Mechanical alloying and molding by spark plasma sintering of telluride based glasses – in SPIE OPTO
Alternative way of synthesis for high refractive index tellurides based glasses has been experimented, in addition to low temperature Spark Plasma Sintering. The composition tested, Ge25Se10Te65, has been chose in the Ge-Se-Te system and characterized. Its index refractive index of 3.12 and overall optical, thermal and mechanical properties makes it the perfect candidate for IR application. However, due to its relative instability regarding crystallization, formation of GeTe crystals occurs during mechanical alloying using raw elements. Transparency has not been achieved in the sintered samples using this powder, as the crystallization rate is accelerated by the pressure during the process. In parallel, glass samples synthesized by melt-quenching have been used to determine optimal sintering parameters for this composition. The main issue met during those tests has been the carbon contamination, reducing overall transparency of the samples through scatterings. As such, it has been shown that the critical parameter to consider to limiting this pollution is the powder granulometry, needing to be above 100μm for optimal performance. This shows the potential for this method to produce high refractive index IR optics, using even unstable glasses.