CaF2:Eu(2+) is a well known phosphor having efficient excitation in the near ultraviolet (NUV) range. Phosphors with NUV excitation are required in newly emerging applications such as photoluminescence liquid crystal displays (PLLCD), solid-state lighting (SSL), and down-conversion for solar cells. However, emission of CaF2:Eu(2+) is around 424 nm. Eye sensitivity drops considerably at these wavelengths. It is thus not useful for display applications for which emission in one of the primary colours (blue - 450 nm, green - 540 nm or red - 610 nm) is required. Efforts were made to modify the Photoluminescence (PL) spectra of CaF2:Eu(2+) to meet these requirements using co-dopants. A Ca0.49 Sr0.50 Eu0.01 F2 phosphor showing better colour coordinates and having an emission maximum around 440 nm was discovered during these studies.
NaMgF3‐based phosphors have been described frequently in the literature. Their synthesis faces difficulties typical of fluoride materials. A simple precipitation synthesis for NaMgF3‐based phosphors is described in this paper. This consisted of mixing aq. NaF and MgCl2/MgSO4 solutions. Various activators could be incorporated by adding the required salts during this process. Characteristic emission of the activators was observed in the prepared phosphors. As‐prepared samples exhibited predominantly trivalent lanthanide emission. After thermal treatment in a reductive atmosphere, europium‐doped samples showed the intense emission of Eu2+. By virtue of the intense nature of the emission, lifetime measurements could be made for this sample. Notably, intense thermoluminescence and optically stimulated luminescence were observed in NaMgF3:Eu. A simple, fast method for the synthesis of NaMgF3 was therefore developed.
Hexafluorosilicates such as K2SiF6 (Hieratite) exists in nature as minerals. The common formula is M2SiF6 where M represents alkali ion. All the alkali fluorosilicates including K2SiF6 decomposes in the temperature range of 300 to 700 °C with SiF4 as residual product. SiF4 has an important application in the solar cells fabrication industry. Due to low thermal stability, it is difficult to prepare these complex fluorides by the conventional methods. Hence, a one step simple wet-chemical route was adopted. Confirmation of successful precipitation of K2SiF6 during our process of synthesis was done by using various analysis techniques. Results obtained through XRD, EDAX and SEM measurements are reported and discussed here in brief.
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