Preparation of rare earth borides by reaction among rare earth oxides, boron carbide, and calcium

Rare earth (RE) borides are important functional materials used for cathodes. In this paper, based on high-temperature reaction among rare earth oxides (RE x O y ), boron carbide (B 4 C), and calcium (Ca), a convenient method for synthesizing RE borides is designed. Fifteen rare earth oxides RE x O y (RE = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) are used to prepare their corresponding borides. Through the high-temperature reaction at 1573 K, two Ca-doped hexaborides (REB 6 , RE = La and Eu) and eleven Ca-doped tetraborides (REB 4 , RE = Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm) are successfully synthesized. The experimental results are reasonably interpreted according to thermodynamic calculations, phase characterization, and element analysis.