Study of the electric field gradient at ^sup 111^Cd in the RAl^sub 3^ compounds synthesized under high pressure

The electric quadrupole interaction parameters for impurity 111Cd nuclei in intermetallic RAl3 compounds (R = La, Ce, Sm, Gd, Tb, Dy, Ho, Er, Yb, or Lu) synthesized under high (8 GPa) pressure at high (1800–1900°C) temperatures have been measured using the method of perturbed angular γγ correlations. It has been established by X-ray diffraction analysis that with an increase in the atomic number of the R element the obtained high-pressure phases are crystallized successively in the orthorhombic, hexagonal, and cubic structures. In the compounds with R = La, Ce, Sm, and Gd, deviation from the known structural types and formation of new ones due to the change in the stoichiometric composition have been observed. The data obtained by the method of perturbed angular γγ correlations have confirmed deviation from the specified stoichiometric composition 1R: 3Al for the LaAl3, CeAl3, SmAl3, and GdAl3 compounds and verified the correctness of the stoichiometric composition and the presence of the Cu3Au structural type for the remaining RAl3 high-pressure phases.