Crystal growth and characterization of KY(WO4)2 and KGd(WO4)2 for laser applications

Potassium yttrium tungstate (KYW) and potassium gadolinium tungstate (KGW) single crystal are technologically important materials due to their third order non-linear optical properties and as laser host materials. Several flux systems namely K2WO4, K2W2O7, K2W3O10 etc. can be used for the growth from solution. In the present communication, KYW and KGW single crystals were grown by top seed solution growth method (TSSG), with two different flux systems, K2WO4 and K2W2O7. The color of the doped crystals varies from deep violet to transparent violet depending on the concentration of Nd dopants. Co-doping Yb with Nd slightly improves the transparency of the as-grown crystals. X-ray powder diffraction result confirms the α-phase of the grown crystals and the peaks corresponding to different phases were indexed. Prominent Raman line for these crystals was identified at 904 cm−1 and the peaks corresponding to impurities like CO2 and H2O stretching are observed as trace. FT-IR analysis on these crystals confirms the presence of all functional groups related to the composition of the α-phase.