Growth and Photoluminescence of Cr4+-DopedCa3Ga2Ge3O12 Single Crystals

Abstract
Pure and Cr-doped single crystals of Ca3Ga2Ge3O12 have been prepared by the Czochralski method in oxygen gas of 1-1.2 atm. The pure crystals are colorless and transparent, whereas the doped ones are green. Photoluminescence with a broad peak around 1400 nm is observed on the Cr-doped crystals by optical excitation with a Nd:Y3Al5O12 laser beam of 1064 nm. This spectrum is ascribable to an electronic transition of Cr4+ in the tetrahedral Ge4+ sites.