| Abstract [eng] |
Aerogels are attracting increasing attention from scientists due to their structure. The pores give aerogels unique properties – low density, large surface area, low thermal conductivity. Due to these properties aerogels are applicable in many fields, for example, in aeronautics, pharmacy or agriculture. Gadolinium phosphate aerogels are receiving much attention in medicine, because they are stable, non-toxic, have magnetic properties. Recently, there have been an attempts to combine the magnetic properties of gadolinium with the optical properties of other lanthanides, which is why gadolinium phosphate is doped with optically active lanthanides. In this work, europium and terbium doped gadolinium phosphate aerogels were synthesized via hydrothermal method. Initially, the optimal molar ratio of reagents was selected – <Gd>:<P> = 1:1.2, since long nanowires are required for aerogel synthesis. Later, the optimal gel volume – 10 ml and the heating temperature (915 oC) were determined. Initially, europium and terbium were introduced separately, and later together, keeping constant the concentration of one of these lanthanides. By increasing the concentration of Eu3+ and Tb3+ in the aerogel, it was found that the intensity of the luminescence peaks increased up to a certain concentration. With large amounts of Eu3+ and Tb3+, non-radiative relaxation begins to occur, during which energy is not emitted in the form of light. This is shown by the increasing efficiency of energy transfer, which increases with increasing amount of introduced lanthanide ions. Non-radiative relaxation leads to weaker emission of aerogels, faster decay time and lower quantum efficiency. |
