19F nuclear magnetic resonance in CdF2–ErF3

Abstract

The 19F NMR of a single crystal of CdF 2 :≃ 10% ErF3 has been investigated at 8 and 16 MHz. Weak NMR lines were observed whose shifts relative to the main CdF2 peak were found to be field dependent. These shifts showed axial symmetry about the [111] crystallographic directions with (Δ H/H) ∥ =−8.73 ± 0.01) × 10 −3 and (Δ H/H) ⊥ =+(5.83 ± 0.10) × 10 −3 . The small NMR lines are attributed to those lattice fluorides which have one nearest neighbor Er3+ occupying a normal Cd2+ site. The anisotropic portion of the shift is shown to be due to the dipolar contribution of spin on the erbium ion with no unpaired spin in the fluorine p orbitals. Analysis of intensity ratios supports a random distribution of Er3+ among Cd2+ sites with no preferential formation of clusters.