A Novel Low Temperature Phase Transition in Mixed Valent Sm₄Bi₃

Abstract

Evidence for the mixed valent character of Sm₄Bi₃ (body centered cubic, anti-Th₃P₄ structure) has so far mostly come from lattice parameter measurements in the series of R₄Bi₃compounds (R = rare earth).¹ One finds a trivalent state for all the rare earths except for Sm, Eu and Yb. For the latter two one finds lattice parameters corresponding closely to the divalent state, while for Sm₄Bi₃ an intermediate value is observed corresponding to 3 Sm ions being in the divalent and one in the trivalent state. The relatively high electrical resistivity (ρ = 2.6 mΩ cm) at room temperature indicates semimetallic behavior.