Complex magnetic ordering in Eu3InP3:: A new rare earth metal zintl compound

Eu(3)lnP(3) has been prepared as large single crystals with an indium flux reaction. The structure of the new compound is isotypic to Sr(3)lnP(3) and crystallizes in the orthorhombic space group Pnma with unit cell dimensions of a = 12.6517(15) angstrom, b = 4.2683(5) angstrom, and c = 13.5643(14) angstrom (Z = 4, T = 140 K, R1 = 0.0404, wR2 = 0,0971 for all data). The structure consists of one-dimensional chains of corner-shared distorted [InP2P2/2](6-) tetrahedra separated by rows of Eu2+ ions. Two of the three crystallographically distinct europium sites have a short Eu(1)-Eu(2) distance of 3.5954(7) angstrom, which yields Eu-Eu dimers. The Eu-P bond distances range from 2.974(2) to 3.166(2) angstrom. The temperature dependence of the conductivity indicates that Eu(3)lnP(3) is a small band gap semiconductor. Both magnetization and Eu-151 Mossbauer spectral measurements indicate that the europium in Eu(3)lnP(3) is divalent and that at least two magnetic transitions occur. Magnetization studies reveal magnetic transitions at 14, 10.4, and similar to 5 K. These transitions are also observed in heat capacity studies of Eu(3)lnP(3). The Mossbauer spectra indicate that the two europium sites are ordered at 12 K and that all three europium sites are ordered at 8 K.