Magnetic Properties of Rare-Earth Aluminoborates RAl3(BO3)4 (R = Th, Er, OR Ho) at High Temperatures

A temperature dependence of the magnetic susceptibility [χ(T)] of rare-earth borates RAl₃(BO₃)₄ (R = Tb, Er, or Ho) is measured by the Faraday method at temperatures in the interval 20–850°C. Nonlinear anomalies caused by structural transitions are observed in the dependences χ^–1(T). It is established that the dependences χ^–1(T) for each phase obey the linear Curie–Weiss law. The Curie temperatures and the magnetic moments corresponding to the chemical formula of the compounds have been found.