Determination of the thermal expansion coefficient of boron carbide $\rm B_{13}\rm C_2$

X-ray diffraction studies of boron carbide $\rm B_{13}\rm C_2$ crystals were performed within a temperature range of $25$–$700^{\circ}$C. The thermal expansion coefficeint of boron carbide $\rm B_{13}\rm C_2$ crystals was determined. The temperature dependence of the thermal expansion coefficient was established to have a kink in the temperature region of $420$–$465^{\circ}$C. The change of thermal expansion anisotropy was revealed. The results of X-ray diffraction indirectly confirm the literature data on the existence of a phase transition in boron carbide in the region of $439$–$444^{\circ}$C.