Crystal structures and magnetic properties of quaternary manganese sulfides, BaLn(2)MnS(5) (Ln = La, Ce, and Pr)

The crystal structures and magnetic properties of quaternary manganese sulf ides BaLn(2)MnS(5) (Ln = La, Ce, and Pr) are reported. The quaternary manga nese sulfides were synthesized by a solid state reaction and determined to have tetragonal structures with space group I4/mcm by the Rietveld method. Their EPR spectra show that the Mn ions are in the S-6(5/2) state. The magn etic susceptibilities and the specific heats were measured from 2 to 300 K. The results of the measurements for BaLa2MnS5, BaCe2MnS5, and BaPr2MnS5 ex hibit the antiferromagnetic orderings for Mn2+ ions at 58.5, 62, and 64.5 K , respectively. For BaCe2MnS5 and BaPr2MnS5, the Ce and Pr ions are in the paramagnetic state down to 2 K. The specific heat for BaCe2MnS5 shows a Sch ottky anomaly at low temperatures. (C) 2000 Academic Press.