Optical floating zone method growth and photoluminescence property of MgNb2O6 crystal

MgNb2O6 single crystals are grown by the optical floating zone method. The as-grown crystals are dark brown and have dimensions of Ø 4–6 mm × L 87 mm, with the largest crystal domain being Ø 5 mm × L 32 mm. After being annealed, the crystals fade to light brown. The powder X-ray diffraction analysis shows that the crystals have a columbite-type MgNb2O6 structure. The crystal grows along the c-axis and the cleavage plane is the (0 1 0) plane. Transmission polarized light microscopy measurements show that the crystal is free of low-angle grain boundaries and inclusions. The crystals have been characterized by Raman scattering, which reveals the change of Nb–O band in annealed and non-annealed samples. The photoluminescence spectra exhibit a broad and strong blue emission band centered at 435 nm.