Influence of dopant concentration (Eu/Nd) on the physical and chemical properties of yttrium oxyhydroxide

In this paper we have studied the influence of europium and neodymium concentration, added to a water solution in the salt form, on the properties of yttrium oxyhydroxide, which was synthesized via the sol-gel route, using yttrium nitrate as a precursor. By synchronous thermal analysis it has been found that ions of europium and neodymium interact with yttrium oxyhydroxide in different ways, but in every case the thermoanalytical curves and mass spectra of gaseous thermolysis products (18, 30, 44 mass/charge) become more complicated. It is clear that europium and neodymium affect not only the phase composition and luminescent properties, but also the yttrium oxyhydroxide precipitation. For neodymium, its content in the precipitate is lower than in the initial solution; for europium, a different tendency is characteristic and its amount in the precipitate is greater than in the solution, i. e., it prevents the transfer of polymer particles of yttrium oxyhydroxide into the solid phase. By the method of X-ray phase analysis, the shift of the peaks in the diffraction patterns of relatively undoped yttrium oxyhydroxide by 5…7° has been revealed, which indicates the partial introduction of dopants into the crystalline formations of yttrium oxyhydroxide. The EDX and SEM methods reveal that both dopants are uniformly distributed in the matrix of materials. Neodymium-doped materials form coarse particles, while europium-doped ones form more finely dispersed spherical and lamellar particles (subject to dopant quantity). Materials possess luminescence properties in UV range with maximum at 300 nm and can be applied as luminophores in sunlamps.