Diffraction and luminescence analysis of extremely rapidly cooled molten system (LiF-CaF2)eut-xLnF3 (Ln=Sm and Gd)
(1. Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 36 Bratislava, Slovakia;
2. Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84 511 Bratislava, Slovak;
3. School of Metallurgy, Northeastern University, Shenyang 110819, China)
2. Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84 511 Bratislava, Slovak;
3. School of Metallurgy, Northeastern University, Shenyang 110819, China)
Abstract: Samples of (LiF-CaF2)eut-xSmF3(-xGdF3) (x=0.03-0.50) were prepared by spontaneous cooling as well by very fast cooling (using the rapid solidification processing (RSP) method) which provide two types of sample morphology: riffle-like and sphere-like fragments. All types of samples were studied by XRD, optical absorption and fluorescence spectroscopy. The presence of LiF stabilises the cubic cell dimension, and the content of lanthanide fluorides presents influence on phases formed, as well as the crystallinity of the system, in both the spontaneously and rapidly-cooled systems. The photoluminescence properties of the investigated systems are dependent on the lanthanide fluoride content. The intensity of the emission bands, corresponding to the Sm3+ ion, reaches the maximum when the Sm content is x(SmF3)=0.03. An even stronger dependence is observed of optical properties on the morphology of the samples, i.e. whether the samples are spontaneously cooled or processed by the RSP method followed by mechanical grinding. Mechanical grinding enhances the luminescent properties and leads to higher emission intensities. It is also shown that the photoluminescent spectroscopy is suitable for detection/approval of lowered local symmetry via significant splitting of spectral bands.
Key words: molten salts; rapidly cooled molten system; SmF3; GdF3; absorption spectra; fluorescence spectra; luminescence properties