Research on scintillating materials is very active since these materials find various applications in high energy physics, non destructive testing and medical imaging. Due to their outstanding properties (high absorption cross section, high damage threshold, high conversion efficiency) lutetium silicates doped with rare earth ions are very good scintillating materials. In the past few years, we have been developing new strategies to prepare various lutetium oxides by soft chemistry routes and in particular the sol-gel process. Among the many advantages of the sol-gel process, the possibility to prepare these materials as thin films is particularly valuable for medical imaging applications. This paper will focus on rare earth doped (Ce3+, Eu3+) Lu2SiO5 (LSO). LSO crystals are actually used in the detection system of PET scanners. The associated cost is very high and alternative solutions would be welcome. LSO coatings have been considered recently in our group. Thanks to the sol-gel procedure, we have been able to prepare Lu2SiO5 thin films by dip-coating, spin coating and spray pyrolysis. Spin coated films are very interesting since they are very homogeneous and of very good optical quality. Spray pyrolysed films on the other hand exhibit high scintillation under X-ray excitation.
The thin films have been characterized thoroughly. In particular spin coated films have been characterized by X-ray Photoelectron (XPS) and Rutherford Backscattering (RBS) Spectroscopies.
RBS results demonstrated that the composition of the films is very close to the nominal one and allowed to determine the thickness of the film. XPS spectroscopy shows a good correlation between the nominal doping concentration and the experimental one demonstrating the efficient doping of the LSO phase with rare earth ions. Sequential ion etching allowed measuring the profiles of the different elements and showed good homogeneity. Surface carbon contamination is also evidenced and is related to the pyrolysis of alkoxides precursors used in the sol-gel process.
Finally the optical properties of the films have been studied and good scintillation is observed under X-ray excitation.
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