Magnetic Interaction of Cerium and Cobalt Ions in Double Nitrate Crystals

The space group of the double nitrate crystals ${M_2}^{\prime }{M_3}^{\prime \prime }{\left(\mathrm{N}{\mathrm{O}}_3\right)}_{12}·24{\mathrm{H}}_2\mathrm{O}$, where $M^{\prime }$ is a trivalent cation and $M^{\prime \prime }$ is a divalent cation, has been determined from x-ray data to be $R\overline{3}m$. The rhombohedral unit cell has sides of 13.1 A, interaxial angles of 49° and contains one molecule. The cerium ions have the locations ±(¼,¼,¼). The line shapes of the derivative with respect to magnetic field of the paramagnetic resonance absorption of small concentrations of cobaltous ions substituted in ${\mathrm{Ce}}_2$ ${\mathrm{Zn}}_3$ ${\left(\mathrm{N}{\mathrm{O}}_3\right)}_{12}$ ·24${\mathrm{H}}_2$O are described and used to determine the spatial relations of the cerium ions and cobalt ions, as well as to justify the assumption of a dipolar interaction between them described by the spin Hamiltonian parameters of the cerium and cobalt ions. It is concluded that the more isotropic of the two paramagnetic spectra of cobalt ions observed in this salt is due to ions in either the special sites ±(0.399,0.399,0.399) or, rather less likely, in the special sites ±(0.101,0.101,0.101) and that the highly anisotropic spectrum of cobalt ions is due to ions in the body-centered site.