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 IR transparent bulks and lenses of telluride glasses. Thermo-mechanical and optical characteristics of the selected Ge₂₅Se₁₀Te₆₅ glass composition were investigated showing a refractive index of 3,12@10 µm and with however a limited resistance to crystallization. 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 lenses. 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 infrared lenses has been demonstrated even with unstable glasses against crystallization.

中文翻译：

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基于通过放电等离子烧结成型的硫属化物玻璃的高折射率红外透镜

在这项工作中，放电等离子烧结用于在低温（<400°C）下模制具有高折射率的非传统硫属化物玻璃。该设备通常用于烧结耐火材料，对于碲化物玻璃的 IR 透明块体和透镜的致密化和高精度成型是有效的。所选 Ge ₂₅ Se ₁₀ Te _{65 的}热机械和光学特性研究了玻璃成分，显示折射率为 3,12@10 µm，但抗结晶性有限。原始 Ge、Se、Te 元素的机械研磨导致主要的非晶相形成小比例的 GeTe 晶体。剩余的 GeTe 晶体在烧结过程中引起快速结晶速率，导致材料不透明。然后使用熔融淬火的玻璃粉末进行 SPS 闪光成型，以生产复杂的镜片。已经发现，达到最佳 IR 透明度的关键参数主要是粉末粒度，它应该优于 100 µm 以防止 MIE 散射。即使使用抗结晶的不稳定玻璃，也证明了生产高折射率红外透镜的可能性。