Síntesis y caracterización estructural de las elpasolitas estequiométricas de Dy$^{3+}$ y Ho$^{3+}$

Abstract

In this research paper, we report an updated set of experimental data, mainly structural in character, accurately determined for pure elpasolite systems such as Cs$_{2}$NaLnCl$_{6}$; M$^{3+}=$Dy$^{3+}(f^{9})$, Ho$(f^{10})$, where the trivalent lanthanide ions occupy sites of octahedral symmetries. There is a vast amount of experimental data from spectroscopic techniques for this type of systems both, pure and doped as well as several attempts leading to the identification and assignment of the various peaks for the associated spectra. The understanding of the experimental data, is central and most relevant, when the many complexities observed in both, the absorption and emission spectra are taken into account showing up the need for carrying out new experiments and developing more general physical models in the spectroscopy of solid state physics. These models should be able to accommodate both the long and short range interactions as well as to include, in an explicit form, the coupling between the internal and the external vibrations for these systems. A further reason to preclude more comprehensive theoretical studies in this area is the well known fact that, for these systems the experimental data available obtained from X-ray and spectroscopic studies is both scarce and incomplete. In the current research paper, we report updated experimental data, essentially structural in character, obtained in our laboratory utilizing X rays diffraction for powders and we also report a neutron diffraction pattern for the Cs$_{2}$NaHoCl$_{6}$.