Optimized growth and anisotropic properties of Li2ZrTeO6 nonlinear optical crystals

Abstract

Li₂ZrTeO₆ crystals have been proved as a novel nonlinear optical material with a high laser-damage threshold (>1.3 GW cm⁻²) and wide transparency window. However, investigations of the anisotropic properties of Li₂ZrTeO₆ are impeded by the difficulty of high-quality crystal growth. Here, centimeter-sized and high-quality Li₂ZrTeO₆ crystals were grown by a modified top-seed solution growth method. The full-widths at half-maximum of (20) and (001) wafers are 33 and 36 arcsec, respectively. Based on a large high-quality crystal, the thermal properties including thermal expansion, specific heat and thermal conductivity were studied in detail. Our results show that the Li₂ZrTeO₆ crystal exhibits a moderate anisotropic thermal expansion (α_a/α_c ≈ 5) from 25 to 500 °C. The specific heat is measured to be 0.77 to 0.902 J g⁻¹ K⁻¹ from 25 to 500 °C. The thermal conductivities along the a and c axes are determined to be 4.14 and 4.86 W m⁻¹ K⁻¹, respectively, which are superior to that of molybdenum-tellurite and tungsten-tellurite crystals. The excellent thermal properties are one of the origins of the high laser-damage threshold. In addition, the relationship between the structure and the anisotropic thermal properties is also discussed. The results indicate that the Li₂ZrTeO₆ crystal is a promising candidate for high-energy laser applications.