Controlled Crystallization and its Effects on Some Properties of Ge-Se-Te Chalcogenide Glass

The nucleation and the crystal growth rates of Ge-Se-Te chalcogenide glass by two step heat-treatment and its effect on the mechanical, optical properties and water-resistance were determined. The maximum nucleation and crystal growth rate were 2.1x10³ /mm³·min at 280℃ and 0.4 ㎛/min at 330℃, respectively. When the crystal volume fraction with crystal size 1.5 ㎛ was about 4%, the hardness and fracture toughness were about 117 kg/mm² and 6.0MPa·mm1/2, which were 15% and 48% higher than those of parent glass (hardness: 99.5 kg/mm², fracture toughness : 3.1MPa·mm1/2), respectively. The weight loss of crystallized glass in water was lower than parent glass (25℃ for 32 hrs : 0.03%, 80℃ for 16 hrs : 0.1%) as 0.01% at 25℃, 0.03% at 80℃, respectively. The IR-transmittance decreased with increasing crystal size and crystal volume fraction. The IR-transmittance of crystallized glass with the crystal size of 1.5 ㎛ (crystal volume fraction : 4%) presented 56%, which was about 4% lower than that of parent glass.prohibitio