New Nonlinear Optical Crystal: NaBa₄Al₂B₈O₁₈Cl₃

Single crystals of NaBa₄Al₂B₈O₁₈Cl₃ have been grown with sizes up to 34 × 34 × 16 mm³ from the NaF–LiCl flux by the top-seeded solution growth method. The compound crystallizes in the tetragonal system, space group <i>P</i>4₂<i>nm</i>, with <i>a</i> = 12.0480 (16) Å, <i>c</i> = 6.8165 (11) Å, α = β = γ = 90°, and two formula units per cell. The NaBa₄Al₂B₈O₁₈Cl₃ compound is built up of infinite anionic groups of [AlB₄O₁₂]^9– formed by two BO₄ tetrahedra, one AlO₄ tetrahedra, and two BO₃ triangles. Optical properties including ultraviolet transmission, IR spectrum, and second-harmonic generation of NaBa₄Al₂B₈O₁₈Cl₃ crystals were reported. Refractive indices were measured by the minimum deviation technique and fitted to the Sellmeier equations. Thermal properties such as the DSC and thermal expansion were reported. The mechanical properties including the hardness, density, and chemical stability were also reported