Optical properties of ZnNb2O6 single crystals prepared via the optical floating zone technology

By using an optical floating zone technology, orthorhombic columbit ZnNb2O6 single crystals are fabricated successfully. The as-prepared sample are blue and transparent rods of Phi 4 to 6 mm x L 48 mm and the biggest domain of Phi 4 mm x L 25 mm. After annealing, the sample fades to colorless. X-ray diffractions indicates that the as-perpared samples are ZnNb2O6 with orthorhombic columbite structure and grows along the a-axis. The micropolariscopy in cross transmission arrangements analyzing give that the crystals are of low-angle crystal boundary-free and bubble-free. Besides, the crystals have also been tested by Raman spectra, optical absorption and photoluminescence spectra before and after being annealed. The luminescence pattern has an emission peak located at 450 nm blue-region.