4. Technical Solutions for In Situ Monitoring of Ammonothermal Processes

The chapter explores the critical aspects of designing and manufacturing high-pressure sight glasses for ammonothermal processes. It delves into the selection of materials based on spectral transmission, mechanical strength, and chemical resistance, with a focus on borosilicate, quartz, and sapphire glasses. The design process includes calculations for window thickness and outer diameter, considering factors such as bending strength, compressive strength, and Poisson’s ratio. The chapter also discusses the importance of manufacturing tolerances, surface quality, and the use of sealing materials like copper, silver, or gold to achieve optimal sealing. Additionally, it highlights the practical applications of these sight glasses in monitoring ammonothermal processes, including UV-VIS spectroscopy, Raman spectroscopy, and X-ray monitoring, providing a comprehensive overview of in situ monitoring techniques.