Thermal Expansion of Ba3Lu(BO3)3 Borate

In this study, Ba3Lu(BO3)(3) borate obtained by solid-phase synthesis is explored by high-temperature X-ray powder diffraction in the temperature range from 25 to 900 & DEG;C. At room temperature, the compound expands slightly anisotropically (& alpha;(max)/& alpha;(min) = 1.2), and with an increase in temperature, the degree of anisotropy increases significantly (& alpha;(max)/& alpha;(min) = 6.9 at 900 & DEG;C). The maximum expansion is observed along the crystallographic axis c (& alpha;(c) = 10.45 x 10(-6)& DEG;C-1 at 25 & DEG;C and 36.34 x 10(-6)& DEG;C-1 at 900 & DEG;C), perpendicular to which the boron-oxygen triangles [BO3] are located, and the minimum is in the plane where the triangles are located.