metal deposition site. An experimental variable such as surface temperature could alter this competition and give some control of the resulting film alloy composition. 

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