 Sintering powders of samarium oxide and boron, in vacuum, yields a powder containing several samarium boride phases, and their volume ratio can be controlled through the mixing proportion. The powder can be converted into larger crystals of a certain samarium boride using arc melting or zone melting techniques, relying on the different melting / crystallization temperature of SmB6 (2580°C), SmB4 (about 2300°C) and SmB66 (2150°C). All these materials are hard, brittle, dark-gray solids with the hardness increasing with the boron content. Samarium diboride is too volatile to be produced with these methods and requires high pressure (about 65 kbar) and low temperatures between 1140 and 1240°C to stabilize its growth. Increasing the temperature results in the preferential formations of SmB6.
