Magnetic Resonance Lineshapes of Pr3+ in Double Nitrate Crystals

The lineshapes for 10 concentrations of Pr³⁺ in double nitrate crystals have been measured. The data have been interpreted in terms of a distribution of zero‐field splittings and a symmetrical broading. The effect of electric‐field‐induced transitions on the interpretation of the shapes is concisely described and the values of the electric field interaction constant are reported for $\mathrm{La}({\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{SO}}_4{)}_3\text{·9}{\mathrm{H}}_2\mathrm{O}$ , $\mathrm{Y}({\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{SO}}_4{)}_3\text{·9}{\mathrm{H}}_2\mathrm{O}$ , ${\mathrm{LaCl}}_3$ , ${\mathrm{La}}_2{\mathrm{Mg}}_3({\mathrm{NO}}_3{)}_{12}\text{·24}{\mathrm{H}}_2\mathrm{O}$ , and ${\mathrm{La}}_2{\mathrm{Zn}}_3({\mathrm{NO}}_3{)}_{12}\text{·24}{\mathrm{H}}_2\mathrm{O}$ . From the concentration dependence of the Pr resonance lineshape, it is concluded that the major source of zero‐field splitting is due to the misfitting of Pr and La ions in the lattice. In ${\mathrm{Pr}}_2{\mathrm{Mg}}_3({\mathrm{NO}}_3{)}_{12}\text{·24}{\mathrm{H}}_2\mathrm{O}$ , there is almost no asymmetrical broadening due to a distribution of Δ, but there is a large symmetrical broadening of about 0.095 cm⁻¹. The origin of this symmetrical broadening appears to be an effective spin‐spin interaction anomalously large for rare earth ions in the double nitrates.