In this work, spark plasma sintering is used to mold non conventional chalcogenide glasses of high refractive index at low temperature (<400°C). This equipment, usually used for sintering refractory materials, is presented as efficient for both densification and high precision molding of chalcogenide lenses and balls of telluride glasses.
Mechanical milling of raw Ge, Se, Te elements leads to a major amorphous phase with the formation of a small proportion of GeTe crystals. Remaining GeTe crystals induce a fast crystallization rate during the sintering process leading to the opacity of the material. SPS flash moldings were then performed using melt quenched glass powders to produce complex chalcogenide lenses and balls.
It has been found that the critical parameter to reach optimal IR transparency is mainly the powder granulometry, which should be superior to 100 µm to prevent from MIE scatterings. The possibility of producing high refractive index chalcogenide lenses and ball has been demonstrated even with unstable glasses against crystallization.
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