Structural and optical properties of GdAlO 3:RE 3+ (RE = Eu or Tb) prepared by the Pechini method for application as X-ray phosphors

Abstract

In this work, GdAlO 3:RE 3+ (RE = Eu or Tb) was successfully prepared by the Pechini method at lower temperatures when compared to others methods as solid-state synthesis and sol–gel process. In accordance to the XRD data, the fully crystalline single-phase GdAlO 3 could be obtained at 900 °C. The differential thermal analysis (DTA) shows a crystallization peak at 850 °C. The samples are composed by monocrystalline particles (50–120 nm) exhibiting the formation of aggregates among them, which indicates the beginning of the sinterization process. This feature indicates a strong tendency to the formation of aggregates, which is a suitable ability for the close-packing of particles, and hence a potential application in X-ray intensifying screens. Luminescence measurements indicate Gd 3+ → RE 3+ energy transfer. The Eu 3+ emission spectra exhibit all the characteristics 5D 0 → 7F j transitions and the observed profile suggests that RE 3+ ions occupy at least one site without center of symmetry. For terbium-doped samples, the 5D 3 → 7F j (blue emission) and 5D 4 → 7F j (green emission) transitions were observed and the ratio between them may depend on the Tb 3+ content due to cross-relaxation processes.