Lanthanum compounds lattice parameters

A ternary compound of lanthanum with copper and antimony of the stoichiometric ratio 3 3 4 was identified and studied by means of X-ray analysis by Skolozdra et al. (1993). La3Cu3Sb4 (3) compound was found to have the Y3Au3Sb4 type with the lattice parameter of a = 0.9837 (X-ray powder diffraction). For experimental details, see the Y-Cu-Sb system. 

Vemiere et al. (1995) observed the existence of the La4lri3Ge9 compound with Ho4lri3Ge9-type structure from an arc melted sample annealed at 1170K for 8 days. No lattice parameters were given. The purity of the starting elements was 3N for the lanthanum, 4N for the iridium and 6N for the germanium. 

It has been seen in the previous section that the ratio of the onsite electron-electron Coulomb repulsion and the one-electron bandwidth is a critical parameter. The Mott-Hubbard insulating state is observed when U > W, that is, with narrow-band systems like transition metal compounds. Disorder is another condition that localizes charge carriers. In crystalline solids, there are several possible types of disorder. One kind arises from the random placement of impurity atoms in lattice sites or interstitial sites. The term Anderson localization is applied to systems in which the charge carriers are localized by this type of disorder. Anderson localization is important in a wide range of materials, from phosphorus-doped silicon to the perovskite oxide strontium-doped lanthanum vanadate, Lai cSr t V03. 

---