The Paramagnetic Resonance of Nd 3+ and Yb 3+ in Zircon Structure Silicates

The electron paramagnetic resonance of the rare‐earth ions Nd 3+ (4f 3 ) and Yb 3+ (4f 13 ) in synthetic single crystals of zircon and hafnon is reported. The spectra, taken to be axial, have highly anisotropic g ‐values making it possible to observe the spectra fully only along one axis. For Nd 3+ g ‖ < 0.5 and for Yb 3+ g ⊥ < 0.5 Fully resolved hyperfine structure is observed for Nd 3+ in ⊥ direction and for Yb 3+ in ⊥‐direction. The spin Hamiltonian parameters are established by fitting the spectra observed for various angles θ between ‖‐ and ⊥ ‐directions. The parameters indicate the resonance takes place between the Zeeman split levels of an isolated doublet, though fitting the g ‐values fully would require consideration of level mixing.