Infrared radiation (IR) refers to the region of the electromagnetic radiation spectrum where wavelengths range from about 700 nm to 1 mm. Any object with a temperature above absolute zero (0 K) radiates in the infrared region, and a material that transmits radiant energy in the range of 0.74 to 1.4 um is referred to as a near-infrared optical material. Germanatebased glass is attracting attention as a glass material for infrared optical lenses because of its simple manufacturing process. With the recent development of the glass molding press (GMP) process, thermal imaging cameras using oxide-based infrared lenses can be easily mass-produced, expanding their uses. To improve the mechanical and optical properties of commercial materials consisting of ternary systems, germanate-based heavy metal oxide glasses were prepared using a melt-cooling method. The fabricated samples were evaluated for thermal, structural, and optical properties using DSC, XRD, and XRF, respectively. To derive a composition with high glass stability for lens applications, ZnO and Sb2O3 were substituted at 0, 1, 2, 3, and 4 mol%. The glass with 1 mol% added Sb2O3 was confirmed to have the optimal conditions, with an optical transmittance of 80 % or more, a glass transition temperature of 660 °C, a refractive index of 1.810, and a Vickers hardness of 558. The possibility of its application as an alternative infrared lens material to existing commercial materials capable of GMP processing was confirmed.

• 박상진(목포대학교 신소재공학과) | Sang-Jin Park (Department of Advanced Materials Science and Engineering, Mokpo National University, Muan 58554, Republic of Korea)
• 오복현((주)카이로스) | Bok-Hyun Oh (KAIROS Corp., Seongnam 13494, Republic of Korea)
• 이상진(목포대학교 신소재공학과, 목포대학교 세라믹산업기술연구소) | Sang-Jin Lee (Department of Advanced Materials Science and Engineering, Mokpo National University, Muan 58554, Republic of Korea, Research Institute of Ceramic Industry and Technology, Mokpo National University, Muan 58554, Republic of Korea) Corresponding author