Thermal Expansion of Ba3Lu(BO3)3 Borate

Abstract

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°C. At room temperature, the compound expands slightly anisotropically (αmax/αmin = 1.2), and with an increase in temperature, the degree of anisotropy increases significantly (αmax/αmin = 6.9 at 900°C). The maximum expansion is observed along the crystallographic axis c (αc = 10.45 × 10–6°C–1 at 25°C and 36.34 × 10–6°C–1 at 900°C), perpendicular to which the boron-oxygen triangles [BO3] are located, and the minimum is in the plane where the triangles are located