Single crystal growth, optical absorption and luminescence properties under VUV-UV synchrotron excitation of type III Pr(3+):KGd(PO3)4.

Scintillator materials are widely used for a variety of applications such as high energy physics, astrophysics and medical imaging. Since the ideal scintillator does not exist, the search for scintillators with suitable properties for each application is of great interest. Here, Pr(3+)-doped KGd(PO3)4 bulk single crystals with monoclinic structure (space group: P21) are grown from high temperature solutions and their structural, thermal and optical properties are studied as possible candidates for scintillation material. The change in the unit cell parameters as a function of the Pr(3+) level of doping and temperature is studied. Differential thermal analysis reveals that KGd0.942Pr0.058(PO3)4 is stable until 1140 K. The 5d3, 5d2 and 5d1 levels of Pr(3+) with respect to the (3)H4 ground state are centred at 166, 196 and 218 nm, respectively, in this host. The luminescence of KGd0.990Pr0.010(PO3)4, by exciting these 5d levels, shows intense emissions centred at 256 and 265 nm from the 5d1 to (3)F3,4 and (1)G4 levels of Pr(3+) with a short decay time of 6 ns. The (6)P3/2,5/2,7/2 --> (8)S7/2 transitions of Gd(3+) appear after exciting the 5d levels of Pr(3+) and the 4 f levels of Gd(3+), showing an energy transfer between Pr(3+) and Gd(3+).