Fig. 5: Scale-up of autoclave and as-grown H-KTP in the past 46 years.
From: Hydrothermal growth of KTiOPO4 crystal for electro-optical application
The horizontal axis is the year, and the vertical axis is the inner diameter of the autoclave. The size of the crystal is largely determined by the inner diameter of the autoclave, so it is listed together in the graph, marked with a solid symbol to distinguish it from the hollow symbol representing the inner diameter of the autoclave. Due to the difficulty of equipment and technology, there are only a handful of institutional teams involved in hydrothermal growth of KTP after past 46 years
