HYPERFINE INTERACTION PARAMETERS IN GDPD2AL3 AND GROUND-STATE OF CEPD2AL3 AND NPPD2AL3

GdPd2Al3 has been studied by Gd-155 Mossbauer spectroscopy. This compo und was shown to order at 16K. A pure axial single site quadrupolar sp ectrum with a rather large and positive V-zz was observed in the param agnetic state. At low temperatures the hyperfine spectrum consists in a superposition of at least two magnetic patterns with different angle s between the magnetization and V-zz axes. The quadrupolar interaction data were used to evaluate the second order B-2(0) crystal held term in the rare earth RPd(2)Al(3) series. The ground state for the Ce3+ an d Np3+ ions in the CePd2Al3 and NpPd2Al3 compounds was inferred from t he experimental results.