[en] In this work an ambitious multidisciplinary investigation project is improved, in which CCHEN and University of Chile investigators participate by means exhaustive studies are making, so much experimental and theoretical in stoichiometric and non stoichiometric elpasolites. The development of this activity is allowing to incorporate diverse nuclear and non nuclear analytical techniques, with object of obtaining an abundant and modernized mass of experimental data. The validity of our calculation models in the interpretation of the physical observable will be analyzed. The stoichiometric and non stoichiometric elpasolites are the materials, object of our study. They are highly attractive from the technological and spectroscopical point of view. Their applications in the laser industry, in the electroluminescence devices productions, in the superconductors preparations, in the study of energy transfer processes and in the development of calculated models to interpret the spectral intensity mechanism, they have wakened up the interest of diverse investigators. In this work we present the synthesis of diverse stoichiometric elpasolites whose crystallographic date it has not still been published in the literature (Cs₂NaLnCl₆, where Ln³⁺ = Cw³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Ho³⁺, Er³⁺ and Yb³⁺). The synthesis processes, by means of a solid state reaction in controlled atmosphere is made. By means of thermal analysis (DTA/TGA), in a temperature range understood between 20^oC and 900^oC, they notice the good conditions for the thermal treatment, which during two hours is carried out to the crystallization temperature. By means of the use of IR-Raman and luminescence spectroscopical technique, the most intense picks in the spectrum are assigned, allowing the analysis of the electronic transitions attended by odd normal ways of vibration. Structural studies using DRX, neutron diffraction and by means of the use of fit software (Rietveld profiles refinement method) have been made to obtain some crystalline parameters, such us lattice parameter, bending distances, angles distances, etc. In additional form, exploratory studies by means of diffuse scattering are made, being discussed the weaknesses and strengths of the used methods of structural analysis and the projections of their applications later on in the non stoichiometric elpasolites study