Pseudobinary compounds

International Agreement, The first report of the Commission for the Reform of the Nomenclature of Inorganic Chemistry was written in 1926 by Delepine. Subsequent rules (1940, 1959) were expanded and improved in 1990 to provide the basis for naming inorganic compounds. They retain most of the well established names for biliary and pseudobinary compounds and for the oxoacids of the nonmetals and derivatives. 

The solution to equations 12-14 for the growth of a pseudobinary compound, A JB C, can be expressed in analytical form (94) for the three common temperature programs ramp or equilibrium cooling, step cooling, and supercooling. The expressions for thickness as a function of time are given by ... 

There are six (3 2) layers in the repeating unit because P and O positions are equivalent in a ccp structure. The space group for the cubic is Oj, Pn/3 /, a0 = 4.123 A. More than 50 compounds are known with the CsCl structure (Table 7.1), including pseudobinary compounds, K(NF2), N(CH3)4(IC12), PC14(IC12), and NH4(C102). 

Shaltiel, D., Jacob, I., Davidov, D. (1977) Hydrogen absorption and desorption properties of AB2 Laves-phase pseudobinary compounds J.Less-common metals 53, 117-131. 

The pseudobinary compounds Gd(Ali-j,CUjj)2 are used to study the effect of the variation of the conduction electron concentration on the ordering temperature and the resistivity (Sakurai et al., 1977). The p vs. T curves of several samples of this cubic pseudobinary system are given in fig. 25. The concentration dependence of Pspd and of the Curie temperature are shown in fig. 26. Pspiix) and Tc(x) vary in a similar manner with increasing Cu concentration. The change in these two quantities can be explained by the variation of the exchange integral with conduction electron concentration (Sakurai et al., 1977). 

These pseudobinary compounds crystallize in the CrB structure. Pure GdNi is a ferromagnet with a Curie temperature = 72 K. The d-band of GdNi is full and there is no magnetic moment due to the Ni component. The d-band empties progressively as Co is substituted for Ni until the concentration of Co reaches a value X = 0.25. The Curie temperature therefore increases with x since the d-band is now polarizable. This can be seen clearly in the resistivity as shown in fig. 71 (Gratz et al., 1980c). The pseudobinary system becomes unstable when X > 0.25. This instability can be detected by the occurrence of a discontinuity in the residual resistivity as a function of the Co concentration (fig. 72). 

Features (i) and (ii) are related to the presence of local structural and magnetic distortion (Gratz et al., 1981a). X-ray investigations of the R(Alo. To.i)2 (T = Co, Fe) show considerable broadening of the X-ray reflections. Furthermore, it has been found that the magnetization of the pseudobinary compounds with Fe or Co is extremely hard to saturate. 

The thermopower of some Gd4(Co, NOs pseudobinary compounds is given in fig. 84 (Gratz et al., 1982b). Note that the substitution of only 5% for Co causes a pronounced change in the S vs. T curve. This could possibly imply that a variation of the conduction electron concentration has considerably more effect on the thermopower than the substitution of the isoelectronic Gd by Y ions (see section 4.2.2.4). Fig. 84 shows that the kink disappears with increasing Ni concentration. This is also seen in the behaviour of the resistivity of these compounds (see section 4.2.1.5). 

Some of the pseudobinary compounds in this group have transport properties which give evidence of high substitutional disorder. For example, the residual resistivity of R6(Fe, Mn)23 compounds is 250 cm and the p vs. T curves show a negative temperature coefficient of resistivity at some concentrations. 

With the help of NMR, spin reorientations - with temperature in H0C02 (Guimaraes et al. 1987) or with concentration x in pseudobinary compounds like Gdi Dy Al2 (Ichinose et al. 1984a) or Tbi Dy Co2 (Hirosawa and Nakamura 1982b) - were also analysed. We have compiled many other examples for this type... 

The intermetallic compound LaNi is well-known as a suitable material for hydrogen storage. Pseudobinary compounds with the same CaCu -type structure can be easily formed by partial substitution of nickel. Depending upon the rate and the nature of substitution, the hydriding properties (stability, maximum H-content, interstitial sites occupied by hydrogen. ..) are modified (1). 

Using this table pseudobinary compounds can be constructed in such a way as to minimize the magnetic anisotropy while still maintaining a large positive (or... 

LR-moment (and then parallel to the external field Bq). The applied field will strengthen the effective field acting on the Co subsystem and easily bring the pseudobinary compounds LR Yi 2 Co2 with to the MT. We present in figs. 39a,b the... 

Shinar et al. (1981) found experimental evidence indicating that an analysis of the diffusion-related experimental data in terms of a simple Arrhenius type of activation law is an over-simplification for other reasons as well. For a number of hydrides based on binary and pseudobinary compounds they show that the activation energy cannot be taken to be temperature independent, as is usually done. 

The plateau pressures corresponding to the equilibrium a + xH2 P are found to depend strongly on the temperature. The results obtained for the pseudobinary compound LaNi4,7Alo,3 by Huston and Sandrock (1980), shown in fig. 18, may serve to illustrate this point. It is seen that, starting from room temperature, an increase in temperature of about 100 degrees pushes the pressure from about 0.4 atm to above 5 atm. 

Fig. 18. Hydrogen absorption isotherms for the pseudobinary compound LaNq Aloj (after Huston and Sandrock, 1980).

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