Structural and magnetic properties of a new cubic Pr-based compound PrOs2Sn2Zn18

A quaternary derivative of the Pr- ” 1-2-20 ” system, PrOs 2 Sn 2 Zn 18 , was successfully synthesized in single-crystal form and characterized by X-ray diffraction, specific-heat, electric resistivity and magnetic susceptibility measurements. Unlike the parent compound PrOs 2 Zn 20 , which undergoes a structural phase transition at T s = 87 K, no indication of such a transition was observed in PrOs 2 Sn 2 Zn 18 down to the lowest temperature of 2 K. The magnetic susceptibility χ exhibits typical Van Vleck-type temperature-independent paramagnetism below approximately 10 K, suggesting a nonmagnetic crystalline electric field (CEF) ground state. The magnetic specific heat at low temperatures shows a Schottky anomaly centered around 6 K. Analysis based on a two-level model indicates that the CEF ground state is a doublet, with the first excited state being a triplet. These results suggest that the CEF ground state is a non-Kramers Γ 3 doublet. The nature of the non-Kramers ground state and the low-lying CEF excitations of Pr 3 + ion are discussed in detail. In addition, the structural stability of PrOs 2 Sn 2 Zn 18 is examined in comparison with isostructural compounds, R Os 2 Zn 20 ( R = La, Pr), highlighting the role of Sn substitution in suppressing structural phase transitions.