Paramagnetic behavior of R2Fe14B systems (R=Pr, Nd, Dy, or Er)

Abstract

R₂Fe₁₄B compounds, R = Pr, Nd, Dy, or Er, were prepared from high purity rare earths obtained from the Ames Laboratory. The magnetic properties of these and related systems with other rare earths are under investigation in our laboratories. In the present study magnetic susceptibilities were determined from the Curie temperature (T_C) (556–596 K) up to a characteristic temperature T_t. Above T_t the susceptibility was observed to increase sharply and to become history‐dependent, suggesting sample decomposition or a phase change. T_t = 830, 920, and 960 K for R = Pr, Nd, and Er, respectively. Curie–Weiss behavior is observed for the Pr and Nd compounds but not for Dy₂Fe₁₄B and Er₂Fe₁₄B. The susceptibility of the latter material follows the hyperbolic form described by Néel, i.e., 1/χ=1/χ₀+T/C−σ/(T−θ). For R=Pr and Nd, near T_C χ follows the expression χαt^−γt=(T−T_C)T⁻¹_C]. γ=1.37 for R=Pr and 1.41 for R = Nd. The iron paramagnetic moments are 4.02, 4.06, 4.09, and 4.10 μ_B for Pr₂Fe₁₄B and Nd₂Fe₁₄B, Dy₂Fe₁₄B and Er₂Fe₁₄B, respectively, which are close to the value (3.97 μ_B) obtained for Y₂Fe₁₇. The Weiss constants are 575 and 602 K, respectively, for Pr₂Fe₁₄B and Nd₂Fe₁₄B. Results indicate little itineracy of the 3d electrons in the R₂Fe₁₄B systems.