Thermo-physical properties of a new UV nonlinear optical crystal: NaSr₃Be₃B₃O₉F₄

NaSr₃Be₃B₃O₉F₄ (NSBBF) as a new UV nonlinear optical crystal has aroused great interest in recent years. This study investigates the thermo-physical properties of NSBBF, including thermal expansion, thermal diffusivity, thermal conductivity and specific heat, which are important parameters for applications. The specific heat of NSBBF is comparable to that of CsLiB₆O₁₀ (CLBO) and larger than that of β-BaB₂O₄ (β-BBO), indicating that NSBBF has a very high laser damage threshold. The thermal expansion coefficients of NSBBF are determined as α_a = 1.05 × 10⁻⁵ K⁻¹ and α_c = 1.34 × 10⁻⁵ K⁻¹, exhibiting much smaller anisotropy than those of CLBO and β-BBO. The thermal diffusivity and conductivity of NSBBF are also obtained in the temperature region from 323 to 573 K, showing comparable anisotropies to β-BBO. All these results show that NSBBF is suitable for high-power UV laser generation.