Optical properties of Nd3+-doped Tutton salts crystals

Tutton salts doped with Nd3+ were prepared by the slow evaporation method at room temperature and characterized through X-ray diffraction, optical absorption, emission spectra and decay curve measurements. X-ray powder diffraction shows that these compounds crystallize in the monoclinic system with space group P21/a. Optical absorption spectra have been analyzed. The emission spectra exhibit three peaks at 810, 890 and 1050 nm associated to the electronic transitions: F-4(5/2) -> I-4(9/2), F-4(3/2) -> I-4(9/2) and F-4(3/2) -> I-4(11/2) respectively. Since the luminescence efficiency of the Nd3+ ion depends on the surrounding environment, a comparative study of the influence of the M2+ cation has been carried out. The results show that infrared emission of K2Mg (SO4)(2)center dot 6H(2)O:Nd3+ is four times more intense than that of K2Zn(SO4)(2)center dot 6H(2)O:Nd3+ and 1.6 times more intense than that of K2Ni(SO4)(2)center dot 6H(2)O:Nd3+. The decay lifetime for the F-4(3/2) level proves that energy transfer processes in these materials take place. In order to characterize the nature of the process that affects the luminescence in the K2Mg (SO4)(2)center dot 6H(2)O:Nd3+ sample, the lifetime of the F-4(3/2) emission level has been analyzed as a function of temperature.