Growth, morphology and anisotropic thermal properties of Nd-doped Sr3Y2(BO3)4 crystal

Abstract

A high-quality Nd3+:Sr3Y2(BO3)4 laser crystal has been grown by the Czochralski method. The phase purity and accurate unit cell parameters were determined using X-ray powder diffraction; the unit cell parameters are calculated to be a=7.3933 (1)Å, b=15.9461 (2)Å, c=8.6967 (1)Å, and V=1025.29 (5)Å3. Effective segregation coefficients were measured and the optical homogeneity was further characterized by interferometry. A series of possible growth faces (hkl) were also deduced and compared with the as-grown crystal boules using the Bravais–Friedel–Donnay–Harker (BFDH) theory. A full set of thermal properties, including the thermal expansion, thermal diffusivity, specific heat, and thermal conductivity, were measured as a function of temperature. The average linear thermal expansion coefficients along different crystallographic directions were measured to be α11=7.04×10−6K−1, α22=15.32×10−6K−1 and α33=14.35×10−6K−1 over the temperature range 303.15–770.15K. The specific heat was measured to be 0.573Jg−1K−1 (92.64calmol−1K−1) at 330K. The thermal conductivity at room temperature was calculated to be 0.74Wm−1K−1, 1.00Wm−1K−1, and 0.67Wm−1K−1 along the a-, b- and c-axis, respectively. It was found that thermal conductivity increases with increasing temperature, which indicates a glass-like behavior.