New Magnetic Zintl Phases in Eu-In-P System

Single crystals of two new compounds, Eu3InP3 and Eu3In2P4, were prepared by In flux synthesis. Eu3InP3 crystallizes in the Pnma orthorhombic space group with a = 12.6517(15) A, b = 4.2683(5) A, c = 13.5643(14) A, and Z = 4 while Eu3In2P4 belongs to Pnnm space group, a = 6.6999(6) A, b = 16.1019(13) A, c = 4.2725(4) A, and Z = 2. These two compounds are isotypic to the main group compounds Sr3InP3 and Sr3In2P4 respectively. Both structures consist of distorted In-P tetrahedra and isolated Eu2+ ions. In Eu3InP3 these tetrahedra share corners to form one-dimensional chains. The Eu2+ ions occupy three different sites, and form a complicated network containing some triangles. In Eu3In2P4 these tetrahedra form edge-shared dimers, and these dimers form chains. Eu3InP3 shows unusual magnetic properties: there are three magnetic ordering transitions at 14 K, 10.4 K, and around 5 K and the magnetization curve shows steps in the low temperature region. Eu3In2P4 magnetically orders at 14.5 K. Its magnetization curve saturates at around 1T. Eu3InP3 and Eu3In2P4 are both semiconductors.