Simultaneous fluorination and carbonation to approach a high infrared transparent magnesium fluoride

Abstract

In this research study, magnesium fluoride nanoparticles were successfully produced by the fluorination and carbonation method. MgF2 nanoparticles were calcined at temperature of 100, 300, 400, 500, 600, 640, and 680 °C. Also, polycrystalline magnesium fluoride ceramics were prepared using a hot-pressing process from calcined powders. The optical, structural, and mechanical characteristics of the magnesium fluoride samples were then investigated. The X-ray diffraction proved that magnesium fluoride nanoparticles were formed with a single-phase structure and no impurities. By using simultaneous fluorination and carbonation technique, crystalline MgF2 nanoparticles with a particle size of 50–60 nm were synthesized at a minimum temperature of 100 °C. Increasing the calcination temperature led to the evaporation of the volatile products and increased the crystallinity and particle size of MgF2 nano-particles. The optimal calcination temperature of 640 °C created a ceramic MgF2 with a hardness of 560 HV, and considerable relative density of 100%, and a high transmittance of over 90% in the 3.2–5.5 μm range. The obtained results, thus, revealed that the transparency of MgF2 ceramics was a function of the porosity and the grain size distribution. The microstructure of hot-pressed MgF2 confirmed a Gaussian grain size distribution in the range of 100–1000 nm, contributing to the enhancement of densification. An intra-granular fracture occurred in magnesium fluoride, which was related to the fine-grained structure of MgF2.