High-precision parallel-beam X-ray system for high-temperature diffraction studies

A recently developed Rigaku parallel-beam X-ray diffraction system equipped with a parabolic graded-multilayer mirror in the incident beam and a parallel-slits analyzer in the diffracted beam was used for precision high-temperature diffraction studies. The lattice parameters a and c of α-Al 2 O 3 at room temperature and up to 1473 K were determined with precision in the range of 0.6–7.3×10 −5 . The thermal expansion coefficients for a and c agreed with literature values to better than 3%. The system was used successfully also to determine the Debye characteristic temperature of Si and to study structural phase transition of LaCoO 3 from rhombohedral at room temperature to cubic at 1700 K.