@Article{JLumin_134_678, author = {P. Pal and T. Penhou{"e}t and V. D'Anna and H. Hagemann}, title = {{Effect of Pressure on the Free Ion and Crystal Field Parameters of Sm$^{2+}$ in BaFBr and SrFBr Hosts}}, journal= {J. Lumin.}, ISSN = {0022-2313}, volume= {134}, pages = {678-685}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0022231312004115}, eprint= {http://www.unige.ch/sciences/chifi/publis/refs_pdf/ref01309.pdf}, doi= {10.1016/j.jlumin.2012.07.010}, keywords= {Sm2+;high pressure luminescence;crystal field;BaFBr;SrFBr}, abstract = {{The emission spectra of Sm$^{2+}$ doped in BaFBr and SrFBr hosts were measured at 10 K from ambient pressure to 8 GPa. The crystal field energy levels determined from the emission spectra were used to extract the free ion parameters ({\em F}$_{{\em k}}$ and {\em $\zeta$} ) and crystal field parameters ({\em B}{\em $_{q}$}{\em $^{k}$}). The variation of {\em F}$_{{\em k}}$ and {\em $\zeta$} as a function of pressure was studied systematically and was discussed in relation to the central field and symmetry restricted covalency models. The change of the spin orbit coupling parameter ({\em $\zeta$}) with pressure for SrFBr:Sm$^{2+}$ showed very different behavior than in other matlockite hosts. Moreover the variation of {\em B}{\em $_{q}$}{\em $^{k}$} under pressure was studied. The pressure dependence of the {\em B}{\em $_{q}$}{\em $^{k}$} was described quantitatively using the Superposition Model (SM) with the help of structural parameters as a function of pressure, obtained from periodic DFT calculations. The validity of the SM was tested for Sm$^{2+}$ in BaFBr and SrFBr. It is shown that this model does not apply to SrFBr, in contrast to other matlockite host materials.}}, year = {2013} }