Magnetic susceptibility of several germanium garnets

The general chemical formula for a garnet oxide is represented as {C}3[A]2(D)3O12, where the three cation sites are C-, A-, and D-sites. These cation sites are surrounded by oxygen ions O2− at dodecahedron, octahedron and tetrahedron, respectively. Several germanium garnets of {Ho2Mg}[Mg]2(Ge)3O12, {Tm2Mg}[Mg]2(Ge)3O12, {Ca}3[Ho]2(Ge)3O12, {Ca}3[Tm]2(Ge)3O12, {Sr}3[Ho]2(Ge)3O12, and {Sr}3[Tm]2(Ge)3O12 are synthesized. Magnetic susceptibilities of these garnets obey well the Curie-Weiss law. Paramagnetism with negative intercept of the 1/χ versus T curve is observed. The results indicate that all the Ho and Tm ions possess tri-valence states as Ho3+ and Tm3+ ions with the effective number of Bohr magnetons peff=11/Ho3+-ion and peff=7.6/Tm3+-ion approximately, regardless of the consequences of the site preference problem.