Pressure effects on the luminescence properties of CaWO4:Pr3+

Steady state and time resolved emission measurements of CaWO4 doped with Pr3+ have been carried out as a function of hydrostatic pressure in the 1-315 kbar range. The increase of pressure induces several effects: a progressive red shift of the spectral features and a decrement of the decay times of both P-3(o) and D-1(2) emitting levels, the decrease of the intensity of the P-3(o) emission, that is completely quenched at around 100 kbar, and the increase of the 1D2 emission intensity in the 1-120 kbar range followed by a fast decrease at higher pressures. In addition, a variation in the structure of the emission manifolds has been observed in the 80-100 kbar range as a consequence of the tetragonal to monoclinic phase transition of the host lattice induced by pressure. These effects have been accounted for by means of a model that takes into account the role played by a praseodymium trapped exciton in the excited state dynamics of the investigated material.