Optical properties of potassium erbium double-tungstate KEr(WO4)2

Results of spectroscopic investigations of crystalline potassium-erbium double tungstate Ker(WO4)2 are reported. The single crystal of Ker(WO4)2 were grown by Top Seeded Solution Growth technique. They belong to the chain-layered group of materials crystallizing in monoclinic syngony. The investigations were carried out in the broad spectral and temperature range. It was found that the potassium erbium double tungstate belong to the class of the diaxial crystals and it is a pleochroic. The main optical absorption spectra are determined.