Synthesis and Electron Paramagnetic Resonance of Europium(III, II) Metaphosphate

A nanodispersed composite with two luminescence centers including Eu(PO3)3 and Eu(PO3)2 phases and designated as Eu(PO3)3:Eu2+ was synthesized by extraction-pyrolytic method at optimally low temperature and time of pyrolysis of organic precursors. The composite was studied by electron paramagnetic resonance (EPR) at various temperatures. The EPR spectrum of nanodispersed Eu(PO3)3:Eu2+ powder contains three components that differ in the peak-to-peak linewidth and intensity and effective spectroscopic splitting factors. The broad component of the spectrum is the envelope of the set of unresolved hyperfine structure components of single Eu2+ centers averaged over all orientations of the powder particles. The two narrower symmetric and asymmetric components of the spectrum may belong to Eu2+ in clusters with strong dipole–dipole interaction that average the fine and hyperfine structures and to defects in the metaphosphate structure, respectively.