Effects of Eu:Ag codoping on structural, magnetic and mechanical properties of lead tellurite glass ceramics

Structural, magnetic and mechanical properties of lead tellurite glass ceramics doped with variable amounts of Eu2O3 (0-10 mol%) and codoped with fixed amounts of Ag2O (0.50 mol%) or Ag metallic nanoparticles, AgNPs, (0.33 mol%) have been studied. The investigation of the samples was performed by X-ray diffraction (XRD), EPR spectroscopy, magnetic susceptibility and elastic modulus measurements. XRD investigation shows that the studied samples were glass ceramics. XRD data were used to determine the nature and the quantitative ratio of the crystalline phases present in the samples. EPR spectroscopy was used to obtain information on the presence of europium and silver paramagnetic centers (Eu2 +, Ag0, and Ag2 +). No EPR signals assignable to these paramagnetic centers were registered. Magnetic susceptibility data show that the magnetic behavior of the studied glass ceramics is due to the europium ions present in the host matrix as Eu3 + and Eu2 + ions that show a very important clustering tendency. The fact that the paramagnetic Eu2 + ions are involved in aggregates explains why these ions were not detected by EPR in spite of the fact that Eu2 + ions are present in appreciable amounts. The level of the europium doping and the nature of the silver codopants (Ag2O or AgNPs) influence the structural, magnetic and mechanical behavior of the samples. In general, the structural effect of the codoping with Ag2O (that provides Ag+ ions capable to enter the host matrix) is more important than that of the AgNPs.