An ultrahigh‐pressure furnace assembly to 100 Kbar and 1500°C with minimum temperature uncertainty

An ultrahigh‐pressure furnace assembly using a multi‐anvil‐type apparatus, capable of conducting phase equilibrium studies up to 100 kbar and 1500°C with temperature uncertainty similar to that of piston‐cylinder apparatus, is reported. Temperature distribution within the furnace assembly was studied by a compositional mapping of diopsidic clinopyroxene coexisting with orthopyroxene and garnet. A graphite heater with a 5° tapered inner wall (3 mm O.D., 11 mm long) was found to give a temperature gradient less than 50°C/mm, whereas that in a conventional straight‐wall heater was greater than 200°C/mm.