Design, growth, and characterization of Y₂Mo₄O₁₅ crystals for Raman laser applications

A new crystal Y₂Mo₄O₁₅ with dimensions of 14 × 12 × 5 mm³ was successfully grown via a top-seeded solution growth (TSSG) method. The crystal structure shows that Y₂Mo₄O₁₅ crystallizes in the monoclinic space group P2₁/c (No. 14, a = 6.8110(4) Å, b = 9.5833(6) Å, c = 10.5124(7) Å, β = 105.512(7)°, and Z = 2) with Mo₄O₁₅ and YO₇ polyhedra as basic structural units. Optical transmittance spectra of the Y₂Mo₄O₁₅ crystal exhibited a broad transmission range from 345 nm to 5575 nm. The group theory calculation and spontaneous Raman spectra show that the Y₂Mo₄O₁₅ crystal has 63 IR-active modes (32A_u + 31B_u) and 60 Raman-active modes (30A_g + 30B_g). The strongest Raman shift is located at 953 cm^-1 caused by the asymmetric stretching vibrations of the Mo-O bonds. The spontaneous Raman spectra and the possibility of rare-earth doping to the Y₂Mo₄O₁₅ crystal indicate the Y₂Mo₄O₁₅ crystal to be a promising Raman and self-Raman crystal.