Magnetic Properties of Rare-Earth Ferro- and Aluminoborates RM3(BO3)4 (M = Fe OR Al and R = Y, Gd, Er, or Dy)

A temperature dependence of the magnetic susceptibility [χ(T)] of rare-earth borates RFe 3 (BO 3 ) 4 and RAl 3 (BO 3 ) 4 (R = Y, Gd, Er, or Dy) is measured by the Faraday method at temperatures 20–850°C. Nonlinear anomalies observed in the dependences χ –1 (T) are caused by structural transitions. It is established that the dependences χ –1 (T) obey a linear Curie–Weiss law for each phase. The Curie temperatures and the magnetic moments corresponding to the chemical formula unit of crystals are calculated.