The physical and mechanical properties of monocrystals Bi2Te3, alloyed by two kinds of impurity are investigated: being easy diffusionable and hard diffusionable. Easy diffusibility of the additive (nickel, iron, silver, copper) at the certain parities (ratio) inside quintet and in among slide space can consolidate or ldquoto loosenrdquo layers. This is increases the defect of packing, concentration electrons in a zone of conductivity simultaneously decreases, that in a result reduces durability of crystals Bi2Te3 and Bi2Se3. Hard diffusibility of an impurity is thin earth elements (Sm, Nd etc.), also can consolidate the given materials. It can achieve at the expense of allocation dispersible of particles of the second phase in process crystallization of an alloy. Such hardening was achieved in fourfold systems (Bi2Te3-Sb2Te3-Na2Te3).