The composition and dissociation reactions during the growth of gadolinium gallium garnet (GGG) crystal, doped with neodymium grown by the Czochralski (Cz) technique have been studied. The properties of structural Nd:GGG were investigated by the X-ray diffraction (XRD). The X-ray analyses confirm the thermodynamic calculations results. Our thermodynamic calculations show that there is a critical temperature about 2068 +/- 5 K degrees at standard condition. When the growth temperature is higher than this temperature, the metallic iridium could be observed on the crystal-melt interface. (C) 2010 Elsevier B.V. All rights reserved.