Structural characterization of KLa2F7 and spectroscopic study of KLa2F7 : Nd3+

The crystal structure of the fluoride KLa2F7 was refined at 10 K by the Rie tveld method using neutron powder diffraction data. KLa2F7 is cubic, a = 5. 918(1) Angstrom, space group Fm3m. The structure derives from that of an an ion excess fluorite-type compound. The neodymium fluorescence decay kinetic in the doped compound KLa2F7:Nd3+ was studied. The lifetime value of the F -4(3/2) excited state is close to 470 mus. The kinetic microparameters CDA related to the cross-relaxation and C-DA related to the energy migration pr obabilities, were found to be equal to 3.6 x 10(-40) and 0.94 x 10(-40) cm( 6)s(-1), respectively. Three broad bands, for which the relative intensitie s depend on the Nd3+ concentration, were identified on the spectra in the r egion of the I-4(9/2) --> P-2(1/2) transition. Therefore, at least three di fferent sites for Nd3+ ions exist in KLa2F7.