Using optical absorption spectra, PCL, X-ray diffraction, X-ray photoelectron spectroscopy, and an electron probe in inert and reducing atmospheres (at high temperatures), a strong chemical interaction of beryllium ceramic crucibles with metal melts containing f-elements has been established. Beryllium oxide in the diffusion zone is reduced in places to a metallic state, which leads to the destruction of the walls of ceramic crucibles. This limits the use of these crucibles for melting alloys containing rare earth metals. Il. 2, bibliography: 6 titles.