One- and three-dimensional antiferroelectric ordering in PrCl3

Electric-susceptibility and specific-heat measurement in Pr${\mathrm{Cl}}_3$ show that electric dipole ordering occurs at low temperatures. One-dimensional ordering is observed above 0.4 K and is well described by the linear-chain $\mathrm{XY}$ model. Three-dimensional antiferroelectric ordering occurs at 0.4 K. The electric dipole moments are developed by the non-Kramers-doublet ground states of the praseodymium ions. The nearest-neighbor electric dipole-dipole interaction calculated from the measured dipole moment is of the correct sign and of approximately the correct magnitude to account for the nearest-neighbor interaction deduced from the fitting of the specific heat to the one-dimensional $\mathrm{XY}$ model. The small change in the magnitude of the specific-heat anomally (∼ 15%) and the small shift of the three-dimensional transition temperature (∼ 5%) when a magnetic field of 2.2 T was applied provides further evidence that the ordering in Pr${\mathrm{Cl}}_3$ is of nonmagnetic origin.