Magnetic and transport properties of structural variants of Remeika phases: Th₃Ir₄Ge₁₃ and U₃Ir₄Ge₁₃

Th3Ir4Ge13 and U3Ir4Ge13 crystallize with primitive cubic Tm3Co4Ge13 and noncentrosymmetric rhombohedral HT-Y3Pt4Ge13 type of structures, respectively, which are derivatives of the cubic Yb3Rh4Sn13 prototype. Measurements of magnetic susceptibility, electrical resistivity, specific heat, thermopower, and thermal conductivity reveal that Th3Ir4Ge13 is a diamagnetic bad metal and undergoes a first-order phase transition at approximate to 200 K. Charge-density wave (CDW) and structural phase-transition scenarios for Th3Ir4Ge13 are discussed. U3Ir4Ge13 is Curie paramagnetic (mu(eff) = 4.05 mu(B)) and orders ferromagnetically at T-C = 15 K. For U3Ir4Ge13 the oxidation state of U is investigated by x-ray absorption spectroscopy. The U 5f electrons in this compound are predominantly of itinerant nature