Since the crystal-field strength at the Cr3+ site is very close to the excited-state crossover (ESCO), this work investigates the optical properties of Cr3+-doped Gd3Ga5O12 (GGG) nanoparticles as a function of temperature and pressure in order to establish the effect of the ESCO on the optical behaviour of nanocrystalline GGG. Luminescence, time-resolved emission and lifetime measurements have been performed on GGG: 0.5% Cr3+ nanoparticles in the 25-300 K temperature range, as well as under hydrostatic pressure up to 20 GPa. We show how low temperature and high pressure progressively transforms Cr3+ T-4(2) -> (4)A(2) broadband emission into a ruby-like E-2 -> (4)A(2) luminescence. This behaviour together with the lifetime dependence on pressure and temperature are explained on the basis of the spin-orbit interaction between the T-4(2) and E-2 states of Cr3+.
Temperature and pressure dependence of the optical properties of Cr3+-doped Gd3Ga5O12 nanoparticles
BETTINELLI, Marco Giovanni
2011-01-01
Abstract
Since the crystal-field strength at the Cr3+ site is very close to the excited-state crossover (ESCO), this work investigates the optical properties of Cr3+-doped Gd3Ga5O12 (GGG) nanoparticles as a function of temperature and pressure in order to establish the effect of the ESCO on the optical behaviour of nanocrystalline GGG. Luminescence, time-resolved emission and lifetime measurements have been performed on GGG: 0.5% Cr3+ nanoparticles in the 25-300 K temperature range, as well as under hydrostatic pressure up to 20 GPa. We show how low temperature and high pressure progressively transforms Cr3+ T-4(2) -> (4)A(2) broadband emission into a ruby-like E-2 -> (4)A(2) luminescence. This behaviour together with the lifetime dependence on pressure and temperature are explained on the basis of the spin-orbit interaction between the T-4(2) and E-2 states of Cr3+.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
