Anisotropic properties and Raman spectra of a LiNa5Mo9O30 single crystal grown by the TSSG method

Abstract

A single crystal of LiNa₅Mo₉O₃₀ of 52 × 44 × 8 mm³ was successfully grown using the top-seed solution growth method. The full width at half maximum of the high-resolution X-ray diffraction rocking curve for the (100) plane is 17′′. The LiNa₅Mo₉O₃₀ single crystal can transmit well from 0.31–5.35 μm. It was easily processed with a moderate hardness of 5.2. The specific heat curve increases slowly without an inflection point. The thermal expansion coefficients were measured to be α_c > α_a > α_b, and the structure–property relationship was discussed in detail. It exhibits good thermal conductivity with κ_a = 2.67 W m⁻¹ K⁻¹, κ_b = 3.61 W m⁻¹ K⁻¹, and κ_c = 3.22 W m⁻¹ K⁻¹, respectively. As a molybdenum crystal, the spontaneous Raman spectra along the a-axis with different Raman configurations were characterized. There is a strong Raman shift at 946.6 cm⁻¹, which can be used for Raman laser applications. Our results show that the LiNa₅Mo₉O₃₀ single crystal is not only a second order nonlinear optical crystal but also an excellent candidate for stimulated Raman scattering.