Electric field gradient at 99Ru nuclei in the series of intermetallic compounds Ce1−xLaxRu2 synthesized at high pressure

Parameters of the electric quadrupole interaction for the first excited state (E=89.7 keV) of 99Ru nuclei for a number of the cubic Laves phase compounds Ce1−xLaxRu2, synthesized at high pressure, were determined by the perturbed angular γγ-correlation method. Compounds were synthesized at 8 GPa. It was revealed that the decrease of the average valence of a rare earth ion, caused by the substitution of La for Ce, results in the monotonous decrease of the quadrupole frequency νQ from 43.3 MHz for CeRu2 to 33.1 MHz for LaRu2.