Lattice pressure

P = Po(v) + G(v, T) RT/v where p0(v) denotes the lattice pressure along the zero degree isotherm, R is the universal gas constant, and the G factor accounts for the thermal contribution to the pressure arising from intermolecular forces. For the purpose of this report, the problem of formulating the (p-v-T) equation for a single species can be considered... 

Avagadro s number, molecules per kilomole. number of holes in the lattice, number of molecules of component i. surface area parameter for the lattice, pressure, pascals, reduced pressure, characteristic pressure, pascals, surface area parameter of component i. group area parameter for group k. partition function. 

Thompson et al. 1983, Martin and AUen 1985). In general, such volume-collapse transitions occur in a variety of lanthamde and actinide materials (Benedict et al. 1986, Franceschi and Olcese 1969), see figs. 38a and b, with IV SmS as a different characteristic case, where real charge fluctuations play a more important role (Grewe et al. 1980). In CeCug (Thompson and Fisk 1985) the f-occupation in the Kondo-lattice state is mildly reduced by pressure. Here, as in a number of other cases (Lawrence et al. 1984), external or lattice pressure can also cause continuous transitions with considerable volume changes as is, e.g., apparent from fig. 38d. 

Fisk and Matthias explained their experimental results by assuming that the effective lattice pressure exerted on the Pr impurities by the ZrBi2 host environment was about 200 kbar, thus giving rise to a virtual bound 4f level close to the Fermi level. 

Recalling the above-mentioned work of Fisk and Matthias on (ZrPrfBg, they pointed out that while there should be almost no lattice pressure effect in (I Pr)Ru2, Ce impurities were known (Hillenbrand and Wilhelm, 1970) to be nonmagnetic in (LaCe)Ru2, and thus the possibility of a virtual bound 4f state in ( Pr)Ru2 could not be ruled out. 

In contrast, if the divalent ion is smaller than iron(II), as is the case for cobalt(Il) and nickel(II), which have ionic radii of 0.072 and 0.070 nm respectively, then substitution will place iron in a smaller than expected lattice site. In this case the positive lattice pressure will produce shorter iron-ligand bonds, and a stronger effective crystal field potential which will favour the low spin configuration and/or a higher spin crossover temperature. This is exactly what is observed in a series of... 

SmS is particularly interesting because of its first-order metal-insulator phase transition at about 6 kbar (Maple and Wohlleben 1971), and the fact that it was the first f material to be identified as having a valence transition. This phase transition may be understood as a sudden change in the size of the Sm ion, i.e., with a change in the Sm valence. By alloying with Y the lattice pressure in (Sm,Y)S can be arranged so that this change in valence... 

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... 

Holtzberg, F., 1974, Effects of Lattice Pressure on Samarium Valence States in Monosulphide Solid Solutions, in AIP Conference Proceedings, No. 18, Part 1, pp. 478-489 (Nineteenth Annual Conference on Magnetism and Magnetic Materials, Boston, 1973). 

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