Structural and Electronic Properties of a Triangular Lattice Magnet NaPrTe2 Compared with NaNdTe2 and NaTbTe2

NaPrTe2, NaNdTe2, and NaTbTe2 are found to be triangular lattice magnets with the α-NaFeO2 structure, where lanthanoid atoms with 4f electrons form a triangular lattice, based on the structural analysis and physical property measurements of synthesized polycrystalline samples. The α-NaFeO2 structure is a new polymorph of NaPrTe2, which has been reported to crystallize in the cubic LiTiO2 structure. Polytypism in NaPrTe2 is discussed based on the structural parameters determined by Rietveld analysis. NaPrTe2 is suggested to be in the proximity of the phase boundary between the LiTiO2 and α-NaFeO2 types, compared to NaNdTe2 and NaTbTe2, indicating that this compound may be interesting from the perspective of the dimensional control of geometrically frustrated lattices. The magnetic susceptibility and heat capacity data indicate that NaPrTe2 do not exhibit a long-range magnetic order or spin-glass transition above 2 K.