SYNTHESIS AND CHARACTERIZATION K2UP3SE9 - THE FIRST ACTINIDE SELENOPHOSPHATE

The reduction of U with a molten mixture of K2Se/P2Se5/Se at 490 degre es C produced the quaternary compound K2UP3Se9 as black, plate-like, a ir stable crystals. It crystallizes in the triclinic space group P - 1 with a = 10.407(3) Angstrom, b = 16.491(7) Angstrom, c = 10.143(3) An gstrom, alpha = 107.51(3)degrees, beta = 91.74(2)degrees, gamma = 90.2 8(3)degrees, Z = 4. The compound features an elaborate lamellar struct ure made of (U2Se14)(x) columns linked in two dimensions by the [P2Se6 ](4-) anions. The compound melts congruently at 573 degrees C. The mag netic susceptibility data are consistent with strong paramagnetic beha vior, conforming to Curie-Weiss law, above 100 K, whereas below this t emperature a transition occurs followed by antiferromagnetic ordering.