Crystal Structure in Quadrupolar Kondo Candidate PrTr2Al20 (Tr = Ti and V)

We have performed the crystal structure analyses of PrTr2Al20 (Tr = Ti and V). From the anisotropic thermal ellipsoids and the temperature dependence of the lattice constant, it is clarified that the thermal vibration predominantly propagates through the Tr–Al framework. The Pr–Al cage, especially for PrV2Al20, is anisotropically deformed from a sphere; this modifies the crystalline-electric-field levels of Pr3+. This information would provide a clue to understand the anomalous properties in PrTr2Al20.