Abstract: A process produces a crystal of a material with non-congruent melting using at least one first element and a second element. The process includes (a) placing, in a vertical alignment and maintaining under a controlled atmosphere, a bar of the first element gripped between a lower bar and an upper bar made out of the material, (b) transforming the bar of the first element into a floating zone by heating to a temperature that avoids the evaporation of the first element, the heating being obtained by heating means that provides a temperature gradient in the floating zone so that the lower face of the upper bar appears as a cold face, and (c) contra-rotating the lower and upper bars around the alignment axis and moving the whole bar assembly upwards in relation to the heating means in order to obtain the crystal on the cold face by growth in solution.