Many authors in the last thirty years have reported results obtained on alloys based on Bi, Te, Sb and Se. From these studies it appears that the Bi2Te3-Bi2Se3 solid solutions are the best n-type materials fro refrigeration at room temperature. Interesting results were obtained but never in a reproducible way. This is due both to the use of halogen dopants and to the growth technique. Indeed, most of the samples were grown by a Bridgman or a Czochralsky method which which do not allow the obtaining of homogeneous ingots. in our previous papers on thermoelectric properties of p-type materials (1) we have shown that Travelling Heater Metho (T.H.M>) is an appropriate technique to get homogeneous ingots with high figure of merit (Z=3.1x10-3 K-1) in a reproducible way. But if we want to apply this technique we must first know the thermodynamical equilibriums of a given solid with a liquid in the Bi-Te-Se terary system. Thus we will present the results obtained for the interesting part of this diagram; from this moment we will be able to grow well defined and homogeneous ingos of Bi2(Te1-xSex)3 with x=0.05 and x=0.1. Then we characterize the samples as a function of stoichiometric deviations. The results will be compared with those performed on Bi2Te3 (2).