Structure, magnetism, and magnetoresistance of ternary Zintl phases in the europium-indium-phosphorus system

Transition metal and rare earth metal containing Zintl compounds have been extensively studied in recent decades for their interesting structures and physical properties. To further explore possible new structures and to better understand the magnetic and colossal magnetoresistant (CMR) properties in these systems, especially in Eu14MnP11, an intensive investigation of the structures and properties in the Eu - In - P ternary system was initiated. During this research, we discovered four new compounds: Eu3InP3, Eu3In2P4, EUIn2P2, and Eu14InP11.; Eu3InP3 and Eu3In2P 4 are discussed in Chapter 1 and Chapter 2, respectively. The structures of both compounds contain one-dimensional chains of In - P tetrahedra. EU 3InP3 shows three complicated magnetic transitions below 14.5 K and exhibits metamagnetism. The magnetic properties of Eu3In 2P4 show indications of both ferromagnetism and antiferromagnetism. Both compounds are semiconductors, and Eu3In2P 4 shows obvious magnetoresistance below about 30 K.; EuIn2P2 crystallizes in a new structural type. It contains alternate layers of Eu atoms and an In2P2 framework. This compound is proposed to be a canted ferromagnet below 24 K. Resistivity also shows a transition at 24 K, and a large CMR effect was observed around this temperature. The details are discussed in Chapter 3.; In the last chapter, the synthesis, structure and magnetism of Eu 14InP11 are reported. This compound is isostructural with Eu14MnP11. It has a magnetic transition at 17 K.