Magnetic susceptibility of californium fluorides.

Abstract

Results of magnetic measurements are presented for polycrystalline samples of ${\mathrm{CfF}}_{3}$ (both the hexagonal-${\mathrm{LaF}}_{3}$-type and orthorhombic-${\mathrm{YF}}_{3}$-type crystal structures) and ${\mathrm{CfF}}_{4}$ (monoclinic-${\mathrm{UF}}_{4}$-type). Measurements were performed at temperatures between 4.2 and 340 K and in magnetic fields of up to 50 kG. The effective paramagnetic moments, ${\mathrm{\ensuremath{\mu}}}_{\mathrm{eff}}$, and the Weiss constants, ${\mathit{FTHETA}}_{\mathit{P}}$, have been determined in the Curie-Weiss temperature region (150--340 K). In the trifluorides no significant differences in ${\mathrm{\ensuremath{\mu}}}_{\mathit{e}\mathit{f}\mathit{f}}$ and ${\mathit{FTHETA}}_{\mathit{P}}$ were observed as a function of crystal structure or sample age (radiation damage). For the tetrafluoride, two distinct sets of values for ${\mathrm{\ensuremath{\mu}}}_{\mathit{e}\mathit{f}\mathit{f}}$ and ${\mathit{FTHETA}}_{\mathit{P}}$ were obtained depending on the sample age. Antiferromagnetic ordering was observed in both Cf compounds at temperatures below 12 K. Crystal-field effects were evident in the temperature range between about 12 and 150 K. The calculated susceptibilities for these compounds are presented and discussed.